IMPACT OF HUMIC ACID AND PHOSPHORUS LEVELS ON YIELD AND PHOSPHORUS USE EFFICIENCY IN FABA BEAN CULTIVATED UNDER SANDY SOIL CONDITIONS

Efficient phosphorus use in faba bean production is critical for sustainable agriculture particularly in sandy soils with low nutrient availability. The present study aimed to assess the influences of different levels of humic acid (HA) and phosphorus (P) fertilizer on phosphorus use efficiency and faba bean productivity under sandy soil conditions. Field experiment was conducted during two growing seasons of 2020/2021 and 2021/2022 at the experimental farm of the Faculty of Agriculture, Zagazig University, El-Khattara, Sharkia Governorate, Egypt. Faba bean plants were treated with three HA levels: control (H0), 3 kg HA/Fad.. (H1), and 6 kg HA/Fad.. (H2), and four phosphorus levels: control (P0), 12.5 kg P2O5/fad.. (P1), 25 kg P2O5/Fad.. (P2), and 37.5 kg P2O5/Fad. (P3). The highest HA level (6 kg HA/Fad.) produced the maximum seeds per plant, number of pods and seed weight per plant, 100-seed weight, total phosphorus uptake, and phosphorus uptake efficiency (PUPE). Combined analysis of two seasons indicated that HA application at 3 kg/Fad. significantly increased seed yield per Fad., harvest index (HI), and phosphorus use efficiency (PUE). However, phosphorus utilization efficiency (PUZE) decreased by increasing HA levels. Phosphorus harvest index (PHI) was unaffected by HA levels. Increasing P levels up to 37.5 kg P2O5/Fad. significantly enhanced number of pods and seeds, seed weight per plant, 100-seed weight, seed and biological yield per Fad., HI, and total phosphorus uptake. Notwithstanding, higher P levels led to reductions in PHI, PUPE, PUZE, and PUE.