Sustainable Intensification and Conservation Agriculture
Moderator, Global Platform for CA Community of Practice, FAO, Italy
Convener, Land Husbandry Group, Tropical Agriculture Association, UK
Visiting Professor, School of Agriculture, Policy and Development, University of Reading, UK
The no-till farming system involving soil cover and crop diversification, known as conservation agriculture (CA), is fundamentally changing farming practices and management of the land resource base, the landscape and the environment. CA enhances ecosystem services and resilience, and offers additional economic and environmental benefits that are difficult or impossible to achieve with conventional tillage agriculture.
CA is practiced on 125 million hectares (about 9% of cropland) across all continents, and has expanded by 8-9 million hectares per annum in recent years (Table 1). Some 50% lies in developing countries, including in ACP countries, namely Kenya, Lesotho, Malawi, Mozambique, Tanzania, Zambia and Zimbabwe (Table 2). CA can support farmers in achieving sustainable intensification, thus simultaneously improving yields, efficiency, resilience and ecosystem services (see Box 1).
Given that CA can contribute to the goal of sustainable intensification, more research and extension effort is needed on all aspects of CA to inform policy formulation and development strategies.
What is sustainable intensification?
The term ‘sustainable intensification’ has become popular in recent years and while its definition can vary, it can be considered in both a narrow and a broader sense. The narrow definition applies to the pursuit of the dual goals of higher yields (output) and productivity efficiency with fewer negative consequences on the environment while building resilience, natural capital and enhancing the flow of environmental services. This included development of integrated production systems and landscape management in rainfed and irrigated landscapes. The concept includes a whole range of ecosystem services including: maintaining soil health, the quality of drinking water and air, control of erosion and other forms of land degradation, protection of water, nutrient and carbon cycling, pollination services and issues such as the protection of landscapes, habitats, biodiversity for ecosystem functioning.
In the broader context, sustainable intensification would encompass the above dimensions, the biological products provided to and utilised by consumers and with minimum food wastage, as well as human and economic dimensions of socio-cultural aspirations, organizations and social equity and economic growth. It also implies improving the capacities of people and their informal and formal institutions to deliver and use inputs efficiently, manage systems, distribute and use outputs efficiently so as to avoid excessive wastage, and harness large-scale ecosystem services that benefit producers and consumers alike.
However sustainable intensification is defined, it is necessary to achieve increased yields in ways that do not harm the resource base and the environment, and even improve them. In recent years, this situation has begun to change as CA systems have spread.
Production intensification in the 20th Century
Much of the conduct of agricultural research, past and present, targeting increases in productivity, market access and economic gains for producers and other service providers, uses a narrow yield increase (area productivity) approach to achieve development objectives. Even when market-oriented business approaches are used, development objectives are narrowly defined in terms of ‘silver bullets’ or products that can be made commercially viable. This corresponds to the use of a narrow range of technological inputs: modern seeds, agro-chemicals, tillage and other mechanization, vaccines and drugs. Commercial viability is often based on partially costed economic gains for the farmer and the dealers that generally ignore the social and economic costs of any associated negative externalities such as soil erosion, soil degradation and loss of soil health, chemical pollution of water and environment, greater greenhouse gas emissions, and destruction of habitats and biodiversity. Consequently, wider costs do not receive adequate attention at the design and implementation phase, leading to suboptimal developmental change of the household and community resource base, the surrounding environment and ecosystem services on the one hand and of the socio-cultural fabric and social capital base on the other. The beneficiaries, in most cases the poor smallholder farmers, and their governments, the research-for-development community and aid/donor agencies also lose. Elaborating the science and policy implications of sustainable intensification based on CA concepts and principles, requires an understanding of the agricultural science and wider knowledge base as well as the current policy framework.
