Soil Test-Based Crop Response Phosphorus Calibration Study on Bread Wheat (Triticum Aestivum L) in Liban Chukala District, East Shewa Zone, Oromia, Ethiopia

Nutrient mining due to sub-optimal fertilizer use on one hand and unbalanced fertilizer use on the other have favored the emergence of multi-nutrient deficiency in Ethiopian soils. Therefore, the study was conducted on twenty-one farmers’ fields in the Liban Chukala District of East Shewa Zone of Oromia, during the main cropping seasons of 2019-2022. The study aimed to determine the economically optimum rate of nitrogen fertilizer in the first year. However, in the second two consecutive years the experiment was conducted to determine phosphorus critical (Pc) and phosphorus requirement factor (Pf and the treatments consisted of six levels of phosphorus (0, 10, 20, 30, 40, and 50) kg ha-1 combined with a single level of nitrogen (69 kg ha1) that gave a total of seven treatments. The experiments were laid out in randomized complete block design (RCBD) with two replications and the gross plot, size was 4 m x 5 m (20 m2) was used to determine phosphorus critical (Pc) and also harvested from 4m2 plot areas. The analysis of variance indicated that, thousand kernels weight, and harvest index were not significantly (p<0.05) influenced by applied NP fertilizers. On the other hand, the analysis of variance indicated that Plant height, spike length, number of seeds per spike, biomass yield, and grain yield were highly significantly (p <0.01) influenced by soil test-based phosphorus fertilizer application. The result indicated that the highest (87.82 cm) plant height, the highest (1013 kg ha-1) biomass, and the highest (4517 kg ha-1) grain yield were recorded by 40 kg P ha-1. Moreover, 23ppm phosphorus critical (Pc) and 9.86ppm phosphorus requirement factor (Pf) were identified for bread wheat production for the farmers of Liban Chukala District.