Effects Of Remediation Materials On Soil Environment And Agricultural Product Quality Of Rice And Turtle Co-cropping

Rice and turtle co-cropping is a kind of ecological breeding mode which is mutually beneficial for the growth of aquatic animals turtle and rice.It is one of the planting modes with good efficiency of rice and fishery comprehensive planting and breeding,and has great production potential.In recent years,due to the irrational use of land and the development of industrial and mining enterprises,the soil has been polluted by heavy metals in different degrees.In the cultivated land polluted by heavy metals,part of rice and fishery comprehensive planting and breeding area is also included.At present,the remediation of heavy metal pollution in farmland soil mainly focuses on traditional rice farming,and there are few studies on soil heavy metal pollution remediation of rice and fishery comprehensive planting and breeding.Given the particularity of the rice and fishery comprehensive planting and breeding in the field project,which cannot damage the soil tillage layer and minimize interference with farmers’ production processes and reduce labor costs.In the remediation of heavy metal pollution in soil of rice and fishery comprehensive painting and breeding,the remediation method of fully mixing remediation materials with soil is not considered.Therefore,the paper chooses the amino acid water soluble fertilizer,calcium magnesium phosphate fertilizer and cysteine leaf control agent without turning the soil when applied as the test repair materials,and carried out field tests in rice and turtle co-cropping field in Yujiang District,Yingtan City.The effects of remediation materials on soil physical and chemical properties were studied under the rice and turtle co-cropping mode,and the effects of remediation materials on soil comprehensive fertility were explored by principal component analysis.Effect on the transformation of Cd form in soil,the correlation analysis method was used to explore the correlation between soil physical and chemical properties and soil Cd morphology.Using path analysis to study the direct and indirect factors that affect the Cd content of brown rice.Effects on protein and amino acid content of brown rice and Cd content of turtle muscle.The correlation analysis method was used to explore the correlation between soil physical and chemical properties and brown rice protein and 16 amino acids total amount.This study can provide reference for the application of amino acid water soluble fertilizer,calcium magnesium phosphate fertilizer and cysteine leaf control agent in ensuring food safety and agricultural safety production,so as to provide scientific basis and technical support for the green production and healthy development of rice and fishery comprehensive planting and breeding.The main research results are as follows:(1)Compared with rice and turtle co-cropping control(CK),the treatment with calcium magnesium phosphate fertilizer(T3)had the best effect on improving soil p H value and available phosphorus content in the whole growth stage and mature stage.Amino acid water soluble fertilizer(T1)significantly increased soil organic matter and cation exchange capacity during the whole growth period.Compared with traditional rice(CT),the contents of soil organic matter,cation exchange capacity,available phosphorus and alkali-hydrolyzable nitrogen in all treatments were higher than those in CT during the whole growth period.The results of principal component analysis showed that the soil comprehensive fertility of the treatment with T1 was the highest,and the comprehensive score of CK was higher than that of CT,indicating that rice and turtle co-cropping could improve the soil fertility.(2)At tillering stage and mature stage,the residue Cd content of soil treated with amino acid water soluble fertilizer(T2)was significantly higher than that of CK,with an increase of 85.26% and 181.64%.Compared with CT,the content of Cd in soil residue in T2 treatment increased by 120.63% and 103.73%,respectively.At heading stage,compared with CK,T3 treatment significantly increased soil residue Cd content,with an increase of 71.05%,compared with CT,the increase is 83.39%.The effects of restoration materials on soil Cd restoration efficiency and migration rate were analyzed.The results showed that the passivated restoration efficiency of soil Cd was the highest and the migration rate was the lowest in the treatment of T2 at tillering and maturity stages.In the heading stage,T3 treatment had the highest passivation repair efficiency and the lowest migration rate of soil Cd.The correlation analysis between soil physical and chemical properties and Cd morphology showed that soil organic matter,cation exchange capacity,alkaline nitrogen,available phosphorus were significantly positively correlated with acid extracted Cd.There were significant positive and negative correlations between available phosphorus and available potassium and residual Cd,respectively.(3)The Cd content of rice plants conforms to the rule of root > stem > leaf >brown rice.T2 treatment had the best effect on reducing the Cd content of rice roots,stems and leaves,while leaf spray of cysteine(T4)had a significant effect on reducing the Cd content of brown rice.Brown rice and turtle muscle Cd content did not exceed the national standard limit.Application of amino acid repair materials reduced the protein and 16 amino acids total amount in brown rice,T4 treatment had the most significant reduction effect.According to path analysis,soil-brown rice enrichment coefficient played a direct role in the enrichment of brown rice Cd content,while acid-extracted Cd,oxidizable Cd and stem-leaf transport coefficient played an indirect role.According to the correlation analysis,the protein and 16 kinds of amino acids total amount in brown rice were affected by nitrogen,and had significant positive correlation with soil alkali-hydrolyzed nitrogen.(4)The input routes of field Cd in the experimental area were fertilizer,bait,irrigation water and straw returning.The Cd content per unit of fertilizer,bait and irrigation water did not exceed the national standard limit.The output routes were paddy harvesting,turtle harvesting and straw removal.The Cd content per unit of paddy does not exceed the national standard limit.By analyzing the mass balance of input and output of Cd in the experimental area,it was found that the largest proportion of input and output flux was straw returning to the field and straw removal.Because the net flux > 0,it indicates that the soil Cd in the experimental area is a net input,and the experimental area is in the state of Cd accumulation.Systematic cluster analysis showed that Cd content in rice root contributed the most to Cd input of straw returning.