Rational fertilization is a key measure for improving grassland productivity; however, the optimal effects of nitrogen (N), phosphorus (P) and potassium (K) rationing vary across grasslands with different salinity–alkalinity conditions. To determine the optimum fertilization ratio for typical saline–alkaline degraded grasslands in the agro-pastoral transition zone of northern China, we carried out an experiment with different ratios of N, P and K to investigate the effects of fertilization on biomass, plant diversity, plant nutrient uptake and soil nutrient contents. The results showed that fertilization increased biomass, plant diversity, nutrient uptake and soil nutrient contents in all levels of saline–alkaline grasslands. Compared with the control, N2P2K2 treatment resulted in the significantly highest biomass, with an increase of 4.52 and 2.39 t ha−1 in slightly and moderately saline–alkaline grasslands; N2P2K1 resulted in the significantly highest biomass, with an increase of 1.14 t ha−1 in severely saline–alkaline grasslands. We integrated plant and soil properties to construct a second-order response surface model (RSM), and our recommended optimum N–P–K fertilization ratios for slightly, moderately and severely saline–alkali grasslands are 103.7–88.1–78.0, 125.5–91.5–74.1 and 85.2–68.1–58.2 kg ha−1, respectively. Reasonable fertilization can improve soil fertility, biomass yield and plant diversity, while excessive fertilization has negative effects on soil and plant traits. Our results provide theoretical support and practical guidance for the scientific fertilization of grasslands with varying salinity and alkalinity.
Liu et al. (Sat,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: