滴灌施氮对春玉米氮素吸收、土壤无机氮含量及氮素平衡的影响

为解决吉林省半干旱区滴灌施肥条件下氮肥合理施用问题,通过2年(2015—2016年)田间试验,研究了覆膜滴灌条件下施氮量(0,70,140,210,280,350kg/hm~2)对春玉米产量、氮素吸收利用、土壤剖面无机氮含量变化及氮素平衡的影响。结果表明:施氮量在70~210kg/hm~2范围内玉米产量随施氮量的增加显著增加,当施氮量超过210kg/hm~2后,处理间产量无显著差异;将玉米产量(y)与施氮量(x)拟合,得出最佳施氮量分别为195.1,201.0kg/hm~2。施氮显著提高了玉米各生育时期氮积累量,其中灌浆期和成熟期氮积累量以施氮量210kg/hm~2处理最高。氮素当季回收率、农学利用率和偏生产力均随施氮量的增加而下降。玉米成熟期0-200cm剖面土壤硝态氮和铵态氮含量随土层深度增加呈逐渐下降的趋势;施氮提高了0-200cm土壤硝态氮和铵态氮含量,其中施氮量280,350kg/hm~2处理40-200cm土层硝态氮含量显著高于其他施氮处理。玉米吸氮量、土壤无机氮残留量和氮表观损失量与施氮量呈极显著的正相关;玉米吸氮量、土壤无机氮残留量和氮表观损失量分别占增加纯氮的21.6%~23.3%,33.0%~37.4%,41.0%~43.7%。综上所述,在本试验条件下,综合产量、氮素吸收利用、土壤剖面无机氮含量变化及氮素平衡等因素,在吉林省半干旱区滴灌施肥适宜施氮量应控制在195~210kg/hm~2。

Effects of Drip Irrigation with Nitrogen on Nitrogen Uptake, Soil Inorganic Nitrogen Content and Nitrogen Balance of Spring Maize

To find optimum application rate of nitrogen under drip irrigation in the semi-arid region of Jilin province, two years (2015 - 2016) field experiments were conducted in spring maize fields mulched with plastic film to study the effects of different nitrogen application rates (0, 70, 140, 210, 280 and 350 kg/hm2) on yield, nitrogen absorption and utilization, inorganic nitrogen accumulation in soil profile (0 - 200 cm) and nitrogen balance under drip irrigation. The results indicated that maize yield increased with the increase of nitrogen application rate when the nitrogen application rate was in the range of 70 ~ 210 kg/hm2, and no significant difference was found among treatments when the nitrogen application rate was over 210kg/hm2. Based on the fitting model between maize yield and nitrogen application rate, the optimal parameter was 195.1 and 201.0 kg/hm2, respectively. Nitrogen application significantly increased nitrogen accumulation at different growth stages of maize, and the highest nitrogen accumulation showed in the treatment supplied with 210 kg/hm2 of nitrogen at the grain filling stage and the mature stage. Recovery efficiency, agronomic efficiency and partial factor productivity of nitrogen all decreased with the increasing of it application rate. At the mature stage of maize, NO3--N and NH4+-N contents both gradually reduced with the increasing depth of soil profiles (0 - 200 cm). Compared with the control, NO3--N and NH4+-N contents of 0 - 200 cm soil layers were both increased in treatments applied with nitrogen, and NO3--N contents of 40 - 200 cm soil layers in treatments supplied with 280 and 350 kg/hm2 of nitrogen were significant higher than those in other treatments. Nitrogen absorption of maize , soil inorganic nitrogen accumulation and nitrogen apparent loss were positively correlated with the nitrogen application rate, and they accounted for 21.6% ~ 23.3%, 33.0% ~ 37.4% and 41.0% ~ 43.7% of the nitrogen input. Under the experimental conditions, according to the comprehensive yield, nitrogen absorption and utilization, soil inorganic nitrogen content and nitrogen balance and other factors, the appropriate amount of nitrogen fertilizer for spring maize should be controlled at 195 ~ 210 kg/hm2 under drip irrigation with plastic mulching in the semi-arid region of Jilin province.