The Stoichiometric Effect Of Carbon,nitrogen And Phosphorus Under Grass Returning Technology

The Loess Plateau is the main producing area of high-quality apples in my country,and the apple industry has become the leading economic industry and advantageous industry to increase farmers’ income,promote regional economic and social development,and promote rural revitalization.Growing grass in orchards is a soil management model for the sustainable development of orchard soils that is widely implemented in fruit-producing developed countries.As one of the ways to utilize the orchard’s green grass,it is widely used in production.It plays an important role in improving the soil structure,improving the fertility of the orchard,and balancing the nutrient cycle of the orchard ecosystem.Carrying out research on soil stoichiometry changes in orchards by turning grasses back into the fields will help reveal the interaction and balance constraints between soil carbon,nitrogen and phosphorus elements in orchards,optimize soil nutrient management,and optimize the orchard grass growing technology.important meaning.This study is based on the localization test of grass growing in apple orchards on the Loess Plateau of Weibei,and analyzes the dynamic changes of soil C:N:P and microbial biomass C:N:P after in-situ overturning with different grass species and different overturning amounts.To further explore the relationship between the stoichiometry of plant residues and soil stoichiometry for different grass species,the main research results are as follows:(1)The dynamic characteristics of soil carbon,nitrogen and phosphorus stoichiometry under different grass species and different amounts of overturning were revealed.Different grass species and their overturning amount changed soil C:N:P pattern.From different periods,soil C:P and N:P showed a downward trend as a whole,while soil C:N showed no obvious change with time.From the perspective of grass species,the soil C:N and C:P after tumbling of CV and WC were lower than those of OG,among which the tumbling of OG was more conducive to the accumulation of organic carbon.The soil N:P was too low after the three kinds of grasses were overturned,and there might be nitrogen limitation.From the point of view of the amount of returning to the field,the soil C:N of the CV and WC after tumbling and returning to the field are lower than that of the soil that were not returned to the field,while the soil C:N of the OG after tumbling and returning to the field is higher.The soil C:N in the non-returning soil;the soil C:P and N:P after the three kinds of grasses were turned and returned to the field increased with the increase of the turning-returning amount.Combined with principal component analysis,the results showed that the effect of C:P on the available nutrients was greater in the soil C:P and the soil C:N in the soil C:N had a greater effect on the available nutrients.The nutrient dynamic changes in the full-returning of the CV and WC were larger,and the nutrient dynamic changes in the half-returning of OG were larger.(2)The dynamic characteristics of soil microbial carbon,nitrogen and phosphorus stoichiometry under different grass species and different overturning amounts were revealed.Different grass species and their overturning amount changed the MBC:MBN:MBP pattern.From different periods,MBC:MBN,MBC:MBP and MBN:MBP have no obvious change rule with time.In terms of grass species,the MBC:MBN and MBC:MBP of WC after pressing were lower than other grasses.Judging from the amount of returning to the field,the MBC:MBN,MBC:MBP,and MBN:MBP of the CV,OG and WC after turning were lower than those of the non-returning treatment.Grass turning and returning to the field changed the MBC:MBN:MBP internal stability characteristics.The stability characteristics of MBC:MBN after the three grasses returned to the field gradually changed from non-steady state to steady state,and MBC:MBP and MBN:MBP remained non-steady state in most periods.(3)The stoichiometric characteristics of plant residues and their relationship with soil and microbial stoichiometry during the decomposing process of different grass species were analyzed.The C:N of the residues of CV,OG,and WC were all less than 25,which indicated that the nutrients of the three kinds of grasses could be well released.Viewed from different periods,the C:N,C:P,N:P of the plant residues of CV,OG,and WC had no obvious change rule with time.From the perspective of grass species,the C:N of the grass plant residues in different grasses is as follows: OG > CV and WC,and C:P is represented by CV > OG > WC,N:P performance is: CV > OG and WC.The results of correlation analysis showed that there were positive or negative correlations between the carbon,nitrogen and phosphorus stoichiometry of plant residues and soil and microbial biomass carbon,nitrogen and phosphorus stoichiometry.The results of principal component analysis further showed that the C:N of plant residues in the field had a greater impact on soil and microbial ecological stoichiometry.Combining correlation analysis and principal component analysis,the selection of WC for returning to the field has more advantages in the long-term benefits of orchard grass.