Soil Properties Spatial Variability and Delineation of Site-Specific Management Zones Based on Soil Fertility Using Fuzzy Clustering in a Hilly Field in Jianyang, Sichuan, China

Abstract

Avoiding soil degradation and improving crop productivity could be achieved by performing sustainable soil nutrient management with an appropriate understanding of soil properties' spatial variability. The present fertilizer recommendations for the region where the study area is located are typically symmetric for large regions. This leads to the under-application of fertilizers in zones with low nutrient contents and over-application in zones with high nutrient contents. Therefore, this study was conducted to assess soil management zones (MZs) in the study area for effective soil nutrient management and to evaluate soil properties' spatial variability. A total of 100 geo-referenced soil samples were collected at a depth of 0-20 cm, processed and analyzed for pH, available nitrogen (AN), available phosphorus (AP), available potassium (AK), soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP), while C:N, C:P and N:P ratios were calculated. Soil properties' coefficients of variation (CVs) widely varied from low (1.132%) to moderate (45.748%). Ordinary kriging and semi-variogram analysis showed differed spatial variability patterns for the studied soil properties with spatial dependence ranged from weak to strong. MZs were delineated by performing principal component analysis (PCA) and fuzzy K-means clustering. Four PCs with eigen values more than 1 dominated 84.44% of the total variance, so they were retained for clustering analysis. Three MZs were delineated based on the two criteria modified partition entropy (MPE) and fuzzy performance index (FPI). The studied soil properties differed significantly among MZs. Thus, the methodology used for MZ delineation could be used effectively for soil site-specific nutrient management for avoiding soil degradation concurrently with maximizing crop production in the study area.

Application of Geophysical and Hydrogeochemical Methods to the Protection of Drinking Groundwater in Karst Regions

“…The fuzzy matrix constructed by the distance obtained from the optimized calculation formula is a fuzzy similarity matrix R. Because it is not necessarily transitive, the intra group connection method is used to achieve its transitivity [54]. In the fuzzy matrix, all samples in the sample set U are classified and gradually merged to form a dynamic clustering diagram.…”

Integration of PCA and Fuzzy Clustering for Delineation of Soil Management Zones and Cost-Efficiency Analysis in a Citrus Plantation

“…Considerable advances in statistical techniques and modeling approaches have allowed different agricultural zones to be accurately delineated with new methods like machine learning, GIS, remote sensing, geostatistics, and kriging at a regional and farm scale [5,9]. Several methods and approaches, such as delineating by an active canopy sensor [10], using soil properties by fuzzy k-means cluster analysis [11,12], fuzzy c-means clustering algorithm, principal component analysis (PCA) [12][13][14][15][16][17], and soil fertility analysis [13] have been used to delineate different MZs. However, the selection of the techniques or approaches depends on the purposes of the determination of MZ and the complexity of each approach.…”

“…Different types of environmental and soil data could be used for delineating the MZs [10]. For instance, pedo-geomorphological factors [18], soil nutrients [19,20], intrinsic soil properties (e.g., electrical conductivity (EC), pH, particle size distribution, soil organic matter, cation exchange capacity, nitrogen, phosphorous, and potassium) [9,10,12,15,21] can be used for this purpose. Different types of information can be integrated to define MZs by using a clustering algorithm.…”

“…This effective approach is capable of identifying zones or regions in the fields or farms that internally have similar soil properties, conditions, and productivity potentials [5]. In the application of site-specific management zones, several studies reported successful application of MZ delineation for agricultural purposes, fertilizer application, and farm management [12,22,23]. Aggelopooulou et al [24], in an apple orchard in Greece, delineated four zones using soil and tree properties, which required different management of irrigation, fertilizer, and cultural activities.…”

Evaluating the Spatial Distribution of some Soil Geotechnical Properties Using Various Interpolation Methods (Case Study: Sulaimani Province, Iraq)

“…Soil is one of the most important materials on earth surface that most structures foundations are placed on it. Spatial variability of geotechnical properties of soils is a significant index of quality of soils, in addition to suitability for construction projects (Metwally et al, 2019). Hence, civil engineers have to study its geotechnical properties which helps to discover an understanding about their suitability for foundation laying material (Khatri, 2018).…”