不同氮肥用量与施肥时期对冷浸田单季稻 生长及农学效率的影响

冷浸田为福建省主要低产田类型之一。基于福建省浅脚烂泥田、青泥田与锈水田主要冷浸田类型,通过田间3个点试验研究不同氮肥用量(105、150与195 kg/hm~2)与施用时期(基蘖肥︰穗肥=10︰0与基蘖肥︰穗肥=7︰3)运筹组合对单季稻生长的影响。结果表明,增施氮肥促进了各类型冷浸田水稻分蘖期分蘖生长速率。不同氮肥组合的锈水田、青泥田与浅脚烂泥田水稻籽粒产量分别较不施肥(CK)增幅14.5%~45.5%、9.4%~13.5%和10.4%~15.9%,但在105 kg/hm~2用量基础上再进一步增施氮肥,籽粒增产效果明显放缓。施用氮肥显著增加了成熟期水稻有效穗数,但对每穗实粒数及千粒重影响不明显。105、150、195 kg/hm~2 3种氮肥用量下各类型冷浸田的农学效率均值分别为17.4、13.3与12.8 kg/kg。除浅脚烂泥田施用穗肥的秸秆产量有显著差异外,其余氮肥不同施肥时期的籽粒与秸秆产量均无显著差异。增施氮肥有提高籽粒氮的趋势,但同时降低了籽粒钾含量。鉴于冷浸田土壤氮素水平较高,单季稻氮肥经济用量宜控制在105~150 kg/hm~2中低水平,超过150 kg/hm~2,农学效率递减,且无明显增产效果。另从人工成本及效益考虑,宜选择基蘖肥︰穗肥=10︰0的施氮方式。

Fertilizing Time on Single Cropping Rice Growth and Agronomic Efficiency in Cold-waterlogged Paddy Field

Cold-waterlogged (CW) paddy fields are low-yield paddy fields in Fujian Province. Based on main CW paddy field types (including shallow-foot mud paddy field, blue mud field and paddy field with rust) in Fujian Province, the effects of different combinations of nitrogen applying rates (105, 150 and 195 kg/hm²) and fertilizing time (base and tillering fertilizer : earing fertilizer=10:0; base and tillering fertilizer : earing fertilizer=7:3) on single cropping rice growth and agronomic efficiency were investigated by field experiments conducted in three sites. The results showed that increasing nitrogen applying rate improved rice growth rate at the tillering stage. Compared to CK, nitrogen combination treatments increased rice grain yields by 14.5%-45.5%, 9.4%-13.5% and 10.4%-15.9% for paddy field with rust, blue mud field and shallow-foot mud paddy field, respectively, but the yield increasing effect significantly slowed down when nitrogen applying rate was over 105 kg/hm². Applying nitrogen fertilizer significantly increased the effective panicles of rice in the harvest stage, but there was no significant difference in the grain number per panicle and 1 000-grain weight for all treatments. The agronomic efficiencies of different CW paddy field types were 17.4, 13.3 and 12.8 kg/kg respectively under the 105, 150 and 195 kg/hm² of nitrogen applying rates. Except for the shallow-foot mud paddy field in which the straw yield showed significant differences with earing fertilizer, the yields of rice grains and straws had no significant difference between other different fertilizing time treatments. Increasing nitrogen applying rate had tended to improve nitrogen content but decreased potassium content of rice grains. Given the higher nitrogen levels of CW paddy fields, the suitable nitrogen applying rate should be controlled within 105-150 kg/hm², otherwise the agronomic efficiency will diminish and the yield-increasing effect is little when it is over 150 kg/hm². In addition, considering labour cost and economic benefit, all the nitrogen fertilizer should be used as of base and tillering fertilizer.