氮添加对巴音布鲁克高寒湿地土壤无机磷形态的影响

为探究在全球气候变化敏感区的干旱区高寒湿地上,氮添加对土壤无机磷形态的影响。在保护良好的巴音布鲁克高寒湿地沼泽(S)、沼泽草甸(SM)和草甸(M)布设野外原位试验,依据巴音布鲁克草原氮沉降量,设置0(CK),8(N1),16(N2) kg·N/(hm²·a)的施氮量,研究短期氮添加对高寒湿地土壤无机磷形态的影响。结果表明:(1)高寒湿地土壤全磷含量平均为1.09 g/kg,总无机磷平均为492.71 mg/kg,而总无机磷平均占全磷的45.67%。(2)3种湿地类型土壤无机磷主要以Ca—P形态存在,在Ca—P中以Ca₁₀—P为主,占无机磷含量的50.27%~64.69%。S区土壤Al—P、Fe—P含量显著高于SM和M区,SM区Ca₂—P、Ca₈—P、O—P含量显著高于S和M区,M区土壤Ca₁₀—P含量显著高于S和SM区。(3)氮添加显著影响高寒湿地土壤各形态无机磷的含量,氮添加下,S和SM区土壤Al—P含量较CK显著增加了9.92%~17.35%,而Ca₈—P含量显著降低3.18%~9.36%。[JP]S和M区土壤Fe—P含量显著降低了3.18%~9.36%,S区土壤Ca₂—P含量显著降低了10.31%。氮添加下3种湿地类型土壤O—P含量均显著增加,较CK显著增加21.83%~25.94%。(4)土壤pH、有机碳、碱解氮和速效钾均是影响无机磷形态的重要因子。不同湿地类型土壤无机磷形态含量存在显著差异,氮添加显著改变了土壤各无机磷形态含量,主要是通过增加土壤中难利用无机磷(O—P)含量,使高寒湿地土壤的供磷潜力降低。研究结果有助于预测未来氮沉降持续增加背景下全球高寒湿地土壤无机磷形态的变化趋势。

Nitrogen Addition Significantly Affected the Soil Inorganic Phosphorus Forms in Bayinbuluk Alpine Wetland

In order to investigate the effects of nitrogen addition on soil inorganic phosphorus forms in alpine wetland in arid area sensitive to global climate change Field in situ experiments were arranged in the well protected Bayinbuluk alpine wetland Swamp (S), Swamp meadow (SM) and Meadow (M). According to the nitrogen deposition of Bayinbuluk grassland, the nitrogen application rates of 0 (CK), 8 (N1) and 16(N2) kg·N/(hm²·a) were set to study the effect of short~term nitrogen addition on soil inorganic phosphorus forms in alpine wetland. Results showed that:(1) The average total phosphorus content under alpine wetland soil was 1.09 g/kg, and total inorganic phosphorus was 492.71 mg/kg, and total inorganic phosphorus accounted for 45.67% of total phosphorus on average. (2) The soil inorganic phosphorus of the 3 wetland types mainly exists in the form of Ca-P, and Ca₁₀-P is the main form of Ca-P, accounting for 50.27%~64.69% of the inorganic phosphorus content. The contents of soil Al-P and Fe-P in S area were significantly higher than those in SM and M area, the contents of Ca₂-P, Ca₈-P and O-P in SM area were significantly higher than those in S and M area, and the content of soil Ca₁₀-P in M area was significantly higher than those in S and SM area. (3) Nitrogen addition significantly affected the content of various forms of inorganic phosphorus in alpine wetland soil. Compared with CK, the content of soil Al-P in S and SM areas increased significantly by 9.92%~17.35%, and the content of Ca₈-P decreased significantly by 3.18%~9.36%. The content of soil Fe-P in S and M areas decreased significantly by 3.18%~9.36%. The content of soil Ca₂-P in s area decreased significantly by 10.31%. It is worth noting that under the addition of nitrogen, the soil O-P content of the 3 wetland types increased significantly, which was 21.83%~25.94% higher than that of CK. (4) RDA showed that soil pH, organic carbon, available nitrogen and available potassium were important factors affecting the form of inorganic phosphorus. In conclusion, there are significant differences in the content of inorganic phosphorus forms in different wetland types. Nitrogen addition significantly changes the content of inorganic phosphorus forms in the soil, mainly by increasing the content of difficult to use inorganic phosphorus (O-P) in the soil, so as to reduce the phosphorus supply potential of alpine wetland soil. This study is helpful to predict the changes of soil inorganic phosphorus in alpine wetlands under the background of continuous increase of nitrogen deposition.