连续4年施钾的甘蔗产量及土壤钾素平衡

以甘蔗品种‘粤糖03-393’（‘粤糖60号’）为试验材料,采用随机区组设计,通过4 a（造）钾肥水平（0、225、450、675、900 kg/hm²）定位试验,研究长期施用钾肥对甘蔗产量、农学效应、植株吸钾量、钾肥利用率、土壤钾素含量、土壤钾素平衡和钾肥经济效益的影响。结果表明：随着钾肥施用量的增加,甘蔗农学效应、产量、钾肥利用率呈先增后降的趋势,产投比逐渐减小,450 kg/hm² 处理的产量和钾肥利用率最高,225 kg/hm²处理的农学效应和产投比最高;甘蔗植株的吸钾量、土壤钾素含量、钾素平衡系数呈升高的趋势,出现植株奢侈吸收、土壤钾素含量过高、表观盈余过多、钾素资源浪费现象。合理施用钾肥能增加农学效应和产量,而过量施钾会降低农学效应和钾肥利用率,还造成资源浪费和养分流失。考虑农学效应、肥料利用率、土壤钾素表观平衡、综合效益等因素,甘蔗钾肥施用量建议为225~450 kg/hm²K₂O。

Sugarcane Yield and Soil Potassium Balance in Potassium Application of Four Consecutive Years

A four-year (2014 to 2017) potassium fertilizer field experiment designed by a random block with cultivar ‘Yuetang 03-393’ (‘Yuetang 60’) and five K₂O levels of 0, 225, 450, 675 and 900 kg/hm² respectively was conducted to evaluate the effects of the long-term application of potassium fertilizers on sugarcane yield, agronomy efficiency, plant potassium (K) uptake, potassium use efficiency and soil potassium content. Under a certain K₂O application range, with the increase of potassium application rate, the agronomy efficiency, yield and potassium use efficiency of sugarcane increased and then decreased, while the output-input ratio was down. The yield and potassium use efficiency of the treatment with 450 kg/hm² K₂O were the highest, and the agronomy efficiency and output-input ratio of the treatment with 225 kg/hm² K₂O were the best. With the increase of potassium fertilizer dosage, the potassium uptake, soil potassium content and potassium equilibrium coefficient of sugarcane plants increased, resulting in luxury absorption of plants, excessive soil potassium content, excessive apparent surplus and waste of potassium resources. The reasonable application of potassium fertilizers could increase the agronomic benefit and yield. However, the excessive application of potassium fertilizers could reduce the agricultural effect and potassium use efficiency, and also result in the waste of resources and loss of K nutrients. Considering agronomy efficiency, fertilizer use efficiency, apparent balance of soil potassium and comprehensive benefits, the recommended amount of potassium fertilizers for sugarcane is K₂O 225-450 kg/hm².