Agricultural Systems ( IF 6.1 ) Pub Date : 2021-11-06 , DOI: 10.1016/j.agsy.2021.103305 Ruixuan Xu 1, 2 , Haiming Zhao 3 , Guibo Liu 3 , Yuan Li 3 , Shoujiao Li 1, 2, 4 , Yingjun Zhang 1, 2 , Nan Liu 1, 2 , Lei Ma 5
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CONTEXT
The sustainability of winter wheat (Triticum aestivum L.) − summer maize (Zea mays L.) rotation (W − M), which is commonly practiced in the North China Plain (NCP), is threatened by severe groundwater deficits and environmental pollution due to excessive nitrogen (N) applications.
OBJECTIVE
Considering the need for protein-rich forages by local livestock operations and the environmental benefits of growing perennial legumes, we propose that an alfalfa (Medicago sativa L.)-based system is worth introducing for field practice in the NCP.
METHODS
An integrated evaluation was used in this four-year study to compare the agronomic, economic, and environmental performances of the following four cropping patterns: alfalfa monoculture (AA), alfalfa and silage maize intercropping with or without N input which is designed for local climate condition, maize monoculture with or without N input which is much-discussed as a resources-saving substitution and commonly practiced W − M.
RESULTS AND CONCLUSIONS
W − M obtained the highest aboveground dry matter (DM) productivity (P < 0.05) based on the highest irrigation water and N fertilizer consumption (P < 0.05) which caused considerable soil mineral N (Nmin) accumulation. The production cost of maize monoculture was the lowest as well as the DM yield, nitrogen accumulation and the net revenue compared with other systems (P < 0.05), moreover, there was a great risk of N losses during the offseason period. The alfalfa and silage maize intercropping with a low N input (120 kg ha−1 which is close to local practice for maize season) achieved 26.6%–34.9% more DM yield compared with AA and maize monoculture, and 12.5%–163.9% more N output compared with W − M and maize monoculture during four experimental years with same total economic revenue as W − M and AA did. The N input in alfalfa and silage maize intercropping dramatically improved the system productivity by assisting intercropped maize growth while did not lead to excessive Nmin accumulation within 0–210 soil layer compared with the intercropping system without N addition. The planting of alfalfa would not affect the water storage in the 0–60 soil layer after maize harvesting each year. For the effects of interspecific competition, the production of the intercropped alfalfa and maize was significantly decreased in 2020 and a three-year period of production is recommended for optimal use of the alfalfa and silage maize intercropping.
SIGNIFICANCE
Alfalfa and silage maize intercropping with an appropriate N input, which acquired comprehensive performances in terms of productivity, environmental impacts as well as economic profits, would be an optimal alternative system in the NCP.
中文翻译：
与华北平原的小麦-玉米系统相比，苜蓿和青贮玉米间作提供了可比的生产力和盈利能力，但对环境的影响较小
语境
华北平原 (NCP) 普遍采用的冬小麦 ( Triticum aestivum L.) - 夏玉米 ( Zea mays L.) 轮作 (W - M)的可持续性受到严重地下水短缺和环境污染的威胁过量的氮 (N) 应用。
客观的
考虑到当地畜牧业对富含蛋白质的草料的需求以及种植多年生豆类的环境效益，我们建议在 NCP 的实地实践中引入基于苜蓿 ( Medicago sativa L.) 的系统。
方法
在这项为期四年的研究中使用了一项综合评估来比较以下四种种植模式的农艺、经济和环境绩效：苜蓿单一栽培 (AA)、苜蓿和青贮玉米间作，有或没有氮输入，专为当地气候而设计条件下，有或没有 N 输入的玉米单一栽培作为一种资源节约替代方法被广泛讨论，并且普遍采用 W-M。
结果和结论
W - M 获得最高的地上干物质 (DM) 生产力 ( P < 0.05) 基于最高的灌溉水和氮肥消耗 ( P < 0.05)，这导致了大量的土壤矿物质 N (Nmin) 积累。与其他系统相比，玉米单作的生产成本、干物质产量、氮素积累和净收益最低（P < 0.05），而且在淡季期间存在较大的氮损失风险。低氮输入的苜蓿和青贮玉米间作（120 kg ha -1接近当地的玉米季节实践）与 AA 和玉米单作相比，DM 产量增加了 26.6%–34.9%，与 W-M 和玉米单作相比，在 4 个试验年中，N 产量增加了 12.5%–163.9%。 W-M 和 AA 的经济收入。与不加氮的间作系统相比，苜蓿和青贮玉米间作的氮输入通过帮助间作玉米生长显着提高了系统生产力，同时不会导致 0-210 土层内的 Nmin 过度积累。种植苜蓿不会影响每年玉米收获后0-60土层的蓄水量。对于种间竞争的影响，
意义
苜蓿和青贮玉米间作适当的氮投入，在生产力、环境影响和经济利润方面获得综合性能，将是NCP的最佳替代系统。
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