ZINC DISTRIBUTION IN ZIMBABWEAN SOILS AND ITS RELATIONSHIP WITH OTHERSOIL FACTORS

The distribution of zinc in some major Zimbabwean soils was studied us ing 120 profiles taken from 22 different locations. The total zinc sta tus (TL-Zn) of the horizons of soils studied was low (8 ppm), and the range was narrow (3.7 to 16.3 ppm). The residual zinc (RS-Zn) fraction was about 65 percent of the total zinc found in the soils, while 15 p ercent was organically bound zinc (OG-Zn), 14 percent was available zi nc (MG-Zn), and 6 percent was zinc associated with hydrous metal oxide s (OX-Zn). The total zinc status of the soils was related to parent ma terial. Generally, texture had a significant effect on zinc distributi on with heavier textured soils having more zinc in most fractions than the lighter textured soils. A decrease in zinc down the profile was o bserved for available, residual, and total zinc. If cropped intensivel y, 32 per cent of the soils with less than 1 ppm available zinc have t he potential for zinc deficiency. Multiple stepwise regression analysi s showed that organic matter, silt and clay contents, available copper , and resin P2O5 contents were important for predicting the available zinc content of the soils, while texture and organic matter content we re important in predicting total zinc content.