EFFECTS OF SONCHUS (S. oleraceous) IN MAIZE AND COWPEA CROPPING SYSTEMS

Abstract

Diversification of farming systems in the face of small land holding of less than 0.05 ha and climate variability is important to offer multiple sources of food and income while acting as insurance against risks. Intercropping is one of the most promising options in farm diversification for sustainable agricultural production. Maize is a major food for most households in Kenya and source of income as well, and is amenable to intercropping system. The objectives of the study were to: 1) investigate the effects of Sonchus on maize and cowpea cropping system; 2) establish the nutrient composition of soils colonized by Sonchus; 3) determine the productivity of maize, cowpea and Sonchus intercropping system. A field experiment laid down in a randomized complete block design replicated thrice was set up, with a total of seven treatments namely: sole maize, sole cowpea and sole Sonchus; maize/Sonchus, cowpea/Sonchus; maize/cowpea and maize/cowpea/Sonchus intercrops. Soil samples were randomly collected and analyzed in the laboratory to ascertain soil composition of fallow areas colonized by Sonchus. The data collected were subjected to analysis of variance using SAS, statistical software (Version 9.2). The means obtained were separated using the least significant difference (LSD) at P < 0.05. The results indicated that grain yield was high in the sole crops compared to the intercrops. The computed LER were greater than 1 indicating that intercropping was advantageous. The results indicated that where soils are fairly fertile intercropping Sonchus with other crops like maize is feasible. Thus, Sonchus oleraceous can be included in maize cropping systems as a diversification strategy for provision of nutrients as a vegetable. However, where the soils are poor Sonchus will offer competition to other crops. Further research should be conducted to determine the optimal spacing between Sonchus and other crops; and the rate of removal of nutrients by sonchus to be able to develop a practical package for the same for up-scaling.