Effects of Soil Degradation on Crop Productivity in East Africa

Abstract

ABSTRACT A rapid increase in population is causing severe strain on natural resources and environment of East Africa. Per capita arable land area is declined in several densely populated regions of East Africa. Two major issues in soil and environmental degradation, i.e., greenhouse effect and water quality are described. Three principal soil degradation processes with reference to productivity are physical, chemical and biological degradation. Soil physical degradation can affect crop growth and yield by decreasing root depth and available water and nutrient reserves and soil erosion can lead to yield loss by affecting soil organic carbon, nitrogen, phosphorus, and potassium contents and soil pH. Reduction in maize grain yield on moderately and severely eroded soils compared with uneroded soils in Tanzania was 14 to 39%. Chemical degradation is caused by the processes of nutrient depletion and/or loss of organic matter, acidification and toxic aluminum, salinization, and industrial and mining activities. In Tanzania, a modest cropping system of maize and bean removed about 58,13, and 56 kg ha−1 of N, P, and K, respectively. The average use of fertilizers in this cropping system was only 22.5 kg ha−1 and thus resulting in “nutrient mining.” Principal issues of agricultural sustainability are discussed.