Assessment Of Soil Health In Cultivated Land Based On Versatility

Cultivated land soil health is not only related to agricultural production and food security,but also closely related to ecosystem quality.It is of great significance to carry out the strategy based on farmland management and technological application and promote the construction of ecological civilization.The international soil health assessment has established a relatively comprehensive system with emphasizing on multiple functions evaluation.However,the current work on soil health assessment in China mainly focuses on soil production function,which is difficult to reflect the value of soil ecosystem services comprehensively.Therefore,there is an urgent need to carry out quantitative assessment of soil health related research.On the basis of combing the international theories and methods of soil health assessment,this paper constructed the index system and method of cultivated land soil health assessment from the perspective of soil multi-functionality.It took five typical agro-ecosystems of Fengqiu,Luancheng,Yucheng,Shangqiu,and Dongtai in the Huang-Huai-Hai Plain as examples.Via the systematic collation and analysis of the soil data and environmental background data of climate,biology,etc in the study area,we constructed the index system and assessment method suitable for the case area,thus to comprehensively evaluate the soil health status of each typical agro-ecosystem and analyze their changing trends.In addition,we proposed some countermeasures and suggestions to promote soil health according to the assessment results.The following results and conclusions were obtained from the study:(1)This study followed the procedure of "management goal-soil function-assessment index-assessment model-assessment result" and referred to the German Müncheberg soil index scheme to construct an assessment index system based on multi-functionality of cultivated land soil health.In this paper,soil functions were categorized into five aspects: crop production,water holding and purification,nutrient transport and buffering,carbon sequestration,and habitat and diversity function.Further,for each function,the corresponding basic indices were selected separately according to two directions of inherent(I)or dynamic(D)attributes,and then the comprehensive evaluation model was used to calculate the I and D values of soil health basic scores.On this basis,considering the difference in the degree of influence of the restricting indices,the I and D values were coefficient corrected and added respectively to obtain the total scores of each soil function.Then the five functions were weighted and summed to get the comprehensive soil health index values.In this thesis,the soil function assessment was no longer limited to the production function,but a comprehensive evaluation for soil multi-functionality,and we distinguished the impact of limiting factors on inherent attributes and dynamic attributes.It not only reflected the contribution of soil basic indices,but also reflected the different roles of different limiting factors.(2)The research data analysis showed that the typical agro-ecosystems in the case area had good water and heat conditions,with deep soil layer,and the surface soil texture was mainly loamy.p H ranged from 7.9 to 8.8,and soil itself was overall weak alkaline.The soil nutrients were at a medium level.Besides,there was no pollution risk for the time being,and the cultivation potential was relatively great.Through the analysis of soil index data of comprehensive and auxiliary sample plots in Fengqiu,Luancheng,and Yucheng ecological stations,it was found that the soil fertility of the comprehensive observation fields was comparatively high,and the soil nutrient contents of the No.01 auxiliary sample plots without fertilization were significantly lower than other sample plots.The contents of available phosphorus and potassium in No.02 auxiliary plot of Yucheng station,treated with fertilization and straw returning,were significantly higher than those in other plots.Thus,there were some differences in soil physicochemical properties and fertility status among the typical agroecosystems in the case area.(3)From the changes of soil physical,chemical,and biological indices,the surface soil bulk density changed little in general compared to the period of the second soil census.The nutrient contents of topsoil were generally on the rise,and only a few sample plots showed a decreasing trend in individual indicators.A comparative analysis revealed that transformations of fertilization and tillage measures were the main factors which could cause such changes.In addition,the net primary production(NPP)of each typical agro-ecosystem showed an overall increasing trend.The NPP value of the Yucheng station in 2015 increased by 87.5% compared to 2000 with the largest growth.On the whole,after long-term soil management and conservation tillage,the soil physical and chemical properties and biological characteristics of typical agro-ecosystems in the Huang-Huai-Hai Plain had been significantly improved.(4)The results of soil health assessment showed that the overall soil health level of agroecosystems in the case area was good,among which the soil health of the Shangqiu station was the best.Nevertheless,the soil salinization in coastal shoal area in Dongtai was repetitive and long-term,so the soil health score was relatively low.Fengqiu station had the highest production function score and its productivity was the largest.In terms of changing trends,after more than30 years of cultivation and management,the soil health of each agro-ecosystem had been greatly improved.Shangqiu station had the fastest soil health improvement speed,and the soil health score of the comprehensive sample plot in 2015 increased by 72.3% compared with the second soil census period.The soil health of Luancheng station was stable and at a relatively high level.Fengqiu and Yucheng were historically threatened by salinization.After the improvement of saline-alkali soil and the transformation of medium and low yield fields,the level of soil health also improved considerably,with an increased rate of 24.9% and 36.0%,respectively.Dongtai had better water and heat conditions,and the soil health had also been improved to a certain extent in recent years.However,its comprehensive health index was still low compared with other agro-ecosystems due to the limitation of salinization.Further validation of the soil carbon sequestration function and production function showed that the R2 reached 0.64 and 0.56,respectively,indicating that the evaluation system and method established in this study are reasonable.This thesis improves the international existing soil assessment framework,constructs a soil health assessment system for cultivated land based on multi-functionality,and analyzes the soil health status and changing trends in the case area,which can provide some support for soil health management in similar regions.