Phosphorus Efficiency in Wheat as Affected by Foliar Spray with Zinc, Humic Acid and Biofertilizer (Bacillus megatherium sp.) Addition Under Calcareous Soil Conditions

To enhancing the efficiency use of phosphate fertilizer in calcareous soil by bio inoculation with (Bacillus megatherium sp.) as PGPR strain and foliar spray with Zn and humic acid (HA) on wheat (Triticium aestavium L., cv. Sakha 93) productivity and nutrients availability in soil after harvest, two field experiments were conducted at El-Nubaria Agricultural Research Station, Alexandria Governorate, Egypt during 2014 and 2015 seasons. The studied treatments involved three P application rates i.e, 0, 6.5 and 13 kg P fed.^-1, foliar spraying with Zn (1.5 kg ZnSO₄ /400 L water), humic acid (HA) 1.2 L/400 L water and Zn+HA without and with bio-inoculation with (Bacillus megatherium sp.). The results could be summarized as follow: Available N, P, K, Fe, Mn and Zn were significantly increased due to the above mentioned treatments. Foliar spraying with Zn and humic acid in combination with biofertilizer under different P fertilizer rates increased wheat yields and 1000-grain weight as well as N, P, K, Fe, Mn and Zn content and uptake by grains in combined data. Total chlorophyll content and carbohydrates were increased as well as protein content and protein yield. Highest yield efficiency (82.7%) and harvest index (44.7%) were obtained due to the treatment of 6.5 kg P fed.^-1 + Zn + bio and 6.5 kg P fed.^-1 + Zn, respectively. Apparent P-recovery (APR), P agronomic efficiency (PAE) and P use efficiency (PUE) were markedly decreased with increasing P-addition rates in presence or absence of bio fertilization. Hence, the plants treated with 6.5 kg P fed.^-1 + foliar spray with Zn, HA and Zn + HA when inoculated with Bacillus megatherium gave the highest mean values of APR, PUE and PAE. Generally, the treatment of P fertilization (13 kg P fed.^-1 combined with Zn + HA) when inoculated with Bacillus megatherium had superior effect in improving soil properties and increasing wheat production, protein content and nutrient uptake with compared to the other treatments under calcareous soil conditions but, in most of them without significant differences with lower rate of 6.5 kg P fed.^-1.