eChapters

Introduction

Rice straw is produced as a by-product of rice production at harvest. Agricultural Waste Burning (AWB) is a major contributor of air pollution in many countries, particularly in South Asia. Exposure to fine particulate matter less than 2.5 μm (micrometer), also known as PM 2.5, released by AWB can cause premature mortality due to respiratory and cardiovascular diseases (Brauer et al.,2012). Combine Harvesters used on the spring rice crop leave behind stubble and straw on the field (Sidhu et al., 2007). Farmers burn the rice residue while preparing the field for wheat sowing season that follows. Further, migrant labour from neighbouring states of Bihar and Uttar Pradesh has decreased (Sirhindi, 2019), and resulted in an increase in the cost of agricultural labour during the rice harvest season (Sharma,2018). Farmers find it both convenient and economical to burn residue to clear and prepare their fields for the next crop. In 2018, over 20 million metric tons of rice residue was generated in Punjab, of which almost 10 million metric tons was subject to open-air burning (MoA, 2019). The time window between rice harvesting and wheat sowing is just 20 to 30 days towards the conclusion of the Kharif season, which is one of the primary reasons of crop waste burning (Balwinder et al., 2016).

Introduction

Soil organic matter is an indispensible component of soil health management. It plays an important role in improving soil physical, chemical and biological environment. Soil health refers to the capacity of the soil in terms of physical, chemical and biological properties for maintaining ecosystem services. With respect to agricultural lands, soil health implies the capability of the soil towards improving crop growth and yield, while also supporting environmental sustainability. Some important determining properties of soil health maintenance are soil reaction, salinity or alkalinity, soil organic matter, soil texture, soil structure/aggregation, water holding capacity, porosity, internal drainage, and nutrient retention capacity. Simultaneously, the key properties maneuvering soil health are soil aeration, internal drainage, nutrient cycling, susceptibility to erosion etc. Except some of the basic properties (soil texture) and processes (soil erosion), most of the determinant properties and processes are maneuvered by the presence of soil organic matter. A healthy soil must have strong resistance to degradation processes and able to recover following a perturbation because of inherent resilience (Magdoff 2001).

Nitrogen

Most commonly, complex organic compounds, ammonia, molecular nitrogen, nitrite, and nitrate are the forms of nitrogen found in soils. The physical and chemical conditions of the soil control the majority of the microbiological interconversions that change nitrogen.

Ammonia build-up, ammonia loss by volatilization, denitrification, nitrogen f ixation, and leaching losses of nitrogen are the primary changes that occur in submerged soils. The nutrition of rice is significantly impacted by these changes. Given the favourable circumstances for quick soil transformations and nitrogen loss, it is obvious that rice soils are nitrogen deficient.

Principle

β-Glucosidase (BG) plays a major role in the degradation of soil organic matter and plant residues. It catalyzes the hydrolysis of β-d-glucopyranosides, the final, rate-limiting step in the degradation of cellulose, the most abundant polysaccharide providing simple sugars for the soil microbial population. BG has been shown to be sensitive to changes in soil and residue management as well as an early indicator of changes in SOC before these changes are reflected in total or organic C analyses. The method is based on colorimetric determination of the p-nirtrophenol released by β-glucosidase when soil is incubated with buffered PNG solution and toluene.

8.1 The purpose of erosion research

The need for research

A soil conservation programme needs to be based on factual information about rates and quantities of erosion. For example some land obviously needs to be protected by mechanical works such as channel terraces, some land equally obviously does not need any protection, and a great deal of land lies somewhere between the two extremes. At some point the terraces become unnecessary or uneconomic, but a logical decision on where to draw the line can only be made if data are available on how much soil erosion is occurring and how much it would be reduced by terraces. Similarly, the effect of channel terraces should be compared with the effect of alternative measures, and the effect should also be measured on the different soils and crops which are likely to be encountered.

Nowadays there are excellent opportunities for research workers to exchange the results of their work. The national and iniernational journals are packed with accounts and results of research reports in their proceedings (as listed in Further reading). Some of the reported research results can be usefully applied in countries other than where the research was done, but care is required in any transfer of technology. If the local conditions of soil, climate, or land use, are different, the results may not apply. However, research in other situations can often serve as a pilot trial to show which factors should be studied locally. Even when local conditions are so different that the results do not apply at all, the techniques and apparatus developed by other workers can still be helpful.

7.1 The purpose and type of models

Sometimes the simplest way to estimate the effect of a physical process is to use an established equation, or formula, or charts and diagrams based on existing knowledge. The current fashion is to call such aids and solutions models, and they tend to become increasingly complicated and consequently dependent on computers to handle the mathematical processes.

It is important to identify the exact objective and purpose of models which are designed to estimate soil erosion. Two main divisions are models for prediction and models to assist with explanation. If the purpose is to predict amounts of erosion under alternative management practices then empirical models such as the USLE are efficient and effective. For an understanding of the processes of erosion it is necessary to turn to physically-based or deterministic models. The two objectives should not be cross-threaded onto the wrong kind of model, i.e. the USLE should not be seen as a vehicle for research studies on the mechanics of erosion. Neither should sophisticated simulation models be used as the basis for evaluating conservation practices which are better designed on the basis of experience, and evaluated by direct testing in the field.

