Peter Hobbs

The role of conservation agriculture in sustainable agriculture

The paper focuses on conservation agriculture (CA), defined as minimal soil disturbance (no-till, NT) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. Cultivation and tillage play an important role in agriculture. The benefits of tillage in agriculture are explored before introducing conservation tillage (CT), a practice that was borne out of the American dust bowl of the 1930s. The paper then describes the benefits of CA, a suggested improvement on CT, where NT, mulch and rotations significantly improve soil properties and other biotic factors. The paper concludes that CA is a more sustainable and environmentally friendly management system for cultivating crops. Case studies from the rice–wheat areas of the Indo-Gangetic Plains of South Asia and the irrigated maize–wheat systems of Northwest Mexico are used to describe how CA practices have been used in these two environments to raise production sustainably and profitably. Benefits in terms of greenhouse gas emissions and their effect on global warming are also discussed. The paper concludes that agriculture in the next decade will have to sustainably produce more food from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. Promoting and adopting CA management systems can help meet this goal.

Conservation agriculture: What is it and why is it important for future sustainable food production?

Conservation agriculture (CA), defined as minimal soil disturbance (no-till) and permanent soil cover (mulch) combined with rotations, is a more sustainable cultivation system for the future than those presently practised. The present paper first introduces the reasons for tillage in agriculture and discusses how this age-old agricultural practice is responsible for the degradation of natural resources and soils. The paper goes on to introduce conservation tillage (CT), a minimum tillage and surface mulch practice that was developed in response to the severe wind erosion caused by mouldboard tillage of grasslands and referred to as the American dust bowl of the 1930s. CT is then compared with CA, a suggested improvement on CT, where no-till, mulch, and rotations significantly improve soil properties (physical, biological, and chemical) and other biotic factors, enabling more efficient use of natural resources. CA can improve agriculture through improvement in water infiltration and reducing erosion, improving soil surface aggregates, reducing compaction through promotion of biological tillage, increasing surface soil organic matter and carbon content, moderating soil temperatures, and suppressing weeds. CA also helps reduce costs of production, saves time, increases yield through more timely planting, reduces diseases and pests through stimulation of biological diversity, and reduces greenhouse gas emissions. Availability of suitable equipment is a major constraint to successful CA, but advances in design and manufacture of seed drills by local manufacturers are enabling farmers to experiment and accept this technology in many parts of the world. Estimates of farmer adoption of CA are close to 100 million ha in 2005, indicating that farmers are convinced of the benefits of this technology. The paper concludes that agriculture in the next decade will have to produce more food, sustainably, from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. This will be a significant challenge for agricultural scientists, extension personnel, and farmers. Promoting and adopting CA management systems can help meet this complex goal.

Nutritious subsistence food systems

The major subsistence food systems of the world that feed resource‐poor populations are identified and their capacity to supply essential nutrients in reasonable balance to the people dependent on them has been considered for some of these with a view to overcoming their nutrient limitations in sound agronomic and sustainable ways. The approach discusses possible cropping system improvements and alternatives in terms of crop combinations, external mineral supply, additional crops, and the potential for breeding staples in order to enhance their nutritional balance while maintaining or improving the sustainability and dietary, agronomic, and societal acceptability of the system. The conceptual framework calls for attention first to balancing crop nutrition that in nearly every case will also increase crop productivity, allowing sufficient staple to be produced on less land so that the remaining land can be devoted to more nutrient‐dense and nutrient‐balancing crops. Once this is achieved, the additional requirements of humans and animals (vitamins, selenium, and iodine) can be addressed. Case studies illustrate principles and strategies. This chapter is a proposal to widen the range of tools and strategies that could be adopted in the HarvestPlus Challenge Program to achieve its goals of eliminating micronutrient deficiencies in the food systems of resource‐poor countries.

How conservation agriculture can contribute to buffering climate change.

Agriculture contributes significantly to greenhouse gas (GHG) emissions: CO 2 , CH 4 and N 2 O. Promoting agricultural practices that mitigate climate change by reducing GHG emissions is important; but those same practices also have to improve farmer production and income and buffer the production system against changes in climate. New agricultural practices also need to prevent further soil degradation and improve system resilience. Conservation agriculture (CA), based on minimal soil disturbance, permanent ground cover and crop rotations is a management system that achieves these goals; it results in improved soil physical and biological health, better nutrient cycling and crop growth. CA also increases water infiltration and soil penetration by roots, which allows crops to better adapt to lower rainfall and make better use of irrigation water. Water and wind erosion are also reduced by CA since the soil surface is protected and water runoff is lowered as more water enters the soil profile. CA can also help to mitigate climate change. Growing rice with less water and adopting CA practices results in less CH 4 emissions. However, care has to be taken with fertilizer management to minimize N 2 O emissions that can increase under resulting aerobic conditions. CA can also substantially reduce CO 2 emissions through reduced diesel use and increased sequestration of C in the soil. This chapter recommends that an integrated research and participatory extension is needed to fine tune CA to specific locations to convince farmers to adopt this technology.

CONSERVATION AGRICULTURE IN THE INDOGANGETIC PLAINS OF INDIA: PAST, PRESENT AND FUTURE

This paper follows the progress made in India for research and farmer adoption of conservation agriculture (CA) since the publication of Erenstein (2012), who contested the idea that zero-till (ZT) establishment of wheat in rice–wheat systems could be further developed into full CA systems. Data presented in this paper show that research has successfully found solutions for both the wheat and rice phases of the rice–wheat systems of the Indo-Gangetic Plains (IGP) in the past 8 years. It shows that by finding solutions in both the rice and wheat phases, yields, water use efficiency and profits increased, while labour needs reduced. Indian scientists have also confirmed these benefits in participatory on-farm research in various locations, both east and west regions of the IGP. Farmers see for themselves through experimentation that they get higher yields with less cost and with more efficient use of inputs and water. A key factor has been the development of improved seed drills with the help of Indian private sector manufacturers of agricultural equipment. Indian scientists have also successfully conducted CA research on several other crops and in other regions besides the IGP. The paper shows that it is better to introduce parts of the CA management practices in a step-wise fashion first, rather than introducing the entire package at once since farmers first have to test and evaluate a new technology to understand how it benefits them personally before they will adopt it. The paper concludes that in the rice–wheat systems of South Asia, adoption of CA is indeed possible to achieve although it is still a work in progress. CA is a complex technology package and it takes time to overcome all of the contested issues mentioned in Erenstein (2012).

Important Rainfed Farming Systems of South Asia

Rainfed farming in South Asia uses some 60% of agricultural land. Much of this land receives no irrigation but some receives a partial or life-saving water supplement. These rainfed lands have a wide array of climates, rainfall regimes and soil types, which determine their cropping systems. The major systems in Afghanistan, Bangladesh, India, Nepal and Pakistan are described. Various common features are discussed, including use of animals, fallowing, mixed cropping, rotations, legumes, manual labour, cow dung for cooking, water harvesting and need for off-farm income. These rainfed areas have benefited from the introduction of new crop varieties and modern technology, including farm mechanization, although to a lesser extent than in the irrigated areas. Crops and livestock are both crucial to these systems with the animals often providing draught power and fiscal security. The highly variable rainfall is an important source of risk to millions of the poorest people in South Asia. However, suitable policies and greater emphasis and funding for these rainfed areas could improve livelihoods and contribute substantially to the economies of South Asian countries.