暗管农田不同类型肥料对向日葵生长及土壤氮素分布的影响

为了探明暗管排水条件下不同肥料对作物生长和土壤氮素环境的影响，明确盐渍化暗管排水农田合理的施肥模式，采用田间试验，设置普通尿素（CK）、控释肥（CF）和有机硅水溶性缓释肥（OF）3个处理，在保证施纯氮量均为225 kg·hm^-2的情况下，对各处理向日葵生育期间的生长状况、产量和氮肥利用效率，以及土壤、排水中的氮素含量进行分析。结果表明：与CK相比，CF和OF处理均可提高向日葵各生育期株高、叶面积指数、光合速率及产量。其中，CF增产效果最为显著，两年内较OF、CK分别提高了14.07%和40.54%。此外，CF处理有利于0~40 cm土层土壤氮素的持续有效供应，可增加植株氮素积累量、氮肥偏生产力和氮收获指数，更好地促进作物对养分的吸收利用。与CK、OF相比，CF可有效减少向日葵收获后期0~160 cm土层NO₃^--N残留量，降幅分别为14.92%和7.87%。两年试验中各处理之间的暗管排水量、排盐量较接近，但NO₃^--N及NH₄⁺-N流失量差异明显，其中OF、CK处理下的NO₃^--N流失量分别是CF的1.25、1.50倍，NH₄⁺-N流失量分别是CF的1.22、1.95倍。研究表明，控释肥可以更好地促进作物对养分的吸收利用，提高氮肥利用率，显著增加作物产量，同时还可以降低土壤中氮素的深层淋洗，减少氮素流失量，是暗管排水条件下较为适宜的肥料品种。

Effects of different types of fertilizer on sunflower growth and soil nitrogen distribution in subsurface farmland

To clarify the effects of various fertilizers on crop growth and soil nitrogen environment under subsurface drainage conditions and determine the reasonable fertilization mode suitable for saline subsurface drainage farmland, under the condition of 225 kg·hm^-2 pure nitrogen application, a field experiment with three fertilizer treatments was conducted. These treatments included common urea fertilizer (CK), controlled-release fertilizer(CF) and silicone water-soluble slow-release fertilizer(OF), and the sunflower growth, yield, and nitrogen usage efficiency, as well as the nitrogen content in soil and drainage were measured. The results showed that the plant height, leaf area index, photosynthetic rate and crop yield in CF and OF were greater than that in CK during the growing period. The yield in CF increased most significantly over the two years, which was increased by 14.07% and 40.54% compared to OF and CK, respectively. In addition, CF was conducive to the continuous and effective supply of soil nitrogen in 0~40 cm soil layer, which could increase the plant nitrogen accumulation, nitrogen partial productivity and nitrogen harvest index, and promote the absorption and utilization of nutrients by the crops. CF could effectively reduce the NO₃^--N residue in 0~160 cm soil layer after harvest, which was 14.92% and 7.87% lower than CK and OF, respectively. In the two-year experiment, the subsurface drainage and salt discharge of each treatment were relatively close, but the NO₃^--N and NH₄⁺-N losses were significantly different. The NO₃^--N losses in OF and CK were 1.25 and 1.50 times of that in CF, and the NH₄⁺-N losses were 1.22 and 1.95 times of that in CF, respectively. In summary, compared to the other fertilizers, CF can better promote the absorption and utilization of nutrients by crops, improves the utilization rate of nitrogen fertilizer, and significantly increases the crop yield. At the same time, it can also reduce the deep leaching of nitrogen in the soil and reduce nitrogen loss. Therefore, it is a suitable fertilizer variety under the condition of subsurface drainage.