eChapters

Introduction

The resource conservation technologies (RCTs) is primarily focussed on resource savings through minimal tillage, ensuring soil nutrients and moisture conservation through crop residues and growth of cover crops, and adoption of spatial and temporal crop sequencing. These practices have long been practised by the farmers in the Indo Gangetic Plains (IGP) but it got eroded in recent times due to various geo-socio economic- political reasons. This region (10.5 million ha) comprises of Punjab, Haryana, Uttar Pradesh, Himachal Pradesh, Bihar and West Bengal and have major share in production of rice and wheat due to adoption of green revolution technologies followed by area expansion. It has been reported that rice-wheat system has strained the natural resources of this region (Swarup and Singh, 1989; Kumar and Yadav, 1993; Lal et al., 2004). In present scenario there is little scope to meet future target by earlier approaches like area expansion and intensive use of natural resources. Therefore, RCTs can be regarded as energy, water and labour efficient system to sustain soil health and production environment and produce more at less cost (Jat et al., 2012; Gathala et al., 2011b).

Major emphasis is given upon the RCTs components like zero/reduced tillage, direct seeded rice, crop residue management and crop diversification. However, other RCTs like site specific nutrient management, leaf colour chart, laser land leveller, nutrient use efficient genotypes, integrated crop and pest management provide options to the farmers as per their resource endowment.

Introduction

Persistent income from agriculture is most important for sustaining the farming sector. Conservation agriculture (CA) is a resource-saving agricultural production system that aims to achieve production intensification and high yields while enhancing the natural resource base through compliance with three interrelated principles, along with other good production practices of plant nutrition and pest management (Abrol and Sangar, 2006). Conservation agriculture is largely promoted as one of the few win–win technologies affordable to farmers, in the sense that potentially it improves farmers’ yields (in the long term) at the same time conserving the environment. CA is described by FAO (http://www.fao.org.ag/ca) as a concept for resource saving agricultural crop production which is based on enhancing the natural and biological processes above and below the ground. As per FAO definition CA is to a.) Achieve acceptable profits, b.) High and sustained production levels, and c.) Conserve the environment. It aims at reversing the process of degradation inherent to the conventional agricultural practices like intensive agriculture, burning/removal of crop residues. Shifting from tillage-based agriculture to no-tillage CA systems removes unsustainable elements in the current tillage based systems and replaces them with CA elements that make the production systems profitable and ecologically sustainable. Conservation agriculture offers an opportunity for arresting and reversing the downward spiral of resource degradation, decreasing cultivation costs and making agriculture more resource – use-efficient, competitive and sustainable.

Introduction

Precise and continuous measurement the greenhouse gases (GHGs) fluxes/ emissions in agricultural systems are required for accounting and budgeting of carbon. Further, the long-term measurements of GHGs fluxes are equally important as precise measurement. Therefore, high frequency and long-term measurement of GHGs across the cropping systems are essential for chalking out the GHGs emissions mitigation strategies. Various technologies with definite working principles are used for estimation of GHGs emissions in agriculture.

Greenhouse Gases Estimation Techniques

Two basic principles are followed to estimate greenhouse gases in agriculture. One is the collection of GHGs from the field and subsequent analysis of the concentration of gases through gas chromatography (GC). Another principle is based on sensors measurement with the help of infrared gas analyze (IRGA). The two techniques used for the measurement are (i) ‘closed chamber method’ (manual/automatic), and (ii) ‘sensor-based method’. Generally, the GHGs fluxes in agricultural crop field are estimated by ‘closed chamber method’ for methane (CH₄) and nitrous oxide (N₂O). And for carbon dioxide (CO₂) measurement either soil respiratory chamber or canopy chamber is used that measures CO₂ with the help of infrared gas analyzer (IRGA).

Introduction

Intensive soil tillage, burning of crop residues and over use of fertilizer and irrigation water under current agricultural practices has accelerated the pace of degradation in Indian agriculture. Intensive soil tillage increases soil erosion and nutrient runoff into nearby waterways. Crop residue burning resulting in loss of plant nutrients and release of greenhouse gases (GHGs) in the atmosphere. Imbalanced use of chemical fertilizer leads to soil compaction, slows down the fertilizer utilization rate and contaminates the local environment. Increasing demand of irrigation water causes water shortage and harms the environment in several ways including increased salinity, nutrient pollution, and the degradation of flood plains and wetlands. In the face of these management and environmental challenges, there is a need to formulate such agricultural practices which improve the productivity of natural resources as well as of external inputs and help to prevent soil degradation. Conservation agriculture (CA) practices such as reduced tillage, residue retention and proper crop rotations offer such solutions. CA also helps in making agricultural systems more resilient to climate change and safeguard ecosystem services.

Introduction

Conservation of biodiversity and mitigation of global warming are two major environmental challenges today. In the context of climate change and the global carbon cycle, the relationship between plant biodiversity and soil organic carbon (SOC) sequestration has become a subject of considerable scientific interest. The Earth’s terrestrial vegetation plays a pivotal role in the global carbon cycle. Not only are tremendous amounts of carbon stored in the terrestrial vegetation, but large amounts are also actively exchanged between vegetation and the atmosphere. Anthropogenic perturbations exacerbate the emission of CO₂ from soil caused by decomposition of soil organic matter (SOM) or soil respiration (Schlesinger, 2000). The emissions are accentuated by agricultural activities including tropical deforestation and biomass burning, plowing, drainage of wetlands and low-input farming or shifting cultivation. In addition to its impact on decomposition of SOM, macroclimate has a large impact on a fraction of the SOC pool which is active. Conversion of natural to agricultural ecosystems increases maximum soil temperature and decreases soil moisture storage in the root zone, especially in drained agricultural soils (Lal, 1996). Thus, land use history has a strong impact on the SOC pool (Pulleman et al., 2000). The dynamic relationship between plant biodiversity and SOC depicts that any land use practices that increase vegetative cover, or reduce its removal, could have an influence on the global carbon budget by increasing the terrestrial carbon sink.

Introduction

The inevitability of detrimental effects of climate change is looming large not only on the sustenance of agriculture, but also on the survival and progress of mankind. Estimates by the Organization for Economic Cooperation and Development (OECD) reveal that the atmospheric concentration of GHG would exceed 680 parts per million (ppm) CO₂-equivalents by 2050, which is about 50% higher than baseline year 2010 (OECD, 2012). Additionally, global temperature is predicted to increase by 2°C within this period, resulting in meansea level rise and erraticweather conditions. Consequently, the catastrophic effects on food consumption pattern by the end of 2050 will create malnutrition in at least 290 million people. Agricultural crops provide 63% of the human protein, and additionally supply almost 100% protein to the livestock, which are the second major sources of protein in human diet. Altogether, the detrimental effect of climate change on agriculture would make about 300 million additional people malnourished. Add to that a 2.7 billion increase in human population by 2050, coupled with shortage of water availability that would affect 3.9 billion people by 2050, and one can easily perceive the grim scenario for our kind in not so distant future.

Introduction

The basic needs of life are food, clothing and shelter. In the 21^st century a fourth need added to mankind is energy. According to the laws of physics, energy is defined as capacity to do work. Energy, economics and the environment are mutually dependent. Also, there is very close relationship between agriculture and energy. The level and pattern of energy use in agricultural production system depends on variety of agronomic and socio-economic factors. Energy use in agriculture encouraged maximization of yields from limited available arable land, minimization of labour intensive operations and improving standard of living. Efficient and effective energy use in agriculture is one of the conditions for sustainable agricultural production, since it provides financial savings.

