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.
Highlights
Soil degradation due to inadequate agriculture practices has become a global problem [1], which is clearly appearing in China due to fertilization mismanagement and the over exploitation of agricultural lands
According to the soil nutrient classification standard in China [68], the means of soil organic carbon (SOC) and total nitrogen (TN) content were low in the study area, while the mean soil AK and available phosphorus (AP) content were medium with a value of 147.10 and 17.02 mg/kg, respectively
Whereas the mean available nitrogen (AN) content was 35.42 mg/kg, which indicated that the study area’s AN content was very low. This shortfall in SOC, TN and AN might be due to removing the topsoil which is caused by water erosion, resulting in reducing soil nutrients and organic matter [6]
Summary
Soil degradation due to inadequate agriculture practices has become a global problem [1], which is clearly appearing in China due to fertilization mismanagement and the over exploitation of agricultural lands. China’s population has increased rapidly during the last 50 years, likewise the production of the main crops has increased. Such increases in productivity have been mainly attained by using unsustainable agricultural practices and inadequate and imbalanced fertilization. A depletion in soil nutrients occurs due to increasing crop yield in the land unit area, which will cause detrimental impacts on agricultural productivity in the future [2]. Intensifying agriculture using balanced fertilization and environmentally sustainable practices will be the best solution for China
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