Optimizing Soil Moisture and Nitrogen Use Efficiency of Some Maize (Zea mays) Varieties under Conservation Farming System

In Zambia, small holder farmers depend on producing maize (Zea mays), which is a major staple food for many Zambians. Maize productivity among the smallholder farmers is quite low, giving only 2.3 tons per hectare. The low yields are attributed to insufficient and erratic rain fall, low soil fertility, and poor farming practices. Therefore, the objective of this study was to evaluate the performance of maize genotypes for nitrogen use efficiency and soil moisture utilisation under conservation farming system. The trials were carried out at two sites with different soil types. Three maize varieties i.e. ZMS 606, GV 640 and GV 635 were evaluated in maize – cowpea rotation. Four cowpea varieties used for rotation with maize, i.e. Bubebe Lutembwe, BB 14-16-2-2 and LT 11-3-3-12. BB 14-16-2-2 and LT 11-3-3-12 are mutation-derived lines of Bubebe and Lutembwe cowpea parent varieties respectively. The experimental design used was split plot with three replications. The NUE was significantly (P< 0.05) higher in CF and accounted for 27 % and 15% more than conventional farming system which valued 17% and 3% at Chisamba and Batoka, respectively. while soil moisture content was higher at Batoka than Chisamba in CF system. ZMS 606 and GV 640 varieties were superior over GV 635 for NUE. Cowpea variety BB 14-16-2-2 significantly increased NUE of maize varieties. Therefore, smallholder farmers in Zambia can increase maize productivity in maize - cowpea rotation system due to the increased NUE. Recommendations are made for farmers to select improved nitrogen efficient maize varieties to optimize productivity of maize in conservation farming system.