Contents - Previous - Next
This is the old United Nations University website. Visit the new site at http://unu.edu
The overall objective of agricultural or farming system design and management is the creation of environmental conditions that remain favourable for crop and animal production or even increase their productivity in perpetuity while at the same time minimizing adverse impacts on the resource base or, where possible, enhancing it. Consequently, it is necessary in any effort at designing sustainable farming systems to begin with:
In addition to the various causes of unsustainability indicated in figure 4.1, or the characteristics of resources and inputs which may, in association with certain practices cause unsustainability for which remedies are given (table 4.2), there are overall general issues that need to be taken into account in designing sustainable agricultural systems. These include:
Table 4.2 Selected Sustainable Agriculture Resource Input Features and Practices, Effects and Remedies
|Resource characteristic||Practice or factor contributing to unsustainability||Ameliorating or restoration technology or practice|
|1. Land tenure||Lack of security of tenure||Secure land permanently or for period that commodity is in field|
|2. Land use||Absence of plan or agreement on plan||Start as early as possible to get authorities thinking of and evolving plan|
|Land in dispute||Early settlement before use, especially for perennial crops|
|3. Vegetation management||Use of heavy mechanical equipment||Selective mechanization, e.g. use of shear blade and partially mechanized clearing; avoid very heavy equipment|
|Avoid burning large amount of dry biomass for long periods at high temperatures|
|Overgrazing||Relate stocking rate to pasture condition; use rotational grazing and fence partitioning|
|Relate all land use to the capability|
|(a) Structural damage or decline||Fire pasture||Early burning of limited dry biomass|
|Excessive or mechanical cultivation||Develop appropriate fire management for specific land use requirement|
|Fallowing and bare soil; overgrazing and loss of cover; machinery and animal traffic||Ensure adequate cover by vegetation or mulch|
|Rotational grazing and cover management|
|Relate tillage and stocking rate to pasture condition and soil type|
|(b) Acidification nutrient loss||No lime used on acid soil; use of acidifying fertilizers||Lime application if possible and|
|Use most appropriate recommendations|
|Use of resistant or acid tolerant varieties|
|(c) Erosion||Removal of vegetation cover and exposure of soil||Retention of vegetation cover by stocking adjustment, good pasture and/or wildlife management, stubble mulch - rough surface retention|
|Degradation resulting from poor cultivation technique||Use of reduced or minimal tillage, deep ripping, pasture rotation and measures to rejuvenate fragile soil|
|Use of wind-breaks and alley cropping|
|Adoption of land use that is not compatible or does not match capability of land||Improvement of capability assessment and better matching of use to it|
|5. Fire management||Uncontrolled use of fire in clearing, hunting, pasture management, etc.||Controlled use of fire; early burning in pasture management and to maintain desired species composition|
|6. Water quality||Inadequate drainage, waste and effluent water disposal||Improved engineering works to carry drainage water and effluent from animal housing; provision of sanitary inspection to enforce laws|
|Contamination of surface and groundwater by fertilizer and pesticides||This is not of common occurrence and is limited to a few large-scale "modern" farms|
|Care in use of pesticides near open water|
|Measures to minimize access of chemicals to groundwater|
|Use suitable fertilizer type and method of application to increase uptake|
|Apply fertilizer in amounts needed by crops as determined by analysis|
|Sediment and salt run-off into surface water||Better management to minimize soil erosion and salinity|
|7. Soil salinity, water- logging (irrigated agriculture)||Inefficient/excessive water use by flooding, too frequent irrigation, low infiltration||Improved water scheduling|
|Conjunctive reuse of groundwater|
|Drainage and gypsum to improve infiltration|
|Inadequate/deteriorating infrastructure||Improved water distribution networks|
|Poor site selection for irrigation areas||Soil selection should be consistent with soil and land capability|
|8. Soil salinity (dryland)||Excessive clearing of deep-rooted perennials causing rise in groundwater levels||Identification and revegetation of recharge areas|
|Strategic tree and shrub planting/management|
|Use of deep rooted perennials wherever possible|
|9. Use of monoculture crops||Reliance on a single crop without rotation or use of row crops||Better to use tested and row rotations|
|Use mixed crop sequences rather than just row sole crops|
|10. Pesticide residues resistance||Overreliance and persistent use of pesticides||Use of integrated pest and management|
|Overreliance on chemical control of crop weeds||Biological control of pests|
|Selection of genetically resistant species|
|Low pesticide use farming|
|Use of biodegradable pesticides|
|Use of rotations to reduce pest, weed or pathogen infestation|
Sources: Adapted from SCA (1991) and Lal and Okigbo (1990).
Table 4.3 Yield in Gram Equivalents and Percentage of Crop Land for Various Levels of Production Inputs in the World
|Farming system or technology input level||Yield t/ha||Crop land (%)||Average area of arable land needed (ha/caput)|
Source: FAO (1991b).