The different kinds of models need a short explanation:

An empirical solution or model is one based on observation or experiment, and not derived from theory. It fits observed facts, and allows us to predict what will happen in certain circumstances, because we know what has happened before in those circumstances. The reliability of such methods depends on the database of experience: we might say This will certainly happen’ (because it always does), or “Will probably happen’ (because it usually does), or ‘it may happen’ (because it sometimes does). An empirical solution may be a simple approximate relationship or a complex multiple regression equation.

12.1 The nature of gully erosion

Gully erosion is spectacular and widespread, and so it is often used by conservationists as a characteristic symptom of erosion. As a result there is a danger of its importance being over-emphasized. Certainly it is most important as a source of sediment in streams, but in terms of damage to agricultural land or reduction of agricultural production, it is usually not very important for the simple reason that most land subject to severe gully erosion is of little agricultural significance. The really spectacular erosion so popular in non-technical reports shows large areas cut up by deep interconnecting gullies, but this situation is usually found in semi-arid climates unsuitable for any serious agriculture, or on soils which have such adverse chemical or physical properties that their potential production is very low. Added to this is the fact that gully control is always difficult and expensive, so the cost of reclamation usually exceeds the value of the land. Certainly in the sense of reducing the amount of eroded soil choking the dams and rivers it may be highly desirable to do something about gully erosion, but it is very much a case of prevention being better than cure. Limited resources in manpower, money and materials can usually be better employed in preventing future gullies than in curing existing ones.

The worldwide occurrence and recognition is well demonstrated in the variety of names: in English and American - gully, in Egypt - wadi, in South Africa - donga, in French-speaking lands - ravine, in India - nulla, in South America - carcava, or arroyo, and many others. The definition is the same in any case, a steep-sided eroding watercourse which is subject to intermittent flash floods. They are more common in semi-arid climates with infertile soils and sparse vegetation, but some spectacular examples are found in tropical forests in deep soils with dense vegetation.

5.1 Definitions

The erodibility of soil is its vulnerability or susceptibility to erosion, that is the reciprocal of its resistance to erosion. A soil with a high erodibility will suffer more erosion than a soil with low erodibility if both are exposed to the same rainfall. Whereas the erosivity of rainfall was shown in chapter 4 to be a fairly straightforward measure of the rain’s physical properties, the assessment of erodibility is more complicated because it depends upon many variables. There are alternative uses of the term erodibility. In the widest sense it can be used to include all the variables which effect erosion except the erosivity of rain, as in the first line of figure 2.2. It is also used in the narrower sense as a measure only of the effect of physical characteristics of the soil, as in the erodibility index K of the Universal Soil Loss Equation, where the effects of land management and crop management are assessed separately, as shown in the last line of figure 2.2.

5.2 Factors influencing erodibility

In this chapter we will look at the three broad groups of factors which affect erodibility. First, there are the physical features of the soil, including the chemical and physical composition. Second, there are the topographic features, such as the slope of the land. Third, there is the management of the land, i.e. how it is used.

6.1 Quantities and rates of runoff

Before a start can be made on the design of the channels and ditches and other works which can deal with surface runoff we need to know the probable quantity of water. If the object is to impound or store the runoff then it may be sufficient to know the total volume of water to be expected, but the usual conservation problem is conveying water from one place to another, and in that case the rate of runoff is more important, and particularly the maximum rate at which runoff is likely to occur. That is the flow which a channel must be designed to accommodate.

In a hypothetical catchment area* with an impervious surface and no losses the maximum rate of runoff would be directly proportional to the rate of rainfall. In natural catchments there are other factors: some of the rain is intercepted by vegetation, some infiltrates into the soil, some starts moving over the surface but is trapped in depressions, and some is lost by evaporation. Estimates of rates of surface runoff therefore depend on two processes: estimating the rate of rainfall, and estimating how much of the rainfall becomes runoff.

There are several empirical methods for doing both and for combining the two factors, but because they are empirical two points must be stressed. Firstly, as with all empirical solutions, data, tables, and formulae developed in one situation should not be applied in different conditions without careful checks on whether the method is valid in the new situation. Secondly, each of the three main methods which will be

Introduction

Modern agriculture has been of great help in alleviating hunger from the world, because the world population more than doubled itself during the last half of the 20th century; it increased from 2.5 billion in AD 1950 to 7.1 billion in 2012 (USCB, 2013). It is predicted that the world population will again double itself by the end of the 21st century and will touch the 12 billion mark. Most of this increase in population has been, and will be, in the developing countries in Asia, Africa and South America. India occupies 2.4 percent of the total land area of the world, but supports 16.7 per cent of the world population. Like many other developing countries in the world, population in India is increased from 345 million in 1947 to 1210 million as per the 2011 census with a growth rate of 1.76 during last decade. Therefore, pressure on land has been mounting up at an alarming rate. Population growth coupled with live stock population expansion, urbanization and industrialization are major contributory factors to it. The unscientific and unplanned exploitation of this limited resource takes its toll in terms of degrading the land. A large proportion of the land area shows clear evidence of advanced and continuing degradation seriously affecting the country’s productive resource base (Abrol and Sehgal, 1994). Jammu & Kashmir and  Nagaland  have maximum share of their land (94%) under degradation. This is primarily due to large areas under mountains, cold deserts and other such degraded lands. In the agriculturally prominent states like Uttar Pradesh (63%), Madhya Pradesh (50%) and Karnataka (46%) (Shalander Kumar, 2011) the extent of land degradation is of great concern and posing a big threat to the natural resources, resulting in almost 5 billion tonnes soil and 6 million tones of nutrient loss every year (Singh, 2009).

