Crop production intensification will be built on farming systems that offer a range of productivity, socio-economic and environmental benefits to producers and to society at large
Crops are grown under a wide range of production systems. At one end of the continuum is an interventionist approach, in which most aspects of production are controlled by technological interventions such as soil tilling, protective or curative pest and weed control with agrochemicals, and the application of mineral fertilizers for plant nutrition. At the other end are production systems that take a predominantly ecosystem approach and are both productive and more sustainable. These agro-ecological systems are generally characterized by minimal disturbance of the natural environment, plant nutrition from organic and non-organic sources, and the use of both natural and managed biodiversity to produce food, raw materials and other ecosystem services. Crop production based on an ecosystem approach sustains the health of farmland already in use, and can regenerate land left in poor condition by past misuse1.
Farming systems for sustainable crop production intensification will offer a range of productivity, socio-economic and environmental benefits to producers and to society at large, including high and stable production and profitability; adaptation and reduced vulnerability to climate change; enhanced ecosystem functioning and services; and reductions in agriculture’s greenhouse gas emissions and “carbon footprint”.
These farming systems will be based on three technical principles:
- simultaneous achievement of increased agricultural productivity and enhancement of natural capital and ecosystem services;
- higher rates of efficiency in the use of key inputs, including water, nutrients, pesticides, energy, land and labour;
- use of managed and natural biodiversity to build system resilience to abiotic, biotic and economic stresses.
The farming practices required to implement those principles will differ according to local conditions and needs. However, in all cases they will need to:
- minimize soil disturbance by minimizing mechanical tillage in order to maintain soil organic matter, soil structure and overall soil health;
- enhance and maintain a protective organic cover on the soil surface, using crops, cover crops or crop residues, in order to protect the soil surface, conserve water and nutrients, promote soil biological activity and contribute to integrated weed and pest management;
- cultivate 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.
Those three key practices are generally associated with conservation agriculture (CA), which has been widely adopted in both developed and developing regions. Conservation agriculture is now practised on about 117 million ha worldwide, or about 8 percent of total crop land. Highest adoption levels (above 50 percent of crop land) are found in Australia, Canada and the southern cone of South America. Adoption is increasing in Africa, Central Asia and China.
However, in order to achieve the sustainable intensification necessary for increased food production, they need to be supported by four additional management practices:
- the use of well adapted, high-yielding varieties with resistance to biotic and abiotic stresses and improved nutritional quality;
- enhanced crop nutrition based on healthy soils, through crop rotations and judicious use of organic and inorganic fertilizer;
- integrated management of pests, diseases and weeds using appropriate practices, biodiversity and selective, low risk pesticides when needed;
- efficient water management, by obtaining “more crops from fewer drops” while maintaining soil health and minimizing off-farm externalities.
Ideally, SCPI is the combination of all seven of those practices applied simultaneously in a timely and efficient manner. However, the very nature of sustainable production systems is dynamic: they should offer farmers many combinations of practices to choose from and adapt, according to their local production conditions and constraints2-5.
|Contribution of sustainable intensification farming system practices to important ecosystem services|
|Objective||Mulch cover||Minimized or no tillage||Legumes to supply plant nutrients||Crop rotation|
|Simulate optimum “forest-floor” conditions|
|Reduce evaporative loss of moisture from soil surface|
|Reduce evaporative loss from upper soil layers|
|Minimize oxidation of soil organic matter and loss of CO2|
|Minimize soil compaction|
|Minimize temperature fluctuations at soil surface|
|Provide regular supply of organic matter as substrate for soil organism activity|
|Increase, maintain nitrogen levels in root zone|
|Increase cation exchange capacity of root zone|
|Maximize rain infiltration, minimize runoff|
|Minimize soil loss in runoff and wind|
|Permit, maintain natural layering of soil horizons through action of soil biota|
|Increase rate of biomass production|
|Speed recuperation of soil porosity by soil biota|
|Reduce labour input|
|Reduce fuel/energy inputs|
|Reduce pest-pressure of pathogens|
|Rebuild damaged soil conditions and dynamics|
Applied together, or in various combinations, the recommended practices contribute to important ecosystems services and work synergistically to produce positive outcomes in terms of factor and overall productivity. For example, for a given amount of rainfall, soil moisture availability to plants depends on how the soil surface, soil organic matter and plant root systems are managed. Water productivity under good soil moisture supply is enhanced when soils are healthy and plant nutrition is adequate. Good water infiltration and soil cover also minimize surface evaporation and maximize water use efficiency and productivity, in which the plants’ own capacity to absorb and use water also plays a role.
