Effects Of Phosphorus Application On Soil Fertility And Different Forms Of Inorganic Phosphorus In Cotton Field

Soil fertility comprehensively reflects the various aspects of soil properties.The composition and intensity of soil phosphorus forms play an important role in improving the phosphorus bio-availability of crop and the utilization efficiency of phosphorus fertilizer.The paper applied 4 rates of P fertilizer(0 kg/hm2(P0)、75 kg/hm2(P75)、150 kg/hm2(P150)、400 kg/hm2(P400)),through field experiment,studied the effects of phosphrous application on soil fertility and inorganic phosphrous in cotton field of three cotton cultivars(XLZ57,XLZ50,XLZ13).The main result are:(1)Compared with the control treatment(P0),under the low P level(P75),the available phosphorus,organic matter,available nitrogen in seedling stage root layer(0～20 cm soil layer)averagely increased by 102.82%,10.09%,41.52%,in bud stage root layer(0～20 cm soil layer)averagely increased by 16.39%,11.54%,54.56%,in blooming-boling stage root layer(0-20 cm soil layer)averagely increased by 20.94%,15.04%,39.77%,in boll opening stage root layer(0～20 cm soil layer)averagely increased by 29.59%,19.62%,74.72%respectively,and under the proper P level(P150),in seedling stage root layer averagely increased by 159.41%,20.30%,85.68%,in bud stage averagely increased by 45.54%,18.40%,78.86%,in blooming-boling stage averagely increased by 52.29%,25.14%,99.82%,in boll opening stage averagely increased by 57.94%,37.01%,126.43%,respectively,and under the surplus P level(P400),in seedling stage averagely increased by 276.02%,27.05%,51.92%,in bud stage averagely increased by 91.11%,53.43%,62.95%,in blooming-boling stage averagely increased by 77.96%,51.54%,52.24%,in boll opening stage averagely increased by 97.50%,83.30%,42.93%,respectively.Phosphorus application had no significant effect on soil available potassium.Under the same phosphorus condition,the soil available phosphorus content of XLZ57 and XLZ50 were significantly higher than that of XLZ13,and the soil organic matter,available nitrogen,available potassium content of XLZ57 and XLZ13 were significantly higher than that of XLZ50 during the whole growth period of cotton.(2)Compared with the control treatment(P0),under the low P level(P75),the Ca2-P,Ca8-P,Ca10-P,Fe-P,Al-P in seedling stage root layer(0～20 cm soil layer)averagely increased by 68.5%,42.0%,-17.6%,38.8%,60.5%,in blooming-boling stage root layer(0～20 cm soil layer)averagely increased by 52.8%,18.8%,-17.7%,38.3%,44.7%,respectively,and under the proper P level(P150),in seedling stage averagely increased by 148.9%,88.1%,-31.5%,65.5%,46.7%,in blooming-boling stage averagely increased by 113.7%,54.5%,29.4%,77.6%,27.7%,respectively,and under the surplus P level(P400),in seedling stage averagely increased by 58.6%,53.4%,44.4%,105.8%,32.8%,in blooming-boling stage averagely increased by 52.3%,19.3%,40.8%,143.8%,13.7%,respectively.Under the different phosphorus conditions,the soil Ca2-P,Ca8-P,Ca10-P,Fe-P content of XLZ50 was higher than that of XLZ57 and XLZ13,the soil Al-P content of XLZ57 was higher than that of XLZ50 and XLZ13 in seedling stage,and the soil Ca2-P,Ca8-P,Ca10-P content of XLZ50 was higher than other two cotton cultivars,the Fe-P and Al-P content of XLZ57 was higher than other two cotton cultivars in blooming-bolling stage.Phosphorus application can significantly increase soil available phosphorus,organic matter,available nitrogen and various forms of inorganic phosphorus during the whole growth period of cotton,soil available N content in the 150 kg/hm2 treatment was highest,soil available P and organic matter content in the 400 kg/hm2 treatment was highest,and soil Cat-P content in the 150 kg/hm2 treatment was highest.Different cotton cultivars also have different efects on soil fertility and inorganic phosphorus accumulation.Under the same phosphorus condition,the soil available phosphorus content of XLZ57 and XLZ50 were significantly higher than that of XLZ13,and the soil organic matter,available nitrogen,available potassium content of XLZ57 and XLZ13 were significantly higher than that of XLZ50 during the whole growth period of cotton.The soil Ca2-P content of XLZ57 was higher than other two cotton cultivars during the critical periods in the 150 kg/hm2 treatment.Therfore,rational application of phosphorus fertilizer(150 kg P2O5/hm2)and selecting of cotton cultivars(XLZ57)can improve the soil fertility and the available phosphorus source,and improve the phosphorus fertilizer use efficiency.