[Effects of N application reduction and fertilizing distance on saving fertilizer and improving yield in...

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.