Introduction

The organic matter added to soil externally as FYM, crop residues, leaf fall, root deposition etc. has been a part and parcel of Indian agriculture. The total carbon added to soil is subject to microbial decay and slowly the major portion of it finds way back to the atmosphere. There is every possibility that atmospheric CO₂ concentration will increase in near future; that will further lead to increased attention of scientific community to make soil a possible sink for atmospheric CO2. when the carbon sequestration is thought with the perspective of reducing carbon dioxide emission for healthy atmosphere at one hand and improving soil health on the other, there is utmost need to opt for technologies that can fulfill both these objectives. There is growing interest in the use of charcoal or ‘biochar’ to sequester carbon in soil and improve soil fertility (Lehmann and Joseph, 2009). There are many types of soil additives and fertilizers used to improve the structure and functions of soil. Biochar has re-emerged as an issue in the last ten years as everyone is looking for sustainable ways to improve soils and decrease use of chemical fertilizers. 

Introduction

Climate change has undoubtedly resulted in greater public and scientific involvement. Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity (IPCC, 2007). The United Nations Framework Convention on Climate Change (UNFCC) defined it as a change of climate that is attributed directly or indirectly to human activity which alters the composition of the global atmosphere and that is in addition to natural climate variability observed over comparable time periods. World Meteorology Organisation defines climate change as statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). 

Introduction

Carbon on earth is stored primarily in rocks and sediments. Only a tiny fraction resides in mobile reservoirs – the atmosphere, oceans, soil and terrestrial biosphere – to play a vital role in biological, physical and chemical processes at the earth’s surface. The small fraction of C present in the atmosphere as CO₂ is especially important, as its abundance is a major regulator of the climate of the planet. The rapid increase in atmospheric concentrations of CO₂ over the past 150 years, reaching current concentrations of about 380 ppm, corresponds with combustion of fossil fuels since the beginning of the industrial age. Conversion of forest lands to agricultural use also redistributed C from plants and soils to the atmosphere and altered ecological balance through physiological effects on vegetation. The understanding of C sources and sinks has advanced enormously in the last decade. However, we cannot yet quantitatively define the global effects of human activities such as agriculture and forestry on climate change. An understanding on the long-term changes in atmospheric concentration will help enhance understanding on how the earth’s climate will evolve in future.

Introduction

Inappropriate land use and cultivation practices are one of the main reasons for the poverty and food insecurity faced by smallholders in most parts of the rural regions in India and other developing countries. Unsustainable agricultural practices lead to an exhaustion of soil resources, which results in reduced land productivity, aggravated land degradation, and a reduction in biodiversity. Conservation agriculture (CA),  has shown to improve, conserve and use natural resources in a more efficient way through integrated management of available soil, water and biological resources. It is now widely recognized as a viable concept for sustainable agriculture due to its comprehensive benefits in economic, environmental and social terms. Its ability to increase grain yields to provide better economic performance and reduce production risks and to improve energy use efficiency has been well-documented. 

Introduction

Indian agriculture is entering in a new phase. The major research and development efforts in the Green revolution era focused on enhancing production and productivity of selected food grains crops and only in Indo-Gangetic plains. The new challenges demand that issues of resource and input use efficiency receive high priority to ensure past gains can be sustained and further enhanced to meet the emerging needs. Issues of conservation have assumed importance in view of widespread resource degradation and the need to reduce production costs, increase profitability and make agriculture more competitive. The conventional mode of agriculture through intensive agricultural practices was successful in achieving goals of production, but simultaneously led to degradation of natural resources. The growing concerns for sustainable agriculture have been seen as a positive response to limit both low-input, traditional agriculture and intensive modern agriculture (relying on high levels of inputs for crop production). Sustainable agriculture relies on practices that help to maintain ecological equilibrium and encourage natural regenerative processes. Agricultural systems relying on such approaches are not only able to support high productivity, but also preserve biodiversity and safeguard the environment. Conservation agriculture has come up as a new paradigm to achieve goal of sustained agricultural production. It is a major step toward transition to sustainable agriculture.

Introduction

The hills and mountains are one of the most important agro-ecosystems that supports life of half of the mankind either directly or indirectly. In India, hills are rich source of bio-diversity and possess enormous potential for sustaining agriculture, including horticulture and animal husbandry. The ecological fragility and vulnerability of the Himalayas to climatic aberrations, increasing demand for land to grow more food have been issues of concern for quite some time. Nearly 59% of the total work force in the Himalayas is engaged in subsistence agriculture which is barely enough to feed the growing population for 5-6 months in a year (Raizada et al., 2009). The North-West Himalayas (NWH) consisting of Jammu & Kashmir, Himachal Pradesh and Uttarakhand spreads to 33 million ha, habited by 25 million humans and 19 million livestock. Though, the whole economy of the region is based on agriculture, the total cultivable land is only 3.2 million ha of the total geographical area of the region (Srivastva et al., 2009).

Introduction

Cotton is a major commercial crop grown on nearly 12 m. ha area. About 65% of the area is rain dependent. It is grown on a wide range of soil types and climatic conditions. Soils supporting cotton in the rainfed areas are Vertisols (Vertic intergrades), Inceptisols and Alfisols. Rainfall ranges from 500-1200 mm in these regions. Both Alfisols and Vertisols have different potentials and problems but both need organic C improvement and soil moisture conservation measures to restore their productivity. This can only be achieved through resource conservation strategies. Conservation agriculture (CA) is one such strategy that focuses on resource conservation. It refers to a system of raising crops without disturbing the soil while retaining crop residues or soil surface. 

