Priyal Pandey, Assistant Professor, Department of Soil Science
Akanksha Pandey, Assistant Professor, Department of Agricultural Extension
College of Agriculure and Research Station ,Katghora, korba, IGKVV, C.G.
Introduction:
The main challenge for Indian agriculture is attaining food security for a growing population, and palliating poverty with sustainable measures keeping current scenario of depleting natural resources in mind, withstanding negative impacts of climatic variability, fluctuating cost of inputs and fickle food prices. Further to these challenges, the principle trafficator of unsustainability of Indian agriculture includes: depletion of soil organic matter, soil erosion, wind erosion, monocropping, intensive tillage, soil degradation, crusting, compaction and salinization. An epitome shift in farming practices is the need of hour by eradicating unsustainable practices of conventional agriculture (disturbance/tilling the soil, organic material depletion, monoculture, residue burning). Conservation agriculture (CA), is a possible solution for maintaining integrity and sustainability in agriculture. It is a means-saving agricultural system that targets production intensification and high quality yields along with improving the natural resource base. Traditional agriculture system is based on inter culture operation and has been accused of being responsible for soil erosion problems, surface and underground water pollution, and more water consumption. Moreover, it is responsible for landdegradation, wildlife and biodiversity reduction, low energy efficiency and contribution to global warming problems. Thus, conservation agriculture (CA) is a possible mean to grow annual and perennial crops, based on minimum tillage with crop residue management and cover crops, in order to provide a permanent soil cover and sequester organic matter in a natural manner.
Conservation agriculture facilitates higher and richer biodiversity and bioactivity in soil, well aggregated soil structure and good physical condition of soil. Considering the importance of conservation agriculturethis chapter includes principles for applying conservation agriculture, brief history, impact of conservation agriculture, strategies, scope and constraints involved in conservation agriculture
Definition and principle
Conservation agriculture is a management system that maintains a soil cover through surface retention of crop residues with no till/zero and reduced tillage. CA is described by FAO (http://www.fao.org.ag/ca) as a concept for resource saving agricultural crop production which is based on enhancing the natural and biological processes above and below the ground. As per Dumanski et al. (2006) conservation agriculture (CA) is not “business as usual”, based on maximizing yields while exploiting the soil and agro-ecosystem resources. Rather, conservation agriculture is based on optimizing yields and profits, to achieve a balance of agricultural, economic and environmental benefits. As per FAO definition Conservation agriculture is a management system is to achieve acceptable profits, high and sustained production levels, and conserve the environment. It aims at reversing the process of degradation inherent to the conventional agricultural practices like intensive agriculture, burning/removal of crop residues. Hence, it aims to conserve, improve and make more efficient use of natural resources through integrated management of available soil, water and biological resources combined with external inputs. It can also be referred to as resource efficient or resource effective agriculture.
Conservation agriculture system is based on three important principles
1. minimum tillage and soil disturbance
2. permanent soil cover with crop residues and live mulches
3. crop rotation and intercropping
1. Minimum tillage and soil disturbance
Growing of crops with minimum soil disturbance since the harvest of previous crop by direct planting is the main principle of minimum tillage. Direct planting can be used with all annual, perennial crops and vegetables. Minimum tillage involves considerable soil disturbancethough to a much lesser extent than that associated with conventional tillage. Minimum tillage is aimed at reducing tillage to the minimum necessary for ensuring a good seedbed, rapid germination, a satisfactory stand and favorable growing conditions.
Tillage can be reduced in two ways:
- By omitting operation which do not give much benefit when compared to the cost.
- By combining agricultural operations like seeding and fertilizer application.
Advantages of minimum tillage
1. Improved soil conditions due to decomposition of plant residues in situ;
2. Higher infiltration caused by the vegetation present on the soil and channels formed by the decomposition of dead roots;
3. Less resistance to root growth due to improved structure;
4. Less soil compaction by the reduced movement of heavy tillage vehicles and less soil erosion compared to conventional tillage.
Disadvantages of minimum tillage
1. Seed germination is lower with minimum tillage.
2. In minimum tillage, more nitrogen has to be added as rate of decomposition of organic matter is slow
3. Nodulation is affected in some leguminous crops like peas and broad beans.
4. Sowing operations are difficult with ordinary equipment.
5. Continuous use of herbicides cause pollution problems and dominance of perennial problematic weeds.
Different methods of minimum tillage
Row Zone Tillage
After primary tillage with mould board plough, secondary tillage operations like disking and harrowing are reduced. The secondary tillage is done in the row zone only.
Plough-plant Tillage
After the soil is ploughed, a special planter is used and in one run over the field, the row zone is' pulverised and seeds are sown.
Wheel Track Planting
Ploughing is done as usual. Tractor is used for sowing and the wheels of the tractor pulverise the row zone.
