ENHANCING THE EFFICENCY OF ROCK PHOSPHATE IN SALINE SOIL AS AN ENVIRONMENTAL FRIENDLY ALTERNATIVE FOR P- MANUFACTURED FERTILIZERS AND ITS EFFECTON MAIZE QUALITY AND PRODUCTIVITY

Abstract

Two field experiments were conducted to enhance the efficiency use of rock phosphate, (RP) in a saline soil at El-Qantra Sharq, Ismailia Governorate, Egypt during the two successive summer seasons of 2011 and 2012. The rock phosphate (RP) was used as an environmental friendly alternative for P mineral fertilizers after alleviating the adverse effects of salt stress on soil and plant by applying compost, (CO) and the phosphate dissolving bacteria, (PDB) Bacillus megaterium var. phosphaticum, whether solely or in combinations with the rock phosphate. The effects of RP, compost and biofertilization applied solely or in combinations on maize grains yield and its quality as well as the macronutrients N, P and K and micronutrients Fe, Mn and Zn contents and uptake values were studied. RP was added at three rates RP0, RP1 and RP2 corresponding to 0, 31 and 47 kg P ha-1. The obtained results could be summarized as follows: the values of weight of grains plant-1, 100-grain weight and grains yield significantly increased due to the different treatments relative to the control. The highest values of weight of grains plant-1 and grains yield (518g and 2.81 Mg ha-1), respectively were attained due to application of RP2 + compost. While, the highest one for 100-grain weight i.e. 58.9 g was achieved due to the treatment RP1+ compost, Uptake values of N, P and K as well as Fe, Mn and Zn by maize grains increased significantly as a result of addition of the treatments solely or in combination with rock phosphate. The highest uptake values of N, P, K as well as Mn and Zn i.e.168, 41.0, 141 kg ha-1 as well as 547 and 401 g ha–1, respectively) were obtained due to addition of RP2 + compost treatment, while the highest Fe-uptake value (1036 g ha–1) resulted owing to the compost treatment. Soil available N, P and K as well as DTPA extractable Fe, Mn and Zn increased while, soil pH and soil ECe decreased as a result of compost and bio treatments added solely or in combinations with rock phosphate. Phosphorus use efficiency, PUE, apparent phosphorus recovery, APR and phosphorus agronomic efficiency PAE decreased as rock phosphate rate increased especially when combined with compost. The treatment RP 47 kg P ha-1 + compost was superior to the other treatments but statistically there were no significant difference with the treatment RP 31 kg P ha-1 + compost for more characters under study.