麦秆还田下钾肥减量对水稻产量及钾肥利用率的影响

我国土壤缺钾程度日益加重,作物秸秆中钾素含量较高,还田后可替代部分化学钾肥,缓解土壤钾素不足。为研究秸秆还田替代钾肥的效果,本文采用田间试验方法,以常规施钾135 kg(K2O)·hm~(-2)]处理为对照,研究了在秸秆粉碎翻压还田(6 000 kg·hm~(-2))条件下钾肥减量10%、20%、30%和40%对水稻钾素吸收累积量、水稻产量、钾肥偏生产力及经济效益的影响。结果表明:在秸秆还田的基础上,水稻植株的钾素含量和累积量随着钾肥施入量的减少而降低。钾肥施用量减少10%~40%,水稻有效穗数、每穗粒数和结实率略有降低,水稻产量和产值有所下降,钾肥减量10%、20%和30%时,对水稻产量和产值的影响不显著(P0.05)。钾肥偏生产力随着钾肥施用量的减少而提高,钾肥减量10%、20%、30%和40%处理的水稻钾肥偏生产力比不减钾处理分别提高8.4%、18.9%、33.8%和44.4%。总体而言,在常规施钾条件下,秸秆还田后随着减钾量(10%~40%)的增加,水稻钾素累积量、产量和产值均呈下降趋势,而钾肥偏生产力呈增加趋势;减钾30%以内可显著提高水稻钾肥偏生产力(P0.05),对水稻产量及产值的影响不显著(P0.05)。

Effects of reducing potassium fertilizer on rice yield and potassium use efficiency under wheat straw return condition

There has been an increasing soil potassium deficiency in China. However, crop residues generally contain high level of potassium that could replace part of the potassium fertilizer requirements after returning straw to the soil, and can therefore alleviate soil potassium deficiency. Crop residue return to field is an effective way to reduce the use of potash fertilizer, which also improves potassium use efficiency. In this study, field experiments were carried out to determine rice yield potassium accumulation and partial factor productivity of potash fertilizer under conventional potash fertilizer application of 135 kg(K₂O)·hm^-2 (control) and reductions by 10%, 20%, 30% and 40% after wheat straw incorporation (6 000 kg·hm^-2). The potassium content and the quantity of accumulated potassium in rice reduced with decreasing potassium fertilizer application after straw incorporation into the soil. The yield, economic benefit, effective panicle number, grains per panicle and seed-setting rate of rice declined with the reduction of conventional potassium fertilizer rate from 10% to 40%. However, when potassium fertilizer was reduced by less than 30%, there was little impact on 1000-grain weight of rice. It also had no significant effect on yield or economic benefit of rice (P>0.05). Compared with conventional fertilization, treatments with chemical potash fertilizer reduction of 10%, 20%, 30% and 40% increased partial factor productivity of potassium fertilizer by 8.4%, 18.9%, 33.8% and 44.4%, respectively. In summary, potassium accumulation in rice plant, rice yield and economic benefit decreased, whereas partial productivity of potassium increased with the reduction of conventional potassium dose from 10% to 40%. When wheat straw was applied and conventional potassium fertilization dose reduced by less than 30%, partial factor productivity of potassium fertilizer increased but had no significant effect on the yield and economic benefit of rice.