The agricultural productivity paradigm, and the systems associated with the Green Revolution, raised output of food and other agricultural products in industrialised and some developing nations. This technological ‘industrial’ input-output model (also referred to as science-based technologies or evidence-based technologies), assumed that if more output is required, then more inputs must be applied. The implicit assumption was that agricultural production systems are essentially closed. It has been guided by the following three principles:
(a) The improvement of genetic potentials of crop and animal genotypes;
(b) Greater application of external inputs of agrochemicals for plant nutrition and pest (weeds, pathogens, insects, parasites) control; and
(c) Increased mechanical disturbance of the soil and terrain for crop establishment and other farming operations.
The results have not only been increased yields and total outputs but seemingly sub-optimal factor productivity and lower-than-optimum agronomic and economic yield ceilings that have become increasingly difficult to manage and more expensive to maintain over time, as negative externalities and inefficiencies increase and production factor productivities decrease. Worse, there have been negative consequences, namely:
- loss of soil organic matter, porosity, aeration, biota (corresponding to declining soil health), leading to the collapse of soil structure, surface sealing, often accompanied by mechanical compaction, decrease in infiltration, leading to waterlogging and flooding) (Plate 1);
- loss of water as runoff and of soil as sediment;• loss of soil rooting zone, leading to stunted root system and loss of resilience as well as functional relationship with soil biota;
- loss of time, seeds, fertilizer, pesticide (erosion and leaching);
- less capacity to capture and slowly release water and nutrients;
- lower efficiency of mineral fertilizer: “The crops have become ‘addicted’ to fertilizers”;
- loss of biodiversity in the ecosystem, below and above the soil surface;
- more pest problems resulting from breakdown of food-webs for micro-organisms and natural pest control;
- falling input efficiency and factor productivities, declining yields;
- reduced resilience, reduced sustainability;• poor adaptability to climate change and its mitigation; and
- higher-than-necessary production costs, lower farm productivity and profit, and degraded ecosystem services;
- technologies are often uneconomic for, and not affordable by poor farmers, thus making development interventions unnecessarily expensive.
So, while the model has contributed to intensification and, certainly enabled global food supplies to remain ahead of growing global demand, there has also been growing alarm at the serious environmental, economic and social consequences. Clearly, 21st century agriculture can no longer repeat what constituted agriculture in the second half of the 20th century, when the challenge is to now produce more from less and with minimum damage to the environment and the resource base and to enhance the flow of ecosystem services. Further, to respond to challenges of scarce resources of biodiversity, land and water, it is necessary to rehabilitate agricultural land that has been degraded and/or abandoned owing to past abuse, and conserve and optimise the use of remaining water and biodiversity resources. This is the new challenge for science and policy. While agriculture can be treated as a closed system with intensive mechanical and chemical disturbances that alter and disrupt ecosystem equilibrium, functions and services, in reality they eventually lead to disequilibrium in which land and environmental degradation of biodiversity and ecological potential set sub-optimal and lower productivity limits as well as sub-optimal system resilience, all of which work against enhancing the natural resource base and strengthening sustainability.
Conservation Agriculture and sustainable intensification
CA fits within the sustainable intensification paradigm of producing more from less; enhancing the resource base and its productivity and ecosystem service capacity over time. Thus, it is not intensification in the classical sense of greater use of inputs but rather of the intensification of knowledge, skills and management practices and sound and the complementary judicial use of other inputs. Outputs of desired products and ecosystem services are built on three interlocked principles and empirical evidence, and increasingly, scientific evidence shows that they become transformed into agro-ecological systems. The principles are:
(i) avoiding mechanical soil disturbance by direct seeding and planting into untilled soil, to enhance and maintain soil organic matter, soil structure and biopores, and overall soil health with associated biodiversity and ecosystem functions;
(ii) maintaining a continuous protective organic cover on the soil surface, using crop residues and cover crops (legume and non-legumes) to protect the soil surface, conserve water and nutrients, increase biologically fixed nitrogen, minimise runoff and erosion, promote soil biological activity, and contribute to integrated management of weeds, pathogens and insects pests;
(iii) growing a wider range of plant species – both annuals and perennials – in associations, sequences and rotations that can include trees, shrubs, pastures and crops, in order to enhance crop nutrition and improve system resilience.
