IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS) e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume 3, Issue 6 (Jul. - Aug. 2013), PP 32-36 www.iosrjournals.org www.iosrjournals.org 32 | Page Effect of Phosphorus Fertilizers on Growth and Physiological Phosphorus Use Efficiency of Three Soy Bean Cultivars Dalshad, A. Darwesh 1 Pakhshan, M. Maulood 2 and Shireen A. Amin 3 . 1 Environmental Science Dept. College of Science, University of Salahaddin-Hawler, Iraq 2,3 Biology Dept., College of Science, University of Salahaddin-Hawler, Iraq Abstract: A pot experiment was conducted to study the effect of difference phosphorus fertilizers on growth and nutrient status of soya bean cultivars. The treatments including, three cultivars of soybean (C1=4.7, C2=43355, C3=44NK), the phosphorus fertilizers including (P1=Control no fertilizer,P2=Triple super phosphate, P3=Di ammonium phosphate,P4=Di potassium phosphate, P5=NPK 20:20:20 with some trace elements and P6=NPK 12:36:12 with Mg) each of them applied in 75 Kg P.ha -1 . The factorial experiment was laid out in a complete randomized design (CRD) with three replicates. The results indicates that the highest values (23.47 g.pot -1 12.07 g.pot -1 and 1117.62 kg.ka -1 ) for shoot dry matter , root dry matter and biological yield respectively were given by the application superphosphate fertilizers in the cultivar 44NK followed by the cultivars 4.7 and 43355 which treated by the PK and NPK (12:36:12) Mg respectively. However the result revealed that the increase in uptake of P with the application of phosphorus over control was 280.49% in case of 44NK cultivar, 255.01 % in case of 4.7 cultivar and 99.75% in case of 43355cultivar. The high values of PUEp (55.556%) and PFE(10.079%) were recorded by the application of superphosphate in 44NK cultivars, while the low values were (4.622% and 0.392%) over control recorded by the application of NPK(20:20:20) trace elements and super phosphate in case of 4.7 and 43355 cultivars respectively. Keywords: DAP, nutrient status, phosphorus fertilizers, Phosphorus use efficiency, Soybean. I. Introduction Soy bean is one of the most important legume crops for human nutrition and has been traditionally cultivated in calcareous soils in arid and semi-arid regions; the agronomical importance of soybean ( Glycine max L.) is linked to its high protein content (25%-29%) [1], Soybean seed is a source of protein and oil for human nutrition and a source of soybean meal for livestock feed. Soybean protein meal and soybean oil accounted for 69% and 30%, respectively in 2006 and 2007, of the world's supply of protein meal and edible oil. Many international and domestic soybean processors prefer soybean with at least 340 g kg -1 protein and 190 g kg oil, assuming 130 g kg -1 seed moisture Soybean seed quality is determined by the quantity and quality of protein and oil content seed composition[2]. A study was conducted in the wet season by [3] to evaluate the effect of phosphorus on the growth and yield of two cowpea varieties sourced from republic of Niger. They results showed significant response to applied P on pods per plant, grain and yield and 100-seed weight with highest response to the application of 60 kg P ha. An experiment was conducted by [4] to study the combination effect of fertilizer sources (Triple superphosphate TSP and Rock phosphate) and their concentration (0, 18.75, 37.5, 75bkg P 2 O 5 /ha) and (1250 and 2500 kg/ha) on crop yields in rice-soybean double cropping. The analysis of data revealed that plots which treated with rock phosphate recorded the maximum grain yield. [5] studied the effect of three levels of phosphorus fertilizer (10, 20, 30) kg P.ha -1 on soy bean grain yield ,the result showed that the phosphorus fertilization significantly increment soybean grain yield the average yield responses to phosphorus varied from 87 kg.ha -1 (P 10 ) to 217 kg.ha -1 (P 30 ). [6] indicated that the application of different levels of phosphorus (30, 60, 90 and 120 kg P 2 O 5 .ha -1 ) caused a significant increase of growth and yield parameters of soybean. The results of study revealed that application 120 kg.ha -1 phosphate gave higher seed yield (1955.56 kg.ha -1 ) compared to control (1274.07 kg.ha -1 ), also the result of same study show plant height was significantly affected by phosphorus application. The maximum plant height (56.2 cm) was recorded in case of application (120 kg P 2 O 5 .ha -1 ), while the minimum plant height (49.37 cm) was observed in control, however, in the absence of a proper crop variety and fertilizer inputs, the yields are low in alkaline soils. The applied P gets fixed immediately after application in calcareous soils and the availability to the crop is poor. Genotypic differences for better growth under alkaline conditions have been demonstrated because genetic effects modifying tolerance to alkaline are heritable. The soybean has been reported to P fertilizers differently in alkaline soils depending on the pH, soil fertility and the nature of genotype [7] and [8]. It has been reported that imbalanced and inadequate nutrition results in poor yields of soybean [9]. The investigation was undertaken to study the performance of different soybean cultivars with different levels of applied P fertilizer. Due to fixation of applied P in Alkali soils, higher dose of the nutrient are required to satisfy the fixation needs and the