Improvement of Livestock Production in Crop-Animal Systems in ...

4. Field assessment of crop–animal systemsIntroductionThis section presents an integrated report on crop–animal systems in the nine countries visited, namelyCambodia, China, Indonesia, the Lao PDR, Malaysia, Myanmar, the Philippines, Thailand and Vietnam.Appendix I contains detailed information on rainfed animal agriculture in these countries.The visits to individual countries provided a valuable insight into the major constraints, the researchpriorities, the extent of work done or under way, and the future research direction for livestock improvementin crop–animal systems in the target AEZs. These visits also helped to clarify and update the desk reviewundertaken initially and provided a sharper focus on the potential opportunities for research, knowledge ofthe institutions and research capacity. Ultimately, the visits enabled the common major constraints toproduction in mixed farming systems to be identified and the researchable issues to be defined.Environment and cropping systemsMuch of the region is characterised by wet climates, in which total precipitation and its distribution areadequate for cropping and temperatures do not limit plant growth. The exceptions included eastern Indonesia,north-east Thailand and central Myanmar where pronounced dry seasons occur. The soils are generally oflow fertility with ultisols and oxisols predominating. These soils are very acidic with problems of aluminiumtoxicity and low levels of available nutrients and organic matter. In areas such as north-east Thailand and theMekong River Valley of the Lao PDR, soils are of a very sandy texture with a low water-holding capacity,which makes them drought-prone and susceptible to erosion.In western Indonesia, the northern uplands of Cambodia, the Lao PDR, Myanmar, the Philippines,Thailand and central Vietnam, environmental problems are associated with the system of shifting cultivation.Human population pressures have resulted in the breakdown of the traditional sustainable system with ashortening of the fallow period. The main effects have been deforestation, erosion and invasion by the grassweed Imperata cylindrica. In Thailand, erosion has resulted from the growing of cassava. In the Lao PDRand Vietnam, government policy is aimed at eliminating the system and introducing the ethnic minoritiesthat practice shifting cultivation to sedentary agriculture. However, to date, these attempts have not beensuccessful. In Malaysia, shifting cultivation is not practised and there is good canopy cover from naturalforest and plantation tree crops in most areas, reducing soil loss.Rice-based systems dominate in the region, but alternative systems of importance are those associatedwith other food crops (e.g. maize and cassava) and, particularly in the ASEAN sub-region, perennial treecrops (coconut, oil palm, rubber and fruit). With the exception of north-east Thailand and parts of Myanmar,multiple-cropping patterns are common, with inter-cropping, relay-cropping and sequential-cropping beingpractised. Even in north-east Thailand there is a trend towards greater diversification of cropping.Animal production systemsCrop–animal integrationIn all nine countries, animals have multiple uses on small, mixed farms. Apart from producing beef and milk,large ruminants are a cash asset to be realised at critical periods and are often the only means by which theprosperity of farmers can be enhanced. Buffaloes and cattle provide manure, the main fertiliser input forcropping, and draft power for various crop cultivation practices and transportation. Small ruminants arevalued for income generation and the provision of manure. In upland farming systems, animals may accountfor over 50% of the cash income of smallholders. Significant crop–animal interactions occur through theprovision of traction and manure, the utilisation of crop residues and AIBP; the control of weeds in tree cropplantations and the provision of opportunities to introduce forage legumes into annual food and perennialtree crop systems.