夏玉米施用不同缓释化处理氮肥的效果及氮肥去向

【目的】研究不同缓释化处理氮肥对夏玉米的产量、氮肥去向及氮素平衡的影响,为提高夏玉米一次性施肥的氮肥利用率并降低氮肥的环境影响提供理论依据。【方法】试验于2014—2015年以郑单958为供试品种,在华北地区中低产田连续两年进行大田试验,共设置6个处理,分别为:不施氮(CK)、尿素(CU)、树脂包膜尿素(CRF)、控失尿素(LCU)、凝胶尿素(CLP)和脲甲醛(UF)。在玉米成熟期采集植物和土壤样品,用于测定植物含氮量和土壤无机氮含量,并计算作物吸氮量、氮肥利用率、土壤无机氮积累量、氮肥损失量等。【结果】(1)氮肥缓释化处理能够明显提高夏玉米的产量,促进氮素吸收。与尿素相比,脲甲醛、凝胶尿素、树脂包膜尿素和控失尿素可分别提高夏玉米产量18.9%、16.8%、13.7%和13.6%,同时氮肥农学利用效率分别提高6.5、4.8、4.0和3.7 kg·kg-1。(2)不同氮肥处理的作物吸收肥料氮以及肥料氮在0—100 cm土层残留量之间存在显著性差异。脲甲醛、凝胶尿素、树脂包膜尿素、控失尿素和尿素的氮肥表观回收率分别为54.9%、42.4%、38.3%、38.3%和22.0%,肥料氮在0—100 cm土层残留量分别占施氮量的28.3%、43.8%、39.2%、46.2%和46.6%。此外,与尿素相比,氮肥缓释化处理能够显著降低肥料氮的损失,凝胶尿素、控失尿素、脲甲醛和树脂包膜尿素分别降低了47.6%、43.1%、40.8%和26.7%。(3)综合分析不同氮肥处理的农田氮素平衡,脲甲醛处理的夏玉米吸氮量最高,为245.0 kg·hm~(-2),其次是凝胶尿素,为222.5 kg·hm~(-2)。脲甲醛的0—100 cm土层残留量在缓释化氮肥中最低,为153.4 kg·hm~(-2),树脂包膜尿素、凝胶尿素和控失尿素分别为173.1、181.5和185.7 kg·hm~(-2)。凝胶尿素处理的氮表观损失量最低,为35.6 kg·hm~(-2),控失尿素、脲甲醛和树脂包膜尿素的氮表观损失量分别为38.8、41.2和51.3 kg·hm~(-2)。【结论】在华北地区中低产田土壤上,氮肥缓释化处理能够显著促进夏玉米对氮素的吸收、减少氮素损失。脲甲醛和凝胶尿素的效果相对较好。

Effects of Different Slow-Released Nitrogen Fertilizers on Summer Maize and Nitrogen Fate in the Field

【Objective】 The effects of different slow-released nitrogen (N) fertilizer on yield, N fate and N balance of summer maize were studied for providing a theoretical basis in improving N use efficiency and reducing the environmental impact. 【Method】A field in-situ experiment of two years was conducted in a sandy soil in North China Plain and maize variety “Zhengdan958” was used as materials. There were six N fertilizer treatments, including no N fertilizer (CK), urea (CU), polymer-coated urea (CRF), release-controlled urea (LCU), polymer gel urea (CLP) and urea formaldehyde (UF). Plant and soil samples were collected at the maturing stage of maize, and then the contents of N in plant and soil inorganic N were determined. Thereafter, the N uptake, N use efficiency, soil inorganic N accumulation and N loss were calculated. 【Result】(1)The N fertilizer slow-release treatments could obviously improve the yield of summer maize and promote N absorption. Compared with the urea, the average yield under UF, CLP, CRF and LCU increased by 18.9%, 16.8%, 13.7% and 13.6%, respectively, and the average N agronomic efficiency increased by 6.5 kg·kg^-1, 4.8 kg·kg^-1, 4.0 kg·kg^-1 and 3.7 kg·kg^-1, respectively. (2)There was a significant difference in the soil 0-100 cm N fertilizer residues between different N fertilizer treatments. The average N recovery efficiency of UF, CLP, CRF, LCU and CU was 54.9%, 42.4%, 38.3%, 38.3% and 22.0%, respectively, and the N fertilizer residue in 0-100 cm soil profile of them accounted for 28.3%, 43.8%, 39.2%, 46.2% and 46.6% of the applied N rate, respectively. Compared with urea, the loss of N fertilizer of CLP, LCU, UF and CRF decreased by 47.6%, 43.1%, 40.8% and 26.7%, respectively. (3) When analyzing the field N balance of different N fertilizer treatments comprehensively, the average N uptake of UF was the highest (245.0 kg·hm^-2), followed by CLP which was 222.5 kg·hm^-2. The average soil 0-100 cm N residues of UF was the lowest among the slow-released N fertilizers which was only 153.4 kg·hm^-2, and the average soil 0-100 cm N residues of CRF, CLP and LCU was 173.1 kg·hm^-2, 181.5 kg·hm^-2 and 185.7 kg·hm^-2, respectively. The average N apparent loss of CLP was the lowest (35.6 kg·hm^-2) and that of LCU, UF and CRF was 38.8 kg·hm^-2, 41.2 kg·hm^-2 and 51.3 kg·hm^-2, respectively. 【Conclusion】The N fertilizer slow-release treatments could significantly improve the uptake of N in summer maize and reduce the loss of N in the north of North China Plain, and urea formaldehyde and polymer gel urea performed better for the high efficiency and less N loss.