Effects of Tillage, Soil Amendment and Weed Management Regime on Performance of Lowland Rice (Oryza sativa L.) in the Guinea Savannah

Abstract

Field experiment was carried out during the 2015 and 2016 cropping seasons at Integrated Water and Agricultural Development Limited (IWAD) in the Mamprugu Moaduri district of Northern region. The objectives of the study were to evaluate tillage system, soil amendment and weed management regime on the growth and yield of rice under lowland conditions. The experiment was laid out in split-split-plot design in three replications with tillage, soil amendment and weed management which constituted the main-plot, sub-plot and sub-sub-plot factors respectively. Tillage, soil amendment and weed management, each at three levels, were respectively made-up of zero tillage (ZT), minimum tillage (MT) and conventional tillage (CT); 2.5 tons/ha organic manure, 2 tons/ha biochar and 250 kg NPK/ha; and hand weeding at 3 and 6 weeks after planting (WAP), pre-emergence herbicide, and post-emergence herbicide. Post-emergence herbicide application supported earliest flower initiation (80-85 days) compared to manual weeding (82-92 days) and pre-emergence herbicides (83-90 days). The combination of zero tillage and pre-emergence herbicide weed management gave the highest number of tillers of 34.3 per hill and maximized grain yield (6661 kg/ha). Longest rice root length was 34 cm in zero tillage with compost amendments and pre-emergence herbicide treatments. Soil carbon stock below 40 cm soil depth was highest in zero tillage (0.89% C) compared to minimum tillage (0.65% C) and conventional tillage (0.55 % C). Results gave good indication of best land preparation, soil amendment and weed management practice that could promote sustainable cropping in sandy-loam textured lowland soils.