Increased Maize Yield in Response to Applied Phosphorus and Nitrogen in the Greenbelt Zone, in South Sudan

Aims: The study focused on assessing the impact of applying phosphorus and nitrogen fertilizers on maize yield in the Greenbelt zone of South Sudan, where nutrient deficiencies often limit crop growth.

Study Design: Field experiments involved a 4 x 4 x 4 factorial experiments in a randomized complete block design. The field experiment was conducted in Sakure and Nginda Payams in Nzara and Yambio Counties respectively, between August 2020 and January 2022.

Methodology: The treatments involved Triple Super Phosphate (TSP, 0-46-0) applied at 20, 40 and 60 kg P ha -1 without N, Urea (46% N) applied at 40, 80 and 120 kg N ha-1 without P, combinations of each level of P with varying levels of N and an absolute control (P0N0). Maize variety was an open pollinated called NARD 1. Plot size was 16 m2, all maize plant above ground was harvested in a net plot (8.5 m2) after 120 days.

Results: The average maize yield in response to applied fertilizer P and N in the three sites was 4.7 t ha-1 an increase of about 62 % over the control (2.9 t ha-1), and was statistically significantly at P = .05

Conclusion: 20 kg P ha-1 and 120 kg N ha-1 rates were profitable and therefore were recommended as optimum application rates that can contribute to food security and economic progress in the area. However, more research is recommended to establish long-term fertilizer effects on maize performance, optimal application rates, and environmental considerations. The study stressed the need for diversified fertilizer research across seasons and emphasized community awareness about fertilizer benefits for sustainable maize production and farming system research.