Conservation Agriculture

Global Prospects and Challenges

Ram Jat, Kanwar Sahrawat, Amir Kassam, Ram Jat, Kanwar Sahrawat, Amir Kassam

• Editore: CAB International
• Anno: 2013
• ISBN:
  9781789243871
• Argomento: Technik & Maschinenbau
• Categoria: Nachhaltige Landwirtschaft

The book covers the spread of conservation agriculture (CA) to regions including Brazil, Argentina, Canada, Australia, Europe and emerging CA destinations in Asia and Africa. Topics covered include the various components of CA, and how their individual and combined implementation influence productivity, soil health and environmental quality under diverse edaphic and climatic conditions. The book will be useful to teachers, researchers, extensionists, farmers, and students interested in environmental quality.

1 Conservation Agriculture for Sustainable and Resilient Agriculture: Global Status, Prospects and Challenges

Ram A. Jat,^1,2 Kanwar L. Sahrawat,² Amir H. Kassam^3,4 and Theodor Friedrich^3
1Directorate of Groundnut Research, Junagadh, India; ²International Crops Research Institute for the Semi-Arid Tropics, Patancheru, India; ³Plant Production and Protection Division, Food and Agriculture Organization of the United Nations, Rome, Italy; ⁴School of Agriculture, Policy and Development, University of Reading, Reading, UK

1.1 Introduction

Achieving food security for a burgeoning population, particularly in the less developed nations, and developing sustainable agricultural production systems are among the major challenges before the world in 21st century. The challenge is not only to ensure sufficient food for all the people but also to meet the ever increasing demand for meat, eggs, fruits and vegetables by the rapidly expanding middle class population in developing nations. The challenges are getting further confounded due to imminent climate change-related risks, the adverse effects of which have already started being experienced in one or other form in agricultural production systems in various parts of the globe. As more and more agricultural land is being diverted towards industrial and residential uses throughout the world, we have to produce more and more food from increasingly less-cultivated land. This will further strain the already fragile natural resource base, particularly land and water, making it more difficult to meet the food requirements of the world. Therefore, there is urgent need to conserve or even improve the natural resources from being degraded by water and wind erosion, which is accelerated manifold due to human activities.

Although more than 99% of the world’s food comes from the soil, experts estimate that each year more than 10 Mha of crop land are degraded or lost as rain and wind sweep away topsoil. An area large enough to feed Europe – 300 Mha, about ten times the size of the UK – has been so severely degraded it cannot produce food, according to UN figures (The Guardian, 2004).

Soil degradation is rampant both in developed and less developed nations. In fact the highest levels of land degradation are in Europe. ‘Specifically degraded soils are found especially in semi-arid areas (Sub-Saharan Africa, Chile), areas with high population pressure (China, Mexico, India) and regions undergoing deforestation (Indonesia)’ (Philippe Rekacewicz, UNEP/GRID-Arendal, 2007). The perception that land is an infinite natural resource has taken a heavy toll, leading to severe land degradation in many parts of the world. Every year millions of tonnes of sediments are discharged with runoff water throughout the world. This not only causes loss of agriculturally precious topsoil, but also affects aquatic ecosystems negatively by dumping nutrients and the silting of water bodies. Furthermore, widespread and severe decline of soil quality in almost all production regions also raises questions about the sustainability of current agricultural production practices (Verhulst et al., 2010).

According to IPCC-based climate change predictions, most of the rainfall will occur in the form of high-intensity short-duration rain events due to global climate change effects (IPCC, 2007). If that becomes true, efficient use of rainwater through both in situ and ex situ moisture conservation practices will be imperative to achieve the objective of getting higher yields and conserving the natural resource base. This warrants that more proactive efforts should be made for developing and adopting resource-conserving technologies to increase global food production in a sustainable way amid the confounding challenges facing agriculture. Conservation Agriculture (CA), consisting of minimum mechanical soil disturbance, soil cover with plant biomass/cover crops and diversified crop rotations or associations, is viable and seems a more sustainable cultivation system than that presently practised. CA reduces soil erosion, improves soil quality, reduces soil compaction, improves rainwater use efficiency, moderates soil temperature, gives higher and stable yields, saves inputs, reduces cost of cultivation and helps in climate change mitigation and adaptation (Machado and Silva, 2001; Kassam et al., 2009; Hobbs and Govaerts, 2010; Lal, 2010; Jat et al., 2012b). CA principles are universally applicable to all agricultural landscapes and land uses with of course locally adapted practices (Kassam and Friedrich, 2012).

