小麦/玉米/大豆和小麦/玉米/甘薯体系中玉米产量及养分吸收的差异

分别在四川2个玉米主产区川中丘区射洪县和川西山区雅安市，采用单因素随机区组设计，通过3年田间试验对比研究了小麦/玉米/大豆和小麦/玉米/甘薯模式下玉米产量、养分吸收积累规律以及与耕层土壤养分的关系。结果表明:两种套作模式经过一年种植后，小麦/玉米/大豆模式下玉米产量均高于小麦/玉米/甘薯模式下的玉米产量，但差异不显著，第二、三年分带轮作后，小麦/玉米/大豆模式下玉米产量显著高于小麦/玉米/甘薯模式下的玉米产量，二年平均分别高出 679.5 kg/hm2和 839.1 kg/hm2，增产9.4%和12.6%，射洪试验点增产作用较雅安试验点显著；分带轮作后两种套作体系玉米氮素吸收积累在拔节前差异不显著，拔节后小麦/玉米/大豆模式下玉米氮素积累量显著高于小麦/玉米/甘薯，磷的吸收积累则相反，从拔节期到开花期，小麦/玉米/大豆模式下玉米磷的吸收积累均显著低于小麦/玉米/甘薯，小麦/玉米/大豆模式下玉米钾素吸收积累量高于小麦/玉米/甘薯；不同作物带耕层土壤养分含量差异达显著水平，大豆带残留的硝态氮、速效氮、速效钾2个试验点平均分别比甘薯带高18.4%、24.1%、6.0%，而铵态氮和速效磷甘薯带较大豆带分别高18.9%和17.1%，两种套作模式中玉米带耕层土壤养分含量差异不显著，经第二、三年分带轮作后，耕层土壤养分含量差异减小，表明分带轮作玉米能较好均衡田间养分。

Study on yield and differences of nutrient absorptions of maize in wheat/maize/soybean and wheat/maize/sweet potato relay intercropping systems

To analyze and compare the differences of maize yields, nutrient absorptions and soil nutrients of the cultivated layers between the intercropping systems, wheat/maize/soybean and wheat/maize/sweet potato, a three-year field experiment designed with single-factor at random was conducted in two main maize producing areas in Sichuan, Shehong in the middle and Ya’an in the west. The results show that after one-year planting in the intercropping systems, the maize yields of the wheat/maize/soybean are higher than those of the wheat/maize/sweet potato, however the differences are not significant. After two or three-year’s strip rotation, the maize yields of the wheat/maize/soybean are considerably higher than those of the wheat/maize/sweet potato. The two year’s productions are more than those of the previous year with 679.5 kg/hm2 and 839.1 kg/hm2 on average and with the increases of 9.4% and 12.6% in the two study areas, which reflects a more significant productivity in Shehong than that in Ya’an. In general, the uptakes and accumulations of nitrogen of maize are insignificant in the two intercropping systems after the strip rotation before the jointing stage of maize; however, they are significantly higher in the wheat/maize/soybean after the jointing stage of maize. The uptakes and accumulations of phosphorus in the wheat/maize/soybean are lower than those in the wheat/maize/sweet potato significantly, while, the uptakes and accumulations of potassium in the wheat/maize/soybean are higher than those in the wheat/maize/sweet potato from the jointing stage to the flowering stage. The contents of soil nutrients in different crop stripz are varied greatly. The residuals of nitrate nitrogen, available nitrogen and available potassium in the soybean strip are higher than those in the sweet potato strip, with increases of 18.4%, 24.1% and 6.0%, however, the residuals of ammonium nitrogen and available phosphorus in the sweet potato strip are higher than those in the soybean strip, with increases of 18.9% and 17.1%. The contents of soil nutrients in the maize strip are insignificant after two and three-year’s strip rotation, and the differences of soil nutrients in cultivated soil layers become small, which indicates that maize can balance the field nutrients better by the strip rotation.