Impact of Climate Change on Maize and Pigeonpea Yields in Semi-Arid Kenya

The objective of this study was to assess the impact of climate change on intercrops of maize and improved pigeonpea varieties developed. Future climate data for Katumani were downscaled from the National Meteorological Research Centre (CNRM) and Commonwealth Scientific and Industrial Research Organization (CSIRO) climate models using the Statistical Downscaling Model (SDSM) version 4.2. Both models predicted that Katumani will be warmer by 2°C and wetter by 11% by 2100. Agricultural Production Systems Simulator (APSIM) model version 7.3 was used to assess the impact of both increase in temperature and rainfall on maize and pigeonpea yield in Katumani. Maize crop will increase by 141–-150% and 10–-23 % in 2050 and 2100, respectively. Intercropping maize with pigeonpea will give mixed maize yield results. Pigeonpea yields will decline by 10–20 and 4–9% by 2100 under CSIRO and CNRM models, respectively. Intercropping short and medium duration pigeonpea varieties with maize will reduce pigeonpea yields by 60–80 and 70–90% under the CSIRO and CNRM model, respectively. There is a need to develop heat and waterlogging-tolerant pigeonpea varieties to help farmers adapt to climate change and to protect the huge pigeonpea export market currently enjoyed by Kenya

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

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