Practices based on these principles and supported by “good agricultural practices” provide a robust ecological underpinning to any rainfed or irrigated production system including arable, horticulture, agroforestry, plantation, pasture, crop-livestock and mixed systems, thereby making them ecologically sustainable while predisposing them to respond efficiently to any applied production inputs to achieve intensification. They work synergistically to produce positive outcomes in terms of individual and overall factor productivities, and resilience.
The relationship between components of CA and desired soil and agro-ecosystem conditions and benefits are listed in Table 1. For example, many of the benefits under the no-till component and under the mulch cover component are not necessarily possible under tillage agriculture. The main criterion is the provision of an optimum environment in the root-zone to maximum possible depth. Roots function effectively and without restrictions to capture plant nutrients and water, and interact with a range of soil microorganisms beneficial for crop performance. Water thus enters the soil so that: (a) plants rarely suffer water stress that would limit the expression of their potential growth; and (b) residual water passes down to groundwater and stream flow, not over the surface as runoff. Beneficial biological activity, including that of plant roots, thus occurs in the soil, where it maintains and rebuilds soil architecture, competes with potential in-soil pathogens, contributes to soil organic matter and various grades of humus, and contributes to capture, retention, chelation and slow release of plant nutrients. The key feature of a sustainable soil ecosystem is the biotic actions on organic matter in suitably porous soil. Thus, ‘conservation-effectiveness’ encompasses not only conserving soil and water, but also the biotic bases of sustainability. CA principles are universally applicable to all agricultural landscapes and land uses with locally adapted practices.
What are the implications of low-input agriculture with CA for the environment and farmers?
Tillage-based low-input agriculture as currently being practiced either manually or with animal traction is unsustainable or sub-optimal, as explained earlier. A hand-operated hoe has the same effect on the soil health and soil functions as an animal-drawn (Plate 2) or tractor-drawn plough-based system, creating a compact ‘hoe and feet’ pan below the destructured top soil. This leads to a low-equilibrium trap of poor productivity response to any purchased inputs of seeds and fertilizer, and increased drudgery for the farmer, because every season the degraded soil has to be mechanically loosened but the temporary benefits of tilling soon disappear. For the farmer, this situation leads to poor return to land and labour, greater risks of failure from abiotic and biotic stresses, and sub-optimal performance and consequently to abandonment of the land and moving to new land, or giving up farming altogether.
The new CA-based paradigm for achieving a different kind of ‘Green Revolution’ that is sustainable is taking roots globally. It is agro-ecologically more in harmony with nature and natural processes and involves a more responsible engagement by farmers because it is less of an industrial ‘black box’ paradigm being imposed on farmers and the public institutions, including education, research and extension services. While many conventional agronomists and socio-economists are still arguing for current tillage farming, agro-ecological approaches are being tested and are spreading on all continents with farmers being very much at the centre of this transformation and driving the spread and adaptation process. CA (not just no-till) is a quintessential example of the agro-ecologically based sustainable intensification approach that requires lower amounts of all production inputs including energy, seeds, agro-chemicals, machinery, and time, and offers greater productivity than the non-CA counterpart systems.
CA works equally well with traditional varieties and requires much less inorganic fertilizer. It can be made to operate with no fertilizer if there is a supply of nutrients through a combination of legumes as cover crops in the cropping system and some organic source of plant nutrients. In low-input situations, adopting CA gradually reduces the labour required for weeding too because the soils become healthier as soil biodiversity returns and soil structure develops, partly because the weed seed bank, when left undisturbed in the soil, rots away over time, and the soil surface mulch and cover crops suppress weeds. Thus CA provides an alternative approach to achieving sustainable intensification in low-input agriculture using traditional varieties and methods of maintenance of soil fertility. CA allows slash-and-burn systems to be developed into simple slash-and-mulch systems that can, over time, be improved by introducing legume and pasture cover crops and increasing crop and livestock biodiversity.
What are the science and policy implications?