Introduction

India agriculture is now at turning point as we have travelled a long way after the advent of green revolution. Over the past four to five decades our strategies, policies and actions were guided by goals of ‘self-sufficiency’ in foodgrains production via green revolution. Indian agriculture has been successful in achieving increased food grains production albeit at a low level of satisfaction. While the mission of increasing foodgrains production stands somehow achieved, these gains were accompanied by widespread problems of resource degradation and high factor productivity, which now pose a serious challenge to the continued ability to meet the demand of an increasing population and lifting our people above the poverty line (Tan et al., 2010). Indian agriculture has reached a point where it must seek new directions – those by way of strategies, policies and actions which must be adopted to move forward addressing sustainable intensifications. The past strategies to increase food grains production, however, have resulted in massive exploitation of natural resources, contributing to unsustainable growth; there is need to change this approach in the future. This will call for strategies, which are different than the ones we adopted in the ‘green revolution’ era. High levels of fertilizer use and decreasing resource use-efficiency are increasingly contributing to groundwater pollution and increased emissions of green-house gases (GHGs) (Gupta, 2004). High level uses of pesticides in many areas have become a major health hazard. Thus, with continuously deteriorating resources, widespread problem of soil and water contamination and eroding ecological foundation, sustainability of agriculture is becoming highly questionable (Conway and Barbier, 1990). There is need to seriously debate on the strategies required to ensure that agriculture continues to play a critical role in the overall development.

Introduction

Conservation tillage is a model of sustainable agriculture as it leads to profitable food production while protecting and even restoring natural resources. Conservation agriculture benefits farmers because it reduces production costs and increases yields, but it also has positive impacts on the whole society: enhancement of food security thanks to a better soil fertility, improvement of water quality, reduction of erosion and mitigation of climate change by increasing carbon sequestration. Conservation agriculture (CA) systems are also less sensitive to extreme climatic events and therefore contribute to the adaption of climate change and the resilience of agricultural systems. Hence, CA becomes a fundamental element of sustainable production intensification, combining high production with the provision of environmental security.

CA is based on healthy functioning of the whole agro-ecosystem with a maximum attention and focus on the soil. The soil is the entry point and it has to be considered not only as simple physical support to roots and plants, but as a living entity with its physical, chemical and biological characteristics. The focus of CA embraces not only the nutrient contents of the soil but also its biological and structural status, which are determinants of sustained productivity.

The paradigm of CA is that an undisturbed soil has the opportunity to develop and produce healthier plants. Soil life can develop in a stable habitat in quantity and quality better than on tilled soils, the structural integrity of soil is maintained, so continuous vertical macro-pores are not destroyed and remain as drainage channels for rainwater into the soils. Seeding under conditions of minimum soil disturbance is achieved by direct seeding through the mulch cover without tillage.

Introduction

The main aim of conservation agriculture is to sustain and improve the crop productivity and to provide protection against biotic and abiotic stress, while at the same time protecting and enhancing the biological activities of the soil. The essential principles of conservation agriculture are no-tillage (and direct seeding) or reduced tillage, the maintenance of a cover of live or dead vegetative mulch on the soil surface and the wise use of crop rotations. The crop sequences are planned in such a way that which will discourage the buildup of pests or diseases and will help to optimize plant nutrient use by synergy between different crops of the rotation. While deciding the crop rotation, the locally important crops should be considered and there should be deep rooted and shallow rooted crops in the sequence so that the utilization of soil nutrients is maximized. At least one leguminous crop should be there in the crop sequence. The use of plant residues influences the soil physical, chemical and biological properties by reducing surface temperature, rate of evaporation and maintaining water content, nutrient load and rate of organic matter decay. The soils under conservation agriculture are happened to be highly active and diverse biologically and can supply plant nutrients for a longer period of time because of their higher nutrient loading capacities.

Soil biodiversity comprises of all organisms whether single-cell organisms or multi-cell animals or plants that live in the soil. Soil microbial diversity includes “genetic diversity, that is the amount and distribution of genetic information within microbial species, diversity of bacterial and fungal species in microbial communities, and ecological diversity, that is variation in community structure, complexity of interactions, number of trophic levels and number of guilds (Nannipieri et al., 2003).

Introduction

There is a widespread degradation of natural resource, e.g., soil erosion, nutrient loss, water-logging, salinity, alkalinity, acidity, decline in soil organic carbon (SOC) content, ground water depletion and micronutrient depletion. The major causes are washing away of topsoil and organic matter due to water erosion, intensive deep tillage and inversion tillage, dismally low levels of fertilizer application, mining and other commercial activities, faulty agricultural practices, no or low use of organics, indiscriminate use of herbicides, pesticides, fungicides etc. Other cause is loss of organic matter with higher temperatures, which increase rate of microbial decomposition of organic matter due to adverse effect of climate change. Climate change due to global warming as a result of increased concentration of GHGs in the atmosphere is a well-established fact. Impacts of climate change are experienced throughout the world. Increases in global mean temperature, rise in sea-level, and occurrence of extreme events are the consequences of climate change. These changes may deplete the SOC pool and soil structural stability, increase soil’s susceptibility to water runoff and erosion, disrupt cycles of water, carbon, nitrogen, phosphorus, sulphur and other elements, and cause adverse impacts on biomass productivity, biodiversity and the environment. Climate change is likely to have a variety of impacts on soil quality. In order to restore soil quality, enhance productivity, it is of utmost importance to focus on conservation agriculture practices on long-term basis. Conservation Agriculture (CA) is gaining importance as an alternative to conventional agriculture.

Introduction

Increase in population in our country with decrease in cultivable land is putting the challenges to the scientists and policy planners for increased food supply. There is very little scope for horizontal increase in cultivable land. Hence, the way to meet the need for providing food to ever increasing population is to increase the production of food per unit area of cultivable land.

Farmers, generally apply fertilizer to soil on blanket recommendation. Sometimes, the addition of nutrients is inconsistent. Sometimes, the application of fertilizer is much higher than the recommended dose. Imbalanced application of fertilizer to soil results in low nutrient use efficiency and low crop yield. There is need of site specific nutrient management for increased crop yield and for achieving higher nutrient use efficiency. Proper care should be taken for selection of fertilizer, method of application of fertilizer, rate of fertilizer application and also time of nutrient supply to the soil. Excess application of fertilizer has an adverse effect on soil health.

Traditional tillage may affect physico-chemical as well as biological properties of soil. Change in tillage practice from conventional tillage to conservation agriculture method may have an impact on soil properties and nutrient dynamics. Conservation agriculture affects soil health, proper fertilizer application, both rate and time, along with efficient use of soil moisture improves nutrient use efficiency. For obtaining a good crop yield nutrient should be available for plants in adequate quantity and in right proportion. Nutrients removed by the crop should be replenished by application of inorganic fertilizers alongwith incorporation of organic manures. Soil test is an important tool for determining the quantity of nutrients available in the soil. Based on soil test values and nutrient requirement of the crop rate of fertilizer to be applied in the soil for the plant is determined. Ample quantity of farm yard manure is not available nowadays. Hence, other organic manure such as town waste, green manure etc should be used.

Introduction

The green revolution is exemplified by too much adoption of high soil disturbance, modern varieties, energy exhaustive technologies, high amount of capital investment and simplification of farming systems (Meeus, 1993), resulting in uniform and featureless landscapes (Nassauer and Westmacott, 1987) in the most intensively farmed arable areas. In post-green revolution epoch, we had experienced a period of remarkable escalation in food productivity, despite rising land values and increasing land scarcity. Farmers from both developing and developed countries get exposed to several production constraints for achieving a sustainable, cost-effective and assured return from their field. Depending upon the circumstances and the scale of farm activities, farmers face varying degrees of climate risk, biotic invasion, and economic uncertainty. Thus, from the context of economical ambiguities, volatile food prices, social pressure to buffer ups and downs of agricultural production and achieving food security for ever growing population and curtailing poverty, farmers must be equipped with novel cultural practices to achieve a sustainable and assured cost-effective grain production. Research experiments throughout the globe found that the principal indicators for unsustainability of agricultural systems are: (1) intensive tillage induced decrement of soil organic matter (OM), structural degradation of soil, accelerated water and wind erosion, reduced water infiltration rates, surface sealing and crusting, soil compaction, (2) insufficient return of organic materials into soil, and (3) monocropping.

