Influence of Nitrogen and Phosphorus Levels on Yield and Chemical Composition of Soybean to Improve Their Efficiency in Animal Feed

Abstract

A field experiment was conducted to evaluate the effects of nitrogen and phosphate fertilization levels on growth, yield components, and chemical composition of soybean under desert conditions to enhance its value in animal feed. Two trials were conducted during the 2022 and 2023 summer growing seasons at the experimental farm of the Environmental Studies and Research Institute, University of Sadat City, Menofiya Governorate, Egypt. A split-plot arrangement in a randomized complete block design with three replications was used. Main plots received nitrogen at 20, 30 and 40 kg N fed-1, while sub-plots received phosphate at 30, 40, and 50 kg P₂O₅ fed-1. Applying 40 kg N fed-1 significantly improved growth rate, chlorophyll content and leaf number, while phosphate affected only plant height at 50 kg P₂O₅ fed-1. Nitrogen influenced most yield traits except seeds per pod, harvest index and shelling percentage. The highest pod number per plant was recorded with 30 kg N fed-1, while 40 kg N fed-1 increased 100-seed weight, pod weight, seed number and total yield per fed. Phosphate at 50 kg P₂O₅ fed-1 also improved yield traits. Interaction between nitrogen and phosphate levels was significant for most traits, with 40 kg N fed-1 and 50 kg P₂O₅ fed-1 treatment producing the highest seed yield. Nitrogen significantly affected protein and oil content; 40 kg N fed-1 gave the highest protein, while 20 kg N fed-1 gave the highest oil. Phosphate influenced protein, oil, and fiber; 30 kg P₂O₅ fed-1 gave the highest protein, while 50 kg P₂O₅ fed-1 increased oil and fiber. The combined treatment enhanced soybean yield and quality under desert conditions.