eChapters

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

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

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

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

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, 

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

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

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).

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

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

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). 

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).

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

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

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.

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

“Conservation agriculture (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). Aspects of conservation that we normally deal are the management of soil, water, crop diversity, animals, storage of produce (seed, fertilizer, etc.), and maintenance of tools, implements, machinery, etc. Some of the important key principles of conservation agriculture are illustrated as (i) Tillage: practice of minimum mechanical soil disturbance which is essential to maintaining minerals within the soil, stopping erosion, and preventing water loss from occurring within the soil. (ii) Crop residues/Mulch: Managing the top soil to create a permanent organic soil cover for growth of organisms within the soil structure. (iii) Crop rotation: The practice of crop rotation with more than two crop species (iv) Economics: Secure farm level economic viability and stability. To achieve this will involve the development of innovation systems focused on the needs of farmers and will include multiple agents who will use their comparative advantages to adapt the principles of CA to the farmers’ various biophysical and socioeconomic conditions. Crop diversification could also be proved as remunerative.  (v) Environment protection:  The CA has a role to conserve the environment in terms of climate resilient agriculture and emission of green house gases (GHG).

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.

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.