Evolution of soil fertility and nitrogen/phosphorus leaching risk in protected agriculture of the eastern Qinghai-Tibet Plateau北大核心CSCD

Understanding changes in soil fertility and soil environmental risks in protected agriculture with high irrigation and fertilizer inputs are of great significance for ecological protection. In this study, soil samples in the plow layer were collected from greenhouses >100 acres in the eastern Qinghai-Tibet Plateau after different durations of planting time (either ≤ 3, 3-5, 5-10, or 10-20 years) to assess the changing pattern of soil fertility indicators and the potential leaching risk of nitrogen and phosphorus. The results showed that soil organic matter (OM) and total nitrogen (TN) contents in protected agriculture were 17.1 and 1.3 g/kg, respectively, which suggests moderate content levels. Meanwhile, soil alkali-hydrolyzed nitrogen (AN), available phosphorus (Olsen-P), and available potassium (AK) contents were 160.9, 72.0, and 191.2 mg/kg, respectively, which suggests abundant content levels. As the number of planting years increased, the contents of soil OM, TN, AN, and Olsen-P increased significantly, especially after 10 years, with 41.6%, 44.2%, 26.5%, and 67.4% increases, respectively, compared to ≤ 3 years. As seen, Olsen-P had the most marked increase. In contrast, soil AK and pH decreased with planting years, and soil AK after 5 years decreased by 32% compared to ≤ 3 years. Moreover, the soil pH value in 3-5 years decreased by 2.3% compared to that of ≤ 3 years. The leaching risk of soil nitrogen and phosphorus was intensified after 10-20 years, and the probability of leaching was 0.74 and 0.84, respectively. This study indicated that, in protected agriculture, soil OM, AN, and Olsen-P contents improved, accompanied by a high risk of N and P loss, and AK and soil pH values decreased. It is recommended that the input of nitrogen and phosphorus fertilizers should be controlled, and the input of potassium fertilizer should be increased for more than 10 years of facility cultivation. This study provides a scientific basis for the rational fertilization of agricultural facilities. The findings indicate that after facility planting for 10-20 years, soil organic matter, nitrogen, and phosphorus significantly increased, yet the leaching risk of nitrogen and phosphorus increased as well, suggesting that the input of nitrogen and phosphorus fertilizer should be controlled. After 3-5 years of planting, soil AK and pH values decreased significantly, implicating that potassium and organic fertilizer should be supplemented in a timely manner. © 2022 Science Press. All rights reserved.