Newly-reclaimed alfalfa forage land improved soil properties comparison to farmland in wheat–maize cropping systems at the margins of oases

Abstract

The increased demand for economic benefits has led to an extensive conversion of native sandy steppe at the margins of oases into alfalfa forage land and farmland in northwestern China. Understanding the impacts of alfalfa forage land and farmland on soil properties is crucial for maintaining the stability of oases. However, the effect of this newly-reclaimed alfalfa forage land and farmland on soil properties remains unknown. Native sandy steppe and 10-year-old alfalfa forage land and farmland (both converted from native sandy steppe) were chosen for use in this study. It was shown that the conversion of native sandy steppe to alfalfa forage land and farmland significantly increased the amounts of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP). Over the period of 10 years, the sequestrations of SOC, TN and TP were almost the same for both alfalfa forage land and farmland. After the period of 10 years, the soil water holding ability, water stable macro-aggregates aggregates, soil microbial biomass C (MBC) and microbial biomass N (MBN) contents and urease, β-glucosidase, and alkaline phosphatase activities were all significantly higher in the alfalfa forage land than in the farmland. These results suggest that the newly-reclaimed alfalfa forage land is more propitious for amending soil environments than farmland, thus it should be widely used to improve the soil properties at the margins of oases.