eChapters

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.