Effects Of Phosphorus Supply Intensities On Inorganic Phosphorus Forms And Study On The Effect Of Phosphorus Efficiency

To study the effects of phosphorus supply intensities on soil inorganic phosphorus forms’s difference,crop yield and phosphorus fertilizer utilization efficiency in cotton field.Five different phosphorus supply gradients(0,75,150,300,450 kg P2O5/hm~2)were designed with"XLZ57"as experimental material and Xinjiang north Manas County Xinhu farm as experimental area.The main conclusions are as follows:(1)Changes in soil phosphorus content:The soil phosphorus content under different phosphorus supply intensities is higher than that of no phosphorus treatment,and there are obvious differences.The total phosphorus little by little increased under different phosphorus supply intensities,the P450 treatment got to the maximum,which was 15.36%higher than the P0 treatment;the available phosphorus reached the maximum under the P300 treatment,and the add was 213.62%contrast the P0 treatment;single application of chemical fertilizer had no significant effect on organic phosphorus influences.And through the 2016 to 2019,total phosphorus and organic phosphorus in a homeostat,the available phosphorus was reduced by15.57%without phosphorus treatment,and the annual growth rate of phosphorus treatment was 80.22%;indicating that different phosphorus supply intensities are within a certain range can expand the soil phosphorus pool.The results said that the inorganic phosphorus components of soil responded to different phosphorus supply intensities,and the increase amount was mainly Ca2-P and Ca8-P,followed by Al-P,Fe-P,O-P and Ca10-P among them,Ca2-P,Ca8-P,Al-P and O-P reached the maximum value under P300 treatment,which was significantly higher than that of P0,137.11%,86.06%and 9.34%,respectively.Fe-P and Ca10-P achieved the maximum value under P450 treatment,which was 86.06%and 13.84%higher than that of P0,respectively.The results displayed that P150 treatment could accelerate the transformation of Ca10-P,and the transformation amount was 23.11mg/kg(reduction amount);during 2016-2019,the content of phosphorus components in soil decreased year by year under no phosphorus application,and the decline rates of Ca2-P,Ca8-P,Al-P,Fe-P,O-P and Ca10-P were 19.24%,24.21%,7.20%,8.90%,1.23%and 2.85%;the average annual growth rates of Ca2-P,Ca8-P,Al-P,Fe-P,O-P and Ca10-P were18.10%,14.77%and 14.77%,respectively 13.87%、20.22%、4.65%、3.01%.The proportions of Ca2-P,Ca8-P,Al-P,Fe-P,O-P,Ca10-P and organic phosphorus in total phosphorus were 1.51%～3.27%,8.55%～20.89%,4.66%～6.68%,3.30%～5.35%,2.00%～2.63%,44.39%～58.78%,16.95%～20.37%,respectively.The correlation between Ca2-P,Ca8-P,Al-P,Fe-P,O-P,Ca10-P and available phosphorus was Ca8-P>Fe-P>Al-P>Ca2-P>Ca10-P.(2)Accumulation and distribution of phosphorus in cotton:under different phosphorus supply intensity,the accumulation of phosphorus in cotton increased slightly.Phosphorus accumulation reached the maximum at P300,which increased by 71.59%,141.19%,47.46%,23.92%and 49.58%compared with P0.The phosphorus accumulation of cotton plants in2017 increased by 1.35%compared with that in 2016.(3)Through the correlation analysis between yield with inorganic phosphorus:different phosphorus supply intensities have an impact on cotton bolls per plant,boll weight,bolls per hectare,and seed cotton yield.Boll weight reaches the highest at P75,which is higher than P0at 34.05%,the number of bolls per plant,the number of bolls per hectare and the yield of seed cotton reached the highest under P150,which increased by 19.24%,17.16%,and 54.66%on average compared with P0.The annual growth rate of seed cotton yield under this treatment was 17.77%.And the yield has a very obvious correlation with Ca2-P and Ca8-P;it has a significant correlation with Al-P,Fe-P;it has no obvious linear correlation with O-P;when the phosphorus application rate is 75kg/hm~2～300kg/hm~2,cotton yield and Ca10-P are negatively correlated.(4)Phosphorus fertilizer utilization rate and its correlation with inorganic phosphorus:the phosphorus fertilizer utilization rate reached the maximum value of 22.19%in P75treatment.During 2016-2019,the phosphorus fertilizer utilization rate increased year by year under P75 and P150 treatment,but decreased year by year under P300 and P450 treatment;under P75 and P150 treatment,the phosphorus fertilizer utilization rate had a significant positive correlation with Ca2-P,Ca8-P,Ca10-P;under the P300 treatment,the phosphorus fertilizer utilization rate was basically positively correlated with Ca2-P,Ca8-P,Ca10-P under P450 treatment,there was significant or extremely significant negative correlation between phosphorus utilization rate and Ca2-P,Ca8-P,but no significant negative correlation with Fe-P,Al-P,O-P and Ca10-P.In conclusion,reasonable application of phosphorus fertilizer(75kg/hm~2～150kg/hm~2)can expand and improve soil phosphorus pool,promote the synthesis and operation of nutrients in plants,optimize the accumulation and distribution of nutrients,increase crop yield,and achieve the maximum economic benefits on the basis of saving resources,which improves the practical significance for the sustainable development of cotton field under mulch drip irrigation.