It is expected that the use of mineral fertilizers will continue to rise if the cultivated areas and the intensity of production continue to increase. However, it will be possible to minimize the rate of increase in fertilizer use if emerging technologies such as variable rate application (VRA) and site-specific management (SSM) are extensively practiced. Plant breeders should explore the possibilities of producing crops, which are higher yielding but less demanding as regards nutrient requirements. Agroforestry, intercropping, integrated farming systems (animals and crops) and the use of crop organic wastes would reduce the dependence on mineral fertilizers.
Variable rate application and site-specific management are proving to be very effective and promising management practices for improving fertilizer use efficiency (FUE). Fertilizers are becoming increasingly expensive and their overuse is causing environmental concerns, due to pollution of soil and water resources. As a result, conventional practices of fertilizer application (broadcast, deep banding, top dressing, side dressing etc), based on blanket recommendations of average fertilizer rates on a hectare basis, should give way to VRA and SSM of fertilizers. This would minimize the waste of fertilizers and reduce the quantities used per hectare.
Integrated farming systems (IFS), are being promoted vigorously in Malaysia in order to support agriculture and to reduce dependence on mineral fertilizers for crop production. The emphasis is on agroforestry and mixed farming and on organic farming. It is expected that IFS will increase the smallholder's average income from RM200 to above RM1 000 per month. The DOA is promoting rice cultivation integrated with vegetables, sweet corn, fruits, fish and duck rearing; intercropping of coconut with fruits and vegetables; intercropping of rubber with banana, groundnut, maize, pineapple and vegetables; maize production integrated with cattle feed lots (Wan Abu Bakar, 2003). The processing of compost is being encouraged. Integration of sheep in rubber growing smallholdings also contributes additional income, providing organic manure and reducing weeding costs.
The oil-palm plantation sector and land development schemes, which account for a large proportion of the cultivated area in Malaysia, also practice integrated farming. The immediate benefit in this case is a reduction in labour costs for weeding through grazing by cattle, deer and other ruminants. At the end of 2000, 167 estates and 300 blocks of FELDA settlers, involving 115 390 beef cattle, adopted the integration of cattle with mature oil-palm (Rosli, 2001).
The impact of these measures on soil fertility is generally known but the particular benefits in the farming scenarios in Malaysia are not well documented. However, they are attracting a lot of research interest.