Introduction

Global agriculture is under tremendous pressure to meet the demands of rising populations using finite, often degraded, natural resources. Globally, these resources are predicted to be further stressed/degraded by the impact of climate change. The ongoing buildup of greenhouse gases (GHGs) in the atmosphere is prompting shifts in climate across the globe that will affect agro-ecological and growing conditions. In addition, agriculture and land use change are prominent contributing sources of global GHG emissions. Further, the application of fertilizers, rearing of livestock, and land clearing influences levels of GHGs in the atmosphere and in turn affects the soil carbon storage as well as sequestration processes. The 2010 World Development Report draws (WDR, 2010) on analysis of the Intergovernmental Panel on Climate Change (IPCC, 2007) to calculate that agriculture directly accounts for 13 percent of global GHG emissions in CO2 equivalents and indirectly accounts for an additional 18 percent of emissions, when land use and conversion for crops and pasture are included in the calculations. Therefore, whilst ongoing climatic changes are affecting agricultural production, the sector itself also provides opportunities for emissions reductions.

Introduction

The demand of cereals to meet the food requirements of the burgeoning population is increasing while on the other hand most vital inputs of agriculture viz. productive arable land, water and labour are depleting day by day. Rice is the major Kharif crop of India and it is estimated that rice is being grown in 43.97 million ha with 104.32 million tonnes of production during 2011-12 (Agricultural Statistics at a glance, 2012). In the eastern region of India, rice is produced by the conventional system of cultivation which involves puddling and transplanting which is basically water, labour and energy intensive thereby adversely affecting the environment. Therefore, to sustain the long term production of rice, more efficient alternative methods of rice productions are needed. For this, conservation agricultural practices which comprises of technologies which are water, labour and energy efficient along with eco-friendly characteristics will be a better alternative to conventional practices (Kumar and Ladha, 2011). 

Increasing consciousness about environmental and coupled health hazards with agrochemical usage in farming and resultant consumers’ preference to safe and chemical-free food are the major factors that lead to the interest in eco-friendly forms of farming in the world. Organic agriculture is one such broad spectrum of production methods in consonance with conservation agriculture that are supportive of the environment and is now practiced in not less than 130 countries to the tune of 30.4 mha in 0.7 million organic farms. In India, about 1.02 mha area is reported to be under organic farming (certified area and area under conversion) with nearly 0.5 lakh certified organic farms. It is believed that adoption of ecologically sustainable farming practices can provide twin benefits of reversing the declining trends in crop productivity and protecting the environment. The demand for organic food is showing an increasing trend with an average growth rate of 20-25% per annum.

Introduction

India, with only 2.5% of the world’s geographical area, is home to 17% of the global population. Population has increased from 361 million in 1951 to 1140 million in 2011, more than threefold increase over 50 years and expected to reach 1.5 billion by 2050. The food consumption levels of India will increase from the current level of 2400 k cal/ per capita/ day to about 3000 k cal/ per capita/ day in 2050 (Singh, 2009). The production deficits are expected for cereals and pulses not only to meet the growing food requirements but also to meet the growing demand for animal based products which require higher quantities of food grains. It is estimated that despite realizing the full irrigation potential in the country, nearly 40% of the net sown area will remain rainfed. Rainfed areas with nearly 60 per cent of the cultivated area contributes for 40 per cent of country’s food production in the country, home to about 40% of the human and 60% of the livestock population,

Introduction

Cycling of plant material is required for any production system for biological activity, humus formation and thereby formation of a dark colored top soil. Incorporation of biomass results in production and proliferation of soil biota. But under annual crops compared to forest, production is much less, the biomass is largely removed, the soil is tilled several times each year. Consequently, less food and moisture are available for earthworms, insects, micro-flora and fauna; and their habitats are repeatedly disturbed or destroyed. Therefore, the primary need of our agricultural activities is to feed soil organisms (bacteria, fungi, earthworms etc.) and to regulate their living conditions while protecting them from chemical and mechanical impacts.

Introduction

Agriculture is the most important sector in India accounting for 13.7 per cent of the country’s GDP and employs more than 60 per cent of the labour force. Our country has recorded the highest food grain production of 257 million tonnes during 2012-13, under favourable weather conditions those prevailed throughout the year. The mission of increasing food grain production, though realized to a commendable extent at present, but under risk due to climatic aberrations and reduced availability of land, water, nutrients along with poor and continuous degradation of the resources to cope up with the demands of increasing population. Although the country had attained self sufficiency in food grain production through intensification of agriculture with high–yielding varieties, fertilizer application and chemical pest control during the green revolution, productivity is still low and is stagnating.

Introduction

It is estimated that about 16 per cent of total geographical area of India (329 m ha) has moisture index value below - 66.6% and is thus classified arid. This area is further classified into hot arid (36.8 m ha) and cold arid (15.2 m ha) regions (Ramakrishna et al., 2000). The hot arid region is characterized by extreme temperatures, low (<500 mm) and erratic rainfall, very high wind velocities, low humidity, high PET (>1800 mm) and frequent severe droughts which occur once in three years to alternate years in general. The soil moisture and soil temperature regimes are aridic and hyperthermic, respectively. The hot arid region exists in Rajasthan, Gujarat, Andhra Pradesh, Punjab, Haryana, Maharashtra, and Karnataka (Fig 1).