Introduction

Since the dawn of the civilization when mankind started agriculture, soil erosion has been the single largest environmental problem and has remained so till date (Sullivan, 2004). This is so because removal of the topsoil by any means has, through research and historical evidence, been severally shown to have many deleterious effects on the productive capacity of the soil as well as on ecological wellbeing. Doran and Parkin (1994) captioned the impact of soil erosion in their popular maxim that “the thin layer of soil covering the earth’s surface represents the difference between survival and extinction for most terrestrial life”. Soil degradation implies decline in its capacity to provide ecosystem services (ESs) of interest to humans and useful to nature’s functions. Principal processes of soil degradation are erosion, salinization, nutrient and carbon (C) depletion, drought, decline in soil structure, and tilth. Examples of ESs provided by soil include ecological/supporting (biomass production, nutrient cycling), regulating (water purification and flow, C sequestration, temperature fluctuations), provisional (food, fiber, fuel, and forages), and cultural (aesthetical, spiritual, and cultural). Erosion-induced degradation diminishes soil’s capacity to provide ESs, and support ecosystem functions.

Although fertile top soils could be lost when scraped by heavy machineries (Ngwu et al., 2005), the key avenues of topsoil loss include water erosion and wind erosion. Sometimes erosion can be such gradual for so long a time as to elude detection in one’s lifetime, thus making its adverse effects hard to detect. Eswaran et al., (2001) propose an annual loss of 75 billion tons of soil on a global basis which costs the world about US $400 billion per year. A review of the global agronomic impact of soil erosion identifies two severity groups of continents and reveals that Africa belongs to the more vulnerable group (Biggelaar et al., 2004). Soil erosion by water seems to be the greatest factor limiting soil productivity and impeding agricultural enterprise in the entire humid tropical region. This is evident in many regions of Africa (Dregne, 1990), mainly in the humid and subhumid zones of Sub-Saharan Africa (SSA) where population pressure and deforestation exacerbate the situation and the rains come as torrential downpours, with the annual soil loss put at over 50 t ha⁻¹ (FAO, 1995).

Introduction

The 21st Century agriculture needs knowledge integration and maximum input efficiency. Crop simulation models offer possibilities to evaluate and target agricultural information towards sustainability (Elliott et al., 2015; Van Oort and Zwart, 2018). All the modern day’s crop growth models not only predict the growth and yield, but also they are strong Decision Support System (DSS). Due to the impact of climate change, land degradation and biodiversity loss, the agricultural production system becomes the most vulnerable one (Araya et al., 2017). Crop intensification is inevitable to meet the ever-increasing food demand for the billions of populations. It leads to deterioration of soil physical health, reduction of the organic carbon percentage and micro-environmental pollution. Conservation agriculture (CA) has a great potentiality to enhance the inherent resilience against all sorts of degradation and possess the potentiality to regenerate the degraded lands (Haggblade and Tembo, 2003). CA is a farming system that maintains a permanent soil cover to assure its protection, avoids soil tillage, and cultivates a diverse range of plant-species to improve soil conditions, reduce land degradation and increase water and nutrient use efficiency (Friedrich et al., 2012; Sapkota et al., 2015; Bell et al., 2019; Steward et al., 2019). For last few decades, climate change becomes a serious threat to agriculture in context to influence crop and livestock production, hydrological balances, input supplies and other components of agricultural system (Kabir, 2015; Kumar and Kumar, 2016). Agriculture is inherently sensitive to climatic conditions and conservation agriculture may be the only answer to combat the negative impact of climate change.

Introduction

The resource conservation technologies (RCTs) primarily focus on resource-savings management systems for agricultural production through minimal tillage operation, maintaining soil health for available plant nutrients and conserving soil moisture through crop residues and/or cover crops, and following cropping sequence in spatial and temporal scale. The integration of resource-conserving technologies working in synergy is commonly referred to as conservation agriculture (CA). The CA is “a concept for resource-saving agricultural crop production that strives to achieve acceptable profits together with high and sustained production levels while concurrently conserving the environment” (FAO 2007). The CA envisages four principles: (i) minimizing mechanical soil disturbance and seeding directly into untilled soil, (ii) maximizing crop residue retention and/or growing cover crops, (iii) optimizing diversification of cropping sequences and rotations, and (iv) minimizing mechanical soil compaction through controlled traffic. The CA technologies involving no- or minimum-tillage with direct seeding and bed planting, residue management and crop diversification have potential for improving productivity and soil quality, mainly by soil organic matter build-up. Conservation agriculture systems appear to be appealing options to achieve sustainable and intensive crop production under different agroecological environments because they use available resources efficiently and maintain soil fertility. However, there is a need for wider scale testing of these new technologies under diverse production systems, as the CA technologies are site specific and therefore appraisal of CA is important to have significant adoption (Ramesh et al., 2016)

Introduction

Attaining food and nutritional security for a growing population and reducing poverty while sustaining agricultural production under the current scenario of depleting natural resources, increasing cost of inputs and impending negative impacts of climatic change are the major challenges the country is currently facing (FAO, 2009). In addition to these challenges, decline in soil organic matter, consequent deterioration of soil health, large scale erosion of fertile top-soil are the other bottle-necks for increasing agricultural productivity from a finite land resource base. These constraints are evolving mainly due to: (1) intensive tillage induced soil organic matter decline, soil structural degradation, water and wind erosion, reduced water infiltration, surface sealing and crusting, soil compaction, (2) insufficient return of organic material to soil owing to prevalent crop residue removal and burning (Prasad et al., 1999) and (3) mono-cropping. Conservation agricultural (CA) is a panacea to address these challenges the farming community of this country is presently facing. The CA system incorporates a holistic approach to agriculture that results in improved soil health and water quality, lower water and nutrient consumption, reduced soil loss, strategic land use and healthy biodiversity. It involves minimum soil disturbance, permanent soil cover through crop residues or cover crops, and crop rotations for achieving higher productivity (Hobbs et al., 2008).

Introduction

Environmental friendly Insect Pest Management (IPM) relies on preventive rather than reactive strategies. The cropping program should focus primarily on preventive practices above and below ground such as crop management and soil management to build the farm’s natural defenses. Reactive management viz., reactive inputs for pest management and reactive inputs to reduce plant stress are reserved for problems not solved by the preventive or planned strategiesfor supplemental pest management practices and planned supplemental soil practices to reduce crop stress and/or optimize yield and crop quality. Earlier IPM models are designed from the scientific perspective with a focus on ecological, environmental friendly and evolutionary aspects of pest management to reduce or prevent economic losses.There are four major components in the new environmentally pest management model that address various pest management options, the knowledge, and resources the grower has to address the pest issue, planning and organization of information to take appropriate management actions, and maintaining good communication to acquire and disseminate knowledge about pests and their management. These models mainly address the human, environmental, social and economic factors that influence food production.

Introduction

Organic farming is basically a holistic management system, which promotes and improves the health of the agro-ecosystem related to biodiversity, nutrient biocycles, soil microbial and biochemical activities. Organic and bio-dynamic farming emphasises management practices involving substantial use of organic manures, green manuring, organic pest management pratices and so on. It has also come to mean that it is a system of farming that prohibits the use of artificial fertilisers and synthetic pesticides.

Biodynamic agriculture is an advanced form of organic farming system that is gaining increasing attention because of its added advantage of soil health and food quality. It is an alternative variant where the chemical fertilisers are totally replaced by microbial (biological) nutrient givers such as bacteria, algae, fungi, mycorhiza, actinomycetes. Biological Pest management of crops is undertaken by employing predators, parasites and other plethora of natural enemies of pests, in addition to all the rest of option that help to avoid resorting to chemical pesticides. These agents could be augmented into farms or promoted through such activities that favour their flourished activities. Composting, Green manuring, crop rotations. Intercropping, mixed cropping etc. as well as bird perches, trap crops promote such biological activities.

Introduction

Modern intensive agriculture systems based on the principles of yield maximization have been plagued with multiple constraints such as declining factor productivity, decreasing resource use efficiency (fertilizers, water, labour etc.), soil organic matter decline, salinization, soil structure degradation, water and wind erosion, reduced water infiltration rates, soil compaction due to surface sealing and crusting, declining ground water table, pest and disease outbreak, weed resistance and weed shifts (Paustian et al., 2016). To address these overwhelming issue, conservation agriculture (CA) has been defined by FAO as a concept of resource saving agricultural crop production which is based on enriching the natural and biological processes above and below ground. The major purpose for its advancement is to reduce the production cost, save resources, enhance yields and utilize resources like nutrient and water efficiently. Conservation tillage denotes soil management system that follows the principle of at least 30% of the soil surface coverage with crop residues after seeding of the crop (Jarecki and Lal, 2003). CA, a resource-efficient agriculture helps to conserve, improve and utilize natural resources efficiently through integrated management of available soil, water and biological resourwces combined with external inputs and thus contributes to environmental conservation as well as enhanced and sustained agricultural production in the long term. The practice and wider extension of conservation agriculture thus requires a deeper understanding of its ecological underpinnings for managing its various elements for sustainable intensification.

