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以贵州黄壤肥力与肥效长期定位试验为平台,探究有效磷(Olsen-P)与土壤累积磷盈亏、磷肥用量的关系,确定西南黄壤旱地最佳磷肥施肥量,通过Mitscherlich方程模拟作物相对产量对土壤Olsen-P的响应关系,明确西南黄壤旱地的农学阈值.结果表明:施用磷肥可显著提高土壤Olsen-P含量,不同施磷处理间提升幅度主要与磷肥施用量有关;不施磷处理土壤磷素一直处于亏缺状态,施磷处理土壤磷素有盈余,其中全量有机肥配施全量化肥处理(MNPK)作物吸磷量和磷素盈余量最高,同等施磷水平下,与单施化肥处理(NPK)相比,有机肥配施化肥处理(1/4 M+3/4 NPK、1/2 M+1/2 NPK)更能促进作物对磷素的吸收,提高磷素累积利用率.土壤累积磷盈亏与土壤Olsen-P增量呈显著直线相关关系(P<0.05),土壤中磷素每盈余100 kg·hm~(-2),MNPK、1/4 M+3/4 NPK、1/2 M+1/2 NPK、NPK处理Olsen-P分别增加16.4、13.0、21.4、5.6 mg·kg~(-1),有机肥与化肥配施能有效增加土壤Olsen-P含量.西南黄壤旱地Olsen-P的农学阈值为22.4 mg·kg-1;土壤每年磷盈亏和Olsen-P含量与磷肥施用量呈极显著正相关关系(P<0.01),磷肥用量(纯P)为每年33.3 kg·hm~(-2)时,土壤磷盈亏呈持平状态,Olsen-P农学阈值对应的施肥量(纯P)为每年45.9 kg·hm~(-2).西南黄壤旱地Olsen-P含量主要与施磷水平有关,当年施磷量为45.9 kg·hm~(-2)时可获得最佳的作物产量,磷肥利用率高;当年施磷量高于45.9 kg·hm~(-2)时,作物产量对磷肥用量无响应,大量磷素累积在土壤中,增加了磷素的环境流失风险.西南黄壤旱地长期施用有机肥处理单位累积磷盈余量提升土壤Olsen-P的速率大于单施化学磷肥处理.
Based on the long-term experiment of fertility and efficiency of yellow soil in Guizhou Province, the relationship between available phosphorus (P) and P cumulative gain and loss of phosphate fertilizer and the amount of phosphate fertilizer was explored to determine the optimum amount of fertilizers in yellow-paddy dry land in Southwest China. The relative yield of crop was simulated by the Mitscherlich equation Olsen-P.The results showed that the application of phosphate fertilizer could significantly increase the content of Olsen-P in the soil, and the increase rate was mainly related to the amount of phosphate fertilizer application.Unless phosphorus was applied to treat the soil phosphorus Which was in a deficit state. There was a surplus of phosphorus in the soil for phosphorus application. Among them, the total phosphorus uptake and phosphorus surplus of MNPK were the highest. Under the same phosphorus application level, NPK), the application of chemical fertilizer (1/4 M + 3/4 NPK, 1/2 M + 1/2 NPK) could promote the absorption of phosphorus by crops and increase the accumulation and utilization of phosphorus. There was a significant linear correlation between accumulated phosphorus gain and loss and soil Olsen-P increment (P <0.05). Phosphorus per crop exceeded 100 kg · hm -2, MNPK, 1/4 M + 3/4 NPK, / 2 M + 1/2 NPK and NPK increased Olsen-P by 16.4, 13.0, 21.4 and 5.6 mg · kg -1, Fertilizer and chemical fertilizer can effectively increase soil Olsen-P content.The agronomic threshold of Olsen-P in yellow-green dryland in southwest China was 22.4 mg · kg-1. There was a significant positive correlation between annual phosphorus loss and Olsen-P content and phosphorus application P (P <0.01). When the P (P) was 33.3 kg · hm -2 per year, the P surplus of the soil was in a flat state and that of the Olsen-P agro-threshold was 45.9 kg · Hm ~ (-2). The Olsen-P content in the yellow-green dryland of southwest China was mainly related to the phosphorus application level, and the best crop yield could be obtained when the P application rate was 45.9 kg · hm -2, When the phosphorus application rate was higher than 45.9 kg · hm -2, the crop yield did not respond to the amount of phosphate fertilizer and a large amount of phosphorus accumulated in the soil, which increased the risk of environmental phosphorus loss. Long-term application of organic manure The accumulative phosphate surplus of unit increased the rate of soil Olsen-P more than that of chemical fertilizer alone.