Sulphur, zinc, and boron deficiencies in the Dedza Hills and Thiwi-Lifidzi regions of Malawi

Abstract

Low maize (Zea mays L.) yields are common in the Dedza Hills and Thiwi-Lifidzi Rural Development Projects (RDPs) of Malawi. This study was undertaken to determine if deficiencies of minor nutrients could be reducing yields. "Missing nutrients" trials conducted during the 1990- 91 and 1991-92 growing seasons showed substantial yield responses to S, Zn, and B applications. Tissue analysis indicated that Zn-deficient maize ear leaves had high Fe:Zn ratios, but not low Zn concentrations per se. In 1992, soil samples from 105 farmer sites scattered throughout the Dedza Hills and Thiwi-Lifidzi RDPs indicated widespread S, Zn, and B deficiencies. A nutrient supplement to the standard N and P fertilizers containing S, Zn, and B was applied to 79 farmer sites. The supplement improved yields by an average of more than 1160 kg ha-1 in the region primarily in the Dedza Hills, and 390 kg ha-1 at sites principally in the Thiwi-Lifidzi area. Poor correlation existed between yield and soil analytical results. Evidence is presented that suggests that yield improvements were due primarily to application of Zn and (or) B.