1.2 Conservation Agriculture: the Way Forward for Sustainable Agricultural Production

During the past few decades, rapid strides have been made all over the world to develop and disseminate CA practices. CA has emerged as a major way forward from the existing plough-based unsustainable conventional agriculture (ConvA), to protect the soil from water- and wind-led degradation processes and make agricultural production systems sustainable. Empirical evidences suggest that zero tillage-based agriculture along with crop residue retention and adoption of suitable crop rotations can be productive, economically viable and ecologically sustainable given that farmers are involved in all the stages of technology development and dissemination (Friedrich et al., 2012). CA specifically aims to address the problems of soil degradation due to water and wind erosion, depletion of organic matter and nutrients from soil, runoff loss of water and labour shortage. Moreover, supporters of the CA movement claim that CA is able to address the negative consequences of climate change on agricultural production through improved rainwater use efficiency, moderating soil and plant canopy temperature and timely performance of agronomic operations (Gupta et al., 2010; Jat et al., 2012b). However, there is need to identify, evolve and disseminate region- specific CA practices through active involvement of farmers along with researchers, technicians, machinery manufacturers and policy makers (Fowler and Röckstrom, 2000).

1.3 Conservation Agriculture: Definition and Concept

According to the FAO, ‘CA is an approach to managing agro-ecosystems for improved and sustained productivity, increased profits and food security while preserving and enhancing the resource base and the environment’ (Friedrich et al., 2012). CA has been designed on the principles of integrated management of soil, water and other agricultural resources in order to reach the objective of economically, ecologically and socially sustainable agricultural production.

CA is characterized by three major principles (FAO, 2012):

• Minimal mechanical soil disturbance by direct planting through the soil cover without seedbed preparation;

• Maintenance of a permanent soil cover by mulch or growing cover crops to protect the soil surface;

• Diversifying and fitting crop rotations and associations in the case of annual crops and plant associations in the case of perennial crops.

Usually, the retention of 30% surface cover by residues characterizes the lower limit of classification for CA. The concept of CA has evolved from the zero tillage (ZT) technique. In ZT, seed is put in the soil without any prior soil disturbance through any kind of tillage activity or only with minimum soil mechanical disturbance. In zero-tilled fields, with time, soil life takes over the functions of traditional soil tillage such as loosening the soil and mixing the organic matter. In CA, due to minimum soil disturbance, soil life and biological processes are not disturbed, which is crucial for a fertile soil supporting healthy plant growth and development. The soil surface is kept covered either by crop residues, cover crops or biomass sourced ex situ through agroforestry measures, which provide physical protection for the soil against agents of soil degradation; and equally importantly provides food for the soil life. The burning or incorporation of crop residues is strictly avoided in CA. At the same time varied crop rotations involving legumes in CA help to manage pest and disease problems and improve soil quality through biological nitrogen fixation and addition of organic matter (Baudron et al., 2009).

1.4 Global History, Current Status and Prospects of Conservation Agriculture

The origin of the CA movement can be traced in the 1930s when the dustbowls devastated vast areas of the mid-west USA. The new concepts of reduced tillage were introduced, as against the conventional intensive tillage-based cultivation systems, so as to ensure minimum soil disturbance and to protect the soil from water and wind erosion. Seeding machinery was developed for seeding directly with minimum soil disturbance through the surface-lying residues to ensure optimum crop stand (Friedrich et al., 2012). But it was not until the 1960s that CA could enter into the farming practices in the USA. At present, CA is practised over an area of 26.5 Mha in the USA, which constitutes only 16% of the cropland. Protecting soils from devastating soil erosion, moisture conservation and timely planting of crops have been the major incentives for development and spread of conservation tillage in the USA. The no-till system entered into Brazil in the early 1970s as a potential remedial measure to the severe problem of soil loss due to water erosion in the tropical and subtropical regions of Brazil. The no-till practice was further refined in Brazil to suit the local requirements with the active collaboration of researchers, extension workers, progressive farmers; and with government support. Subsequently, the principles of keeping the soil covered either with crop residues or cover crops, and the adoption of suitable crop rotations/associations were added with the principle of minimum soil disturbance, and the term CA was given to this new concept of farming (Denardin et al., 2008). Brazil became the cradle for evolution of the CA movement.

