滴灌条件下控释专用肥对设施番茄氮钾吸收及其残留的影响

【目的】设施蔬菜生产中水肥的过量投入不仅引发环境污染问题，而且增加生产成本。因此迫切需要通过调整肥料养分释放速率，在满足作物营养充分供应的同时，降低肥料和劳动投入，提高产出。为此，本文研究了习惯施肥与3种番茄控释专用配方肥对京郊番茄产量、品质、氮钾吸收以及土壤中硝态氮和钾残留的影响，以期为番茄的合理施肥提供依据。【方法】采用蔬菜大棚内小区试验的方法，试验设对照（不施氮肥，CK）、 有机肥（只施有机肥，MN）、 习惯施肥（施N 300 kg/hm2，TN）、 控释专用肥Ⅰ（CN1）、控释肥专用肥Ⅱ（CN2）和控释肥专用肥Ⅲ（CN3）共6个处理。3个专用肥的氮由80%的控释氮与20%速效氮构成，作为基肥一次性施入，用量与习惯施肥相同，除CK外其他处理的有机肥用量均为8 t/hm2。 控释肥为自制的聚合物包膜尿素（含N 42%）和包膜硫酸钾（含 K2O 47%）。包膜尿素3种，2个为延迟释放型，1个为直线释放型；2种包膜钾肥均为直线释放型。按不同比例组成3种专用肥。试验采用自压式滴灌系统，每畦安装一条滴灌管，共灌水6次，各小区等量灌溉，分别在移栽及移栽后第44、65、73、79和89 d灌水，每次分别为45、37、35、28、30和27 mm，每小区总量均为202 mm。小区面积为24 m2，每个处理3次重复，随机排列。高畦栽培，畦宽1.4 m，双行定植，行距40 cm，株距40 cm。【结果】 各处理番茄鲜果产量为79.2~87.1 t/hm2，其间无显著差异。CN3处理果实的硝酸盐含量增加，但Vc含量却下降，果实品质有所降低。3个控释肥处理的S型控释肥表现为前控后促的供氮趋势，在果实膨大期无机氮供应达到N102247 kg/hm2，与习惯施肥处理多次追肥形成的供氮规律相似。控释钾肥仅释放23.2%~36.0%，环境温度对于控释钾肥的释放促进作用很小。收获后土壤硝态氮的残留主要集中在表层（020 cm）和次表层（2040 cm），占0100 cm土层的87.1%；060 cm土层内，CN3处理的NO-3|N残留量与习惯施肥相当，而CN1和CN2处理的NO3--N残留比习惯施肥减少37.3%~55.0%，有效降低了硝态氮向下淋洗。施肥增加了各处理表层土壤中的钾含量，表层以下各处理的钾含量差别不大。【结论】3个专用肥处理中控释肥一次性施用不仅节约了施肥时间和劳动成本，而且在果实膨大期提供了充足的氮素供应，实现了与作物氮素吸收的同步。控释专用肥配方1和配方2可以提供合理的氮素供应，在降低劳动投入和节水的情况下，番茄产量和果实品质不降低，并减少了硝态氮的淋洗损失。

Effect of special controlled-release fertilizer application on nitrogen and potassium uptakes of tomato and their residue in soil with drip-irrigation in the green-house

An experiment was conducted in a plastic greenhouse in a Beijing suburb to evaluate the effects on tomato yield, fruit quality, nitrogen and potassium uptakes and soil residual NO3--N and K with three controlled-release special fertilizers and traditional fertilizers. Six treatments were conducted in this study: no fertilizer N treatment (CK), manure fertilizer (MN), traditional fertilization (TN), controlled-release special fertilizerⅠ(CN1), special fertilizerⅡ(CN2) and special fertilizer Ⅲ(CN3). The results showed that fruit yields were 79.1-87.2 t/ha and there were no significant differences among all treatments，however, the fertilizer application time and labor input were saved. Nitrogen supplying was sufficient in the fruit expending stage with a single application of controlled-release fertilizers, which resulted in synchronization with the crop nitrogen uptake and in an increasing trend in fruit N and K concentration. A sigmoid nitrogen supply was found from the use of controlled-release nitrogen fertilizers, however, only 23.2 to 36.0 percent of the controlled-release potassium fertilizers was released and there was little effect of environmental temperature on the release of coated potassium fertilizers. The soil mineral nitrogen supply was consistent with the sigmoid release pattern of the controlled-release nitrogen fertilizers, which is better for high yield and high efficiency cropping production. Soil nitrate was concentrated in the top layer(0-20cm) and the sub-top layer(20-40cm)，where nitrate accounted for 87.1% of the total nitrate in 0 to 100cm soil layer. NO3--N accumulation for CN1 and CN2 treatments in 0-60cm soil layers was 37 to 55 percent less than the TN treatment at harvest, resulting in less nitrate leaching down to the deeper soil layer. Exchangeable K content in the top soil layer was increased in all treatments with potassium fertilizers. There were no significant differences in potassium contents in 20-100cm soil among all treatments, and no movements of potassium down to deep layers were also observed. In conclusion, the use of controlled-release special fertilizerⅠand fertilizerⅡcan provide reasonable nutrient supplyings without any topdressing, whereby both nitrate leaching loss and farmers labor input were reduced without yield losses.