河套灌区盐渍化土壤玉米水氮耦合效应

为了探求适用于盐渍化地区的节水、施肥优化模式，采用大田试验，以玉米为研究对象，选取了轻度和中度两种盐分土壤，设置了10种不同水、氮处理，建立不同盐分土壤玉米产量与灌水量及施氮量之间的回归模型并对其进行了分析，研究不同盐分土壤水、氮用量对玉米产量的影响。结果表明：在轻度和中度盐分土壤条件下，灌水和施氮对玉米均有增产效应，水、氮交互作用为正效应，水分的作用大于施氮的作用。通过边际效应分析可知，轻度和中度盐分土壤施氮肥的增产速率没有明显差异，轻度盐分土壤灌水的增产效率明显高于中度盐分土壤。轻度和中度盐分土壤玉米最高产量分别为13 581 kg·hm^-2和11 115 kg·hm^-2，对应的水、氮配比均为灌水编码为0.77（全生育期灌水量2 250 m³·hm^-2），施氮编码为0.69（总施氮量225 kg·hm^-2）。通过模型寻优，得到轻度和中度盐分土壤种植玉米的最佳水、氮配比方案均为全生育期灌水量为1 900.95~2 389.08m³·hm^-2，总施氮量为174.04~240.7 kg·hm^-2。优化方案的水、氮用量分别比当地灌水量（2 925 m³·hm^-2）节水18.2%~35%, 施氮量（325 kg·hm^-2）节肥26.0%~46.4%。优化范围包含了轻度和中度盐分的最高产量水、氮用量，产量与当地产量基本一致，符合当地灌水施肥要求。但从维持目前玉米产量和长期盐碱地改良的角度看，建议中度盐化土壤应选取水、氮优化范围中中等偏上灌水量和中等偏下的施肥量，以便于从根本上降低土壤盐分背景值，便于长期产量的提高；轻度盐分土壤选取优化范围适中的水、氮用量。

Effect of water and nitrogen coupling on maize in salinity soil of the Hetao irrigation area

In order to explore an optimized mode of saving water and fertilizer, suitable for salinized areas, this paper selected maize as the research object a field experiments. The experiment had 10 treatments including different water and fertilizer combination in light and moderate saline soils. Regression model between maize yield and irrigation amount and nitrogen (N) amount was developed in different saline soils. The results showed that water and N had increased yield in slight and moderate saline soils. The interactions of water and N had positive effects. Also, the effect of water was more important than that of nitrogen. Through the analysis of marginal effect, the rate difference of increasing yield of N was not significant in slight and moderate saline soil. Water increased yield more efficiently in slight saline soil than that in moderate saline soil. The maximum yields in slight and moderate saline soils were 13 581 kg·hm^-2 and 11 115 kg·hm^-2, respectively. The irrigation number was 0.77 (the irrigation amount in whole period of growth was 2 250 m³·hm^-2). The N number was 0.69 (the total N amount was 225 kg·hm^-2). It showed that salt stress decreased the maize yield with the same irrigation and N amount. Through the model optimization, the best model of water and N in slight and moderate saline soils was the same. The irrigation amount in whole period of growth was 1 900.95~2 389.08 m³·hm^-2. The total N amount was 174.04~240.7 kg·hm^-2. Compared with the local irrigation amount (2 925 m³·hm^-2) and N amount (325 kg·hm^-2), the optimized model saved 18.2%~35% water. It also saved 26.0%~46.4% of N. The optimized scope contained the irrigation and N amount of the highest yield in slight and moderate saline soils. The yield was consistent with the local yield. However, from the view of maintaining maize yield and improving saline\|alkali soil for a long\|term, the above\|moderate irrigation amount and below\|moderate fertilizer amount were recommended as the optimized scope for the moderate saline soil. The measures were taken to decrease the background value of soil salinity radically and increase the yield in a long\|term. It was advised to select moderate amount of irrigation and N in slight saline soil.