THE CURSE OF LOW SOIL FERTILITY AND DIMINISHING MAIZE YIELDS IN SEMI-ARID KENYA:CAN PIGEONPEA PLAY SAVIOUR?

Abstract

Little research has been conducted in Kenya to ascertain and exploit the ability of pigeonpea  to improve soil fertility and increase cereal yields. An experiment was conducted at Katumani Research Centre between 2009 and 2013 to evaluate the effects of pigeonpea on soil fertility and productivity of maize cropping systems in semi-arid Kenya. The experiment was established as a split-split plot design with sole and intercrops of maize and pigeonpea varieties drawn from three maturity groups and three crop residue application rates as the treatments. Results showed that intercropping maize with pigeonpea reduced (p ≤ 0.05) soil organic carbon and total soil N from 1.4 and 0.2 % in 2009 to less than 1 and 0.1 %, respectively, in 2013. Intercropping maize with long duration pigeonpea and ploughing back 4 t ha-1 of crop residues had no significant effect on available P. However, it increased (p ≤ 0.05) available P from 26 ppm at the start of the study to 50 ppm and 47 ppm in eight seasons under maize-Mbaazi I and maize-Kat 60/8 intercrops, respectively. Exchangeable K, Mg and Ca also declined significantly (p ≤ 0.05). Intercropping maize with long duration pigeonpea and ploughing back 4 t ha-1 of crop residues offers the best option since it gave higher maize (1.9 t ha-1) and pigeonpea (1.4 t ha-1) grain yields per season and sufficient crop residues to feed the livestock and plough back to improve soil fertility.