Effects of Leucaena Leaf Biomass and NP Fertilizer Application on Soil Fertility, StrigaManagement and Sorghum Growth and Yield in Pawe District, Northwestern Ethiopia

Abstract

Effects of Leucaena [Leucaena leucocephala (Lam.) de Wit] Leaf Biomass and NP Fertilizer Application on Soil Fertility, Striga [Striga hermonthica (Del.) Benth] Management and Sorghum [Sorghum bicolor (L.) Moench] Growth and Yield in Pawe District, Northwestern Ethiopia

Sorghum production in Pawe District is often constrained by low soil fertility resulting from continuous cropping with minimum or no input which in turn encourages Striga infestation. Field experiment was conducted during the 2010 cropping season to investigate the effects of Leucaena leaf biomass incorporation and NP fertilizer application on sorghum growth and Striga control. Two levels of Leucaena leaf biomass (2.5 and 5 t ha^-1) were applied with 50% recommended dose of urea (RDU) with or without 50% recommended dose of diammonium phosphate (DAP). The experiment included a standard treatment of 100% recommended dose of fertilizer (RDF i.e. 100 kg urea + 100 kg DAP) and farmers’ practice of growing sorghum without any input as a control. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Plots treated with 5 t ha^-1 Leucaena + 50% RDF and 5 t ha^-1 Leucaena + 50% RDU gave significantly higher soil organic carbon (OC), cation exchange capacity (CEC), total N and leaf N content whereas significantly higher available P and plant tissue P content were recorded in the 5 t ha^-1 Leucaena + 50% RDF-treated plots, respectively, over the control plots. Grain yield and aboveground biomass of sorghum were increased by 133 and 123%, and 368 and 385% in the 5 t ha^-1 Leucaena + 50% RDF and 5 t ha^-1 Leucaena + 50% RDU-treated plots, respectively, over the control plots. The number of Striga plants at 65 days after sowing (DAS) of sorghum was also reduced by 82.33% and 96.33% in the 5 t ha^-1 Leucaena + 50% RDF and 5 t ha-1 Leucaena + 50% RDU-treated plots, respectively, over the control plots. Aboveground biomass of Striga at 95 DAS decreased by 41.6 and 39.32% in the 5 t ha^-1 Leucaena + 50% RDF and 100% RDF treated plots, respectively, over the control plots. Plots treated with 2.5 t ha^-1 Leucaena + 50% RDF recorded comparable grain yield (2.160 t ha^-1) and even slightly greater sorghum above ground biomass (23.23 t ha^-1) than the 100% RDF-treated plots which recorded 2.22 t ha^-1 of grain yield and 22.66 t ha^-1 of aboveground biomass, respectively . It is, therefore, concluded that 5 t ha^-1 Leucaena + 50% RDU can be used to improve sorghum productivity and manage Striga in the study area. Further research should be conducted across different locations for at least two seasons to substantiate this conclusion considering the cost benefit analysis of the practice.

Keywords: Aboveground Biomass; Grain Yield; Leuceana Leaf Biomass; Striga Infestation