Introduction

Natural resources, especially those of soil, water, plant and animal diversity, vegetation cover, renewable energy resources, climate, and ecosystem services are fundamental for the structure and function of agricultural systems and for social and environmental sustainability, in support of life on earth. Historically the path of global agricultural development has been narrowly focused on increased productivity rather than on a more holistic integration of natural resource management with food and nutritional security. A holistic, or system-oriented approach, is preferable because it can address the issues associated with the complexity of food and other production systems in different ecologies, locations and cultures. Modern agriculture largely depends on the use of fossil fuel-based inputs, such as chemical fertilizers, pesticides, herbicides and energy intensive farm machinery. While the applications of such high input technologies have undoubtedly increased production and labour efficiency. There is a growing concern over their adverse effect on soil productivity and environmental quality which is emerging to recognize that the farmer has a great social responsibility as a land owner than merely agribusiness considerations. Therefore, there is need to develop agricultural techniques that are ecologically sound, economically viable, and socially responsible. Sustainable agriculture in the context of development helps to achieve production efficiency, protect ecosystem functions, enhance resilience to climate change, ensure healthy communities, satisfies basic needs and ensures optimum use/conservation of natural resources. Organic/biodynamic farming is among the various types of sustainable agriculture. Traditionally these methods has been playing very vital role in the conservation of natural resources in terms of soil health sustenance, environmental protection, food safety, waste recycling, biodiversity conservation with an economically viable approach. The chapter discusses the role of organic/biodynamic agriculture in natural resource conservation.

Introduction

Generally speaking, Conservation Agriculture (CA) includes minimum soil disturbance, permanent soil cover, and crop rotation (Hobbs, 2007). CA has been recognized as an efficient way for sustainably increasing crop yields in different countries (Hobbs et al., 2008; Pittelkow et al., 2015). Farmers following CA will face several managerial problems, and weed management is the most challenging (Wall, 2007; Giller et al., 2009; Farooq et al., 2011). Weed growth in an agroecological system and crop yields are inversely related; so, knowledge on weed dynamics and weed management are vital for achieving the possible yield gains in CA systems. There are few studies that examined both the direct and interactive effects of the 3 basic CA principles on weed dynamics (Chauhan et al., 2012; Giller et al., 2009; Farooq et al., 2011).

For comprehensive understanding the current topic, a diagrammatic representation of an annual weed’s life cycle (Fig. 1) will be useful and the same corresponds to four likely areas managing the weeds:

Introduction

Resource Conserving Technology refers to any management approach or technology that increases factor productivity including land, labour, capital and inputs. The resource conserving technologies (RCTs) involving no or minimum tillage, direct seeding, bed planting and crop diversification with innovations in residues management are the possible alternatives to the conventional energy and input-intensive agriculture. The RCTs with innovations in residue management avoid straw burning, improve soil organic C, enhance input efficiency and have the potential to reduce GHGs emissions (Pathak et al., 2011). Conservation agriculture is one the effective Resource Conservation Technologies, which is based on three principles which are minimum soil disturbance, maintenance of permanent soil covers by the use of crop residues and cover crops and diverse plant associations which included crop rotations. Globally, Conservation Agriculture is being practiced in about 125 M ha area. USA with 26.5 M ha contributes to the major CA-practicing countries followed by Brazil (25.5 M ha), Argentina (25.5 M ha), Canada (13.5 M ha) and Australia (17.0 M ha). However, in the context of climate change to increase the production and productivity, India’s CA adoption is still in preliminary phases in area of 1.5 million ha with adoption of Zero Tillage (Jat et al., 2012, www.fao.org/ag/ca/6c.html). The major CA-based technologies being adopted is zero-tillage (ZT) wheat in the rice-wheat system of Indo-Gangetic Plains.

Introduction

Conservation Agriculture (CA) is a set of soil management practices that minimize the disruption of the soil’s structure, composition and natural biodiversity. These include: i) maintenance of permanent or semi-permanent soil cover (using either a previous crop residue or specifically growing a cover crop for this purpose); ii) minimum soil disturbance through tillage (just enough to get the seed into the ground); iii) regular crop rotations to help combat the various biotic constraints. CA also uses or promotes where possible or needed various management practices listed below: i) utilization of green manures/ cover crops (GMCC’s) to produce the residue cover; ii) no burning of crop residues; iii) integrated disease and pest management; iv) controlled/limited human and mechanical traffic over agricultural soils. When these CA practices are used by farmers one of the major environmental benefits is reduction in fossil fuel use and greenhouse gas (GHG) emissions.

In India, efforts to develop, refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA. Particularly, tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains. The technologies of CA provide opportunities to reduce the cost of production, save water and nutrients, increase yields, increase crop diversification, improve efficient use of resources, and benefit the environment. However, there are still constraints for promotion of CA technologies, such as lack of appropriate seeders especially for small and medium scale farmers, competition of crop residues between CA use and livestock feeding, burning of crop residues, availability of skilled and scientific manpower and overcoming the bias or mindset about tillage. The need to develop the policy frame and strategies is urgent to promote CA in the region. (Bhan and Behera, 2014).

Introduction

Climate change refers to change of weather variables over a long period of time. The Inter-Governmental Panel on Climate Change (IPCC) defined climate change as a “change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer”. This may occur due to natural variability or as a result of human activity. The change may be in the form of magnitude or variability of a single or multiple weather variables or weather phenomena. Global shift in temperature and precipitation pattern as well as increasing frequency of extreme weather events are consequence of climate change which is perceived over several decades. Climate change is indeed increasingly recognized as a considerable risk to agriculture particularly with respect to direct impact on crop production and yield stability (Barzman, 2015).

Effect of Climate Change in Global Warming and Greenhouse Gases

Global warming as the resultant of climate change has become an issue of serious concern worldwide for existence of life on the earth. Over past hundred years, the global temperature has increased by 0.8⁰C and is expected to reach 1.1-5.4⁰C by the end of next century. Major factors affecting the global warming and the climate change is the concentration of greenhouse gases like carbon dioxide, methane and nitrous oxide. On the other hand, CO₂ concentration in the atmosphere has increased drastically from 280 ppm to 370 ppm and is likely to be doubled in 2100 (IPCC, 2007).

Introduction

The Indo-Gangetic Plain is one of the world’s major foodgrain producing regions. The Indian states falling under this region, viz. Punjab, Haryana, Uttar Pradesh, Himachal Pradesh, Bihar and West Bengal, are also the major rice-wheat growing states spread over 10.5 million hectares in the country. During the past 30 years, agricultural production growth in this region has been able to keep pace with population demand for food in the country mainly due to adoption of green revolution technologies inducing yield growth, followed by area expansion. But this opportunity is ceasing very fast due to limited scope for increasing the availability of arable land and natural resources. The other issue is the conservation of the basic resources of land and water for sustainability of agriculture in the Indo-Gangetic Plain. It is generally believed that the rice-wheat system has strained the natural resources in this region and more inputs are required to attain the same yield levels (Swarup and Singh, 1989; Kumar and Yadav, 1993; Lal et al., 2004). It is, therefore, imperative now to promote alternative technologies that would help conserve the much needed but gradually depleting natural resources while boosting productivity growth in the long-run by maintaining soil health and production environment. As a part of this strategy, conservation agriculture and resource conserving technologies play a major role in sustaining and enhancing the productivity of the rice-wheat system at a lower cost of production.