Issues of conservation have assumed great importance in view of widespread resource degradation and the need to reduce production costs, increase profitability and make agriculture more competitive. The growing concerns for sustainable agriculture have been seen as a positive response to limits of both low-input, traditional agriculture and intensive modern agriculture relying on high levels of inputs for crop production. Sustainable agriculture relies on practices that help to maintain ecological equilibrium and encourage natural regenerative processes such as nitrogen fixation, nutrient cycling, soil regeneration, and protection of natural enemies of pest and diseases as well as the targeted use of inputs. Agricultural systems relying on such approaches are not only able to support high productivity, but also preserve biodiversity and safeguard the environment. Thus, Conservation agriculture has come up as a new paradigm to achieve goal of sustained agricultural production. It is a major step toward transition to sustainable agriculture. 

The productivity of agricultural ecosystems depends on the interactions and interdependence of numerous species, such as other plant species, micro-organisms, pollinators, predators of agricultural pests and livestock. Agricultural ecosystems serve as an important habitat for many plant and animal species. Wild species are sometimes used to provide valuable genetic resources, for instance for certain plant breeding. When preserved, these can help to meet future food and livestock production challenges, including adaptation to climate change. Conservation agriculture provides an ample opportunity for the maintenance of agricultural biodiversity. This paper discusses the agricultural development phases, their consequence on the environment and cropping system diversification opportunities in conservation agriculture.

Introduction

In India out of the total 142 million ha of arable land around 67 per cent of them are affected by some form of land degradation due to development of salinity/sodicity or acidification, erosion by water or wind or chemical contamination. Frequent use of tillage operation under conventional cultivation system particularly in rolling terrain is one of the major causes of land degradation through accelerated water and wind erosion. The basic purpose of primary tillage operations are to control weeds, increase the availability of nutrient to plant through accelerated mineralization of organic matter, and to keep the field clean and pulverized for ease of sowing of the next crop. However the bare and pulverized top soil made them vulnerable to accelerated soil loss through runoff and also to erosion loss of soil by wind in drier agro-climatic regions. Besides soil loss, conventional tillage operation breaks the soil aggregates and exposes the soil organic carbon locked inside the aggregates to accelerated microbial degradation and thus results in net loss of organic carbon from the arable ecosystem.

Soil and nutrients are important factors for sustainable crop production in agriculture. Water erosion contributes more than 60% to the area under soil degradation in India. Soil erosion has been a serious threat to sustainable agriculture. However, soil and water conservation measures plays important role in improving the productivity of natural resources. India presently supports 17% of the global population with a geographical area of 329 Mha on merely 2.5% world’s land area and 4% fresh water resources. The net cultivable area in the country is about 140Mha is remaining constant or even squeezing from the pressures of urbanization, industrialization, infrastructure development and to house the ever increasing population. The loss of productive soil is another concern. The loss of fertile top soil by water erosion is estimated to be about 5334 Mt per year with it nearly 8.4 million tonnes (mt) of nutrients was estimated in eroded soil still holds true about in i.e. 2.5 mt nitrogen, 3.3 mt phosphorus and 2.6 mt potassium per hectare is lost due to ill soil and water management practices (Dhruvanarayana and Ram Babu, 1983).

Conservation agriculture (CA) has benefits to farmers in overcoming labor shortages associated with other tillage practices. With the introduction mechanized CA practices, farmers are able to finalize planting earlier, and can even free the equipment for service hire to neighbors. These CA equipment can reduce the delays in planting and also benefit neighbors who can hire this equipment and be able to plant within the first planting window, commonly associated with better yield gains. Smallholder farmers can also form groups to mobilize resources for equipment purchase to overcome the equipment cost problem. Local production of CA equipment for the smallholder agricultural sector has been almost non-existent prior to 2005.

Soil microorganisms are believed to play a major regulatory role in organic carbon dynamics, as key architects in nutrient transformation, and physical engineering of soil structure. The microbial populations of the soil alone encompass an enormous diversity of bacteria, algae, fungi, protozoa, and actinomycetes. Microbial diversity is being regulated by substrate and water availability, temperature, climatic regime and soil structure, which is considered as a transformation agent for soil organic matter and a labile pool of organic and inorganic nutrients. Extensive cultivation with repeated tillage operation often disrupts soil aggregates stability and destroys aggregates carbon and therefore, soil lose their physical properties and nutrient supplying capacity in a long-run.

Introduction

Climate change and climatic variability are expected to reduce agricultural productivity and threaten food security of the world, particularly in developing countries. Producing enough food for the increasing population in a background of decreasing resources and a changing climate scenario, is a challenging task. Agriculture, forestry and land use change account for about 30% of greenhouse gases (GHGs) emissions. Therefore, mitigation of GHGs emission while enhancing production is another challenge in agriculture.
 