When farmers switch to CA from tillage farming, a mix of economic and environmental benefits can be expected, which manifest over time. The mix varies depending on several factors including: agro-climatic conditions and variability within and between seasons, initial status of soil health and drainage under tillage systems, farm size and source of farm power, cropping system sophistication, yield levels under tillage systems, farmer expertise of CA systems and access to production inputs, equipment and machinery, and competition for crop residues as livestock feed and farm and community-level arrangements for its enhancement and management.
In general, CA benefits can include: increased factor productivities and yields (depending on prevailing yield levels and extent of soil degradation); up to 70% decrease in fuel energy or manual labour; up to 50% less fertilizer use; 20% or more reduction in pesticide and herbicide use; some 30% lower water requirement; and reduced cost outlay on farm machinery. Further, it is possible to enhance climate-change adaptability of cropping systems, farms and landscapes because of improved soil-plant moisture relations, while at the same mitigating climate change through greater carbon sequestration and lower emissions of greenhouse gases. Given the much greater rainfall infiltration and reduced runoff and soil erosion, CA can also decrease flood risks, raise water resource quality and quantities as well as reduce infrastructure maintenance costs.
So, key science and policy implications of sustainable intensification based on CA systems would relate to building capacity of relevant institutions in the public, private and civil sectors to change the current conventional food and agriculture systems from sub-optimal economic and environmental status towards a state that is “fit for purpose”. Current scientific knowledge regarding agriculture is focused on tillage-based systems, and there is now need to focus on CA systems and to ensure results are disseminated widely.
What are the key research and extension areas to investigate?
Future farming and agricultural landscapes must be multi-functional and ecologically sustainable. Environmental and social research is needed to facilitate mainstreaming of the ecological and social underpinnings of sustainable intensification of production systems and of food and agriculture systems that can also facilitate pro-poor production intensification and farm systems development as well as household and global food and nutrition security goals, and landscape or terrain-based ecosystem services.
Research and extension must be strengthened in all aspects of CA management from biophysical and agronomic to socio-economic and policy, in relation to crop associations, sequences and rotations. Research and extension in ACP nations should explain the basis for the superior performance achieved with CA, and identify cropping systems management options across all types of farm power – manual, with animal traction, and mechanised – that can maximise such benefits.
Research and extension should also explain and utilise the operational linkages between increase in output and factor productivity and the simultaneous harnessing of soil health, ecosystem services and enhancement of resilience at the plant, crop, cropping system and farm level. Water, carbon, nutrient, soil and soil biota, biodiversity and landscape-related services are particularly relevant in addressing many of the global constraints of food insecurity, escalating prices, land and biodiversity degradation, resource scarcity and climate change. CA approaches and methodologies for sustainable intensification offer effective and affordable pro-poor development options that can integrate and hold together environmental and social aspects with productivity and technological aspects, and offer greater opportunity for participatory research and extension planning, design and implementation. Such approaches and methodologies should be part of the core research and extension strategy of every ACP nation so that information, including regarding the economics of CA, is available to help formulate and implement affordable pro-poor development initiatives for sustainable intensification.
Such initiatives should involve culturally sensitive methodologies in biophysical, technological and policy research. Research on social organization patterns of farmers and their households and on institutional analysis should be encouraged. Institutional learning in areas such as social capital formation and activation, factors of collective action, community and group resource management and studies on social impact of research, and how policy and power relations affect technology adoption by producers and produce social policy and strategy recommendations for intensification with equity is also necessary.
One area where expertise could be strengthened is in sustainable production systems and intensification with a practical background and expertise in CA-related watershed services, carbon-offset management, sustainable soil and landscape management. Social research and extension requiring expertise in rural sociology and social anthropology and familiarity with the role of social and cultural variables in pro-poor sustainable intensification with equity is vital.
