Compatibility of Leucaena leucocephala biomass and cattle manure combination under rainwater harvesting on sorghum (Sorghum bicolor (L.) Moench) productivity in semi-arid region of Zimbabwe

Soil infertility is one of the constraints contributing to poor sorghum production in semi-arid areas across Africa. To increase sorghum production, there is need to address soil fertility issues. Therefore, the objective was to assess the effects of Leucaena/cattle manure combination on grain and stover yields, harvest index and net return of two sorghum varieties (Macia and SV1) under rainwater harvesting techniques. The field experiment was conducted as a randomized complete block design over three cropping seasons in a split-split plot arrangement. Results show significant (P < 0.05) increase in sorghum grain yield with increased applications of Leucaena/cattle manure combination. Macia variety had statistically greater (P < 0.05) grain yield than SV1 variety. Tied contour show considerably higher yield for both varieties across all seasons. Stover yield show significant differences (P < 0.05) as affected by Leucaena/cattle manure and rainwater harvesting techniques. Rainwater harvesting techniques significantly influence (P < 0.05) harvest index, with tied contour and infiltration pits having comparably higher harvest index than standard contour. Application of Leucaena/cattle manure combination show significant increases in harvest index with increased application rates. However, no significant effect was observed at 20 and 30 t ha(-1) from SV1 variety across all seasons. Leucaena/cattle manure combination significantly influenced (P < 0.05) sorghum net return across all seasons except at 5 t ha(-1) where no significant effect was observed. Macia variety had higher net return than SV1. To increase grain yield and net return, farmers can adopt Macia variety, tied contour and 10 t ha(-1) Leucaena/cattle manure combination due to higher incremental yield per tonne.