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土壤非交换性钾的释放总量和释放速率是土壤供钾能力的重要指标.本文采用CaCl2连续提取的方法研究了22年长期不施肥(CK)、NP(不施钾肥)、NPK(施钾肥)、NPKS(钾肥与秸秆还田配施)和S(单施秸秆)对紫色土非交换性钾释放特性的影响,以期为紫色土钾素管理提供科学依据.结果表明:当运用不一样的施肥处理紫色土非交换性钾的释放全部是前期迅速释放、后期缓慢平稳释放的特点.采用4种动力学方程对紫色土交换性钾的释放过程进行模拟发现,前期快释放阶段(1~168h)用Elovich方程(对数曲线方程)模拟最佳,释放量占全过程的74.2%~77.0%;后期慢释放阶段(168~1 472h)用抛物线方程模拟效果最佳.不同处理土壤非交换性钾的释放速率和释放量的差异有统计学意义,其大小为:S>原始土壤>NPKS、CK>NPK>NP,长期不施钾肥的NP处理非交换性钾的释放速率比NPK处理低18.3%,比试验前土壤低26.7%;该处理土壤的非交换性钾累积释放量(133.32mg/kg)仅占NPK释放量的78.69%;化肥配施秸秆土壤非交换性钾释放量为176.26mg/kg,释放速率为16.13mg/kg·h~(-1)略高于氮磷钾施肥,秸秆还田能够提高紫色土供钾能力.
The total amount and release rate of soil non-exchangeable potassium is an important index for soil potassium supply.In this paper, continuous extraction of CaCl2 was used to study the effects of long-term non-fertilization (CK), NP (no fertilizer application), NPK ), NPKS (combined application of potassium fertilizer and straw returning) and S (single straw application) on the non-exchangeable potassium release of purple soil, with a view to provide a scientific basis for purple soil potassium management.The results show that: when using different The release of non-exchangeable potassium in purple soil was all characterized by rapid release in the early stage and slow and steady release in the later stage. Four kinds of kinetic equations were used to simulate the release of exchangeable potassium in purple soil. The early release stage (1 ~ 168h ) Was simulated by Elovich equation (logarithmic curve equation), and the release rate was 74.2% -77.0% of the whole process.The parabolic equation was the best in the slow release stage (168-1472 h), and the non-exchangeability There was a significant difference in the release rate and release of potassium between the two treatments. S> primary soil> NPKS, CK> NPK> NP. The release rate of non-exchangeable potassium was lower by 18.3 %, 26.7% lower than the soil before the test; The non-exchangeable potassium cumulative release (133.32mg / kg) of soil only accounted for 78.69% of the NPK release, and the soil non-exchangeable potassium release was 176.26mg / kg and the release rate was 16.13mg / kg · h ~ (-1) was slightly higher than that of NPK fertilization. Straw returning could increase the potassium supply capacity of purple soil.