Zero Tillage
Zero tillage is also called as no till. Zero tillage is an extreme form of minimum tillage. Primary tillage is completely avoided and secondary tillage is restricted to seedbed preparation in the row zone only.
Till planting is one method of practicing zero tillage. The machinery accomplishes four task in one operation: clean a narrow strip over the crop row, open the soil for seed insertion, place the seed and cover the seed properly. A wide sweep and trash bars clear a strip over the previous crop row and planter-shoe opens a narrow strip into which seeds are planted and covered.
In zero tillage, herbicide functions are extended. Before sowing, the vegetation present has to be destroyed for which broad spectrum, nonselective herbicides with relatively short residual effect (Paraquat, Glyphosate etc.,) are used.
Stubble mulch Tillage
Conventional method of tillage results in soil erosion. Stubble mulch tillage or stubble mulch farming a new approach was developed for keeping soil protected at all times whether by growing a crop or by crop residues left on the surface during fallow periods. It is a year round system of managing plant residue with implements that undercut residue, loosen the soil and kill weeds.
Sweeps or blades are generally used to cut the soil up to 12 to 15cm depth in the first operation after harvest and the depth of cut reduced during subsequent operations. When unusually large amount of residues are present, a disc type implement is used for the first operation to incorporate some of the residues into the soil. This hastens decomposition, but still keeps enough residues on the soil.
Two methods are adopted for sowing crops in stubble mulch farming:
1. Similar to zero tillage, a wide sweep and trash-bars are used to clear a strip and a narrow planter-shoe opens a narrow furrow into which seeds are placed.
2. A narrow chisel of 5 to 10 cm width is worked through the soil at a depth of 15 to 30 cm leaving all plant residues on the surface.
The chisel shatters tillage pans and surface crusts. Planting is done through residues with special planters.
1. Permanent soil cover with crop residue and live mulch
Maintaining a protective layer of vegetation on the soil surface suppresses weeds, protects the soil from the impact of extreme weather patterns, helps to preserve soil moisture, and avoids compaction of the soil. Mulch is an organic material spread over the soil and around the crop to enrich and insulate the soil. Crop residue or live cover protect the soil from direct impact of erosive raindrops, conserve the soil the reducing evaporation and suppresses weed growth. Live mulch are crops incorporated for purpose of providing soil cover.
1. It suppresses weed germination and growth.
2. It improves recycling of nutrients
3. It improves carbon accumulation and carbon sequestration.
4. It protect the soil from erosion by wind and water.
2. Crop rotation and intercropping
Intercropping is a cropping practice that involves growing two or more crops in proximity. This gives higher income than the sole cropping. Intercropping maintains the soil fertility. It reduces the soil runoff. Crop rotation is the process of growing different crop in succession on a piece of land to avoid decrease in the fertility of the soil. Crop rotation gives various nutrients to the soil. Rotation of crops help in the controlling growth of weeds and pests. A well designed crop rotation promotes good soil structure, fosters a diverse range of soil flora and fauna that contributes to nutrient cycling and improved plant nutrition, and helps to prevent pests and diseases.
Advantages of crop rotation and intercropping:
1. Improvement of water use: Crops with different rooting systems also uses soil water at different soil depth.
2. Reduction of pest and disease: Different crops are susceptible to different disease and pest. Therefore growing such crops in rotation will reduce the diseases and pest at no cost.
3. Improve fertility and crop production: Crops having different rooting pattern takes nutrients from different rooting depth. Rotation helps the plant in taking the nutrients more efficiently. In addition leguminous crops fixes nitrogen which benefits the next season cereal crop.
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Conservation agriculture and conventional agriculture Table 1. Difference between Conservation agriculture and conventional agriculture
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Benefits of conservation agriculture
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Figure 2. Benefits of conservation
agriculture |
Impact of conservation agriculture
1. Climate change
Conservation agriculture moderates the impact of high temperature on and within the soil. It prevents the negative impacts of heat on seed germination, gives high agronomic resilence through extending the seeding period and improves seedlings growth. It also suppresses weed growth and creates better condition for root development and seedling growth. Improved infiltration and retention of moisture under conservation agriculture results in less severe , less prolonged crop water stress and increased availability of nutrients Conservation agriculture also adopt to climate changedue to reduction of risk of pest d weed infestation and the total crop failure. It leads to enhanced carbon sequestration and less emission of green house gases.
2. Nutrient recycling
Conversion of organic to inorganic form of nutrients, fixation of nitrogen in soil, solubilization of nutrients, proper distribution of water and nutrients in soil are few advantages of conservation agriculture. Permanent plant cover ensure reduced leaching of nutrients, minimum gaseous loss thus indirectly benefits nutrient recycling.
