沿江潮土稻麦轮作下钾素临界指标研究

Critical values of soil available K in cambosolsalong the Yangtze River for rice-wheat rotation

为了明确沿江潮土麦稻轮作条件下施用钾肥的土壤钾临界指标,进行了小麦、水稻轮作周期的田间试验。结果表明,在土壤基础速效钾57 mg/kg、缓效钾406 mg/kg的水平时,施钾的增产率为小麦12.2%-42.9%,水稻5.9%-15.4%,全期8.6%-24.9%;土壤速效钾的施钾临界值小麦上为77.3 mg/kg,水稻上为81.7 mg/kg;每提高1 mg/kg土壤速效钾含量,每公顷需施K2O,小麦上为9.2 kg,水稻上为12.1 kg;土壤缓效钾含量也可作为钾肥施用的依据,施钾临界值为小麦上411 mg/kg、水稻上419 mg/kg;每提高1 mg/kg土壤缓效钾含量,每公顷K2O的用量为小麦10.7 kg、水稻12.4 kg。

In order to determine the K fertilizing critical values of soil NH4OAc-extractable K（NH4OAc-K）and HNO3-extractable K（HNO3-K）in cambosols along the Yangtze River for rice-wheat rotation,experiments were carried during a period of rice-wheat rotation.The results showed that when soil NH4OAc-K and HNO3-K were 57 mg/kg and 406 mg/kg at basic levels,increased yield rates of K fertilization were 12.2%-42.9% and 5.9%-15.4% for wheat and rice stages,respectively,with 8.6%-24.9% of average increased yield rates for whole rotation period.The K fertilizing critical values of soil NH4OAc-K were 77.3 mg/kg and 81.7 mg/kg for wheat and rice stages and 9.2 and 12.1 kg/hm2K2O need to be fertilized with increasing 1 mg/kg of NH4OAc-K for wheat and rice.Likewise,HNO3-Kcould be used as the index of K fertilization.The K fertilizing critical values of soil HNO3-K were 411 mg/kg and 419 mg/kg for wheat and rice stages and 10.7 and 12.4 kg/hm2 K2O need to be fertilized with increasing 1 mg/kg of HNO3-K for wheat and rice.