Conservation agriculture (CA), with the three core inter-linked principles of minimizing mechanical soil disturbance, enhancing organic matter cover on soil and diversification of crops, is a viable option for sustainable agriculture with an effective solution to climate change adaptation and mitigation. The principles can be integrated and applied into most of the rainfed and irrigated production systems including horticulture, agro-forestry, organic farming, rotational farming and integrated crop-livestock systems to strengthen ecological sustainability. Worldwide about 105 Mha land is under CA and the area is increasing. However countries like USA, Brazil, Argentina, Canada and Australia occupy about 90% of the area under CA. The CA, which is advocated as an alternative to the conventional production system for improving productivity and sustainability, is now adopted by many countries and agencies as a lead model for sustainable agricultural intensification.

Introduction

Soil is considered one of the world’s limited, non-renewable resources. Under cropland conditions, it takes between 200 and 1000 years for 2.5cm of topsoil to form (Piementel et al., 1995). The continued maintenance of fertile soil is essential in order to meet basic human needs. It strengthens the provision of ecosystem services such as food production and climate regulation, and provides the basis of livelihoods for millions of people across the world (Ma, 2005). The multi-functionality of soils is key to the sustainable use of land and soils. A healthy soil performs six essential functions (Andrews et al., 2004) namely: i) Physical Stability and Support, ii) Water Relations, iii) Resistance and resilience- iv) Nutrient Cycling, v) Biodiversity and Habitat and vi) Filtering and Buffering. These soil functions are controlled by various soil properties. Among them soil structure is one of the most important properties of soil, which describes soil condition and has a great influence on crop production.

Introduction  

Developing effective strategies for improving and stabilizing rainfed crop production continues to be a prime concern in the semi-arid region of western India. Rain water management is most crucial aspect in rainfed production systems. Growing uncertainties associated with rainfall pattern (Ali et al., 2007) add to the complexity of the challenge. The medium deep black soil region of Rajasthan is spread predominantly in Jhalawar, Kota, Baran, Bundi, and Sawai Madhopur districts of South-eastern Rajasthan (Fig. 1). This region is characterized by almost flat alluvial plains interspersed with hills of Arawali and Vindhyan ranges and rock outcrops. 

The term soil organic matter (SOM) includes any material that is produced originally by soil organisms (plant or animal) that is returned to the soil and undergoes decomposition process. At any point in time, it consists of an array of materials, ranging from the intact original tissues of plants and animals to the substantially decomposed mixture of materials known as humus (Fig.1.1). Most soil organic matter originates from plant tissues. Plant residues contain 60 - 90 per cent of moisture and the remaining dry matter consists mostly of carbon, oxygen, hydrogen, with smaller amounts of sulphur, nitrogen, phosphorus, potassium, calcium and magnesium. Though present in small amounts, these nutrients are of great significance from the standpoint of soil fertility.

Introduction

With the advent of agricultural intensification, soil quality has been the important concern for the scientists, environmentalists and the planners at the global level. Research efforts have been made at the experimental fields, research laboratories and few specific locations, in order to establish the yardsticks, standards and critical values of soil parameters to ascertain the quality of the soil. The primary aim is the management of soil resources as per the need and their rejuvenation through best practices in hand. The idea, as it was aimed at, has now percolated down to the minds of end users-the farmers. The state and Central governments have been sensitized and are attaching great priority to the soil health. In states like Tamil Nadu, Gujarat, Goa, Uttar Pradesh crores of farmers are given “Soil Health Cards”. Central Govt. has the plan to issue these cards to all farmers in the country, detailing the deficiencies in soil and the amount of fertilizer needed.

Conservation Agriculture (CA) is an agro-ecological approach for sustainable crop production and intensification. CA comprises the resource conserving agricultural production practices that aim to achieve more produce at less cost while enhancing the quality of the natural resource base. CA is all about providing multiple options for farmers, endowed differentially. The basic components of CA include drastic reduction in tillage, adequate retention of crop residues on the soil surface, use of economically feasible diversified crop rotations, avoidance of freewheeling and practice of controlled traffic, if possible. These elements of CA are not site-specific but represent unvarying objectives that are practised to extend CA technologies efficiently across all production conditions. No-till agriculture is considered as a revolutionary step in the direction of preventing land degradation and rehabilitation of the resilient but fragile lands. No-till agriculture together with other associated management practices such as direct seeding into loose crop residues to provide soil cover and to conserve soil moisture, judicious choice of crop rotations and agro-forestry tree species constitutes CA. CA is thus being widely accepted as an important component of the overall strategy for enhancing productivity, improving environmental quality and preserving natural resources for food security and poverty alleviation in such areas.  Recent CA trials conducted in Karnataka, Andhra Pradesh and Tamil Nadu seem to bring out that the rainfed tropical India stands to benefit more from CA than the irrigated areas.

Introduction 

Conservation tillage has been defined based on percent cover of the soil surface with crop residue (CTIC, 2000). Quantifying crop residue cover on the soil surface is important for improving estimates of surface energy balance, net primary productivity, nutrient cycling, and carbon sequestration. Quantifying crop residue cover is also an important factor in controlling soil erosion and evaluating the effectiveness of conservation tillage practices (Barnes et al., 2003). Collecting this information by conventional method of survey and line transact are time-consuming, labor intensive, costly and can involve destructive sampling (Morrison et al., 1993). Moreover, field data are limited because they provide point, rather than area information. Remote sensing technique revealed as promising tool in providing such spatial data over a large area in a time and cost-effective manner.

