Management and Revitalizing Soil Health through Conservation Agriculture Practices

Management and Revitalizing Soil Health through Conservation Agriculture Practices

Abdulgani Nabooji¹ , Sharanappa² , Santosh³ , Shilpa H.D⁴ , Shilpa M.E⁴ , Akarsh S.V⁴

¹Department of Agronomy, College of Agriculture, UAHS, Shivamogga, India

²Department of Agronomy, College of Agriculture, UAS, Raichur, Karnataka, India

³Department of Soil Science and Agricultural Chemistry UAHS, Shivamogga, India

⁴Natural Farming Project, UAHS, Shivamogga, Karanataka, -577204, India

Corresponding Author Email: azeemdeccan123@gmail.com

DOI : http://dx.doi.org/10.53709/ CHE.2021.v02i04.023

Abstract

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Introduction

Attaining food security for a growing population and alleviating poverty while sustaining agricultural systems under the current scenario of depleting natural resources, negative impacts of climatic variability, spiralling cost of inputs and volatile food prices are the major challenges before most of the Asian countries. In addition to these challenges, the principal indicators of non-sustainability of agricultural systems includes: soil erosion, soil organic matter decline, and salinization. These are caused mainly by: [1] intensive tillage induced soil organic matter decline, soil structural degradation, water and wind erosion, reduced water infiltration rates, surface sealing and crusting, soil compaction, [2] insufficient return of organic material, and [3] monocropping. Therefore, a paradigm shift in farming practices through eliminating unsustainable parts of conventional agriculture (ploughing/tilling the soil, removing all organic material, monoculture) is crucial for future productivity gains while sustaining the natural resources. Conservation agriculture (CA) is a concept evolved as a response to concerns of sustainability of agriculture globally, has steadily increased worldwide to cover about 8 % of the world arable land (159.7 M ha) [4]. CA is a resource-saving agricultural production system that aims to achieve production intensification and high yields while enhancing the natural resource base through compliance with three interrelated principles and other good production practices of plant nutrition and pest management.

Sustaining the production and productivity of any system is very important and is achieved by improving the soil’s physical, chemical and biological properties. Conventional tillage operations will alter these properties in every cropping cycle thereby, affecting the soil system. Resource conservation systems have drawn the attention of agronomists and other crop production scientists to devise innovative tillage and residue management techniques for efficient resource management and sustained productivity. This involves soil management practices that minimize the disruption of the soil’s structure, composition and natural biodiversity, thereby minimizing erosion and degradation, control the annual weed. Conservation agriculture system is the best option to mitigate all these problems. Despite the clear benefits and success of conservation agriculture around the world, it is little practiced in less wealthy countries.

• Over the years, India has made rapid progress in the food production mainly due to high yielding crop varieties, fertilizer use and expansion in irrigated land.
• India’s population has also shown tremendous growth from 336 million in the 1950s to 1.2 billion to date and expected to reach 1.6 billion by 2050.
• To feed this growing population, India needs to produce more and more food. Earlier, most of the increase in agricultural output has taken place under irrigated conditions, but the opportunities for continued expansion of the irrigated area are limited.
• The vast potential of rainfed agriculture

Conservation agriculture

Conservation agriculture (CA) is become an universal way to achieve sustainable and profitable agriculture and subsequently aims to improve livelihoods of smallholders farmers and environment through the application of three principles: i) Minimum soil disturbance, ii) Permanent soil cover and iii) Crop diversification.

Objectives conservation tillage

• Seedbed preparation
• Moisture conservation
• Weed control
• Insect and disease management
• Residue management

Principles of conservation agriculture

Conservation agriculture practices perused in many parts of the world are built on ecological principles making land use more sustainable Adoption of CA for enhancing Resource Use Efficiency (RUE) and crop productivity is the need of the hour as a powerful tool for management of natural resources and to achieve sustainability in agriculture. Conservation agriculture basically relies on 3 principles, which are linked and must be considered together for appropriate design, planning and implementation processes. These are

Minimal mechanical soil disturbance

The soil biological activity produces very stable soil aggregates as well as various sizes of pores, allowing air and water infiltration. This process can be called “biological tillage” and it is not compatible with mechanical tillage. With mechanical soil disturbance, the biological soil structuring processes will disappear. Minimum soil disturbance provides/maintains optimum proportions of respiration gases in the rooting-zone, moderate organic matter oxidation, porosity for water movement, retention and release and limits the re-exposure of weed seeds and their germination.

Permanent organic soil cover

A permanent soil cover is important to protect the soil against the deleterious effects of exposure to rain and sun; to provide the micro and macro organisms in the soil with a constant supply of “food”; and alter the microclimate in the soil for optimal growth and development of soil organisms, including plant roots. In turn it improves soil aggregation, soil biological activity and soil biodiversity and carbon sequestration [5].

Diversified crop rotations

The rotation of crops is not only necessary to offer a diverse “diet” to the soil micro organisms, but also for exploring different soil layers for nutrients that have been leached to deeper layers that can be “recycled” by the crops in rotation. Furthermore, a diversity of crops in rotation leads to a diverse soil flora and fauna. Cropping sequence and rotations involving legumes helps in minimal rates of build-up of population of pest species, through life cycle disruption, biological nitrogen fixation, control of off-site pollution and enhancing biodiversity.