3. Physical property of soil
Conservation agriculture favors aggregates and humus formation in soil ensuring improved soil structure, soil porosity and aeration. Proper pore size distribution promotes good water infiltration capacity of soil. Permanent plant coveron soil reduces loss of soil and nutrients present in it by water and wind erosion.. Adoption of conservation agriculture results in reduced crusting and surface sealing, increased soil water storage capacity and reduced evaporation.
4. Chemical properties of soil
Tillage mixes air into the soil. This leads to mineralization of the soil organic matter. In absence of soil tillage, this mineralization is reduced, leading to increased soil organic carbon. Nutrients drawn from stubble and other residues from previous crop enable before nutrient cycling. Adoption of conservation agriculture may initially result in N immobilization. But in long run it stimulates release of nitrogen. Higher extractable phosphorous levels occur in zero tilled than in tilled soils, largely due to reduced mixing of the fertilizer phosphorous with the soil, leading to lower P-fixation.
5. Biological properties of soil
By restoring the biolife in the soil surface, such as earthworms, arthropods, and other insects, conservation agriculture increases the depth of root layer and improves the organic matter. This biolife is the source of food and habitat for diverse soil life, creates channel for air and water, performs biological tillage and provide substrate for biological activity through recycling of organic matter and plant nutrients.Soil macro and micro flora and fauna are re-established under conservation agriculture, resulting in better soil fertility. Tillage through direct physical disruption as well as habitat destruction strongly reduces macro fauna including litter transformer.
6. Environmental quality
The advantage of conservation agriculture on environmental quality emerge rather slowly. If conservation agriculture is adopted on large scale. It would leave most of the residue on the soil preventing the problem of dust, air pollution and fire. Conservation agriculture ensures better soil quality with reduction in global warming and green house gas emission by higher plant cover on soil sequestering carbon.
Problems in adoption of conservation agriculture
A new mind set of farmers, technicians, extension workers and researchers different from soil degrading tillage operations towards plant restoring minimum tillage is necessary for changing attitudes of farmers. Popularization of conservation agriculture is restricted because of lack information of latest tools, technologies and component of conservation agriculture. Major bottlenecks observed in adoption of conservation agriculture are as follows:
- High initial cost of specialized planting equipment and completely new dimension and dynamics of conservation farming system, which requires high management skill and a learning process.
- Burning of crop residues is major constraints observed in successfully adopting conservation agriculture. For timely sowing of the next crop and without machinery for sowing, farmers prefer to sow the crop in time by burning the residue. This has become a common feature in the rice-wheat system in north India creates environmental havoc for the region.
- The whole range of practices in conservation agriculture, including planting and harvesting, water and nutrient management, diseases and pest control etc. need to be evolved, evaluated and matched in the context of new systems. For evolving such strategy deeper understanding of concept is needed.
- There may be a risk of crop failure in initial years of adoption of conservation agriculture. Due to adoption of minimum tillage new pest and disease problem can be observed due to dominant weed species.
- There is no draft available for conservation agriculture, as all the agro ecosystem are different. Resource poor and small landholder might face the greatest challenge in adopting minimum tillage, residue retention in field and diversified farming.
Prospects of adoption of conservation agriculture
The direction that Asian countries take to meet their food and energy needs during the coming decades will have profound impacts on natural resource bases, global climate change and energy security for India. These challenges draw attention to the need and urgency to address options by which threats to Indian agriculture due to natural resource degradation, escalating production costs and climate change can be met successfully. A shift to no-till conservation agriculture is perceived to be of much fundamental value in meeting these challenges.
The promotion of conservation agriculture under Indian/Asian context has the following prospects:
1. Reduction in cost of production
This is a key factor contributing to rapid adoption of conservation tillage. Cost reduction is attributed to savings on account of diesel, labour and input costs, particularly herbicides.
2. Reduced incidence of weeds
Most studies tend to indicate reduced incidence of Phalaris minor, a major weed in wheat, when zero-tillage is adopted resulting in reduced in use of herbicides. It a misconception that conservation agriculture increases use of herbicide as it totally relies on chemicals. But due to plant cover on soil incidence of weed has reduced.
3. Saving in water and nutrients
Limited experimental results and farmers experience indicate that considerable saving in water (up to 20% – 30%) and nutrients are achieved with zero-till planting and particularly in laser leveled and bed planted crops. Higher soil water content under no-till than under conventional tillage is due to the reduced water evaporation and higher plant cover during the preceding period.
4. Increased yields
In properly managed zero-till planted wheat, yields were invariably higher compared to traditionally prepared fields for comparable planting dates. CA has been reported to enhance the yield level of crops due to associated effects like prevention of soil degradation, improved soil fertility, improved soil moisture regime (due to increased rain water infiltration, water holding capacity and reduced evaporation loss) and crop rotational benefits.
