Agroforestry Systems 7:115-120 (1988) 115 © Kluwer Academic Publishers, Dordrecht - Printed in the Netherlands Influence of sheep grazing on soil chemical properties and growth of rubber (Hevea brasiliensis) in Malaysia KAMARUZAMAN JUSOFF Faculty of Forestry, Universiti Pertanian Malaysia, 43400 Serdang, Selangor, Malaysia Key words: sheep grazing, soil chemical properties, rubber Abstract. In a rubber estate in Kelantan, Malaysia, sheep grazing increased N, P, Ca and Mg levels and soil pH. Foliar N, P, Ca, Mg and Na also increased with grazing, but K decreased. The girth of rubber trees under grazing had a higher increment than in the ungrazed areas. I. Introduction In Malaysia, the integration of livestock under plantation crops such as rubber (Hevea brasiliensis) [Wan Mohamed and Kuan, 1976; and Lee et al., 1978] and coconut [Selvadurai, 1967] has been shown to be technically and financially profitable. Such a practice produces extra income for the small- holders and provides effective biological control of weeds. With the in- troduction of sheep under rubber, the overall cost of weeding can be reduced by 15 to 25% compared to chemical control (Rubber Research Institute, 1985). Apart from the biological and economic advantages, it is believed that the droppings of sheep can improve soil fertility. According to Tajuddin [ 1984], an adult sheep can produce about 186 g (dry matter basis) of manure, containing 2.40% N, 0.40% P, 2.89% K, 1.84% Ca, 0.54% Mg, and 507 ppm Na, each day. If added to the soil, this can be expected to increase the supply of nutrients for tree growth. According to Wallingford et al. [1975], organic matter, soil nitrogen and exchangeable cations were in- creased following application of manure. There is some evidence that the introduction of livestock under tree crops may improve yield. A study made by Fernandez [1970] showed that cattle grazing on pasture under coconuts increased yield of nuts from 5,780 to 10,180 per hectare over a four-year period. Studies by Wan Mohamed and Kuan [1976], and Wan Mohamed and Abraham [1976] showed that poultry reared in rubber plantations improved tree growth. Although the benefits of animal manure and grazing on crop yields have been well documented, animal-crop integration may also cause problems.