Three years of cultivating or fencing lands have different impacts on soil nutrients and properties of a subalpine meadow in the Tibetan plateau

Abstract

Tibetan subalpine meadows are being converted rapidly to cultivated lands because of the growing needs of food for humans and fodder for livestock. This land conversion could reduce the pools of C, N and P that are stored in the soil. Consequently, the assessment of the impact of land cultivation or fencing on soil nutrients and properties could improve sustainable grassland management. This study compared soil nutrients and properties of four land use types in a subalpine meadow: (1) natural pasture grazed traditionally by domestic yak and sheep; (2) fenced natural pasture which excluded grazing livestock; (3) land cultivated for oat fodder (oat land); and (4) land cultivated for barley grain (barley land). Soil measurements were done at three depth levels (0–10 cm; 10–20 cm; 20–30 cm) after three years of cultivation or fencing. Compared to the natural pasture, soil carbon and nitrogen parameters all decreased significantly in the barley land, were similar or increased in the fenced pasture and showed mixed but moderate changes in the oat land. Total phosphorus generally showed insignificant changes in all treatments. At the 0–10 cm soil layer, there was a gain in carbon in the fenced pasture (5.18 mg C·ha−1·yr−1), a loss in carbon in the barley land (7.50 mg C·ha−1·yr−1) and a slight loss in carbon in the oat land (0.88 mg C·ha−1·yr−1). Thus, cultivation for barley reduced soil nutrients substantially in the subalpine meadow, particularly in the surface soil layer, while cultivation for oats resulted in moderate changes. We concluded that land cultivation for oats and soil nutrient recovery by short-term fencing after cultivation are preferred alternatives of land use than cultivation for grain barley in the subalpine meadows of the northeast Tibetan plateau.