Predictive Mapping Of Stagnic Anthrosols Soil Series And Evaluation Of Regional Soil Fertility In Plain Agricultural Areas

Chinese Soil Taxonomy(CST)has made great progress at present,and it is at the stage of researching on the standard of basic taxonomic unit classification.The investigation and mapping of soil series has always been the focus of soil series research.Among them,predictive mapping of soil series as a method of predicting regional soil types based on known soil profile points has gradually attracted people’s attention.The landscape slowly changing areas such as plain agricultural areas are wide and flat.It surface fluctuations are not obvious,and the slope is relatively gentle;the natural vegetation is relatively single,and the landscape changes are small;the intense human activities,the land use types are diverse and volatile,therefore,there are relatively few studies on soil surveying and mapping in areas with slowly changing landscapes,where Stagnic Anthrosols is the main representative.At present,the assessment of soil fertility is mostly limited to the soil surface.Although most of the soil nutrients in agriculture are concentrated on the soil surface.It is not enough to consider the soil surface only when evaluating the fertility,especially in Stagnic Anthrosols.The hydromorphic process,the sticking process and the gleying process with leaching phenomenon in the hydragric horizon indicate the active and abundant material exchange phenomenon on the Stagnic Anthrosols profile,as well as the fertility evaluation of the soil Pedon.Necessity and importance.The research objectives of this article include:to find a more convenient and quick soil mapping method suitable for the slowly changing landscape area,and to complete the soil mapping prediction mapping of Stagnic Anthrosols.The research results can provide more detailed soil basic data for regional precision agriculture management,ecological environment modeling,soil simulation and other fields.The soil fertility index of Pedon was calculated by reasonably dividing characteristic soil layers,and the regional soil fertility evaluation map was made by combining with soil system prediction map.The expected research results is the theory and method of soil Pedon fertility evaluation in CST are of great significance.Finally,the variation of soil fertility in different soil layer structures and different soil types under Stagnic Anthrosols in the study area is discussed,In order to reflect the influencing factors of the soil fertility.It provides important theoretical basis and scientific guidance for formulating measures to prevent soil degradation and methods for improving soil.Based on the CST theory and the major soil formation factors on the spatial variability of Stagnic Anthrosols types,8 diagnosis basis of soil were selected according to the soil genetic characteristics of Stagnic Anthrosols.Fuzzy c-means(FCM)was applied to analyze the sample soil,and the output results were interpolated by two geostatistical interpolation methods.Then get the soil series prediction map by defuzzification method.Using the index method of soil evaluation model,the evaluation index is selected,the index weight is determined,and finally the PFQI is calculated.Combined with the soil series prediction map,the regional soil fertility evaluation map was made.The relationship between different soil series types and soil series fertility was further analyzed.Summarizing the research results,the main conclusions are as follows:(1)In order to make the final soil prediction result can match the soil type discriminated by the CST at the soil series level or even at the level of the soil Family,soil subgroup and great group.This paper combines the characteristics of the CST classification system,the characteristics of the Stagnic Anthrosols,and the characteristics of establishing the soil series that should be strongly combined with agricultural production applications.8 kinds of soil diagnosis basis.The cluster centers obtained under the two clustering cases of verification point participation and verification point non-participation in soil fuzzy continuous clustering can establish a good correspondence with the soil series established by manual retrieval.Therefore,it is feasible and applicable to select soil diagnostic layers and diagnostic characteristics as the basis for soil type diagnosis.It is feasible and applicable to carry out numerical soil classification and soil prediction mapping in the basic soil classification unit of landscape slowly changing area.(2)Compare the application results of the two geostatistical interpolation methods in the prediction of soil series.In contrast,the results obtained using the Inverse Distance Weighted(IDW)are more accurate and reasonable.After further analysis by the confusion matrix,the Kappa coefficient is 0.61,and the total classification accuracy is 0.65,which meets the basic requirements for soil mapping accuracy.It shows that the combination of FCM algorithm and IDW can well realize the prediction and mapping of Stagnic Anthrosols in the plain agricultural area.Spatial prediction of soil systems can be widely applied to the spatial prediction and mapping of soil system types in the slowly changing landscape areas of plain agricultural areas on the premise of reasonable selection of soil diagnostic basis.(3)Correlate the soil fertility of Pedon with rice yield:the soil fertility of Pedon and rice yield were significantly related at the 0.01 level(two sides),the correlation was 0.71.The fertility of the tillage layer is significantly correlated with the rice yield at the 0.05 level(bilateral),the correlation was 0.33.It shows that this paper uses the soil diagnosis layer and diagnosis characteristics as the basis for the division of the soil layer,uses the principal component analysis method to determine the evaluation index and the weight of each soil layer,and finally calculates the PFQI.Thr evaluation system is scientific and practical.Also shows that the fertility of Pedon in the Stagnic Anthrosols soil profile has a higher correlation with rice yield than the fertility of the cultivated layer.(4)Analyze the relationship between different soil series types and its fertility.The fertility of the soil series is mainly determined by the soil texture,organic matter,phosphorus and potassium content and other soil nutrients,and also closely related to the thickness and structure of the soil layer.The existence of the gley horizon will have a negative impact on the fertility of the soil series and reduce the fertility level of soil fertility;the soil series with ironaccumulating characteristic layer generally has higher fertility.