However appropriate and realistic the design of a sustainable farming system may be, it is necessary to ensure that threats to it from other sectors are eliminated or significantly minimized. For example, poor road construction could result in flooding, eutrophication and erosion, all of which can seriously damage farm land and even fish-ponds or stream fisheries. A related example is a policy issue such as structural adjustment aimed at increasing export earnings or at reducing debt burdens. This may result in a lot of forest areas being cleared for the commercial row-growing crops, which will expose the soil to erosion. Similarly, removal of subsidies may result in farmers not using fertilizers which, in turn, will result in environmental degradation. Therefore, designing sustainable agricultural or farming systems and adhering to the design alone will not ensure sustainability unless policies, strategies, technologies, systems and components of resource management, and input/technology use in other sectors such as forestry, fisheries, animal production, manufacturing industries, tourism and management of nature reserves and trade are designed to ensure sustainability in development devoid of adverse impacts on the other sectors. A few examples of sectoral activities in one sector which affect other sectors are presented below:
Uncontrolled expansion of agricultural land reduces land available for reserves, forestry and other multiple land use requirements.
All these call for not only integrated land use planning but also adoption of a holistic approach in development planning, in policy formulation and in selecting strategies and the execution of development programmes. The earlier we pay attention to these, the better.
In designing sustainable agricultural production systems, it is necessary to give due consideration to the characteristics of various resources used in production, the ways they are managed or manipulated in the production process and the technologies and practices which render the resultant production system unsustainable. Unsustainability results when impacts of practices and technologies used are economically not feasible and sometimes also culturally unacceptable. In addition to the selection of methods for manipulation of resources and use of practices and technologies which ensure sustainability, there is a need to ensure that other sectoral activities do not render the farming systems unsustainable. At the same time measures must be taken to ensure that various accelerators of agricultural development and factors which ensure enabling the environment for agricultural production for a majority of farmers are present. These include:
The effectiveness of these are accelerated by:
Recommendations on Principles for Designing Sustainable Farming Systems in Tropical Africa
In designing sustainable farming systems there are five principles or objectives that should be aimed at, namely:
Guidelines for Designing Sustainable Systems
The main guidelines to follow in designing sustainable agricultural systems are to:
Table 4.4 Different Operations Performed during Different Stages of Crop Production and Utilization and Extent of Likely Erosion Hazard Involved
|Operations at different stages of crop production and utilization||Extent of possible erosion hazardsa|
|Tillage and pre-planting cultivations||High|
|Subsequent soil management||Low|
|Weeds, pest and disease management||Negligible-high|
|Primary processing (e.g., shelling, winnowing)||Negligible|
Source: Okigbo (1985,1993).
a. Extent of erosion hazard depends on interaction of operations with environment and other factors.
The above principles and guidelines are by no means exhaustive but they are illustrative of the principles and procedures involved in determining: the management schedules; the manipulations of resources; and the input orches tration in amounts, sequences and timing in order to satisfy objectives in pro ducing desirable levels of food, fibre, and other products or otherwise satisfy ing the farmers' objectives. The design can only operate with success where there is an appropriate policy umbrella in the presence of all the accelerators of agricultural development and compatibility among all sectors.
BOA/NRC. 1989. Alternative Agriculture. Committee on the Role of Alternative Farming Methods in Modern Production Agriculture, Board on Agriculture, National Research Council (BOA/NRC). Washington, DC: National Academy Press.
Board for International Food and Agriculture (BIFAD) Task Force. 1988. Environment and Natural Resources: Strategies for Sustainable Agriculture. Washington, DC: United States Agency for International Development (USAID).
Dover, M. and Talbot, L.M. 1987. To Feed This Earth: Agroecology for Sustainable Development. Washington, DC: World Resources Institute.
FAO. 1991a. Issues and perspectives in sustainable agriculture and rural development. Main Document No. 1, FAO/Netherlands Conference on Agriculture and the Environment, s'Hertogenbosch, Netherlands. Rome: FAO, and The Hague: Ministry of Nature Management and Fisheries of the Netherlands.
FAO. 1991b. Sustainable development and management of land and water resources. Background Document No. 1, FAO/Netherlands Conference on Agriculture and Environment, s' Hertogenbosch, Netherlands, 15-19 April 1991. Rome: FAO, and The Hague: Ministry of Nature Management and Fisheries of the Netherlands.
Lal, R. and Okigbo, B.N. 1990. Assessment of soil degradation in the southern states of Nigeria. Environment Working Paper, No. 39, World Bank Sector Policy and Research Staff. Washington, DC: The World Bank.
Okigbo, B.N. 1984. Improved permanent production systems as an alternative to shifting intermittent cultivation. FAO Improved Production Systems as an Alternative to Shifting Cultivation, FAO Soils Bulletin 53: 1-100.
Okigbo, B.N. 1985. Food self-sufficiency in West Africa: an overview with agenda for the future. In K. Ewusi, ea., Towards Food Self-sufficiency in West Africa. Tema: Tema Press of the Ghana Publishing Corporation.
Okigbo, B.N. 1986. Cropping systems and land degradation in the tropics. Ibadan: IITA. Mimeo.
Okigbo, B.N. 1993. The African dilemma and the quest for appropriate technologies for sustainable agriculture and food. In: Marini-Bettolo, ea., Study Week on Agriculture and the Quality of Life: New Global Trends, 17-22 October, pp. 53-96.
Standing Committee on Agriculture (SCA). 1991. Sustainable agriculture. SCA Technical Report Series, No. 36, Report of the Working Group on Sustainable Agriculture, Standing Committee on Agriculture. East Melbourne: Council for Scientific and Industrial Research.
World Commission on Environment and Development (WCED). 1987. Our Common Future. Oxford: Oxford University Press.
Contents - Previous - Next