小麦/玉米/大豆和小麦/玉米/甘薯套作体系中玉米产量及养分吸收的差异

  目的  探讨长期不同轮作方式与施肥条件下对水稻产量、植株养分吸收利用及对土壤养分含量的影响，为黄壤地区合理轮作方式选择提供参考。  方法  依托25年的黄壤（稻田）长期定位试验，选取4种轮作方式：水稻单作（RM）、水稻-小麦轮作（RWR）、水稻－油菜轮作（RRR）、水稻－绿肥轮作（RMR），分析比较各轮作方式作物产量、植株氮磷钾养分吸收情况及土壤养分含量的差异。  结果  不同轮作方式2016 ~ 2020年水稻平均产量表现为RWR > RRR > RM > RMR，但各处理之间差异不显著。与RM处理相比，RWR、RRR和RMR处理水稻秸秆和籽粒平均氮磷钾养分含量分别提高10.9% ~ 37.0%、63.6% ~ 101.6%、11.9% ~ 17.6%和7.1% ~ 20.4%、19.7% ~ 37.6%、6.0% ~ 8.1%；秸秆和籽粒平均氮磷钾养分吸收量分别提高15.0% ~ 45.4%、69.7% ~ 113.9%、16.1% ~ 24.8%和3.7% ~ 22.6%、15.9% ~ 40%、2.6% ~ 10.1%；水稻植株平均氮磷钾养分总吸收量分别提高8.0% ~ 30.2%、22.3% ~ 44.8%、12.9% ~ 21.3%。各轮作处理水稻秸秆和籽粒氮磷钾养分含量、吸收量及吸收效率大小均表现为：RWR > RRR > RMR。与RM处理相比，各轮作处理土壤有机质提高37.0% ~ 41.1%、全氮提高1.7% ~ 28.6%、碱解氮提高24.4% ~ 47.5%、有效磷提高2.2% ~ 54.8%。  结论  在现有种植制度与施肥条件下，多种轮作方式均可维持水稻产量不降低，且能提高单位面积土地生产力、提高水稻植株氮磷钾养分吸收量、改善土壤肥力。

Elucidating variations in nitrogen requirement according to yield,variety and cropping system for Chinese rice production

  objective  The aims were to investigate the effects of long-term rotation and fertilization on rice yield, plant nutrient uptake and utilization, and soil nutrient content, so as to provide reference for rational rotation selection in yellow soil area.  Methods  Based on the 25-year yellow soil (paddy field) long-term located experiments, four crop rotation patterns were selected: rice monoculture (RM), rice-wheat rotation (RWR), rice-canola rotation (RRR), and rice-green manure rotation (RMR). The differences in crop yield, plant nitrogen (N), phosphorus (P) and potassium (K) nutrient uptake and soil nutrients were compared among different crop rotation patterns.  Result  The average rice yield of different rotations from 2016 to 2020 was RWR > RRR > RM > RMR, but there was no significant difference among treatments. Compared to RM processing, RWR, RRR and RMR treatments increased the average N, P and K contents of rice straw and grain by 10.9%-37.0%, 63.6%-101.6%, 11.9%-17.6% and 7.1%-20.4%, 19.7%-37.6%, 6.0%-8.1%, respectively. The average N, P and K uptake of straw and grain were increased by 15.0%-45.4%, 69.7%-113.9%, 16.1%-24.8% and 3.7%-22.6%, 15.9%-40%, 2.6%-10.1%, respectively. The total uptake amounts of N, P and K were increased by 8.0%-30.2%, 22.3%-44.8% and 12.9%-21.3%, respectively. The N, P and K nutrient content, absorption amount and absorption efficiencies of rice straw and grain in each rotation treatment showed the following order: RWR > RRR > RMR. Compared with RM treatment, soil organic matter was increased by 37.0%-41.1%, total N by 1.7%-28.6%, alkali-hydrolyzed N by 24.4%-47.5%, and available P by 2.2%-54.8%.  Conclusion  Under the current cropping system and fertilization conditions, various cropping rotations could maintain rice yield without decreasing, increase land productivity per unit area, increase N, P and K uptake of rice plants, and improve soil fertility.