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采用Tiessen等修正后的Hedley土壤磷素分级方法对西藏日喀则地区(江孜)及山南地区(琼结)不同开垦年限的耕地以及放牧草地土壤进行磷素分级。结果表明,土壤无机磷库中Dil.HCl-Pi(1 mol/L HCl提取无机磷)>Conc.HCl-Pi(浓HCl提取无机磷)>NaOH-Pi(0.1 mol/L NaOH提取无机磷)>NaHCO3-Pi(0.5 mol/L NaHCO3提取无机磷)>H2O-Pi(水溶性磷);随着耕种时间的延长,各无机磷组分都出现增加的趋势,其中Dil.HCl-Pi和Conc.HCl-Pi的增幅相对较大,琼结草地比耕地含有更大的有机磷库,但其无机磷库却相对较小;耕种年限在50年以内的样地,有机磷组分随着耕种年限的延长而降低,但在50年以上的样地又出现上升趋势,即呈“V”字型趋势。NaOH-Po(0.1 mol/L NaOH提取有机磷)与Dil.HCl-Pi呈极显著(P<0.01)负相关,与SOC(有机碳)呈极显著(P<0.01)正相关;Conc.HCl-Po(浓HCl提取有机磷)与Conc.HCl-Pi呈显著(P<0.05)正相关;SOC与Dil.HCl-Pi呈显著(P<0.05)负相关;pH值与Dil.HCl-Pi呈极显著(P<0.01)正相关,与NaOH-Po和SOC呈极显著(P<0.01)负相关。
The Hedley soil phosphorus fractionation method modified by Tiessen et al. Was used to classify phosphorus in cultivated land and pasture grassland with different reclamation years in Shigatse region (Tibet) and Shannan region (Qiongjie). The results showed that Dil.HCl-Pi (inorganic phosphorus extracted with 1 mol / L HCl)> Conc.HCl-Pi (inorganic HCl with concentrated HCl)> NaOH-Pi (inorganic phosphorus extracted with 0.1 mol / L NaOH) > NaHCO3-Pi (0.5 mol / L NaHCO3 to extract inorganic phosphorus)> H2O-Pi (water-soluble phosphorous). With the prolongation of cultivation time, the content of inorganic phosphorus increased with Dil.HCl-Pi and Conc .HCl-Pi increased relatively larger than that of cultivated land, and the agro-grassland had larger organic phosphorus pool than that of arable land, but its inorganic phosphorus pool was relatively small. With the cultivation period of less than 50 years, The extension of the years reduced, but in the plots of more than 50 years there is an upward trend, that is “V ” font trend. There was a significant (P <0.01) negative correlation between NaOH-Po (0.1 mol / L NaOH) and Dil.HCl-Pi and a very significant (P <0.01) correlation with SOC (P <0.05). Conclusions (P <0.05) were positive correlations between -Po (concentrated HCl extract organic phosphorus) and Conc.HCl-Pi; negative correlation between SOC and Dil.HCl- (P <0.01), but negatively correlated with NaOH-Po and SOC (P <0.01).