Characterizing distribution of soil total sulfur and major nutrients in Hequ grassland of Qinghai Province

Sulfur is an indispensable mineral nutrient element, which required for the growth and development in animals and plants, and plays an important role in organic husbandry. The purpose of this study was to characterize the distribution of soil total sulfur, nitrogen, phosphorus, and potassium nutrients in different meadow types and topographies, and to explore the relationships between soil total sulfur and other nutrients in Hequ grassland of Qinghai, China. The total sulfur content of soil and plant samples was analyzed by ICP-OES (iCAP6300), and the contents of total nitrogen, phosphorus, potassium, organic matter, and soil pH were determined by conventional soil nutrient analysis. There were significant differences in the sulfur content in both soil and plant samples from different meadows, but no significant differences were detected in both soil and plant samples from different terrains. The soil total sulfur content in the study area was 1 023.98 mg·kg⁻¹, and plant total sulfur content was 4 120.20 mg·kg⁻¹. The average soil organic matter, total nitrogen, total phosphorus, and total potassium contents were 134.35, 6.44, 1.95, and 23.05 g·kg⁻¹, respectively, and were higher than the average levels of these in the Qinghai-Tibet Plateau. Soil total sulfur content was positively correlated with organic matter content, aboveground biomass, and plant total sulfur (P < 0.05). Soil carbon : sulfur ratio was between 58.90 and 102.18, indicating that soil sulfur was in a net release phase. The current production mode that the element has only output and no human input has not resulted in a soil sulfur deficiency, and sulfur is not a limiting factor for soil nutrients and the livestock industry in Henan County.