DIAGNOSIS AND CORRECTION OF SOIL NUTRIENT PROBLEMS OF COMMON BEAN (PHASEOLUS-VULGARIS) IN THE USAMBARA MOUNTAINS OF TANZANIA

Stages in the diagnosis of an interveinal leaf chlorosis in bean in th e Usambara Mountains of northern Tanzania are described. Leaf tissue a nalysis, soil analysis, a 2(5) factorial trial with treatments of nitr ogen. phosphorus, potassium, the trace elements copper and zinc and li me at one location and data from a series of 4(3) factorial trials of N, P and K demonstrated the leaf condition to be due to potassium defi ciency. Large growth and yield responses to N, P and K were recorded. The responses were accompanied by greater numbers of pods and seeds/po d. The application of N and K increased leaf concentrations of the res pective elements but depressed the concentrations of other major and m inor elements in leaves. There were no effects of trace elements or li me.