Soil Health

The terms soil health and soil quality are becoming increasingly familiar worldwide. [3] defined soil quality as “the capacity of a soil to function, within ecosystem and land use boundaries, to sustain productivity, maintain environmental quality, and promote plant and animal health.” In general, soil health and soil quality are considered

Status of conservation agriculture in India and abroad

In India, CA adoption is still in the initial phases. Over the past few years, adoption of zero tillage and CA has expanded to cover about 1.5 million hectares. The major CA based technologies being adopted is zero-till (ZT) wheat in the rice-wheat (RW) system of the Indo-Gangetic plains (IGP). In other crops and cropping systems, the conventional agriculture-based crop management systems are gradually undergoing a paradigm shift from intensive tillage to reduced/zero-tillage operations. In addition to ZT, other concept of CA needs to be infused in the system to further enhance and sustain the productivity as well as to tap new sources of growth in agricultural productivity. The CA adoption also offers avenues for much needed diversification through crop intensification, relay cropping of sugarcane, pulses, vegetables etc. As intercrop with wheat and maize and to intensify and diversify the RW system. The CA based resource conservation technologies (RCTs) also help in integrating crop, livestock, and land and water management research in both low and high potential environments.

Prospects 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, Asia and the world. These challenges draw attention to the need and urgency to address options by which threats to Indian/Asian 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. Asian farmers/researchers will continue to need assistance to reorient their agriculture and practices for producing more with less cost through adoption of less vulnerable choices and pathways. Therefore, business as usual with conventional agriculture practices does not seem a sustainable option for sustainable gains in food-grain production, and hence CA-based crop management solutions adapted to local needs will have to play a critical role in most ecological and socio-economic settings of Asian Agriculture. The promotion of CA under Indian/Asian context has the following prospects:

Reduction in cost of production

This is a key factor contributing to rapid adoption of zero-till technology. Most studies showed that the cost of wheat production is reduced by Rs. 2,000 to 3,000 ($ 33 to 50) per hectare cost reduction is attributed to savings on account of diesel, labour and input costs, particularly herbicides.

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.

 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 levelled and bed planted crops. [1] stated that higher soil water content under no-till than under conventional tillage indicated the reduced water evaporation during the preceding period. They also found that across growing seasons, soil water content under no-till was about 20 % greater than under conventional tillage.

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 soil degradation prevention, soil fertility, soil moisture regime (due to increased rain water infiltration, water holding capacity and reduced evaporation loss) and crop rotational benefits. Yield increases as high as 200-500 kg ha^-1 are found with no-till wheat compared to conventional wheat under a rice-wheat system in the Indo Gangetic Plains.

 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.

Crop diversification opportunities

Adopting Conservation Agriculture systems offers opportunities for crop diversification. Cropping sequences/rotations and agro forestry 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.

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

Constraints for adoption of conservation agriculture

A mental change of farmers, technicians, extensionists and researchers away from soil degrading tillage operations towards sustainable production systems like no tillage is necessary to obtain changes in attitudes of farmers noted that probably the most important factor in the adoption of CA is overcoming the bias or mindset about tillage. It is argued that convincing the farmers that successful cultivation is possible even with reduced tillage or without tillage is a major hurdle in promoting CA on a large scale. In many cases, it may be difficult to convince the farmers of potential benefits of CA beyond its potential to reduce production costs, mainly by tillage reductions. CA is now, considered a route to sustainable agriculture. Spread of conservation agriculture, therefore, will call for scientific research linked with development efforts. The following are a few important constraints which impede broad scale adoption of CA.

1.         Lack of appropriate seeders especially for small and medium scale farmers

Although significant efforts have been made in developing and promoting machinery for seeding wheat in no till systems, successful adoption will call for accelerated effort in developing, standardizing and promoting quality machinery aimed at a range of crop and cropping sequences. These would include the development of permanent bed and furrow planting systems and harvest operations to manage crop residues.

2.         The wide spread use of crop residues for livestock feed and fuel

The specially under rainfed situations, farmers face a scarcity of crop residues due to less biomass production of different crops. There is competition between CA practice and livestock feeding for crop residue. This is a major constraint for promotion of CA under rainfed situations.

3.         Burning of crop residues

For timely sowing of the next crop and without machinery for sowing under CA systems, 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. This creates environmental problems for the region.

4.         Lack of knowledge about the potential of CA to agriculture leaders, extension   agents and farmers

This implies that 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.

5.         Skilled and scientific manpower

Managing conservation agriculture systems, will call for enhanced capacity of scientists to address problems from a systems perspective and to be able to work in close partnerships with farmers and other stakeholders. Strengthened knowledge and information sharing mechanisms are needed.