The expansion of NT area in Brazil occurred mainly due to the availability of no-till seeders, adapted and developed with the support of research institutions and with farmers’ evaluations as well, the attractive agricultural investment financing, the farmers’ interest in changing their farming system and the machinery industries’ interest in expanding their market’ (Calegari et al., Chapter 3, this volume).

Currently, Brazil along with other Latin American countries of Argentina, Paraguay and Uruguay, is among the leading countries of the world having the largest area under CA of their total cropland. However, there are serious concerns about the quality of CA being practised in these countries; for example, due to market pressures farmers are practising monocropping of soybean without growing cover crops in between two successive crops of soybean, leading to heavy soil erosion and land degradation (Friedrich et al., 2012). In Canada, even though no-till started in the 1970s, its rapid adoption started only in the early 1990s (see Lafond et al., Chapter 4, this volume). The necessity to protect the soil against devastating wind erosion during the fallow dry season, the introduction of winter wheat in the Prairies of Canada, availability of cheaper and effective herbicides, determined efforts of progressive farmers, supportive government policies, knowledge transfer through farmers’ associations, design and development of no-till seeders by the private manufacturers according to the needs of local farmers, were the major factors that contributed to the spread and successful adoption of CA in the Canadian Prairies. Today, with 13.5 Mha area under CA in Canada, with the highest being in Saskatchewan followed by Alberta, Canadian farmers are witnessing the benefits of CA in terms of reduced wind erosion, increased hectarage under winter wheat, improved soil quality and biodiversity, among others.

The CA movement in Australia started in the mid-1970s following the visit of Australian researchers and progressive farmers to the USA and the UK; this was ably supported subsequently with availability of herbicides, particularly glyphosate, at competitive rates by private manufacturers. The main incentives for shifting from conventional intensive tillage-based farming systems to CA-based systems in Australia were: soil protection against water erosion (in northern cropping zones) and wind erosion (in western and southern cropping zones), soil moisture conservation (particularly in the dry western parts of Australia) and timely sowing of the crops. CA adoption was led in northern, central, southern and western states of Australia by the farmers in the more marginal areas where benefits in terms of soil moisture conservation and timely crop sowing were initially more obvious. The Australian government has been proactively supporting the CA movement in their country by giving important incentives through programmes such as ‘Care for our Country’, ‘The Carbon Farming Initiative’ and ‘Clean Energy Future Plan’, which led to a steady increase in hectarage under CA in Australia since the early 1990s (see Rochecouste and Crabtree, Chapter 5, this volume). Currently, Australia and New Zealand together have 17.16 Mha area under CA, which constitutes 14% of global CA hectarage.

CA is not widespread in Europe; the no-till systems cover only 1% of arable crop-land (Friedrich et al., 2012). In Europe, ECAF (European Conservation Agriculture Federation) has been promoting CA since 1999. Spain (650,000 ha), France (200,000 ha), Finland (160,000 ha) and the UK (150,000 ha) are the leading countries in the adoption of CA in Europe. Other countries practising CA to some extent in Europe are Ireland, Portugal, Germany, Switzerland and Italy. The agricultural policies in the European Union such as direct payment to farmers and subsidies on certain commodities, moderate climate and interest groups opposing the introduction of CA are the main reasons for slower adoption of CA in Europe (see Friedrich et al., Chapter 6, this volume).

In Russia, hectarage under CA as per FAO definition is 4.5 Mha, while conservation tillage is reported to be practised on 15 Mha. In Ukraine, area under CA has reached 600,000 ha.

In Central Asia, with the active support of development agencies such as FAO, CIMMYT and ICARDA, Ka...