Contribution of roots and shoots of Brachiaria species to soybean performance in succession

Abstract: The objective of this work was to evaluate the effect of roots and straw of palisade grass (Urochloa brizantha) and Ruzi grass (U. ruziziensis), used as cover crops in autumn-winter, on soybean performance. Seven treatments were evaluated in a randomized complete block design, with four replicates: fallow, during autumn-winter; straw of U. ruziziensis or U. brizantha 'BRS Piatã', distributed in plots kept under fallow in the winter, without roots; plots only with roots of U. ruziziensis or U. brizantha, without straw; and plots with straw and roots of U. ruziziensis or U. brizantha. The grass species were planted during the 2014/2015 crop season, and treatments were evaluated at the end of the 2015/2016 crop season, without drought during the soybean cycle. The oil and protein contents of soybean grains were not affected significantly by the treatments. However, the cultivation of grass species during autumn-winter increased soybean grain yield in comparison with fallow. Grass root effects are more expressive than those of straw. The combined presence of roots and straw confers a better performance to soybean than the isolated presence of roots or straw.

摘要：本研究旨在评估秋冬季节作为覆盖作物（cover crops）的帕利萨德草（palisade grass, Urochloa brizantha）与鲁齐臂形草（Ruzi grass, U. ruziziensis）的根系与秸秆对大豆生产性能的影响。本试验采用随机完全区组设计（randomized complete block design），设置7种处理并设置4次重复：秋冬休耕处理；将鲁齐臂形草或帕利萨德草‘BRS Piatã’的秸秆覆盖于冬季休耕地块（无根系留存）；仅保留鲁齐臂形草或帕利萨德草根系（无秸秆留存）的地块；同时保留鲁齐臂形草或帕利萨德草根系与秸秆的地块。供试禾草于2014/2015种植季栽植，各处理于2015/2016种植季末完成评估，试验期间大豆生育期无干旱胁迫。结果表明，各处理对大豆籽粒的含油量与蛋白质含量无显著影响；但相较于休耕处理，秋冬季节种植禾草可提升大豆籽粒产量。禾草根系的作用效果较秸秆更为突出；根系与秸秆联合施用的处理，其大豆生产性能优于单独施用根系或单独施用秸秆的处理。