Effects Of P Application Depth And P Application Level On Production Performance And C,N,P Stoichiometric Characteristics Of Alfalfa Leaves

Phosphorus fertilizer is an important factor affecting the yield and quality of alfalfa.At the same time,phosphorus in the soil has the characteristics of poor mobility and surface enrichment,which leads to the deep roots unable to fully absorb.Therefore,how to improve the utilization efficiency of phosphate fertilizer,reduce weight and increase efficiency,slow down or avoid the pollution of soil and ecological environment caused by excessive application of phosphate fertilizer is one of the hot issues in the cultivation and management of Alfalfa artificial grassland.In view of the above situation,pot experiment was used to set up 4 P application depths(5,10,15,20cm)and 5 P application levels(0,80.160,240,320kg/hm2).Through the determination of plant height,biomass of each organ,CP,ADF,NDF,C,N,P content,the effects of different P application depths and P application levels on its production performance and C,N,P stoichiometric characteristics were discussed The basis of fertilization management was provided.The results show that:1.The depth of P application had a significant effect on the plant height of the first and the second of alfalfa;the level of P application had no significant effect on the plant height of the first and the second of alfalfa;the interaction between the depth of P application and the level of P application had a significant effect on the plant height of the first and the second of alfalfa;the height of the first of alfalfa was 5cm and 240 The highest value was 40.89cm at kg/hm2,and 55.33cm at 15cm depth and 80kg/hm2 level.2.The depth and level of P application and their interaction have significant or extremely significant effects on the biomass of the first crop,the second crop,the total aboveground biomass,the underground biomass and the total biomass.With the increase of phosphorus application depth,the biomass decreased.With the increase of P application level,the biomass(except underground biomass)increased gradually.The biomass of the first crop,the second crop,the total aboveground biomass,the underground biomass and the total biomass were the highest under the conditions of 15cm depth and 320kg/hm2 level of phosphorus application,with the values of 5370,6598.1,11968.1,7091.43 and 19059.52kg/hm2 respectively.3.The depth of P application had no significant effect on the contribution rate of stem,root and leaf.The contribution rate of P application level and interaction to root,stem and leaf was significantly affected.The contribution rate of leaves was the highest at the depth of 20cm and 80kg/hm2 of P application,which was 45.95%;the contribution rate of stems was the highest at the depth of 5cm and 80kg/hm2 of P application,which was 19.65%;the contribution rate of roots was the highest at the depth of 10cm and 80kg/hm2 of P application,which was 44.75%.4.CP content and RFV in leaves were higher than that in culms,ADF and NDF content were lower than that in stems;the increase of P application depth increased NDF content in first stubble,decreased CP content,and decreased NDF content in second stubble leaves;under P application treatment,ADF and NDF content in culms were decreased,and RFV was increased The RFV value of stem and leaf of the first alfalfa was the highest under the condition of 5 cm depth and 80 kg/hm2 P application level,which were 123.99 and 153.2 respectively.The RFV of the second crop was the highest under the condition of 10 cm depth and 240 kg/hm2 P application level,and its values were 125.97 and 158.64 respectively.5.The depth of P application had a significant effect on the C and P content of the second crop of alfalfa,but had no significant effect on the N content;the level of P application had a significant effect on the C and N content of the second crop,and had a significant effect on the P content of the first and second crop;the interaction between the depth of P application and the level of P application had a significant effect on the C and N content of the first and second crop;the second crop had a significant effect on the P content of the first and second crop The content of C,N and P in the first stubble was the highest under the conditions of 15cm and 320kg/hm2 of P application,15cm and 80kg/hm2 of P application,10cm and 320kg/hm2 of P application,respectively.The content of P in the second stubble was the highest under the conditions of 10cm and 320kg/hm2 of P application.6.The effect of P application depth on C/N of the second stubble leaves was significant,but not on C/P,but on N/P.with the increase of P application depth,C/N of the second stubble gradually increased and N/P gradually decreased;P application level had significant effect on C/N and C/P,but had significant effect on N/P of the second stubble,with the increase of P application level,C/P and N/P of the first stubble and the second stubble gradually decreased;P application depth X P application level crossing The interaction had a significant effect on the first C/P and the second N/P,and the C/P and N/P had a high level without P application.