Adoption of CA has constraints that must be overcome before large-scale dissemination and adoption. For example, establishment can be difficult in the initial years in some semi-arid areas and on heavy clay soils, compacted soils and poorly drained land. Control of pests and diseases can also be a concern where crop residues are left on the soil, and pesticides/herbicides may be required, at least in the initial years in some labour- and mulch-constrained situations where integrated weed management strategy can take longer to establish. Competing uses for biomass as livestock feed, as soil mulch cover and as substrate for soil life can pose a challenge. There can be other location-specific socio-economic issues that must be addressed such as perceived risk of loss in productivity in initial years or possibility of displacement or reassignment of paid farm labour to new activities. On larger farms, the lack of appropriate equipment for seeding and fertilizer placement through surface mulches can be problematic.
The international spread of CA offers lessons which show that the above-mentioned challenges can be and are being overcome by farmers, rich or poor, small or large, through locally-formulated solutions working together with a range of public and private sector stakeholders along different pathways of adoption and transformation, provide lessons for research, policy and practice.
There are several ways to support scaling up of CA:
- Advocate for initial government support in terms of subsidies to make appropriate farm equipment more readily accessible and to reduce any risks of possible productivity loss during the initial years of switching to CA.
- Encourage governments to update their agricultural policies and bring institutional reform that supports the up-scaling of CA, especially in sub-Saharan Africa – where it is perhaps most urgently needed.
- Develop large-scale programmes that would offer payments to CA farmers for harnessing ecosystem services such as carbon sequestration, watershed services for increasing the quality and quantity of water resources, control of soil erosion and reduction in flood risks, and enhancing pollination services.
- Fund more innovative practical research and extension to tackle soil, agronomic and livestock husbandry challenges through universities and research organizations.
- Revise universities’ agriculture curriculums to include teaching the next generation of farmers and agricultural development practitioners about CA as an alternative and sustainable way of farming.
Fuller advantage of the benefits offered by CA can be taken if all stakeholders become involved in facilitating the transformation process, as is happening in countries such as Argentina, Australia Brazil, Canada, Paraguay and USA, . However, a more structured response to the opportunities presented by CA calls for a realignment of agricultural institutions, and greater investments in research, extension and education, as well as providing evidence for updating agriculture development policies to enable CA to become mainstreamed.
FAO 2011. Save and Grow: A Policymakers Guide to the Sustainable Intensification of Smallholder Crop Production. FAO, Rome, Italy.
Goddard, T., Zoebisch; M.A., Gan, T.Y., Ellis, W., Watson, A., Sombatpanit, S. (Eds.) 2007. No-Till Farming Systems. Special Bulletin 3. World Association of Soil and Water Conservation, Bangkok, Thailand.
Government Office for Science, UK. 2011. Foresight. Future of Food and Farming. The Government Office for Science, London, UK.
Lal, R. Stewart, B.A. (Eds.) 2013. Principles of Sustainable Soil Management in Agroecosystems. CRC Press, Taylor & Francis Group, Boca Raton, Florida, USA.
Figure 1: Soil compaction and loss in water infiltration ability caused by regular soil tillage leads to impeded drainage and flooding after a thunderstorm in the ploughed field (right) and no flooding in the no-till field (left). Photograph taken in June 2004 in a plot from a long-term field trial ‘Oberacker’ at Zollikofen close to Berne, Switzerland, started in 1994 by Swiss No-till. The three water filled ‘cavities’ in the no-till field derive from soil samples taken for ‘spade tests’ prior to the thunder storm (Source: Wolfgang Sturny)
Figure 2: Direct seeding into mulch with animal drawn ripper-seeder in Zambia (Source: Josef Kienzle)
Table 1: Global area distribution of CA by continent
|Continent||Area (ha)||Percentage of total||CA as percentage of arable cropland|
|Australia & NZ||17,162,000||14||69.0|
|Russia & Ukraine||5,100,000||4||3.3|
Table 2: CA adoption in African countries
|Country||CA area (ha)|
Table 3: Effects of production system components fully applied together on sustainability and ecosystem services
System component ►
To achieve ▼
(crop residues cover-crops, green manures)
(minimal or no soil disturbance)