Introduction

The Indo-Gangetic plain (IGP) is of great importance for the food security of India. It extends over 1,600 km with a width of 320 km, including the arid and semi arid environments in Rajasthan and Punjab and the humid and per humid deltaic plains in west Bengal (Shankaranarayana, 1982). During the green revolution period in the early 1960s, production increased through area expansion and intensification of the rice –wheat system. Driving forces included suitable thermal regimes for rice and wheat cultivation, development of short- duration, nitrogen responsive cultivars, expansion of irrigation and an ever increasing demand for food from the rising population. The rice –wheat system, covering an area of around 10 million hectares (mha), is the major cropping system in the IGP. These two crops together contribute more than 70 % of total cereals production in India from an area of around 25 mha under wheat and about 40 mha under rice. The small states of Punjab and Haryana contribute 20 % of the total national grain production and 50 % and 85 % of the government procurement of rice and wheat, respectively (Singh, 2000).

Conservation agriculture (CA) refers to a set of agricultural practices involving three basic principles of proven scientific soundness. These include continuous minimum mechanical soil disturbance; permanent organic soil cover with crop residues or cover crops; and diversified, efficient, economically viable, appropriate spatial and temporal crop sequences providing opportunities for saving on inputs (labor, fuel, machinery etc.), improving resource use efficiency (water, nutrient, energy etc.) and mitigating GHGs emission with climate change adaptation. Recently research efforts have been made to refine the crop management technologies which are more resource efficient, improve production and income, and reduce GHGs emission compared to the conventional practices. Resource conserving technologies (RCTs) are increasingly being adopted by farmers in the rice-wheat belt of the Indo-Gangetic Plains because of advantages of saving on labor, water, fuel and cost along with timeliness in operations particularly early planting of wheat.

Introduction

The subject of conservation agriculture CA has emerged as a need given the declining productivity of land and increasing costs of input that is putting tremendous pressure on the farming community. Higher yield expectation from land given also brings pressure to the subject of food security. Considering the markets with the globalisation influence is beyond a farmer’s means of influence and price realisation is not a point of control, the situation has deteriorated to their disadvantage. Climate change and soil degradation on the other hand is a reality and agriculture is both a sufferer and contributor, and cannot ignore this reality. Good physical management of soils is one of the key factors to maintain or improve agricultural productivity, in tropical and subtropical regions, and to reduce soil and environmental degradation (Lal, 2000). Tropical soils often have a stable structure and are well aggregated but management practices like intensive ploughing or avoiding the use of cover crops can lead to rapid deterioration (Madari et al., 2005).

Introduction

Rice is grown 43.7 m ha land in India. It is cultivated in 39.51 m ha under kharif and 4.26 m ha under rabi season. As a whole, rice production in India was 104.32 m t (2011-12) with an average productivity of around 2.6 t ha-1. Majority of rice grown in India in the eastern part of the country comprises the states of West Bengal, Orissa, Chattisgarh, Assam, Bihar and Jharkhand. Maximum area under rice in eastern India in West Bengal (5.94 m ha) with a production of 15.04 mt. Productivity was maximum in West Bengal followed by Jharkhand, Assam, Bihar, Orissa and Chattisgarh (DOSE, MOA, GOA, 2011). There is a plenty of scope to increase the productivity of these region with proper policies and technological interventions. Rice area in eastern region (23.4 m ha) would be divided in different ecologies, namely, irrigated (23.2%), rainfed upland (17.9%), rainfed lowland (43.1%) and flood prone areas (25.1%).

Introduction

Development, refinement and adoption of machinery for a range of soil and cropping situations will be fundamental in any success to promote conservation agriculture systems. This chapter reports on the performance of machinery for minimum/zero tillage, bed cultivation system and crop residues management in different cropping system and outlines the need for continuing efforts. Particularly, the focus will be on developing equipments/implements for fixed path / controlled traffic to minimize the ill effects of wheels in the longer terms.

Introduction

In general economic model, technological change in agriculture is expected to cause the commodity supply curve to shift down and out against a stationary demand curve, giving rise to an increase in quantity produced and consumed, and at a relatively lower price. Agricultural economists have used supply and demand models of commodity markets to represent agricultural research impacts, beginning with Schultz (1953) and Griliches (1958), with important subsequent contributions by Duncan and Tisdell (1971), Akino and Hayami (1975), among others. Such a model is explicitly used in many studies. However, low crop productivity, food insecurity, hunger and malnutrition; inadequate farming knowledge and skills, implements and inputs are characteristic of smallholder agriculture in developing countries including India. Many researchers argue that conservation agriculture can guarantee higher crop productivity, food security, improved net income of the farmers and environmental protection, better than the traditional systems of cultivation practices.

Introduction

Soil organisms contribute to the maintenance of soil quality in that they control the decomposition of plant and animal materials, biogeochemical cycling of elements, including nitrogen fixation; the formation of soil structure and the fate of organics and inorganics applied to soils. Soils and their biodiversity thus play a critical role in maintaining soil health. Non-return or diminished return of organic matter and residues deprive the soil biota of their food with loss of soil health and fertility. A large, diverse, and active population of soil organisms is the most important indicator of a healthy soil. The effects of physical and chemical degradation of soils are obvious. But the effects of biological degradation which is caused due to loss of specific soil organic matter (SOM) fractions (and consequently the loss of microbial species/communities dependent on them for nutrition) as well as and specific toxicity influences on soil flora and fauna are insidious. Proper management of soil biodiversity will help in sustainable agriculture and reduce the cost of external inputs especially for nutrient supply and crop protection.

