Soil quality index as affected by long-time continuous cultivation in a Mediterranean sub-humid region

Abstract

Evaluating the Soil Quality Index (SQI affected by continuous and long-term cultivation operations to identify the threat of soil destruction and its controlling is a severe challenge. The current study has investigated the effects of cultivation operations on SQI in a wide area (37,524 ha), and with various types of soil (three soil orders including Inceptisols, Mollisols, and Vertisols) and the record of several decades of wheat cultivation. After determining the total data set (TDS) and minimum data set (MDS), the SQI was calculated using Integrated Quality Index (IQI) and Nemoro Quality Index (NQI) models. The results showed that most soil indicators (e.g., electrical conductivity, sodium adsorption ratio, organic carbon, and bulk density) were negatively affected by long-term cultivation operations. Compared to the control soils, the values of IQI-T, NQI-T, IQI-M, and NQI-M had been decreased ranging from 17 to 24%, 20 to 27%, 17 to 22%, and 21 to 26%, respectively, in the cultivated soils. The most significant decrease in the average SQI value was observed in the Vertisols (24% decrease), followed by Inceptisols (21% decrease) and Mollisols (19.5% decrease). The regression equations indicated that IQI-T, NQI-T, IQI-M, and NQI-M models could explain 59%, 39%, 53%, and 35% and 57%, 37%, 51%, and 33% of changes in the biological and grain yields of wheat, respectively. The current study provides a quantitative method for evaluating the soil quality at the soil type-scale and creatively analyzes the effects of long-term and continuous cultivation operations on the soil quality and product performance.