Long-Term Cropping Effects on Agricultural Sustainability in Alar Oasis of Xinjiang, China

Agricultural sustainability has become a major concern in arid regions of China. In order to better understand the influence of continuous cropping on soil quality, six experimental fields were established in the Alar Oasis of Xinjiang, including uncultivated land (as a zero year treatment duration) and five different continuous cropping years on cotton fields, with different cropping durations (5, 10, 15, 20 and 25 years, respectively). Thirteen soil indicators were selected including soil physicochemical properties, nutrient properties and enzymatic activities. The results show that duration of continuous cropping of cotton fields significantly influences a number of soil properties. Cultivation durations ranked according to soil quality indexes (SQI) are as follows: 15 years (0.828) > 20 years (0.816) > 10 years (0.668)> 5 years (0.548) > 25 years (0.377) > 0 years (0.205), and sustainable yield index (SYI) are as follows: 10 years (0.830) > 15 years (0.777) > 20 years (0.667) > 5 years (0.586) > 25 years (0.159).