摘要
摘要:为了明确磷肥减量施用对石灰性土壤磷组分及其与作物磷积累量关系的影响, 设置3个施磷量, 按纯磷计分别为150 kg·hm^?2(P150)、37.5 kg·hm^?2(P37)和0 kg·hm^?2(P0), 经过连续2年4季冬小麦-夏玉米轮作, 采用Hedley土壤磷组分分组法, 研究土壤磷组分含量的变化及其存储贡献率、输出贡献率, 并采用回归分析、通径分析和结构方程模型探讨土壤关键磷组分及其与磷肥施用量、作物磷积累量间的关系。结果表明, 与P37处理相比, P150处理导致土壤全磷显著增加, 并显著提高阴离子交换树脂态无机磷组分(resin_P_i)、NaHCO₃提取态无机磷(NaHCO₃_P_i)、NH₄OAc提取态无机磷(NH₄OAc_P_i)、NaOH-Na₂S₂O₆提取态无机磷(Fe_P_i)和NaHCO₃提取态有机磷(NaHCO₃_P_o)等组分含量(P<0.05)。P0处理与P37处理相比, 土壤磷及其组分含量无显著变化。土壤无机磷组分和有机磷组分的存储贡献率分别为72.6%和23.8%。土壤盈余磷主要存储在HCl提取态无机磷(HCl_P_i)、Fe_P_i、NH₄OAc_P_i、resin_P_i和HCl提取态有机磷(HCl_P_o)等组分中。土壤无机磷组分的输出贡献率为41.0%, 有机磷组分的输出贡献率为56.4%。其中HCl_P_o、Fe_P_i和NH₄OAc_P_i的输出贡献率分别为39.44%、17.36%和13.06%。HCl_P_i和resin_P_i的输出贡献率仅为1.91%和0.40%。在结构方程模型中, 施磷量对Fe_P_i、HCl_P_i、NH₄OAc_P_i、resin_P_i、NH₄F_P_o、NaHCO₃_P_i和NaHCO₃_P_o等组分的载荷因子分别为0.078、0.077、0.061、0.036、0.018、0.015和0.012。Fe_P_i、NH₄OAc_P_i和HCl_P_o等组分对作物磷积累量的载荷因子分别为0.355、0.334和?0.039。上述结果表明, 石灰性土壤中, Fe_P_i、NH₄OAc_P_i和HCl_P_o是关键磷组分, 其中Fe_P_i和NH₄OAc_P_i在不施磷时易消耗, 但也易通过施磷得到补充; HCl_P_o有效性高, 不易更新。HCl_P_i有效性低, 是磷肥当季有效性低的重要原因。建议磷肥施用量的决策应以关键磷组分的存储贡献率为依据。
关键词:石灰性土壤/
土壤磷组分/
结构方程模型/
减量施磷/
输出贡献率
Abstract:Excessive application of phosphate fertilizer wastes phosphorus resources and induces eutrophication in lakes and rivers. To study the effect of reduction of phosphorus fertilizer on phosphorus fractions in calcareous soil and its relationship with crop phosphorus accumulation, three treatments were set up, i.e., phosphorus application rates of 150 kg?hm^?2 (P150), 37.5 kg·hm^?2 (P37), and 0 kg?hm^?2 (P0). After two consecutive years of “winter wheat-summer maize” crops rotation, the changes in the contents of soil phosphorus fractions were studied using Hedley soil phosphorus fractionation method, and the storage contribution rate and output contribution rate of each fraction were also estimated. The relationship between soil phosphorus fractions contents, phosphorus fertilizer application rate, and crop phosphorus uptake amount were explored by using regression analysis, path analysis, and structural equation model. The results showed that compared with P37, P150 led to a significant increase in soil total phosphorus content. The contents of inorganic phosphorus extracted with anion exchangeresin (resin_P_i), with NaHCO₃ (NaHCO₃_P_i), with NH₄OAc (NH₄OAc_P_i) and with NaOH-Na₂S₂O₆ (Fe_P_i), and organic phosphorus extracted with NaHCO₃ (NaHCO₃_P_o) in P150 were significantly higher than those in P37, while the other fractions showed no significant change. P0 did not cause a significant decrease in the contents of soil phosphorus fractions. The storage contribution rates of soil inorganic phosphorus fractions and organic phosphorus fractions were 72.6% and 23.8%, respectively. Among them, the storage contribution rates of inorganic phosphorus extracted with HCl (HCl_P_i), Fe_P_i, NH₄OAc_P_i, resin_P_i, and organic phosphorus extracted with HCl (HCl_P_o) were 24.45%, 18.1%, 13.62%, 11.15%, and 9.30%, respectively. The output contribution rate of soil inorganic phosphorus fractions was 41.0%, and that of organic phosphorus fractions was 56.4%. Among them, the output contribution rates of HCl_P_o, Fe_P_i, and NH₄OAc_P_i were 39.44%, 17.36%, and 13.06%, respectively. The output contribution rates of HCl_P_i and resin_P_i were only 1.91% and 0.40%, respectively. In the structural equation model, the load factors of phosphorus fertilizer application rate on Fe_P_i, HCl_P_i, NH₄OAc_P_i, resin_P_i, organic phosphorus extracted with NH₄F (NH₄F_P_o), NaHCO₃_P_i, and NaHCO₃_P_o were 0.078, 0.077, 0.061, 0.036, 0.018, 0.015, and 0.012, respectively. The load factors of Fe_P_i, NH₄OAc_P_i, and HCl_P_o on crop phosphorus uptake were 0.355, 0.334, and ?0.039, respectively. The above results show that in calcareous soil, Fe_P_i, NH₄OAc_P_i, and HCl_P_o were the key phosphorus fractions. Among them, Fe_P_i and NH₄OAc_P_i were easily consumed when no phosphorus fertilizer was applied, but they can be easily supplemented by phosphorus fertilizer application. However, HCl_P_o was available to the crop but was not easily replenished by phosphorus fertilizer application. The high storage contribution rate and low output contribution rate of HCl_P_i fraction were the important reasons for the low efficiency of phosphate fertilizer in the current season. It is suggested that the choice of phosphorus application rate should be based on the storage contribution rate of the key phosphorus fractions.
Key words:Calcareous soil/
Phosphorus fractions in soil/
Structural equation model/
Reducing phosphorus rate/
Output contribution rate



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