To study the effect of N supplied levels and fertilization distances on saving fertilizer and improving yield in maize/soybean intercropping system, a field experiment was carried out with three N supplying levels ( RN1: 210 kg N·hm-2, RN2: 270 kg N·hm-2 and CN: 330 kg N·hm-2) and four fertilizing distances (D1: 0 cm, D2: 15 cm, D3: 30 cm and D4: 45 cm, indicating the distance between fertilizing site and maize in narrow row). Compared with CN, the results showed that dry matter accumulation and translocation, and their contribution to grain of post-anthesis maize under RN2 were increased by 1.4%, 23.0% and 16.0%, respectively. Meanwhile, kernel number per ear and grain yield per plant of maize were increased by 1.6% and 4.9%. For soybean, dry matter accumulation and translocation, and their contribution to grain at pre-anthesis under RN2 were increased by 2.1%, 37.9% and 26.9%, respectively. Both of soybean grain number and yield per plant were increased by 7.3%. For the maize-soybean intercropping system, N uptake and use efficiency of RN2 were 5.0% and 44.4% higher than those of CN. The soil N content of maize was raised by 4.1% under RN2, but decreased by 0.8% for soybean. The saving fertilizer and improving yield effect of D2 were the best among all the fertilizing distances. Under RN2, contribution rate of dry matter accumulation to grain after anthesis and kernel number per ear of maize in D2 were 57.2% and 9.4% higher than those of D1. Compared with D4, the contribution rate of dry matter accumulation to grain before anthesis and grain number per plant of soybean in D2 were increased by 335.2% and 2.4%, respectively. For the maize/soybean intercropping system, N uptake and use efficiency of D2 were 15.1% and 112.4% greater than those of D1, and 21.4% and 66.3% higher than those of D4. The total soil N content of maize in D2 was 6.6% higher than that of D1, and the index for soybean was 16.0% higher than that of D4. Appropriate N application reduction and fertilizing distance would be beneficial to transfer dry matter to grain, improve grain number per plant, 100-grain mass and yield, promote N uptake and increase fertilizer use efficiency in the intercropping system, which could achieve the purpose of saving fertilizer and improving yield.
通过田间试验研究了3种施氮水平(RN1:210 kg N·hm-2;RN2:270 kg N·hm-2;CN:330 kg N·hm-2)与4个施肥距离(与窄行玉米距离, D1:0 cm、D2:15 cm、D3:30 cm、D4:45 cm)对玉米/大豆套作系统增产节肥的影响.结果表明: 与CN相比,RN2下玉米花后的干物质积累量、转移量及对籽粒的贡献率提高1.4%、23.0%、16.0%,玉米穗粒数与单株产量增加1.6%和4.9%;大豆花前的物质积累量、转移量及对籽粒贡献率提高2.1%、37.9%、26.9%,单株粒数与籽粒产量均增加7.3%;RN2下玉米/大豆套作系统的作物氮素吸收量与氮肥利用率比CN提高5.0%、44.4%,玉米的土壤总氮含量提高4.1%,大豆的则降低0.8%.各施肥距离间,以D2处理效果较好;RN2下,D2的玉米花后(大豆花前)干物质积累对籽粒贡献率、玉米穗粒数(大豆单株粒数)分别比D1提高57.2%、9.4%,大豆的则比D4提高335.2%、2.4%;D2的玉米/大豆套作系统氮素吸收量及氮肥利用率分别比D1提高15.1%和112.4%,比D4提高21.4%和66.3%;玉米土壤总氮含量D2比D1提高6.6%,大豆土壤总氮含量D2比D4提高16.0%.合理的减量施氮和施肥距离有利于玉米/大豆套作系统下作物干物质向籽粒转运,提高作物的单株粒数、百粒重和产量,促进作物氮素吸收与氮肥高效利用,达到节肥增产的目的.
Keywords: N use efficiency; fertilizing distancey; maize/soybean intercropping systemy; reduced N applicationy.