Challenges in conservation agriculture

Conservation agriculture as an upcoming paradigm for raising crops will require an innovative system perspective to deal with diverse, flexible and context specific needs of technologies and their management. Conservation agriculture R&D (Research and Development), thus will call for several innovative features to address the challenge. Some of these are

 (a)      Understanding the system

Conservation agriculture systems are much more complex than conventional systems. Site specific knowledge has been the main limitation to the spread of CA system [2]. Managing these systems efficiently will be highly demanding in terms of understanding of basic processes and component interactions, which determine the whole system performance. For example, surface-maintained crop residues act as mulch and therefore reduce soil water losses through evaporation and maintain a moderate soil temperature regime [6]. However, at the same time crop residues offer an easily decomposable source of organic matter and could harbour undesirable pest populations or alter the system ecology in some other way. No-tillage systems will influence depth of penetration and distribution of the root system which, in turn, will influence water and nutrient uptake and mineral cycling. Thus, the need is to recognize conservation agriculture as a system and develop management strategies.

  (b)     Building a system and farming system perspective

A system perspective is built working in partnership with farmers. A core group of scientists, farmers, extension workers and other stakeholders working in partnership mode will therefore be critical in developing and promoting new technologies. This is somewhat different than in conventional agricultural R and D, the system is to set research priorities and allocate resources within a framework, and little attention is given to build relationships and seek linkages with partners working in complementary fields.

 (c) Technological challenges

While the basic principles which form the foundation of conservation agriculture practices, that is, no tillage and surface managed crop residues are well understood, adoption of these practices under varying farming situations is the key challenge. These challenges relate to development, standardization and adoption of farm machinery for seeding with minimum soil disturbance, developing crop harvesting and management systems. (d) Site Specificity-Adapting strategies for conservation agriculture systems will be highly site specific, yet learning across the sites will be a powerful way in understanding why certain technologies or practices are effective in a set of situations and not effective in another set. This learning process will accelerate building a knowledge base for sustainable resource management.

 (e)       Long-term research perspective

Conservation agriculture practices, e.g. no-tillage and surface- maintained crop residues result in resource improvement only gradually, and benefits come about only with time. Indeed, in many situations, benefits in terms of yield increase may not come in the early years of evaluating the impact of conservation agriculture practices. Understanding the dynamics of changes and interactions among physical, chemical and biological processes is basic to developing improved soil-water and nutrient management strategies. Therefore, research in conservation agriculture must have longer term perspectives.

Types of conservation tillage

1. Ridge Tillage: Ridge tillage is a form of conservation tillage that uses specialized planters and cultivators to maintain permanent ridges on which row crops are grown.
2. Minimum tillage: Aims at reducing tillage operations to the minimum necessity for a reasonably good seed bed to establish adequate crop stand and favourable soil conditions for growth and development of crops. Use of herbicide is must for control of weeds.
3. Zero/No tillage: No-till systems, as the name implies, do not use tillage for establishing a seedbed. Crops are simply planted into the previous year’s crop residue. No-till planters are equipped with coulters that slice the soil, allowing a double disc opener to place the seed at a proper depth. The slot is closed with a spring press wheel. Herbicides are typically used as the sole means for weed control in no-till systems.

Agronomic soil conservation measures:

• Use of vegetation
• Crop rotation
• Strip cropping
• Tillage
•  Mulching
• Cultivation of dense plant and grasses

Effect of conservation tillage & crop residue on physical properties of soil

• Improves soil structure and aeration
•  Maintain soil health
• Increase water use efficiency
• Reduce erosion
• Reduce soil water evaporation, soil sealing and crusting
• Increase soil hydraulic conductivity and infiltration
• Improves soil structure, proportion of macro-pores, and aggregate stability

             Deepening of rooting horizon

Effect of conservation tillage & crop residue on chemical properties of soils

• Increase organic matter content
• Improves soil reaction and buffer capacity of soil
• Improves the fertility and productivity of soil
• Improves
• Soil organic C
• Available N
• Available P
• Exchangeable K

Effect of conservation tillage & crop residue on biological properties of soil

• Increase microbial activity
• Increases biological nitrogen fixation
• Improves mineralization of nutrients
• Increases soil C and N
• More abundant soil life – earth worms, etc

Conclusion

Conservation agriculture (CA) practice which minimizes the soil disturbance, maintains soil cover, and rotates crops, is a proven technique that improves soil fertility, reducing soil loss and runoff and conserving soil moisture, increasing grain yield of crops. CA system is recommended for soil conservation as a long-term strategy. Adoption of CA helps to conserve moisture reduced soil erosion and enhance soil organic carbon concentration. Soil carbon sequestration is one of the most effective strategies to mitigate the effect of increasing concentration of CO₂ in the atmosphere. CA helps to reduce atmospheric carbon and increase SOC concentration through no tillage, crop rotation and crop residue retention on soil. CA increase SOC but challenges like diverse cropping system, low yield, non availability of small size seeders, burning of crop residues, use of crop residue for live stock feed and fuel, weed preponderance hinders the adoption of CA. Conservationists are always looking towards the future. In this case CA is a very important process to be looked at for future generation. There are many organizations that have been created to help educate and inform producers and conservationists in the world of CA. These organizations can help to inform, conduct research, and buy land in order to preserve animals and plants

References

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4. Land Use Statistics (2019), Ministry of Agriculture and Farmers Welfare.
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