黄河流域棉区秸秆还田下机采棉的氮肥用量和利用率研究

Nitrogen Rate and Nitrogen Use Efficiency of Cotton Harvested by Machine in the Field with Stalks Recycling in the Yellow River Valley Region

提高种植密度、优化缩节胺(1,1-dimethyl-piperidinium chloride,DPC)化控技术是黄河流域棉区机采棉田的基本管理措施,秸秆还田则是实现农作物化肥零增长的技术途径之一。于2013―2014年在河北省河间市秸秆还田地块,研究了密度、DPC化控和氮(Nitrogen,N)肥用量对棉花产量及其构成因素、干物质和N的积累与分配以及N肥利用率的影响,其中2013年蕾期和花铃期降水量大,2014年比较干旱。研究结果表明,与低密度(6.75×10~4株·hm^(-2))相比,高密度处理(11.25×10~4株·hm^(-2))在干旱年份的籽棉产量和N肥偏生产力分别显著提高8.1%和7.4%,N回收率也显著增加25.5百分点,达到41.6%。与清水对照相比,DPC化控的籽棉产量、N肥偏生产力和农学效率在多雨年份分别显著提高39.2%、43.3%和212.8%,N回收率略增加但差异不显著。提高密度促进了干物质积累,但降低了多雨年份的收获指数;DPC化控的生物量较低,但在多雨和干旱年份均可提高收获指数。N肥用量对棉花产量的影响不显著,但表现出低N处理(105 kg·hm^(-2))的产量高于中N处理(210 kg·hm^(-2))和高N处理(315 kg·hm^(-2))的趋势。低N处理2年的N肥偏生产力分别为24.5 kg·kg^(-1)和54.4kg·kg^(-1),回收率分别为45.2%和41.0%,显著高于中N处理和高N处理。综上所述,增密和DPC化控相结合,有利于机采棉田干物质的积累及向产量器官的分配,有利于维持产量的稳定性;在秸秆还田条件下,棉田的适宜施N量可降至105 kg·hm^(-2)。

High plant populations and multiple applications of the plant growth retardant mepiquat chloride（MC） are required in the production of mechanically harvested cotton（monocropping） in the Yellow River Valley. Cotton-stalk recycling to the field is one of the main approaches to avoid the further increase in fertilizers during cotton production. However, the optimum nitrogen（N） rate and whether N use efficiency would increase under these conditions remains unclear. We conducted experiments involving cotton-stalk recycling to the field at Hejian in Hebei Province（38°41′N, 116°09′E, and 11 m elevation） during the 2013 and 2014 growing seasons. In 2013, there was a considerable amount of precipitation（279.1 mm） in July（flowering period）;however, in contrast, there was only 42.4 mm precipitation in the same month of 2014. We investigated the effects of plant density, MC application and N rate on cotton yield and its components, accumulation and distribution of biomass and N, as well as N use efficiency. In comparison with the low plant density treatment（6.75 × 104plant·hm（-2）, LPD）, the seed cotton yield and N partial factor productivity（PFPN） under the high plant density treatment（11.25 × 104plant·hm（-2）, HPD） significantly increased by 8.1% and 7.4% in the drier year（2014）. In addition, the N apparent recovery efficiency（REN） of HPD also significantly increased to 41.6% in 2014. The MC application significantly increased the seed cotton yield（39.2%）, PFPN（43.3%）, and agronomic efficiency（212.8%） relative to the water control（CK） in the wetter year（2013）. The REN of MC was also greater than that of CK in 2013 but this difference was not significant. The HPD showed increased dry matter, but a decreased harvest index（HI） in 2013. Although less dry matter was produced, the MC increased HI in both the wetter and drier years. The N rate ranged from 0 to 315 kg·hm（-2）did not significantly affect the seed cotton yield, but there was only a tendency that the low N rate（105kg·hm（-2）, LN） had a higher yield compared with the medium（210 kg·hm（-2）, MN） and high N rates（315 kg·hm（-2）, HN）. Therefore, the LN treatment had the highest PFPN, which was 24.5 and 54.4 kg·kg（-1） in 2013 and 2014, respectively. The REN of LN was 45.2% and 41.0% in 2013 and 2014, also significantly greater than those of MN and HN. In summary, the combination of HPD and MC application was in favor of the biomass accumulation and HI increase in addition to the yield stability of mechanically harvested cotton in the Yellow River Valley, and the optimum N rate could be reduced to 105 kg·hm（-2）when stalks are returned to the field.