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长期施用化肥对南方稻田土壤酸化和盐基离子损失的影响

来源：花匠小妙招时间：2025-09-26 16:39

摘要：

【目的】利用长期定位试验评估氮、磷、钾化肥配施对土壤酸化程度、交换性铝产生量和盐基离子损失量的影响，为维持土壤健康生产和农田可持续利用提供依据。【方法】采用始于1984年的肥料长期定位试验，选取不施肥（CK），磷钾肥配施（PK）、氮磷肥配施（NP）、氮钾肥配施（NK）和氮磷钾肥配施（NPK）5个处理，采集每个处理的0—10、10—20、20—40和40—60 cm土层土样，分析土壤pH、交换性酸、交换性盐基离子总量、交换性盐基离子累积量、酸碱缓冲容量和酸化速率等指标。【结果】经过连续33年不同施肥处理的定向培育后，CK、PK、NP、NK和NPK处理0—20 cm土层pH较试验前分别下降0.82、0.91、1.13、0.8和1.19个pH单位，导致表层土壤明显酸化，酸化速率分别达到了1.10、1.22、1.46、1.13和1.58 kmol·hm-2·a-1。与CK处理相比，NP和NPK处理的0—40 cm土层显著酸化，土壤pH分别下降0.28—0.38和0.35—0.46个单位，土壤交换性酸分别增加了35.5%—110.0%和30.4%—120.5%，特别是交换性铝分别增加56.2%—157.6%和73.7%—189.8%，土壤交换性盐基离子总量分别减少6.3%—14.9%和9.9%—13.2%，盐基饱和度降低2.9—14.9和2.6—15.4个百分点；NK处理的0—20 cm土层略有酸化，土壤交换性酸增加53.5%—55.0%，盐基饱和度降低6.0—7.1个百分点；PK处理的0—60 cm土壤酸化均不明显，土壤交换性酸增加和交换性盐基离子总量减少差异均不显著。【结论】长期施化肥对土壤酸化程度和盐基离子损失量的影响表现出明显差异。其中， NPK和NP长期处理加剧土壤酸化进程，且酸化深度到达40 cm，盐基离子损失量和交换性铝的产生量大幅增加，初步估算施用化肥导致土壤pH降低1个单位，土壤交换性盐基离子的损失量约是土壤交换性酸增加量的一倍左右；长期磷钾配施、氮钾配施对土壤酸化的影响较小，盐基离子损失量和交换性铝增加量相对较少。

关键词: 化肥, 长期定位试验, 稻田, 土壤pH, 土壤酸化, 交换性盐基离子

Abstract:

【Objective】 The effects of nitrogen, phosphorus, and potassium fertilizer application on soil acidification, exchangeable aluminum production, and loss of basic ions were assessed, so as to provide the theory basis for maintaining soil health and sustainable development of farmland. 【Method】 The field experiment, established in 1984, was designed to have five treatments, that is, CK (an early rice-late rice rotation without fertilizer), PK (N deficiency), NP (K deficiency), NK (P deficiency), and NPK (balanced chemical fertilizer application), and all the treatments, except CK, were the same rate in N nutrient supply. Soil samples of 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm collected for each treatments after late rice harvest in 2016 were used to measure soil pH, exchangeable acidity, exchangeable base cation, accumulation of exchangeable base cation, pH buffer capacity, and acidification rate, etc.【Result】 After 33 years of continuous application of chemical fertilizer, the soil pH under CK, PK, NP, NK and NPK treatments decreased significantly by 0.82, 0.91, 1.13, 0.8 and 1.19 pH units compared with an initial pH of 6.5 in the 0-20 cm soil layers, respectively, which resulted in obvious acidification of cultivated soil, and the acidification rates reached 1.1, 1.22, 1.46, 1.13 and 1.58 kmol·hm-2·a-1, respectively. Different fertilization treatments were different from CK treatment. Compared with CK treatment, the soil pH of the 0-40 cm layer significantly decreased by 0.28-0.38 units under NP treatment and by 0.35-0.46 units under NPK treatment. The exchangeable acidity of the soil increased by 35.5%-110.0% under NP treatment and by 30.4%-120.5% in the NPK treatment, with a significant increase in exchangeable aluminum by 56.2%-157.6% and 73.7%-189.8%, respectively. The total content of exchangeable bases in the soil decreased by 6.3%-14.9% under NP treatment and by 9.9%-13.2% under NPK treatment, resulting in a decrease in base saturation by 2.9-14.9 and 2.6-15.4 percentage points, respectively. The NK treatment slightly acidified the 0-20 cm soil layer, with an increase in exchangeable acidity by 53.5%-55.0% and a decrease in base saturation by 6.0-7.1 percentage points. The PK treatment did not show significant soil acidification in the 0-60 cm layer, and there was no significant difference in the increase of exchangeable acidity and the decrease of exchangeable bases. 【Conclusion】 Long-term application of fertilizers showed significant differences in the degree of soil acidification and loss of basic ions. Among them, the long-term application of NPK and NP fertilizers intensifies the soil acidification process, with acidification depth reaching 40 cm, and there was a substantial increase in the loss of basic ions and the production of exchangeable aluminum. Preliminary estimation showed that the application of fertilizer could lower the soil pH by one unit, and the loss of exchangeable base in soil was approximately twice the increase in exchangeable acid. Long-term application of PK and NK fertilizers had a relatively smaller impact on soil acidification, with less increase in the loss of basic ions and exchangeable aluminum.

Key words: chemical fertilizer, long-term located fertilization, paddy, soil pH, soil acidification, exchangeable base cation