5. Environmental benefits
Conservation agriculture involving zero-till and surface managed crop residue systems are an excellent opportunity to eliminate burning of crop residue which contribute to large amounts of greenhouse gases like CO2, CH4 and N2O. Burning of crop residues, also contribute to considerable loss of plant nutrients, which could be recycled when properly managed. Large scale burning of crop residues is also a serious health hazard.
6. Crop diversification opportunities
Adopting Conservation Agriculture systems offers opportunities for crop diversification. Cropping sequences/rotations and agroforestry systems when adopted in appropriate spatial and temporal patterns can further enhance natural ecological processes. Limited studies indicate that a variety of crops like mustard, chickpea, pigeon pea, sugarcane, etc., could be well adapted to the new systems.
7. Resource improvement
No tillage when combined with surface management of crop residues begins the processes whereby slow decomposition of residues results in soil structural improvement and increased recycling and availability of plant nutrients. Surface residues acting as mulch, moderate soil temperatures, reduce evaporation, and improve biological activity.
Strategies adopted for conservation agriculture
The following strategies can lead to better adoption of conservation agriculture in India:
1. Change in attitude
Indian farmers are doing conventional agriculture since many years based of primary and secondary tillage various intercultural operations. Changing mentality of farming community is a difficult task to attain. Their concept regarding minimum tillage, residue retention need to cleared. Benefits of conservation agriculture must be explained in a proper manner.
2. Implementing situation and prevailing cost
Agricultural constraints need to identified first for harnessing full benefits from conservation agriculture. Land constraints like compaction, soil degradation, improper drainage, pH, organic matter in soil, nutrient retention power of soil should be taken into consideration for adoption of conservation agriculture in a sustainable manner.
3. Scaling up conservation agriculture practices
There is a need to adapt the CA principles and technological aspects which suits various agro-ecological, socio-economic and farming systems of the region. In India, efforts must be initiated through a network research project for on-farm evaluation and demonstration of CA technology for its promotion.
4. Shift in focus from food security to livelihood security
There is a need to replace food security policy based on cereal production witha well-articulated policy goal for livelihood security. This will help the diversification of dominant rice-wheat cropping systems (occupying about 10.5 million ha) in the Indo-Gangetic Plains, the cultivation of which in conventional tillage practice has overexploited the natural resources in the region. The nature of cropping patterns and the extent of crop diversification are influenced by policy interventions.
5. Better equipment for crop production
Developing, improving, standardizing equipment for seeding, fertilizer placement and harvesting ensuring minimum soil disturbance in residue management for different edaphic conditions will be key to success of conservation agriculture. For many situations for example, in hilly tracts, for small land holders bullock drawn equipment will have greater relevance. Ensuring quality and availability of equipment through appropriate incentives will be important. In these situations, the subsidy support from national or local government to firms for developing low cost machines will help in the promotion of CA technologies.
6. Good database
There is a need for generating a good resource database with agencies involved complementing each others’ work. Besides resources, systematic monitoring of the socio-economic, environmental and institutional changes should become an integral part of the major projects on CA.
7. Networking
Conservation agriculture has to be mainstreamed in relevant ministries, departments or institutions and supported by adequate provision of material, human and financial resources to ensure that farmers receive effective and timely support from well trained and motivated extension staff. Establishment of network of communities of practice, bringing together diverse stalkholders around the world to give concerted support to conservation agriculture will help.
Conclusion:
Conservation agriculture offers a new prototype for agricultural research and development different from the conventional one, which mainly aimed at achieving food security and sustainability targets in India. A shift in paradigm has become a necessity in view of widespread problems of resource degradation, which accompanied the past strategies to enhance production with little concern for resource integrity. Conservation agriculture provide an opportunity for arresting and reversing the downward turn of resource degradation, decreasing cultivation costs and making agriculture more resource-use-efficient, competitive and sustainable. It is an ecological approach that mitigates climate change and achieves to high degree of environmental sustainability of farming and provides many benefits to non-farming population.
References:
Rattan, R.K., Katyal, J.C., Dwivedi, B.S., Sarkar, A.K., Battacharyya R., Tarafdar, J C and Kukal S S (2015). Soil Science: An introduction. pp 255-274. Indian Society of Soil Science, New Delhi.
Bhan S. and Behra U.K. (2014).Conservation agriculture in India – Problems, prospects and policy issue.International Soil and Water Conservation Research, 2 :(4), 1-12.
FAO (2011). Soil carbon sequestration in conservation agriculture. In: conservation agriculture offset consulation-West Lafayette, Indiana, USA, 28-30 October 2008.
FAO (2011a). http://www.fao.org/ag/ca/doc/ca_ssc_overview.pdf
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