Introduction

The Indian agriculture is very complex and carrying out multi-functionalities of providing food, nutrition and ecological security besides employment and livelihood for over 700 million people. Indeed, India has made a marvelous achievement in attaining self-sufficiency in food grain production after the induction of Green Revolution which eventually resulted in maintaining all-time high buffer stock in warehouses of our country. Such rosy picture in production trends turned to be bleak in the past few years. There are various reasons behind this. Shrinking resources of prime lands, deforestation and accelerated erosion, deterioration of soil physical environment, increasing waterlogging and salinity in canal irrigated areas, declining water table in well-irrigated areas, poor management of rainwater, lower efficiency of inputs such as water, fertilizers and agrochemicals, rapid industrialization coupled with pollution and environmental degradation and hazards have aggravated the problem. At the same time, increase in atmospheric concentrations of greenhouse gasses (GHG), of which the most common is carbon dioxide (CO₂), is the primary cause of global warming and the Intergovernmental Panel on Climate change (IPCC) estimates that the current greenhouse gases (GHGs) concentrations are 30% more than the pre-industrial level. C is accumulating in the atmosphere at a rate of 3.5 Pg (Pg = 1015 g or billion tons) per annum, the largest proportion of which resulting from the burning of fossil fuels and the conversion of tropical forests to agricultural production. Under such circumstance, there is an imperative need to produce more from less arable land and water through meticulous management of basic agricultural resources such as soil, water and biological inputs.

Introduction

Persistent use of conventional farming practices based on extensive tillage, especially when combined with removal or in-situ burning of crop residues, has magnified soil erosion losses and swiftly degraded soil resource base. One of the glaring examples for the aforementioned statement is the ‘Dust Bowl’ in the U.S during 1930s in Great plains, where 91 M ha of land was degraded by severe soil erosion (Hobbs, 2007).

One of the primary challenges of our time is to feed growing and more demanding world population with reduced external inputs and minimal environmental impacts (nature paper). Conservation Agriculture (CA) is a set of management practices for sustainable agricultural production without excessively disturbing the soils, while protecting it from the processes of soil degradation like erosion, compaction, aggregate breakdown, loss of organic matter, leaching of nutrients, and processes that are accentuating due to anthropogenic interactions in the presence of extremes of weather and management practices. The organic materials conserved through this practice are decomposed slowly, and much of materials are incorporated into the surface soil layer, thus reducing the liberation rate of carbon as CO₂ into the atmosphere. In the total balance, carbon is sequestered in the soil, and turns the soil into a net sink of carbon. So, CA enhance soil health by improving soil aggregation, reducing compaction through promotion of biological tillage, increasing surface soil organic matter and carbon content, and moderating soil temperature and weed suppression. CA reduces cost of cultivation, saves time, increases yield through timelier seeding/planting, reduces pest and diseases through stimulation of biological diversity, and reduces green house gas emissions.

Machinery development, refinement and adoption for a range of soil and cropping situations will be fundamental in any success to promote conservation agriculture practices. Agricultural machinery or tools, which support conservation agriculture generally refer to the cultivation systems with minimum or zero tillage and in-situ management of crop residues. Minimum tillage is aimed at reducing tillage to the minimum necessary that would facilitate favorable seedbed condition for satisfactory establishment of crop. Zero tillage is however an extreme form of minimum tillage. With the development of direct drilling machines, almost all research work was attempted to define the responses of direct-drilled seeds in relation to soil micro-environments. Different designs of direct drilling machines viz. zero till drill, no till plant drill, strip till drill, and rotary slit no till drill have been developed with controlled traffic measures for energy efficient and cost-effective seeding of crops without tillage. In this paper various issues, challenges and prospects of conservation agriculture in India has been discussed.

Introduction

Climate change is a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures. Eleven years from 1995-2006 rank among the twelve warmest years in the instrumental record of global surface temperature (since 1850). The 100-year linear trend (1906-2005) of 0.74 [0.56 to 0.92] °C is larger than the corresponding trend of 0.6 [0.4 to 0.8] °C (1901-2000) and over the 21st century average temperature of earth surface is likely to go up by an additional of 1.8-4°C (IPCC, 2007). This temperature increase can be attributed to the altered energy balance of the climate system resulting from changes in atmospheric concentrations of the green house gases (GHGs). Among the principal components of radiative forcing of climate change, CO₂ has the highest positive forcing leading to warming of climate. CO₂ has the least global warming potential among the major green house gases but due to its much higher concentration in the atmosphere; it is the major contributor towards global warming and climate change. Agriculture sector in India contributes 28% of the total GHG emissions (NATCOM, 2004). The global average from agriculture is only 13.5% (IPCC, 2007). In future, the percentage emissions from agriculture in India are likely to be smaller due to relatively much higher growth in emissions in energy-use transport and industrial sectors. The emissions from agriculture are primarily due to methane emissions from rice fields, enteric fermentation in ruminant animals and nitrous oxides from application of manures and fertilizers to agricultural soils (NATCOM, 2004).

Introduction

Climate smart agriculture (CSA) refers to the incorporation of adaptation and mitigation practices in agriculture that enhances the system-resistance and recovery-mechanism against climatic hazards. Climatic hazards / disturbances include drought, flood, heat / cold wave, erratic precipitation, sudden dry spell etc. In nutshell, CSA is the ability of the system to bounce back. It can also be explained as an approach to build-up resilience of agricultural systems, to increase adaptive capacities of farming communities to climate change and variability, and to ensure food security (Prasad et al., 2015).

Climate change can be defined as a statistically significant variation in either the mean state of the climate or in its variability, persisting of an extended period, typically three decades or longer (Pathak et al., 2014; NAAS, 2013, Bhattacharyya et al., 2016). The surface air temperature, sea level rise, occurrence of extreme events (heat wave, cyclone, flash flood) is the direct evidences of climate change. The annual average surface temperature has increased by 0.87^°C in 100 years (IPCC, 2018). Recent report revealed that more than 90% of Northern Hemisphere land areas outside the tropics showed at least 1^°C above average, whereas temperatures were less extreme in Southern Hemisphere. Importantly, temperatures were above normal over most of the ocean areas. Global sea level rose to about 15 mm, in between November (2014) and February (2016), as a result of ElNino, which was well above the post-1993 trend of 3.0-3.5 mm year^-1. However, Indian summer monsoon rainfall since 1901 to 2012 showed no long-term trends, with some regional changes. Importantly, night temperatures have increased sharply during recent years, which couple with erratic precipitation could significantly affect agricultural production. The fifth IPCC (IPCC, 2014) reports clearly brought out global and regional impacts of climate change on Agriculture, Forestry and Other Land Use (AFOLU). South Asia has been characterized as one of the most vulnerable regions. Impacts of climate change witnessed all over the world; however, countries like India is more vulnerable because of its huge population primary dependent on agriculture for livelihood, predominance of small and marginal farmers, and fragmented land holding.

Introduction

Water and food security are the key challenges under climate change as both are highly vulnerable to continuously changing climatic patterns. Climate change has resulted in increases in globally averaged mean annual air temperature and variations in regional precipitation and these changes are expected to continue and intensify in the future. The projected changes in climate patterns over India include increase in surface temperature, variations in rainfall, increasing occurrence of extreme weather events like floods and droughts, rise in sea levels and impact on the Himalayan glaciers. Sectors of the Indian economy are most likely to be impacted by such changes in climate are those dependent on natural resources, namely agriculture, water and forestry. The likely impacts such as reduction in food production, water scarcity, loss of forest biomass Climate change is expected to bring more intense and more frequent extreme weather events including droughts and floods in India. The global atmospheric concentration of carbon di-oxide CO₂ for increased from preindustrial value of about 280 ppm to about 410 ppm at the present (2021). The global increase in CO₂ concentration is primarily due to fossil fuel use and land use change. Atmospheric methane was 1803 ppb in 2011, this is 150% greater than before 1750. Atmospheric nitrous oxide (N₂O) was 324 ppb in 2011, this is 150% greater than before 1750 (Table 1). These increase in GHGs have resulted in warming of the climate system by 0.74°C between 1906 and 2005.