One of the main requirements for ecologically sustainable production is healthy soil, creating an environment in the root zone that optimizes soil biota activity and permits root functioning to the maximum possible extent. Roots are able to capture plant nutrients and water and interact with a range of soil micro-organisms beneficial to soil health and crop performance2, 6, 7. Maintenance or improvement of soil organic matter content, soil structure and associated porosity are critical indicators of sustainable production and other ecosystem services.
To be sustainable in the long term, the loss of organic matter in any agricultural system must never exceed the rate of soil formation. In most agro-ecosystems, that is not possible if the soil is mechanically disturbed8. Therefore, a key starting point for sustainable production intensification – and a major building block of SCPI – is maintaining soil structure and organic matter content by limiting the use of mechanical soil disturbance in the process of crop establishment and subsequent crop management.
Minimized or zero tillage production methods – as practised in conservation agriculture – have significantly improved soil conditions, reduced degradation and enhanced productivity in many parts of the world. Most agricultural land continues to be ploughed, harrowed or hoed before every crop and during crop growth. The aim is to destroy weeds and facilitate water infiltration and crop establishment. However, recurring disturbance of topsoil buries soil cover and may destabilize soil structure. An additional effect is compaction of the soil, which reduces productivity9.
One contribution of conservation agriculture to sustainable production intensification is minimizing soil disturbance and retaining the integrity of crop residues on the soil surface. CA approaches include minimized (or strip) tillage, which disturbs only the portion of the soil that is to contain the seed row, and zero tillage (also called no-tillage or direct seeding), in which mechanical disturbance of the soil is eliminated and crops are planted directly into a seedbed that has not been tilled since the previous crop3.
Another management consideration relevant to SCPI is the role of farm power and mechanization. In many countries, the lack of farm power is a major constraint to intensification of production10. Using manual labour only, a farmer can grow enough food to feed, on average, three other people. With animal traction, the number doubles, and with a tractor increases to 50 or more11. Appropriate mechanization can lead to improved energy efficiency in crop production, which enhances sustainability and productive capacity and reduces harmful effects on the environment12, 13.
At the same time, uncertainty about the price and availability of energy in the future suggests the need for measures to reduce overall requirements for farm power and energy. Conservation agriculture can lower those requirements by up to 60 percent, compared to conventional farming. The saving is due to the fact that most power intensive field operations, such as tillage, are eliminated or minimized, which eases labour and power bottlenecks particularly during land preparation. Investment in equipment, notably the number and size of tractors, is significantly reduced (although CA requires investment in new and appropriate farm implements). The savings also apply to small-scale farmers using hand labour or animal traction. Studies in the United Republic of Tanzania indicate that in the fourth year of implementing zero-tillage maize with cover crops, labour requirements fell by more than half14.
Some farming regions present special challenges to the introduction of specific SCPI practices. For example, under conservation agriculture, the lack of rainfall in subhumid and semi-arid climatic zones may limit production of biomass, which limits both the quantity of harvestable crops and the amount of residues available for use as soil cover, fodder or fuel. However, the water savings achieved by not tilling the soil generally lead to yield increases in the first years of adoption, despite the lack of residues. Scarcity of plant nutrients may prove to be a limiting factor in more humid areas, but the higher levels of soil biological activity achieved can enhance the long term availability of phosphorus and other nutrients7, 15.
