Cover Crops in the Weed Management in Soybean Culture

ABSTRACT: The objective of this work was to evaluate the effect of cover crops on weed suppression in no-tillage soybean production systems in Rondonopolis, Mato Grosso. The experiment was carried out in an experimental area and consisted of the evaluation of nine cover treatments and soil management in a randomized complete block design. The treatments were: NT fallow, CT fallow, Crotalaria spectabilis, Crotalaria breviflora, maize + Crotalaria spectabilis, Pennisetum glaucum, Urochloa ruziziensis, Cajanus cajan, sunflower + Urochloa ruziziensis, Stylosanthes, Vigna unguiculata, Urochloa brizantha, maize + Urochloa ruziziensis. The evaluations were carried out before the desiccation for soybean sowing in the crops (10/23/2014) and (09/21/2015), before the post-emergence of soybean (09/12/2014) and (12/11/2015) and in the second season (12/06/2015). The useful area was 5 x 5 m and all weeds were counted and identified, but only the four species with the largest population were collected. The weeds evaluated were: Digitaria horizontalis, Digitaria insularis, Porophyllum ruderale and Tridax procumbens. Fallow treatments presented higher weed populations in relation to the others, in all periods of evaluation. Digitaria horizontalis presented the highest phytomass production in most seasons. The production systems with Urochloa ruziziensis, Pennisetum glaucum, Crotalaria spectabilis and intercropped with maize + Urochloa ruziziensis, sunflower + Urochloa ruziziensis and maize + Crotalaria spectabilis were the best alternatives for integrated weed management, reducing the incidence and increasing control of the main species that were detected during the conduction of the experiment.

摘要：本研究旨在评估覆盖作物（cover crops）对马托格罗索州隆东波利斯市免耕大豆生产系统（no-tillage soybean production systems）中杂草抑制效果的影响。本试验设于试验田内，采用完全随机区组设计（randomized complete block design），对9种覆盖处理及土壤管理方式进行评估。供试处理包括：免耕休闲（No-Tillage, NT）、翻耕休闲（Conventional Tillage, CT）、美丽猪屎豆（Crotalaria spectabilis）、短花猪屎豆（Crotalaria breviflora）、玉米+美丽猪屎豆（maize + Crotalaria spectabilis）、御谷（Pennisetum glaucum）、鲁兹西臂形草（Urochloa ruziziensis）、木豆（Cajanus cajan）、向日葵+鲁兹西臂形草（sunflower + Urochloa ruziziensis）、柱花草属（Stylosanthes）、豇豆（Vigna unguiculata）、糙伏毛臂形草（Urochloa brizantha）、玉米+鲁兹西臂形草（maize + Urochloa ruziziensis）。调查分别于大豆播种前的药剂干燥处理（desiccation）前（2014年10月23日、2015年9月21日）、大豆出苗后（post-emergence）（2014年9月12日、2015年12月11日）以及第二季生育期（2015年12月6日）开展。样地有效面积为5 m × 5 m，对所有杂草进行计数与物种鉴定，仅收集种群数量最高的4个物种。供试杂草包括：升马唐（Digitaria horizontalis）、海岛马唐（Digitaria insularis）、铺散腺果藤（Porophyllum ruderale）以及羽芒菊（Tridax procumbens）。各调查周期内，休闲处理的杂草种群密度均显著高于其余处理。升马唐在多数生育期的生物量积累（phytomass production）量最高。采用鲁兹西臂形草、御谷、美丽猪屎豆，以及玉米与鲁兹西臂形草间作、向日葵与鲁兹西臂形草间作、玉米与美丽猪屎豆间作的生产系统，是综合杂草管理（integrated weed management）的最优方案，可降低试验过程中检出的主要杂草的发生量并提升防控效果。