氮钾配施对油菜产量及氮素利用的影响

实际生产中氮钾肥投入不平衡严重限制了氮肥肥效及作物的产量潜力。为了探明不同施氮量下钾肥施用对油菜产量及氮素利用的影响,于2016—2017年及2017—2018年在湖北省武穴市开展连续2年的田间试验,采用氮钾两因素完全试验设计,设氮0、90、180、270 kg N hm-2和钾0、60、120、180 kg K2O hm-2各4个水平。在油菜成熟期取样测定产量、地上部氮钾积累量以及氮肥利用率。结果表明,在钾供应不足时(K0和K60),冬油菜施用氮肥的平均增产率为113.7%,而在钾供应充足的条件下(K120和K180),施用氮肥的平均增产率高达172.9%;与K0处理相比, K120处理冬油菜氮肥回收利用率平均提高了16.6%,继续增施钾肥对不同施氮量下冬油菜氮肥回收利用率的进一步提高无显著影响;达到区域平均产量时,钾供应充足较低钾(K60)投入平均降低33.9%的氮肥用量。综上所述,氮钾配施显著提高了冬油菜产量和氮肥利用率,在冬油菜实际生产中除了重视氮肥施用外,应增加钾肥投入,通过优化氮钾肥配施比例可进一步提高油菜产量,实现冬油菜高产和养分高效。

Effects of combined application of nitrogen and potassium on seed yield and nitrogen utilization of winter oilseed rape (Brassica napus L.)

The imbalance inputs of nitrogen (N) and potassium (K) fertilizer in current agricultural production severely restricts fertilizer use efficiency and crop yield potential. In order to estimate the influence of K fertilizer application on rapeseed yield and N fertilizer use efficiency under different nitrogen application rates, field experiments using two-factor experimental design were conducted at Wuxue county, Hubei province in 2016/2017 and 2017/2018 winter oilseed rape growing seasons. Four levels of N and K fertilizer application rates were set up, which were 0, 90, 180, 270 kg N ha ^-1 and 0, 60, 120, 180 kg K₂O ha ^-1, respectively. Seed yield, shoot N and K accumulation and N fertilizer use efficiency were measured at the harvest of winter oilseed rape. When K supply was insufficient (K₀ and K₆₀), the average increase rate of seed yield was 113.7%, while under sufficient K supplies (K₁₂₀ and K₁₈₀), the average seed yield increase rate was 172.9%. In contrast to the K₀ treatment, the K₁₂₀ treatment increased N fertilizer use efficiency by 16.6% on average; nevertheless, further increase K fertilizer application rate played minor role in the improvement of N fertilizer use efficiency. Considering the regional average rapeseed yield, adequate K supply could reduce the N fertilizer application rate with the average of 33.9% compared with insufficient K fertilization (K₆₀). Consequently, the combined application of N and K fertilizers could significantly enhance rapeseed yield and N fertilizer use efficiency. In practices, besides paying more attention to N fertilizer application, K fertilizer input also should be strengthened. Optimizing N and K fertilizer application could be beneficial to further achieving higher seed yield and higher fertilizer use efficiency.