14.1. Introduction

Environmental pollution primarily deals with five types of pollution: soil pollution, water pollution, air pollution, sound pollution and light pollution. However, soil, water and air pollutions are considered very important as the pollutants from the environmental compartments may be cycled within themselves, enter the food web and interfere the biological processes adversely of any living species. Soil supplies nutrients and water to plants which, in turn, act as the nutrient supplier to animals and humans. Thus, maintenance of soil quality is considered prerequisite for growth of plants, animals and humans. If soil, water and air are polluted through various mechanisms, living components in the environment are suffered adversely. Soil, water and air pollutions are associated with the build-up of soil contaminants such as toxic organic and inorganic compounds, petroleum hydrocarbons, radioactive materials, salts, disease causing agents etc. above the permissible limit, so that their presence will cast adverse effects on physicochemical and biological properties of soil which in turn exert negative impact on crop growth and on any non-targeted organisms. Common soil contaminants include heavy metals, pesticides, petroleum hydrocarbons, fertilizers if used in excessive amount, and many others. Contamination of the soil, air and water results from intensification of farming activities. Primarily nutrients (particularly nitrogen and phosphorus), sediment, wastes, pesticides and salts are regarded as agricultural nonpoint source pollutant. Realistically, most of the pollutants originate from anthropogenic activities, although there exists many naturally occurring mineral components that may exhibit toxicity towards living system at higher concentration. Land disposal of municipal and industrial wastes, automobile emissions, mining activity, and application of fertilizers and pesticides to agricultural field cause a continuous accumulation of heavy metals and other pollutant components in soils. These pose threats of environmental degradation via soil erosion, loss of biodiversity, climate change etc.

13.1. Introduction

Water is chemically benign. However, its interference in free gas exchange in soil becomes detrimental to crop growth when soils are subjected to waterlogging or plants are submerged with water.Waterlogging of soil refers to a soil condition when the soil attains a moisture regime to such an extent that oxygen is not available in the pore space in enough quantity for plant roots to respire adequately. On the contrary, detrimental gases such as carbon dioxide, methane, hydrogen sulphide, ethylene etc. accumulate in the root zone and adversely influence the growth of plants. Thus, anaerobic condition prevails in waterlogged soil causing depletion of oxygen and increase of CO₂ in root zone, which severely affects aerobic micro-organisms while harmful organisms proliferate and restrict the plant growth. Waterlogging leads to nutrient deficiencies or nutrient toxicities, root tip decomposition and eventually, reduced growth or death of the plant. Physical, chemical and biological activities in the soil are also disturbed due to low temperature. However, this is important to note that plants differ among themselves in their demand for oxygen. Even oxygen demand for same plants differs with its growth stage. Therefore, it is well understood that there is no universal level of soil oxygen that can identify waterlogged conditions for all plants. Mostly waterlogging prevails in the land due to non-permeability of the soil material, the presence of an impervious layer in soil horizon, or a high-water table.

12.1. Introduction

All soils invariably contain soluble salts. However, physico-chemical and biological soil properties start degrading when excessive amount of salts are accumulated in soil, particularly in rhizosphere, due to several anthropogenic activities and environmental conditions, and crop production is severely affected. Then we refer those soils as salt-affected soil.

The need of intensive agriculture to keep pace with the increasing world population for their food requirement necessitates to bring more agricultural land area under irrigation. However, irrigation system without taking enough drainage provision and poor water quality and its poor management may make the situation worst due to the development of salt-affected soils that ensue unproductive soil and low crop yield. Crops grown on salt-affected soils suffer from high osmotic stress, nutritional disorders due to nutrient (N, Ca, K, P, Fe, Zn) deficiency, specific ion toxicities, poor soil physical conditions and as a consequence, a reduced crop productivity.

Although it is considered that the rocks and minerals on weathering lead to salt accumulation in the soil, but the salt-affected soils are not truly originated from the accumulation of such salts in situ. On the contrary, occurrence of salt-affected soils is due to receiving salts that come from other locations with water. Sea water inundation in coastal belt, irrigation with poor quality water including saline groundwater, poor drainage system, irrigation adopting unscientific ways leading to waterlogging, shallow water table etc. contribute heavily toward development of salt-affected soils. Salt-affected soils may occur under almost all climatic conditions. Their distribution, however, is relatively more extensive in the arid and semi-arid regions compared to the humid regions because of poor precipitation to leach soluble salt adequately. Since evapotranspiration greatly exceeds precipitation in these climatic conditions, the soluble salts move upward with water due to capillary action and are left behind on the surface soil and the rhizosphere, once water is evaporated. The commanding ions of accumulated salts in affected soil are sodium, potassium, magnesium, calcium, chlorides, sulphates, carbonates and bicarbonates. The nature and properties of salt-affected soils are so diverse that they require specific approaches for their reclamation and management. Therefore, it is necessary to know their origin, formation, nature, chemistry and properties in detail to classify them into groups for their proper management to maintain sustainable agriculture.

11.1. What is acid soil?

Acid soils refer to those soils that are characterized with the presence of higher concentration of H⁺ in soil solution and at exchangeable sites or characterized with its high proton donating capacity such as aluminium (Al³⁺) on hydrolysis gives rise to proton. Both H⁺ and Al³⁺ are responsible to contribute soil acidity. Al³⁺ causes soil acidity indirectly by generating H⁺ through its hydrolysis, while H⁺ contributes directly. Therefore, due to more abundance of H⁺, they exhibit low soil pH and low base saturation (Ca²⁺, Mg²⁺, Na⁺ and K⁺). Such soil is considered as problematic soil because plant growth is affected adversely under acidic conditions and they suffer root injuries when grown in acid soils. Besides, soil acidity interferes in the soil nutrients availability to plants, making them either deficient to plants (such as phosphorus, calcium, magnesium, molybdenum) or toxic to plants for their more availability. Under acidic condition, Al, Mn and Fe are found in more soluble form. Thus, they are taken up by the plant in such a higher level that they become toxic to plants. Phosphorus becomes immobile due to the formation of insoluble compounds with aluminium and iron under acidic conditions. Ca, Mg and Mo also become unavailable in acid soil and show their deficiency symptoms. Soil acidity also affects soil microbial growth and thus, in turn, affects the nutrient dynamics in soil. Soil acidification is induced heavily under intensive agricultural practices such as increasing leaching due to more irrigation practices, addition of fertilizers, build-up of soil organic matter and many other possible ways.

10.1. Introduction

The soils possessing characteristics that are not suitable and economical for crop growth are termed as Problem soils. These characteristics may be of physical, chemical and biological. For cultivation of crops in these soils, it is necessary to follow specific management interventions and proper reclamation measures. Frequently we come across another term, ’degraded soil’. Degraded soil is also a problem soil. However, there exists a hair-line difference between problem and degraded soil. Problem soils refer to the soils in which the inherent soil characteristics, obtained from its genesis, pose problems for their optimal use, while degraded soils are developed due to anthropogenic activities by unwise management interventions.

10.2. Types of problem

Mainly there are four types of problem that may exist in soils: physical problems, chemical problems, biological problems and nutritional problems as a result of physical, chemical and biological constraints in soils.

9.1. Introduction

Soil biology is a branch of science that studies the soil inhabiting organisms in relation to their ecology, functions, behaviour and impact on various soil processes and plant growth. Soil fertility is directly dependant on humus content as well as the presence of microorganisms in soil, although surface soil does not contain more than 0.5% by weight of living organisms. However, such a small portion of soil constituent as compared to other organic and inorganic constituents plays a significant and major role in transformation of plant nutrients from their unavailable to available form from organic wastes, soils and fertilizers. They have a direct role in improving soil tilth, providing an appropriate environment for root growth, decomposing organic residues to form humus and in turn releasing nutrients for plants use, releasing many plant growth promoters, fixing inert atmospheric nitrogen in plant usable forms and they promote many other important processes without which plants cannot survive. Absence of living organisms in soil leads to its infertility. An understanding of microbial processes in soil environment, keeping in view of soil nutrient status, carbon sequestration, soil health and quality, overall sustainability in agriculture and also global warming in respect of greenhouse gas emissions (nitrous oxide and methane) through agricultural practices, is very important in regulating nutrient release at different plant growth stages. If we are in a state to understand how various biological processes influence various changes in soil environment or in the opposite way that how different soil conditions alter the soil biota in number as well as in their functions and diversity, it is easier to implement soil management practices that promote to gain more benefits.

