The Influence Of Different Phosphate Fertilizer On Growth And Yield Of Maize (Zea Mays L. Cv. Zhengdan 958) And Phosphorus Transformation In Black Soil Of Northeast China

Phosphorus is an indispensable nutrient element in the growth of maize,which affects the yield and quality of maize.The content of available P in the black soil of Northeast China is relatively high,but the utilization rate of P fertilizer is relatively low.Therefore,it is of great significance to change the variety and proportion of P fertilizer to reduce the amount of P fertilizer and improve the utilization rate of P fertilizer.In this study,different phosphate fertilizers were applied to pot experiment:diammonium phosphate（DAP）;ammonium polyphosphate（APP）;Fused Calcium Magnesium phosphate（FCMP）;DAP combined with FCMP（DAP+FCMP）;and no phosphate（control or CK）to（1）evaluate the rate of P nutrient uptake by maize plant grown on black soils with different P application during each growth period（2）determine the consequential influence of P application on the development and growth of aboveground and belowground parts of maize in the black soil and（3）determine the rate of phosphorus transformation after applying 3 different phosphate fertilizers in the black soil.1)The results from the study showed that DAP markedly improved stem weight（60-day）,APP was good at improving leaf and ear weight（at 120-day）,FCMP improved corn ear and tassle at 60-and 120-day accordingly.The combination fertilizer（DAP+FCMP）at 30-day improved whole plant weight and corn ear（at 60-day）.Throughout the experiment the highest P absorption rate was considerably influenced by phosphate fertilizer application for 15,30 and 60 day were reported in FCMP,DAP,stem（DAP）,leaf（APP and DAP）,ear（FCMP）respectively.At the harvest period,phosphate application had slight or no significant effect on P absorption rates of growth parameters.However,APP affected the P nutrient uptake in leaf and grains whereas DAP+FCMP affect P nutrient uptake in stem,cob,and tassle.The yield and yield components at harvest were not significantly affected by P supply.But APP fertilizer application was the most promising to increase yield parameters under this study as well the harvest index.2)It was noted between 15 to 30-day growth period,maize root P uptake was significantly enhanced by the fertilizer supplied,whereas in 60 and 120-day,root nutrient uptake was not affected by P fertilization.FCMP,DAP+FCMP,APP and CK highly influenced roots P uptake in15,30,60 and 120-day growth periods.However,APP and DAP were more hopeful to increase root number and length,respectively.Root shoot ratio was only affected by P at 30-day period with APP fertilizer source.Similarly,at 30-day period,P supplied significantly influenced total absorption area,active absorption area and specific surface area with both APP,FCMP and DAP+FCMP fertilizers.Results from root image analysis shows an inconsistency of P influence.Overall,30-day analysis for surface area,projected area,root volume and average diameter showed some weak significance whereas root length did not.Further,the analysis in 60-day revealed that except root volume and average diameter,the rest of the parameters was insignificantly affected by all phosphate fertilization.3)The results from the study showed that P application significantly（p<0.05）influenced Olsen P content（available P）for plant uptake with increasing and decreasing pattern.The maximum(41.46 mg P kg^-1)Olsen P content was therefore recorded in DAP treatment compared to control at 30-day period.It further showed that the transformational effect on soil total P was significant with APP and FCMP(0.52 g P kg^-1 each)obtaining the highest soil total P content at harvest.Throughout the experiment,the inorganic P fractions were significantly influenced by fertilizer P in that the applied P transformed into P fractions.Overall,the O-P at 30-day increased with presence of P fertilizer and making it the most abundant inorganic P in the current study.The P fractions（Al-P,Fe-P and O-P）significantly correlated positively with total P,whereas Al-P and Ca-P significantly correlated with organic P.The observations of free iron oxides（Fed）reveals that at both 30 and 60 days,phosphate application did not influence the content of Fed with maximum mean value in CK.However,at 120-day growth period the highest Fed content was obtained in FCMP treatment showing a significant impact of P on Fed and could aid in the extraction of iron oxide component in clay black soil.In conclusion,application of APP,DAP,FCMP and DAP+FCMP can increase maize yield,phosphorus uptake and utilization,and improve soil phosphorus availability and conversion of various phosphorus forms,among which APP and DAP have the best effect.