【目的】在沿海滩涂种植甘薯不仅可提供丰富的粮食资源,还可以充分利用宝贵的沿海滩涂土地资源。本文重在阐明在苏北沿海滩涂上盐肥耦合对甘薯生长及土壤氮素营养的影响。【方法】本文在盐碱地上通过正交试验设计进行田间试验,研究了在不同土壤盐分上增施氮肥,甘薯及土壤氮素营养的盐肥耦合效应。【结果】(1)1.0~2.1 g/kg(S_2)的土壤盐分水平下,甘薯生长与0.5~1.0 g/kg(S_1)盐分水平差异不显著。盐分增大到2.1~3.2 g/kg(S_3)、3.2~4.0 g/kg(S_4)水平,甘薯生长受到抑制。增施氮肥后,土壤盐分的抑制作用得到显著缓解,甘薯各项生长指标及鲜薯产量呈现先升后降的趋势。经盐肥耦合作用,土壤盐分为1.0~2.1 g/kg,施氮量为50 kg·hm~(-2)的种植条件(S_2N_2)最有利于甘薯的生长和鲜薯产量的积累。(2)土壤养分含量随着盐分的增大而下降。氮肥的施入可显著提高土壤养分,在50 kg·hm~(-2)(N_2)、100 kg·hm~(-2)(N_3)水平下,土壤有效氮、全氮及微生物氮含量显著提高。0.5~1.0 g/kg(S_1)、1.0~2.1g/kg(S_2)的土壤盐分上氮肥的增产效应较显著,且土壤有效氮的氮肥增产效应大于土壤全氮含量。(3)NAG、LAP活性随着土壤盐分、施氮量及甘薯生长期的变化而变化。甘薯的生长促进了土壤NAG、LAP活性的提高。0.5~1.0 g/kg(S_1)-2.1~3.2 g/kg(S_3)土壤盐分下,甘薯生长期30 d之前,随着氮肥施用量的增加,NAG、LAP活性变化不显著。当生长期达到30 d时,LAP活性提高,酶活呈现N_3>N_2>N_4>N_1的趋势,且差异显著。当生长期达到60~90 d时,各施氮量下的NAG、LAP活性差异显著提高,呈现N_3>N_2>N_4>N_1的趋势。当生长期达到125 d时,NAG活性开始下降,LAP活性仍然呈现逐步上升的趋势。3.2~4.0 g/kg(S_4)土壤盐分下,随着施氮量的增加,NAG、LAP活性变化不显著。【结论】在盐碱地上增施氮肥,其土壤盐分与肥料养分的耦合作用对甘薯的生长发育、鲜薯产量、土壤酶活及养分产生了一系列的影响,包括:土壤盐分为1.0~2.1 g/kg,施氮量为50 kg·hm~(-2)的种植条件最有利于甘薯的生长和鲜薯产量的积累;种植甘薯及增施氮肥能够显著提高土壤NAG、LAP酶活性,增加盐碱地土壤养分,从而促进沿海滩涂生态修复,改善沿海滩涂生态环境。 【Objective】 Planting sweet potato in the coastal beach can not only provide abundant grain resources, but also make full use of valuable coastal land resources. This article focuses on elucidating the effect of salt and fertilizer coupling on the growth of sweet potato and soil nitrogen nutrition along the beach in north Jiangsu. 【Method】 In this paper, field experiments were carried out on saline-alkali soil by orthogonal experimental design to study the coupling effects of salt and fertilizer on the nitrogen nutrition of different soil salinity, sweet potato and soil nitrogen. 【Result】 (1) There was no significant difference between the growth of sweet potato and the salt content of 0.5-1.0 g / kg (S 1) under soil salinity levels of 1.0-2.1 g / kg (S 2). Salt increased to 2.1 ~ 3.2 g / kg (S_3), 3.2 ~ 4.0 g / kg (S_4) level, sweet potato growth was inhibited. With the application of nitrogen fertilizer, the inhibition of soil salinity was significantly alleviated, and the growth indexes of sweet potato and fresh potato production increased first and then decreased. Coupling effect of salt and fertilizer, soil salt content was 1.0-2.1 g / kg, nitrogen application rate was 50 kg · hm -2 (S 2 N 2), which was most beneficial to the growth of sweet potato and the accumulation of fresh potato yield. (2) Soil nutrient content decreased with the increase of salinity. The application of N could significantly increase the soil nutrient content, and the contents of soil available nitrogen, total nitrogen and microbial nitrogen were significantly higher under the conditions of 50 kg · hm -2 and 100 kg · hm -2 N_3 improve. The stimulation effect of nitrogen fertilizer on soil salinity was more significant than that of soil available nitrogen at 0.5-1.0 g / kg (S_1) and 1.0-2.1 g / kg (S 2), and the effect of increasing nitrogen fertilizer was more than that of soil total nitrogen. (3) The activities of NAG and LAP changed with the changes of soil salinity, nitrogen application and sweet potato growth. The growth of sweet potato promoted the increase of soil NAG and LAP activity. Under the salt stress of 0.5-1.0 g / kg (S_1) -2.1 ~ 3.2 g / kg (S 3), the activity of NAG and LAP did not change significantly with the increase of nitrogen application 30 days before the sweet potato growth stage. When the growth period reached 30 d, the activity of LAP increased and the activity of N_3> N_2> N_4> N_1 showed a trend of significant difference. When the growth period reached 60-90 d, the NAG and LAP activities increased significantly under different N rates, showing a trend of N 3> N 2> N 4> N 1. When the growth phase reached 125 d, NAG activity began to decline, LAP activity still showed a gradual upward trend. Under the salt content of 3.2 ~ 4.0 g / kg (S_4), NAG and LAP activity did not change significantly with the increase of nitrogen application rate. 【Conclusion】 Coupling effect of soil salt and fertilizer nutrients on the growth and development of sweet potato, fresh potato yield, soil enzyme activity and nutrients has the following effects: the soil salt content is 1.0-2.1 g / kg, and the nitrogen application rate of 50 kg · hm -2 was the most favorable for the growth of sweet potato and the accumulation of fresh potato yield. Planting sweet potato and increasing nitrogen fertilizer could significantly increase soil NAG and LAP enzyme activities, Soil nutrients, thus promoting the ecological restoration of coastal tidal flats and improving the ecological environment of coastal tidal flats.