局部根区灌溉水氮耦合对设施黄瓜生长及土壤中硝态氮分布的影响

Coupling Effects of Water and Nitrogen Application with Partial Root-zone Irrigation on Growth of Cucumber and Nitrate Nitrogen Distribution in Soil

通过对设施黄瓜进行灌水量、灌溉方式、水氮根区位置的不同耦合,研究了局部根区灌溉下不同水氮耦合措施对设施黄瓜生长、土壤中硝态氮分布及累积的影响。结果表明,灌水量、灌溉方式、水氮根区供应位置对黄瓜地上部生物量及产量存在着不同的交互作用。亏缺灌溉量处理的地上部生物量及产量均低于相应灌溉方式下的正常水量处理。相同灌溉量处理条件下,交替根区灌溉的黄瓜生物量与产量显著高于两侧均水均氮处理,以正常交替水氮异区处理黄瓜地上部生物量及果实产量最大,分别达到1 143kg/hm2(干重)和1.75×105 kg/hm2(鲜重);而固定根区灌溉下,尤其在水氮异区条件下,生物量与产量则下降。在亏缺灌溉量下,交替根区灌溉处理的黄瓜生物量以及产量与常规充足灌溉处理没有显著差异。在正常灌溉量条件下,通过对局部根区灌溉下不同水氮耦合对土壤中硝态氮分布的分析表明,施氮是造成土壤中硝态氮积累的原因,土壤水分的垂向运动是影响硝态氮向下淋洗的一个主要因子。固定水氮同区、交替水氮同区处理硝态氮向下淋洗较强,水氮异区处理硝态氮向下淋洗相对较弱。交替水氮异区处理氮素主要累积在0—110cm土层,深层累积量显著低于其他水氮耦合处理。综合黄瓜生长、土壤硝态氮淋洗等因素考虑,交替水氮异区处理是最佳的水氮耦合处理方式。

Coupling effects of water and nitrogen application on the growth of cucumber and the distribution and accumulation of nitrate nitrogen in facility soil were studied under partial root-zone irrigation （PRI）. The experimental factors included irrigation amount, irrigation method（whole root-zone irrigation; alternate partial root-zone irrigation, APRI; fixed partial root-zone irrigation, FPRI）, and supply position of water and nitrogen in different root-zones. The results indicated that there was an interaction among the experimental factors studied regarding shoot biomass and cucumber yields. The shoot biomass and cucumber yield under deficient irrigation were relative lower than that under full irrigation for the same irrigation method. The shoot biomass and cucumber yield were significantly higher in APRI than whole root-zone irrigation if same amount of water was supplied. The highest shoot biomass and cucumber yield were observed in the APRI treatment with rotated irrigation and application of nitrogen, reaching 1 143 kg/hm^2 （dry weight） and 1. 75 × 10^5 kg/hm^2 （fresh weight）, respectively. Cucumber growth decreased in FPRI, especially when nitrogen fertilizer was supplied to the non-irrigated furrow. In terms of both shoot biomass and cucumber growth, no significant difference was observed between the treatment with fully irrigated root-zone and APRI under deficient irrigation condi- tion. Nitrate distribution in soil profile was examined under APRI and FPRI with sufficient irrigation. The results revealed that nitrogen fertilizer application could cause nitrate accumulation in soil, and vertical movement of water down soil profile was the main factor affecting nitrate leaching. Nitrate leaching was reduced in PRI treatment with nitrogen fertilizer applied to non-irrigated furrow in comparison to applied to the irrigated furrow. Nitrate nitrogen was mainly accumulated in upper 110 cm of the soil profile for the APRI treatment with nitrogen fertilized to the non-irrigated furrow, and its nitrate accumulation in deep soil profile was relaively significantly lower than the other treatments. In conclusion, APRI with nitrogen fertilizer applied to the non-irrigated furrow is a better strategy balancing both cucumber growth and nitrate leaching.