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Phosphorus fertiliser management for high yields in groundnut-maize rotation system in Ebonyi state Nigeria

¹Michael Okpara University of Agriculture Umudike (MOUAU), Dept. of Agronomy, Nigeria
²Michael Okpara University of Agriculture Umudike (MOUAU), Dept. of Soil Science and Meteorology, Nigeria

Abstract

The excessive use of phosphorus (P) fertiliser in crop production can result in a continuous accumulation of soil P, leading to the potential for P leaching from the agricultural ecosystem. However, the effects of balanced P management on soil P availability and crop P absorption remain unknown for groundnut-maize rotation in Ebonyi state Nigeria. To address this gap, a two-season (2018/2019 and 2019/2020) field experiment was conducted on-farm in Ohozara, Ebonyi state on a demonstration plot belonging to Michael Okpara University of Agriculture Umudike (MOUAU), Nigeria. The experiment involved four different P rates (30 kg P ha^-1, 40 kg P ha^-1, 50 kg P ha^-1, and 60 kg P ha^-1) in comparison to a control (0 kg P ha^-1). The primary objective was to assess the impact of a balanced P application strategy on crop yield, P uptake, and soil P accumulation in a groundnut-maize rotation system. The results show that yield and P uptake of groundnut-maize rotation increased with P fertilisation up to 40 kg P ha^-1, beyond which they stabilised, and the critical threshold is 50 kg P ha^-1 for groundnut. Phosphorus fertilisation at 60 kg ha^-1 accelerated the downward movement of soil P and stocked it in the deep soil in the form of soil labile P and moderately labile P, which increased the risk of soil P leaching. The annual application of 60 kg ha^-1 P as 300 kg TSP fertiliser ha^-1 increased the total P concentration by 25%–86% from deep soil to

topsoil compared to the other treatments. Groundnut-maize rotation in the soils of Ebonyi state used for this study required additional P application to reach the agronomic threshold, set at 20 to 30 kg ha^-1 annually by the Ebonyi State Ministry of Agriculture. In conclusion, balanced P fertilisation can reduce soil P surplus and subsoil P stock while maintaining crop yields.

Keywords: Crop yield, fertiliser management, groundnut-maize rotation, phosphorus requirement

Contact Address: Jemrose Chinemerem Ehibe, Michael Okpara University of Agriculture Umudike (MOUAU), Dept. of Agronomy, Umuahia, Nigeria, e-mail: jemroseehibegmail.com