Microorganisms are ubiquitous in nature. Possessing a diverse habitat, they are found everywhere in soil, air and water at a varied temperature and pH. One may find the highest genetic diversity of life within the domain of microorganisms. But unfortunately very few are known to us, so far only 1% of the microbial species on the earth are culturable. However, it is believed that soil of one gram may contain hundreds of millions to billions of microbes which may represent several thousand microbial species. In respect of the population, bacteria top the list followed by actinomycetes, fungi, algae and protozoa in accordance with a decreasing numerical order. Out of three important soil fertility components viz. physical, chemical and biological; the biological component is least understood due to its wide complexity.

8.1. What is an ion exchange reaction and its application in soil system

Ion exchange is a reversible chemical reaction between two substances, either between two electrolytes or between an electrolyte solution and a solid complex as well as between two solid phases (if in close contact with each other), where ions of equal charge may be interchanged in equivalent proportion.

Organic colloids and inorganic micelles (clays) are sites of ion exchange. Soil contains silicate clay minerals which exhibit charges due to isomorphous substitution as well as due to the pH dependant charges for ionisation of hydrogen and hydroxide functional groups. Organic matter present in soil also contributes to the pH dependent charges due to the presence of various active functional groups. Thus, the organic and inorganic colloids present in soil bear positive or negative charges. Electric charge on soil particles is neutralized by equivalent amount of oppositely charged exchangeable counter ions, held by coulomb forces and van der Waals forces. Ca⁺², Mg⁺², H⁺, K⁺, Na⁺, NH₄ ⁺, Al⁺³, Fe⁺³, Fe⁺², Mn⁺², etc. are the common cations present in soil where Ca⁺² serves as the dominant ion. However, Na⁺ and Al(OH)₂ ⁺ are the dominant cations found in the exchangeable phase in strong alkali and strong acid soils, respectively. SO₄ ^- 2, Cl^-, HCO₃ ^-1, NO₃ ^- etc. are the most common anions found in soil to neutralize positively charged soil colloids.

7.1. Introduction

Like all other living organisms such as humans, animals, and microorganisms, plants also need elemental nutrients for their growth and development. They assemble the nutrients from soil, water and air. However, to obtain economical crop yield, nutrients are also supplied to the crops from external sources such as chemical fertilizers and manures and using biofertilizers. It is the present-day need to handle the soil fertility status in a more realistic and careful way to obtain maximum crop harvest. Under poor management practices, soil may become infertile and loose its importance in agricultural use. In modern days, huge food demand for the burgeoning human population does not permit to show luxury to use only fertile soil. Moderately fertile soil or even degraded soil should also be managed properly so that they may be used to grow crops. For this, plant nutrients status of the soil plays a significant role along with other soil properties. For sustainable soil fertility management, parameters such as crop to be raised, its nutrient demand at various growth stages, current nutrient status of the soil, amount of nutrient application based on the soil testing results etc are important to be considered. Balanced nutrition to the plants is the prerequisite to obtain maximum benefit. If nutrients supplied to the plants are low in quantity than their requirement, crop production is lowered down. Similarly, if the nutrients are provided in more amount in the soil or unbalanced way through fertilizer or manure applications, total crop yield is suffered. It is a very common example that excess of phosphorus leads to zinc deficiency in most crop plants and it has been observed that excess N is responsible for potassium starvation in potato. Again, excess of iron, manganese, zinc, copper shows plant toxicity. Addition of nutrients to soils in excess also causes environmental pollution when the excess nutrients are lost from soil by leaching, surface run-off and volatilization. Unscientific way of soil fertilization leads to increasing cost of cultivation and imparts adverse effect to the environment instead of doing any good. Therefore, one should have a clear knowledge on soil fertility to obtain a sustainable productivity.

6.1. What is colloid and colloidal system?

A colloidal particle may be defined as a substance which is microscopically dispersed evenly throughout another phase and is possessing a size of 10^-7 to 10^-3 mm and representing a larger surface area per unit mass. Thus, a colloidal system refers to a two-phase system in which small particles of one phase which might be of solid, liquid or gas is suspended evenly in the second phase of solid, liquid or gaseous material. These colloidal systems may be of solid in liquid or solid in gas or liquid in liquid or liquid in gas. Unique examples of liquid in liquid colloidal system includes the fat droplets dispersed in water of milk. When you put floor disinfectant liquid in water, it forms a white emulsion. Thus, emulsion becomes a colloidal system of liquid in liquid. Likewise, in fog, water droplets are suspended in gaseous air. So, fog is an example of a colloidal system, constituting of liquid dispersed in gas. When we refer smoke, it contains carbon particles (solid) suspended in air (colloidal system of solid and gas). However, smog is composed of smoke and fog. In case of soil colloidal system, soil colloids, which are of tiny particles (<0.001 mm size) and may be of organic and inorganic nature, are suspended in soil solution (water) and referred to as sol. Colloidal chemistry, which involves in the surface reactivity and charge characteristics of colloids, plays a pivotal role in total soil chemistry.

5.1. What is soil organic matter?

Plant and animal residues which are not yet added to the soil are considered as organic materials. However, once they are added to soil, they become soil organic matter. Therefore, organic materials contributing to the soil matrix are referred as Soil Organic Matter (SOM). Sometimes SOM is also used to highlight only the non-living organic materials produced by living organisms. But SOM should be regarded as a broad term that includes biomass, partially decayed residue, and highly decomposed and transformed organic substances, humus. Agricultural soil contains nearly 1-5% of SOM, which is regarded as least amount in soil as compared to other three soil components, minerals (45%), air (25%) and water (25%). However, it contributes enormously to soil productivity. Soil productivity and fertility exhibit direct positive relationship with SOM content in soil. Plants and animals are considered as primary and secondary sources of soil organic matter, respectively. Plant residues and application of organic manures e.g., farmyard manure, compost or green manuring help to build up organic matter in soil and thus, enrich the soil with organic carbon and other plant nutrients. Under natural conditions, roots of grasses in grasslands, the leaves including shoot portion of the large trees in forest lands and after harvesting the crop remnants in agricultural field provide enough incorporation of organic materials in soil. SOM plays a vital role to maintain sustainability in agricultural production through producing healthy soils and thus, healthy crops.

4.1. What is pH?

pH is used to classify substance as acidic, neutral and alkaline, based on the prevalence of free H⁺ ions. Water molecules on autoionization dissociate to produce H⁺ and OH^- in equal number, although degree of dissociation is very small because of its stability (about one molecule in 10 million is ionized at any one time). H⁺ ions later attached to un-ionized water molecule to give rise hydronium ions, (H₃O)⁺

3.1. What is weathering?

Weathering may be defined as the transformation process of solid rocks, involving the disintegration and decomposition of rocks and minerals, into soil.

There are different types of weathering: physical, chemical and biological.

3.1.1. Physical weathering

In physical weathering the chemical composition of the weathered products remains same as that of the parental rocks. It is involved in fragmentation of rocks into comparatively smaller sizes. It does not transform the parental rock into a newer one that may differ from the parental rock in chemical composition. The process is totally physical in nature. But this is also true that physical weathering encourages chemical weathering, and both may be carried out simultaneously because physical weathering promotes more surface area of parental rocks for more interaction with agents of chemical weathering.

2.1. Minerals

Primarily, minerals are usually inorganic substances possessing a definite chemical composition and a definite molecular arrangement which is usually expressed in geometric form. The mineral matter is made up of various elements, combined to form compounds. Usually, minerals consist of more than one constituent elements. Quartz contains two elements, silicon and oxygen. Other minerals may contain many elements, such as amphibole consists of several elements that include sodium, calcium, magnesium, iron, aluminium, silicon, and oxygen. Some elements exist as such without forming compounds. They contain exceptionally one element. Graphite (C), diamond (C), and Sulphur (S). Minerals are naturally occurring crystalline solid where the atoms are arranged in a regular three-dimensional array. A crystal is a solid, formed by a repeating three-dimensional pattern of atoms, ions, or molecules & possessing fixed distances between the different parts. Minerals that do not grow in these regular or crystalline patterns are called amorphous solids. When we talk about ‘naturally occurring’, we exclude the laboratory-synthesized crystalline solids. Glass and amber are also naturally occurring solid, but they are not crystalline and thus, they are not considered as minerals, rather they are referred as amorphous solids.

