潮棕壤速效磷产量临界值和淋溶临界值的计算

确定合理磷肥用量对取得高产、提高经济收益和保护环境都有重要意义，而明确土壤速效磷产量临界值与淋溶临界值是界定施肥量适宜与否的必要前提。本文基于下辽河平原长期定位试验，使用直线-平台、双直线和米氏模型计算土壤速效磷产量临界值，通过土柱淋溶试验确定土壤速效磷淋溶临界值。结果表明：该地区玉米和大豆的速效磷产量临界值分别为12.0 mg·kg^-1和10.8 mg·kg^-1；三个模型中以米氏模型计算的值最高，以直线-平台模型计算的值最低；通过6次淋溶试验，计算的土壤速效磷淋溶临界值在74.6 mg·kg^-1到82.0 mg·kg^-1之间，均值为80.2 mg·kg^-1。在农业生产中应将土壤速效磷控制在12.0～80.2 mg·kg^-1之间，可据此指导施肥，达到保证作物生长所需养分，并减少施肥对环境影响的目标。

Calculating the critical value for yield and leaching of Olsen-P in aquic brown soil

For achieving high yield and economic benefits, as well as protecting the environment, it was necessary to clarify the relevant thresholds to optimize application of fertilizer phosphorus (P). Based on the long-term experiments in lower reach of Liaohe River Plain, the thresholds of soil Olsen-P for yield (TPY) were calculated by linear-linear (LL), linear-plateau (LP) and Mitscherlich type exponential (Exp) models. In addition, the thresholds of soil Olsen-P for leaching (TPL) were determined by soil column leaching experiment. Results showed that the TPY was 12.0 mg·kg^-1 and 10.8 mg·kg^-1 for maize (Zea mays L.) and soybean (Glycine max), respectively. Furthermore, the TPY was the highest as calculated by the Exp model, whereas the least was obtained with the LP model. The TPLs ranged from 74.6 mg·kg^-1 to 82.0 mg·kg^-1, with the mean value of 80.2 mg·kg^-1. It was recommended that Olsen-P concentration should be maintained within the range from 12.0 mg·kg^-1 to 80.2 mg·kg^-1 in the target area, in order to sustain crop production and avoid environmental contamination.