(as crops for fixing nitrogen and supplying plant nutrients)
(for several beneficial purposes)
|Simulate optimum ‘forest-floor’ conditions||√||√|
|Reduce evaporative loss of moisture from soil surface||√|
|Reduce evaporative loss from soil upper soil layers||√||√|
|Minimize oxidation of soil organic matter, CO2 loss||√|
|Minimize compactive impacts by intense rainfall, passage of feet, machinery||√||√|
|Minimize temperature fluctuations at soil surface||√|
|Provide regular supply of organic matter as substrate for soil organisms’ activity||√|
|Increase, maintain nitrogen levels in root-zone||√||√||√||√|
|Increase CEC of root-zone||√||√||√||√|
|Maximize rain infiltration, minimise runoff||√||√|
|Minimize soil loss in runoff, wind||√||√|
|Permit, maintain natural layering of soil horizons by actions of soil biota||√||√|
|Increase rate of biomass production||√||√||√||√|
|Speed soil-porosity’s recuperation by soil biota||√||√||√||√|
|Reduce labour input||√||√|
|Reduce fuel-energy input||√||√||√|
|Reduce pest-pressure of pathogens and insects||√||√||√|
|Re-build damaged soil conditions and dynamics||√||√||√||√|
Box 1: The case of CA in Kenya and Tanzania
From 2004, the CA-SARD Project (Conservation Agriculture for Sustained Rural Development) introduced the concept of CA in rural areas of northern Tanzania and in western and central regions of Kenya, where there was evidence of widespread land degradation, low soil fertility and high soil loss because of poor cover and low organic matter levels. It had the developmental objectives of improving the food security and rural livelihoods of small- and medium-scale farmers, to be approached through Farmer Field Schools, in which all production constraints are identified and farmers and community leaders are involved in learning about CA. The area covered approximately four agro-ecological zones, from the Upper Highlands to the Lower Midlands, across which the climatic conditions correspond with altitudinal gradient in terms of rainfall (400-2200 mm/year), temperature and soil fertility. The higher the altitude, the higher the rainfall and the lower the soil degradation.
In 2008, participatory assessments by practicing farmers showed net financial benefits can be higher under CA than under conventional tillage agriculture, particularly because of savings in labour/time, less fertilizer required to maintain yields, and reduced energy/fuel costs for tillage and spraying operations. Smallholders (2.5-10 ha) covered about 20,000 ha of land parcels, under mixed cropping systems using manual labour or animal traction. They combined no-till and permanent soil cover with legume cover crops such as Dolichos lablab and pigeon pea. By 2008, positive improvements were quantified for earthworm populations, biomass and grain yields.
Livelihood impact assessment in Tanzania in 2011 showed that CA had returned much needed nutrients to depleted soils. Water-use efficiency followed improved water cycle of infiltration, holding and uptake. Land degradation had reduced through the elimination of tillage, use of soil cover and building contour bunds. Farmers adapted to the effects of climate change as evidenced from the noticeable differences in yields between CA and conventional farmers in periods of low rainfall. Through higher output-to-input ratios and subsequent improved efficiency of land and labour, smallholders can make better use of limited resources, improve yields and build financial capital through the sale of surplus crops. Natural capital increased through CA because of the reversal of degradation trends and erosion that have led to reduced yields.
Through the generation of natural and financial capital, smallholders were able to invest in human and physical capital such as education for children, improved health through better nutrition and medicine, and household improvements such as more durable walls and roofing and purchase of solar panels. With the income gains made from higher yields, smallholders were investing in more lucrative livestock practices including dairy cows and poultry. Since CA adoption there had been a shift from the majority of time being spent on growing crops to attending to livestock, highlighting the time-saving aspects of CA and the opportunity this creates to raise more income from livestock. Together, the stakeholders were able to overcome a major issue presented by the potential conflict of crop residue use by training smallholders on livestock management and the implementation and enforcement of bylaws protecting land from grazing.
By 2011, with support from government and NGOs, the spread of CA had increased to 33,000 ha in Kenya and 25,000 ha in Tanzania, mainly on smallholder farms.
From FAO Conservation Agriculture website (http://www.fao.org/ag/ca/)
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