Ridge-till effects on sorghum yields under organic and inorganic fertilizers in a semi-arid region of Zimbabwe

Inadequate soil moisture and poor Roil fertility remain the major constrain ts to successful crop production in semi-arid regions elf Sub-Saharan Afric a. On-farm experiments to determine the effects of ridge-till (RT) system w ith cattle manure or inorganic fertilizer on yields of sorghum (Sorghum bic olor L.) were done in Chivi communal areas in semi-arid natural region IV o f Zimbabwe in 1995/96 and 1996/97. Ridge-till reduced yields (P < 0.01) by 215% (340 vs. 1070 kg ha(-1)) at 0 t ha(-1) and 40% (770 vs. 1080 kg ha(-1) ) at 10 t ha(-1) manure levels on a sandy soil in 1995/96. On a sandy clay soil, RT increased (P < 0.01) grain yields by 172% (1630 vs. 600 kg ha(-1)) at 0 t ha(-1), by 113% (2070 vs. 970) at 10 t ha(-1), and by 144% (2390 vs . 1200 kg ha(-1)) at 20 t ha(-1) in 1995/96. Our study show that with or wi thout fertilizers, RT is better than FT on sandy clay soils in seasons with normal (450 to 500 mm) annual rainfall in natural region IV.