de la Fuente Elba B, Oreja Fernando H, Lenardis Adriana E, Fuentes Marianne Torcat, Agosti Belén, Barrio Antonio, Barberis Santiago, Robredo Julieta, Gil Alejandra, Marzetti Martín, Niccia Eugenia
University of Buenos Aires, Faculty of Agronomy, Department of Vegetal Production, Av. San Martin 4453, C1417DSE, Buenos Aires Argentina.
GTD Chacra Pergamino, Asociación Argentina de Productores en Siembra Directa (AAPRESID), Dorrego 1639 Piso 2 Oficina A, S2000DIG, Rosario, Argentina.
Heliyon. 2021 Jan 30;7(1):e06089. doi: 10.1016/j.heliyon.2021.e06089. eCollection 2021 Jan.
Weeds are one of the main problems in the cropping systems of the Rolling Pampa (Argentina), where glyphosate resistant varieties of soybean sown with no-tillage system became the most important crop in the rotation. The challenge to solve this problem is to apply alternative approaches that both reduce weediness and the use of chemicals. Thus, the objectives of this work were i) to study the impact of crop rotation intensification on the species composition and richness of weed communities and to identify the relationship with some environmental (soil mineral organic matter) and agronomic variables (intensification, cereal crops in the rotation, biomass production and herbicide applications) and ii) to quantify the use and environmental risk of herbicides related to the intensification of crop rotations. From 2012 to 2019, four rotations were performed on three farms combining crops (soybean, maize, wheat and field pea), cover crops (oats and hairy vetch) and mixed pastures. During spring 2018 and autumn 2019 field and seedbank experiments were performed. PCA using presence-absence of species as response variable and intensification index of rotation (IIR), proportion of cereal crops in the rotation (C), biomass production (B), mineral organic matter (OM) and number of herbicide applications (HA) during the six years of the rotation as explanatory variables. The use and environmental risk of herbicides was also assessed. Surveys and seedbank analysis showed that intensification of crop rotations resulted in differences in the floristic composition of weed communities mainly related to IIR and C. Although the use of herbicides decreased as intensification grew, species richness and abundance did not change. Despite of all the variations considered in this study such as different approaches (emerged weeds and seedbank), locations, crops, pastures and sowing dates, intensification consistently filtered species conforming different weed assemblies and reducing the use of herbicides. Thus, promoting sustainable intensification by increasing cover crops, winter crops, cereal crops and pastures in the rotations would be a useful tool to manage weeds since the use of herbicides can be replaced by increasing the IIR without variations in weed abundance.
杂草是阿根廷潘帕斯草原种植系统中的主要问题之一，在该地区，采用免耕系统播种的抗草甘膦大豆品种成为轮作中最重要的作物。解决这一问题的挑战在于应用既能减少杂草又能减少化学品使用的替代方法。因此，本研究的目的是：i）研究作物轮作强化对杂草群落物种组成和丰富度的影响，并确定其与一些环境（土壤矿质有机质）和农艺变量（强化、轮作中的谷类作物、生物量生产和除草剂施用）之间的关系；ii）量化与作物轮作强化相关的除草剂使用情况和环境风险。2012年至2019年期间，在三个农场进行了四种轮作，轮作作物包括大豆、玉米、小麦和豌豆，覆盖作物包括燕麦和毛苕子，还有混合牧场。在2018年春季和2019年秋季进行了田间和种子库试验。主成分分析（PCA）以物种的有无作为响应变量，以轮作强化指数（IIR）、轮作中谷类作物的比例（C）、生物量生产（B）、矿质有机质（OM）以及轮作六年期间的除草剂施用量（HA）作为解释变量。同时还评估了除草剂的使用情况和环境风险。调查和种子库分析表明，作物轮作强化导致杂草群落植物区系组成存在差异，主要与IIR和C有关。虽然随着强化程度的增加除草剂使用量减少，但物种丰富度和丰度并未改变。尽管本研究考虑了所有变化因素，如不同方法（出土杂草和种子库）、地点、作物、牧场和播种日期，但强化始终筛选出符合不同杂草组合的物种，并减少了除草剂的使用。因此，通过在轮作中增加覆盖作物、冬季作物、谷类作物和牧场来促进可持续强化，将是管理杂草的一种有用工具，因为可以通过增加IIR来替代除草剂的使用，而杂草丰度不会发生变化。