1.1. What is Earth?

The Earth is a layered body consisting of three parts: core, mantle, and crust. The radius of the Earth is nearly 6370 km of which crust, mantle and core share a depth of 40, 2850 and 3480 km, respectively (Figure 1.1). Exterior of the Earth contains the outer lithosphere which is surrounded (70% of surface) by water (hydrosphere). Solid and liquid sphere are surrounded by gas (atmosphere). The atmosphere is of 320 km above the lithosphere / hydrosphere. It is believed that there is a progressive increase in temperature with depth, if one goes to the core from the Earth crust. There is a rise of approximately about 1°F for every 64 feet depth on an average. Therefore, one could imagine that the interior of the earth is in molten condition.

The farming of striped murrel is quite old in many south-eastern and south Asian countries including India under traditional farming system. Wee (1981) has given an account of traditional farming of striped murrel in Thailand, where seed of wild stock was stocked in very high density (75-460 numbers/m²) in ponds. Freshwater small fish (FSF) were fed to the seed during pre-monsoon and monsoon seasons and subsequently marine small fish (MSF) mixed with rice bran to satiation level. The fish grew to 700-1000 g in 7-10 months with an FCR of 6.5:1 and production of 9.0-15.6 kg/m². In another culture trial, Diana et al. (1985) have described a poor survival of 9-13%, when they stocked seed @ 40-80 number/m² collected from wild sources and fed them on FSF for 9-11 months. There are records of backyard production of this species also (Wan et al., 1992). The major problems with traditional farming were poor & uncertain survivals, problems of getting SFs and occurrence of diseases due to poor management protocols.

Therefore for a scientific farming of this species, the major bottlenecks are the non- availability of hatchery seed, species & size specific feed, cannibalism at all stages and disease occurrence. These bottlenecks have been addressed to a greater extent by the researchers in recent and protocols for hatchery seed production and cannibalism reduction have been simplified to a greater extent with the availability of commercial pellet diets to boost its farming. Vietnam has been pioneer in the production of farmed striped murrel in recent, following new initiatives and based on its success, neighbouring countries such as Indonesia, Camobodia, Thailand, Myanmar, etc have also taken initiatives to boost production of this high value species in their countries.

Stocking fingerlings in grow-out ponds increases survival rates, cut-down culture duration, better feed management and reduce risk-factors on account of natural as well disease occurrence. In pond culture, good amount of fry-size seed suffer predation from enemies such as snakes, birds and predator fishes, if any and mortalities due to disease occurrence as smaller size fish is more vulnerable. However, fingerling stocking reduces predation loss to a greater extent, increase survivals, allow better feed management and highe production. This is truer with carnivorous fishes and particularly those observe cannibalism. Qin and Fast (1996) stated that the rate of cannibalism is higher in small size (TL) predators than the larger in case of striped murrel, so stocking large size fingerling in culture ponds reduces chances of ICC and hence recommended for grow-out production.

7.1 Traditional Methods of Fingerling Rearing

Wee (1981) has defined traditional system of murrel farming in Thailand in which seed of murrel was procured from wild resources and raised to large fingerling size before stocking. Two type of practices being used to raise fingerlings. In the first one, the pond(s) designated for fingerling production are stocked with brooders of SFs so they could spawn in the stocking pond(s) few days before the stocking of striped murrel fry and could directly feed upon the juvenile SFs. In second system, the fingerlings were reared to accept small-size fish (SF) along with rice bran to cut down cost of feeding on production of fingerling. In recent, more systematic approaches have been made to wean the seed collected from the wild resources on inert diets totally. The protocol adopted for weaning the fingerling on inert diet includes initial feeding with cut pieces of SFs and then gradual supplementation of inert diet till fingerlings start relishing inert diet completely.

The objective of larval rearing is to mass-produce high-quality and healthy juvenile fish. In larval rearing, the management of both rearing environment and feeding regime are the most important aspects. Improving larval rearing technique requires understanding of larval morphology & behaviour and requirements of live food, artificial diet and environmental conditions at different ages of larvae (Liao et al., 2001). Striped murrel is predatory as well cannibalistic species in nature. Therefore understanding about its behavior with respect to feeds and feeding, stocking density with growing age is utmost important. It is a general thinking that fish hatchlings do not require exogenous food until yolk-sac attached to their body is exhausted. But this is untrue with many carnivorous fish species, particularly those observe cannibalism. Larvae of such fish species start feeding much before the yolk-sac absorption; rather delay in getting feed make them weak or force them to feed on the conspecifics. Therefore in order to understand larval behavior of this species in respect of feeds and feeding, knowledge on its ontogenic development is crucial particularly in respect of age at which mouth opens; mouth gape size, food choice, size of food particle at different age-groups and finally the age when gut digestion starts.

Yulintine et al. (2017) have given ontogenetic details of striped murrel larvae since hatching. According to him, mouth opens and exogenous feeding begin in this species when hatchling grows to a size 4.63+0.25mm on second say of hatching. On day-3 after hatching, the buccopharynx channeled with the anterior intestine through a short oesophagus and rather narrow lumen, with having prominent liver developed by this time. Two pyloric caeca appeared on day-25 hph, indicating the transition from larval to juvenile stage and acquisition of an adult type of digestion. This chapter provides strategy for larval rearing of striped murrel based on ontogenic studies and work carried out by various workers in this field including that of authors.

Predation and cannibalism are entirely two different processes. In predation, the animal used to consume other species then their own, whereas cannibalism is a practice of eating one’s own kind. Cannibalism is a common behavior in animal kingdom and has been recorded in more than 1500 species. It is reported in an increasing number of fish species belonging to group/ families such as air-breathing catfishes (Clariidae), pikes (Esocidae), percids (Percidae), characids (Characidae), latids (Latidae), gadids (Gadidae) and in over 30 other families, including cyprinids (Cyprinidae) and salmonids (Salmonidae) (Smith & Reay, 1991; Hecht & Peinaar, 1993; Folkvord, 1991; Baras, 1998; Qin et al., 2004). Cannibalism is a common ecological interaction and depends on genetics and fish behavior; mediated by appetite and metabolism and is promoted by size differences, and is more intense among fast growing larvae and young juveniles than among older fish (Hecht and Pienaar, 1993; Baras, 1998).

Cannibalism is a serious problem in the farming of striped murrel that starts from the early larval stage (Ng and Lim, 1990) and continues at all sizes including during parenting also. Murrels have large mouth gape; sharp jaw teeth for catching & grasping prey and can consume prey fish more than half to two-third of its length (Wee, 1981; Diana et al., 1985; Ng and Lim, 1990 and Qin and Fast, 1996). Its aerodynamic body shape allows fast movement in water and catching the prey with ease. Striped murrel observes two types of cannibalism, Filial and Intracohort, which is discussed in detail in the subsequent sections.

In order to get assured supply of quality seed weaned on formulated diet, the captive spawning is the right choice for successful farming of striped murrel. Captive spawning involves several activities such as broodstock development, induced breeding, hatching of eggs, larval rearing, etc. These activities are given in detail in the following sections.

4.1 Broodstock Development

Brood stock development is an integral part of captive breeding programme in fish and the success of breeding largely depend on it. It involves rearing of healthy brooders of both sexes in captive conditions to meet the targeted production of seed. In striped murrel, maturation of gonad begins in the first year of their life. However, brooders of 2⁺ year age or above are better and recommended for captive breeding (Pati et al., 2004). A size of 400g to 1500g is considered ideal (Fig. 10). Brooders may be procured from wild sources or reared on-farm from farm-raised fingerling. Brooders from wild stocks are to be procured at least 2-3 months prior to spawning season so that they acclimatize to the farm conditions. It is recommended to give them a bath of 50 ppm formalin for about 8 hours under vigorous aeration before stocking in the tank/pond. Formalin treatment removes external pathogens from the fish body. Brooders raised at the same farm do not require formalin treatment, if they are free from any wound.