| At present,there are some problems in the use of cultivated land in China,such as the decrease of the quantity of cultivated land,the decline of quality,the fragmentation of space and the deterioration of ecological environment.The quality of cultivated land in loess Plateau is generally poor,the problem of soil and water loss is serious,and the ability of soil to lock up fertilizer is poor.It is the premise and foundation to realize the "trinity" protection of cultivated land quantity,quality and ecology to evaluate the quality of cultivated land in loess plateau objectively and scientifically.In this paper,the integrated use of literature research,quantitative research method,empirical study,qualitative study method and other research methods,on the basis of the analysis of temporal and spatial distribution and evolution characteristics of cultivated land resources,establish the loess plateau county cultivated land quality evaluation system.Taking Zichang City as an example to study the quality evaluation of cultivated land,analyze its spatial structure characteristics,and diagnose the obstacles to the quality of cultivated land in this area.Finally,some specific suggestions are put forward to provide theoretical and technical support for the protection and construction of cultivated land quality in loess plateau region.The main conclusions are listed as follows:(1)The cultivated land slope in Zichang City is generally larger,and the proportion of cultivated land slope > 25° is 45.96%.In recent 12 years,the dynamic change of cultivated land and forest land,grassland and garden land has taken place significantly.The dynamic change of cultivated land attitude index has a great difference in each slope level,and the cultivated land area of 0～2°,2～6° and 6～15° has a slight increase trend.However,the total cultivated land area of 15～25 °,> 25° and 15-25 ° decreased sharply.The spatial distribution of kernel density of cultivated land at county level showed a significant downward trend,and the landscape shape complexity and spatial shape fragmentation of cultivated land showed an obvious downward trend,and the landscape patch density of cultivated land increased.(2)The distribution of cultivated land quality index(IFI)in Zichang ranged from 0.25 to 0.79,with an average value of 0.43.The overall quality index of cultivated land was low,and the spatial distribution of cultivated land quality in different towns showed great differences.The IFI value of irrigated land in the second class of cultivated land was significantly higher than that of dry land.The change of elevation has little effect on cultivated land quality index in Zichang City.Using such as spacing method can be divided into superior and high,medium,low and,inferior to five grades,smaller city cultivated land quality is given priority to with low,medium and inferior,78.99% of the total area of arable land,smaller city overall cultivated land quality level is low,low level of the cultivated land are mainly distributed in the county in central and northern areas,Superior and superior land is mainly distributed in the southwest of the county.(3)The semi-variogram of cultivated land quality index fitted by exponential function model was the best,and the degree of spatial autocorrelation was in the moderate level.The spatial heterogeneity of cultivated land quality index was greatly affected by random factors.The Moran’s I of the global spatial autocorrelation of cultivated land quality index in Zichang City was 0.272688.There was significant spatial aggregation in the spatial distribution of cultivated land quality,and significant spatial difference in the distribution of cold hot spots of cultivated land quality.(4)Slope,total nitrogen,soil erosion degree,organic matter content,irrigation guarantee rate and other factors were the main factors above the medium intensity in Zichang City.Based on these key factors,relevant suggestions were put forward from the perspectives of tillage measures,soil fertilization measures,engineering measures,forest and grass measures,etc.,to provide reference for regional cultivated land protection and quality construction. |
PDF Full Text Request