Low soil disturbance or zero tillage systems are often seen as unsuitable for farming on badly drained or compacted soils, or on heavy clay soils in cold and moist climates. In the first case, if bad drainage is caused by an impermeable soil horizon beyond the reach of tillage equipment, only biological means – such as tap roots, earthworms and termites – can break up such deep barriers to water percolation. Over time, these biological solutions are facilitated by minimal soil disturbance. In the second case, mulch-covered soils do take longer to warm up and dry, compared to ploughed land. However, zero tillage is practised successfully by farmers under very cold conditions in Canada and Finland, where studies have found that the temperature of covered soils does not fall as much in winter13, 16.
Another misperception of minimized or zero tillage systems is that they increase the use of insecticides and herbicides. In some intensive systems, the integrated use of zero tillage, mulching and crop diversification has led to reductions in the use of insecticides and herbicides, in terms of both absolute amounts and active ingredient applied per tonne of output, compared with tillage-based agriculture12, 13.
In manual smallholder systems, herbicides can be replaced by integrated weed management. For example, since conservation agriculture was introduced in 2005 in Karatu district, the United Republic of Tanzania, farmers have stopped ploughing and hoeing and are growing mixed crops of direct-seeded maize, hyacinth bean and pigeon pea. This system produces good surface mulch, so that weed management can be done by hand without need for herbicides. In some years, fields are rotated into wheat. The overall results have been positive, with average per hectare maize yields increasing from 1 tonne to 6 tonnes. This dramatic yield increase was achieved without agrochemicals and using livestock manure as a soil amendment and fertilizer17.
Another potential bottleneck for wide adoption of conservation agriculture is the lack of suitable equipment, such as zero till seeders and planters, which are unavailable to small farmers in many developing countries. Even where this equipment is sold, it is often more expensive than conventional equipment and requires considerable initial investment. Such bottlenecks can be overcome by facilitating input supply chains and local manufacturing of equipment, and by promoting contractor services or equipment sharing schemes among farmers in order to reduce costs. Excellent examples of these approaches can be found on the Indo-Gangetic Plain. In most small farm scenarios, zero-till planters that use animal traction would meet and exceed the needs of a single farmer.
The way forward
Farming systems for sustainable crop production intensification will be built on the three core technical principles outlined in this chapter, and implemented using the seven recommended management practices: minimum soil disturbance, permanent organic soil cover, species diversification, use of high-yielding adapted varieties from good seed, integrated pest management, plant nutrition based on healthy soils, and efficient water management. The integration of pastures, trees and livestock into the production system, and the use of adequate and appropriate farm power and equipment, are also key parts of SCPI.
The shift to SCPI systems can occur rapidly when there is a suitable enabling environment, or gradually in areas where farmers face particular agro-ecological, socio-economic or policy constraints, including a lack of the necessary equipment. While some economic and environmental benefits will be achieved in the short term, a longer term commitment from all stakeholders is necessary in order to achieve the full benefits of such systems.
Monitoring of progress in production system practices and their outcomes will be essential. Relevant socio-economic indicators include farm profit, factor productivity, the amount of external inputs applied per unit of output, the number of farmers practising sustainable intensified systems, the area covered, and the stability of production. Relevant ecosystem service indicators are: satisfactory levels of soil organic matter, clean water provisioning from an intensive agriculture area, reduced erosion, increased biodiversity and wildlife within agricultural landscapes, and reductions in both carbon footprint and greenhouse gas emissions.
Production systems for SCPI are knowledge-intensive and relatively complex to learn and implement. For most farmers, extensionists, researchers and policymakers, they are a new way of doing business. Consequently, there is an urgent need to build capacity and provide learning opportunities (for example, through farmer field schools) and technical support in order to improve the skills all stakeholders. That will require coordinated support at the international and regional levels to strengthen national and local institutions. Formal education and training at tertiary and secondary levels will need to upgrade their curricula to include the teaching of SCPI principles and practices.
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