减量施氮及施肥距离对玉米/大豆套作系统增产节肥的影响

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.

Effects of N application reduction and fertilizing distance on saving fertilizer and improving yield in maize/soybean intercropping system

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.