Effect of chemical characteristics of soil on orange productivity: A case study of nghe an province, Vietnam

This study was conducted in orange farming area of the central Nghe An province, Vietnam to understand effect of chemical characteristics of soil conditions on orange productivity. Soil samples were collected from 102 sites in three high orange yielding districts (Quy Hop, Nghia Dan and Con Cuong) to analyze 16 chemical factors including pH, macronutrients, some micronutrients and beneficial nutrients. Dataset with 16 factors obtained by chemical analysis was examined with Principal Component Analysis (PCA) to extract combination of chemical factors characterizing soils in the study area. In addition, orange productivity data of five communes of Con Cuong district for the period 2015 to 2018 was analyzed to elucidate the relationship between soil characteristics and orange productivity. The study reveals chemical characteristics of soil and its relationship in the production of oranges in the central NgheAn province. Results of this study show that: (1) Soils in the area is characterized mostly by acidity, where one third area is extremely acidic (pH<4). This can be mainly attributed to sulphate and lower contents of Ca²⁺ and Mg²⁺ in the soil and (2) Low orange productivity in Con Cuong area is caused by extremely acidic soils with excess concentration of Al³⁺ and less concentration of P₂ O₅. Occurrence of extremely acidic soils in the study area can also be attributed to washing out of exchangeable cations from steep slopes due to the soil erosion.