Introduction

Soil biology is the study of the complex system of interrelationships existing among living organisms and their abiotic (physical and chemical) and biotic (living) environments and themselves. The abiotic factors in the environment determine the ability of organisms to live and reproduce. The chemical and physical sampling and analyses provide a broad picture of the parameters that define the aquatic environment. Biological investigation of soil can determine the extent of soil function and activity. To address environmental issues and increase land’s productive potential, we must now go beyond erosion control, soil fertility enhancement and management for soil quality.

Introduction

Carbon is an essential building block of life. It has always been transported from one form or ecosystem to another as a basic part of natural processes. Examples include its transport, through soil erosion, into aquatic ecosystems, or the undersea formation of limestone, the chief component of which is carbon. Much of the world’s carbon is held in soils, including agricultural soils. Another significant carbon pool is in the atmosphere, as carbon dioxide. Ever since agriculture began, between 7,000 and 10,000 years ago, the balance between these two pools has been changing. The loss of soil carbon through soil disturbance has augmented the atmospheric carbon pool. Since about 1750, the burning of fossil fuels has accelerated the process. Carbon dioxide is the largest single agent of climate change.

Climate change is a major issue facing society today with extensive studies being undertaken to find ways to mitigate its effects and impacts in the future. A key factor contributing to climate change is excessive levels of greenhouse gases in the atmosphere and global efforts are focussed on both reducing the emissions of greenhouse gases and increasing the storage (sequestration) of atmospheric carbon.

Introduction

Increasing carbon content in the soil, through better management practices, produce a number of benefits in terms of soil biodiversity, soil fertility and soil water storage capacity and hence productivity. Soil carbon sequestration through the restoration of soil organic matter can further reverse land degradation and restore soil “health” through restoring soil biota and the array of associated ecological processes. In particular, through improved soil water storage and nutrient cycling, land use practices that sequester carbon will also contribute to stabilizing or enhancing food production and optimizing the use of synthetic fertilizer inputs, thereby reducing emissions of nitrous oxides from agricultural land. Conservation tillage practices also reduce significantly the use of fuel and hence gaseous emissions. Soil carbon sequestration is thus very cost effective and could take effect very quickly (FAO, 2008). It also constitutes a valuable win-win approach combining mitigation (CO₂ is removed from the atmosphere) and adaptation, through both increased agro-ecosystem resilience to climate variability and more reliable and better yields (production and income generation). Under climate change scenarios, increased temperature may enhance soil organic matter mineralization in colder regions of the world, releasing carbon dioxide from soils (FAO, 2008). Improved soil management will mitigate the effects of global warming by improved and permanent soil cover. Soil carbon storage was hitherto left out of international negotiations because of envisaged difficulties of validation of amounts and duration/permanency of sequestration. 

Carbon sequestration implies removing atmosphere carbon and storing it in natural reservoirs for extended periods (Lal, 2011). Soil carbon sequestration is the process of transferring carbon dioxide from the atmosphere into the soil through crop residues and other organic solids, and in a form that is not immediately remitted. This transfer or “sequestering” of carbon helps off-set emissions from fossil fuel combustion and other carbon-emitting activities while enhancing soil quality and long-term agronomic productivity. Soil carbon has gained increased interest in the recent past owing to its importance in carbon sequestration studies and its potential impact on sustainable crop production. However, accuracy in estimating soil carbon sequestration to determine best management practices is hindered by inherent variability of soil properties (Srinivasarao et al., 2008 and 2009b). Maintaining or arresting the decline in soil organic matter (SOM) is the most potent weapon in fighting against soil degradation and for ensuring sustainability of agriculture in tropical regions. In India, 65 per cent of agriculture is rainfed, covering the categories of arid, semi-arid and sub-humid climatic zones. Consequences of depletion of organic matter are poor soil physical health, loss of favorable biology and occurrence of multiple nutrient deficiencies. It was stated that in rainfed arid, semi-arid and sub-humid tracts, next to poor rain water management, depletion of nutrients caused by organic matter deficiency is an important cause of soil degradation. Improving organic matter is, therefore, crucial to sustenance of soil quality and future agricultural productivity. Humus is known to favor many useful physical, chemical and biological processes that occur within the soil (Srinivasarao et al., 2011c). Accordingly, 

Introduction

Soil organic matter is an important component of soil quality and productivity; however, its measurement alone does not adequately reflect changes in soil quality and nutrient status. Instead, measurements of biologically active fractions of organic matter, such as microbial biomass carbon and nitrogen, and potential C and N mineralization, could better reflect changes in soil quality and productivity that alter nutrient dynamics. Therefore, measuring microbial biomass is a valuable tool for understanding and predicting long-term effects on changes in land use and associated soil conditions.

Introduction

The basic principle of conservation agriculture is to minimize soil disturbance in order to stabilize the soil structure, increase the fertility and balance the eco-system. Applied together, conservation agriculture practices – no tillage, permanent soil cover, use of crop cover and crop rotation, residue management- have complementary positive outcomes; no tillage maintains soil structure and biological activity; a permanent soil cover protects the soil surface from erosion and creates a stable and favourable micro-climate; cover crops and residue management provides organic matter, reduce soil erosion and improves soil fertility. Management of the soil water balance should be considered as a positive for cover crops and improvement of soil water infiltration, reduction in soil water evaporation, and decreasing water extraction from the soil would impact subsequent plant growth.