冀南夏玉米氮肥效率变异特征与高产限制因子解析

夏玉米产量的形成受气候、栽培、施肥等诸多因素的影响,为找到产量、氮肥效率的变异特征和产量差异在土壤养分和管理措施上的响应,提出科学的优化方案,本研究以河北省曲周县为例,连续4年对农户田块的田间管理和土壤养分进行实时跟踪,研究农户尺度的产量、氮肥效率变异特征;同时采用边界线的分析方法对管理措施和土壤养分进行分析,找出该地区限制高产的主要因素。结果表明:2015—2018年农户夏玉米平均产量为10.26 t?hm~(-2),变异系数为15.64%,年度之间产量和氮肥效率呈波动状。2015—2018年总农户产量差为4.02t?hm~(-2),当季农户产量差的变化范围为1.96～3.68t?hm~(-2),消除产量差可实现16.46%～34.72%的增产。4年内农户获得高产或氮肥高效的次数呈正态分布,获得一次高产和一次氮肥高效的占比最大,同一个农户不同年份的产量、氮肥效率处于不稳定的状况。高产稳定型农户分别在有效穗数、千粒重、播期、密度上与低产稳定型农户有显著差异(P0.05)。产量差的形成均是由各个因素共同导致,不同年份各因素对产量差的贡献不同,总体来看,密度、土壤有机质、播期是造成该区域产量差的主要因素。区域产量的提高,农户间产量差和氮肥效率差的缩减,以及低产农户向高产稳定型农户的转变,都需要土壤养分的改善和综合管理措施的优化。

Nitrogen fertilizer efficiency and high-yield limiting factors of summer maize in the southern Hebei Province

The output of summer maize from the Huanghuaihai region accounts for approximately 35% of the national maize output, and so increasing the summer maize output of this region is of great significance to China''s food security. The formation of summer maize yield is affected by many factors, such as climate, cultivation, fertilization, and so on. To find the yield variation characteristics, improve the nitrogen fertilizer efficiency, understand the different yield responses to soil nutrients and management measures, and propose a scientific optimization plan, this study used the example of Quzhou County of Hebei Province to investigate nitrogen fertilizer efficiency and high-yield limiting factors of summer maize. The management and soil nutrients of farmer''s fields were tracked in real time for 4 consecutive years, and the yield variation characteristics and nitrogen fertilizer efficiency were studied at the farm scale. Meanwhile, the management measures and soil nutrients were analyzed using the boundary line analysis method, to identify the main factors that limit high yields in the region. The results showed that the average summer maize yield for farmers during 2015-2018 was 10.26 t·hm^-2, the coefficient of variation was 15.64%, and the yield and nitrogen fertilizer efficiency fluctuated between years. From 2015 to 2018, the total yield gap was 4.02 t·hm^-2, which varied from 1.96 to 3.68 t·hm^-2 between years. Eliminating the yield gap could achieve a yield increase of 16.46%-34.72%. Over 4 years, the occurrences of farmers obtaining a high yield or nitrogen fertilizer efficiency was normally distributed. The proportions of obtaining one high yield and one high nitrogen fertilizer efficiency were the largest. The yield and nitrogen fertilizer efficiency of a farmer were in an unstable state over the years. The stable-high-yield farmers had significant differences concerning the number of productive ears, 1000-grain weight, sowing date, and density compared with the stable-low-yield farmers (P<0.05). This study showed that, in this region, the optimal sowing date was June 9-14, the optimal harvest density was 56 000-59 000 plants·hm^-2, the optimal N application rate was 210-230 kg·hm^-2, the optimal P₂O₅ application rate was 45-65 kg·hm^-2, the optimal K₂O application rate was 50-60 kg·hm^-2, and the optimal N-bass application ratio was 0.7-0.8. The formation of the yield gap was caused by various factors, and the contribution of different factors to the yield gap was different in different years. Generally speaking, the density, soil organic matter, and sowing date were the main factors that influenced the yield gap. Increasing regional yields, shrinking yield gaps between farmers, and increasing nitrogen fertilizer efficiency, as well as the shift from low-yield farmers to stable-high-yield farmers, all require improvements in soil nutrients and the optimization of comprehensive management measures.