INFLUENCE OF PHOSPHORUS FERTILIZER ON THE YIELD AND YIELD COMPONENTS OF FOUR SOYBEAN VARIETIES AT LAFIA, SOUTHERN GUINEA SAVANNA OF NIGERIA

Field trials were conducted during 2018 and 2019 cropping seasons at the Teaching and Research Farm of the Faculty of Agriculture, Nasarawa State University Keffi, Shabu-Lafia Campus to study the yield performance of soybean varieties under different phosphorus (P) fertilizer levels. The study area fell within the southern Guinea savanna zone of Nigeria, located on latitude 60 150 and 90 300 N and Longitude 60 300 and 110 00E. The treatments consisted of the four P fertilizer levels (0, 13, 26 and 39 kg P2O5 ha-1) and four varieties of soybean (TGX 1448-2E, TGX1987-62F, TGX 1989-19F and TGX 1835-10E). The treatment combinations were laid out in a randomized complete block design (RCBD) and replicated three times. The yield and yield components were significantly (P<0.05) affected by the treatments and each increase in P application resulted in increased number of pods plant-1, number of seeds pod-1, seed yield plant-1, 100 seed weight and seed yield hectare-1 in both cropping seasons. The results also showed that application of 39 kg P2O5 ha-1 produced significantly (P<0.05) highest in all the yield parameters measured while control plots produced lowest in both cropping seasons respectively. The results further revealed that the varietal effect of soybean on all the yield and yield components were significant (P<0.05) with TGX 1987-19F variety produced consistently highest number of pods plant-1, number of seeds pod-1, 100 seed weight and seed yield hectare-1 while TGX 1835-10E variety produced the lowest yield. In view of the results, this study, therefore recommended that soybean farmers in Lafia and its environs should apply P fertilizer at 39 kg P2O5 ha-1 and adopt TGX 1989-19F variety for profitable soybean production.