Corn yield for silage and grains in different integrated crop-livestock systems

Abstract In this study, the objective was to assess the influence of two doses of N (90 and 180 kg N ha-1, added to the winter pastures), two integrated crop-livestock systems (ICLS, with and without trees) and five positions between the tree rows, on the corn (Zea mays L.) quality and productivity, for silage and grain. Adopting the complete randomized block design, the treatments included three replicates. In 2006, following the 14 x 3 m spacing (currently with 158 trees ha-1) the trees were planted in 6 out of the 12 paddocks. While the corn was implemented during summer of 2013/2014, cattle grazing on the annual pasture was done during the prior winter, in both ICLS. Corn for silage was reaped at the R5 phenological stage, whereas for grains it was done at 176 days post seeding. For silage, the corn plants were grinded and then stocked in the experimental mini PVC silos. The silage varied slightly in quality along the positions between the tree rows. The differences observed between N levels in the dry matter, crude protein (CP) and grain productivity are expressions of the residual effects of the winter fertilization. Silage quality was improved by the shade effect which minimized the acid detergent fiber and raised the CP, although it reduced the corn production for silage and grains by 52%. Some feasible techniques to reduce these losses are discussed.

摘要 本研究旨在评估两种施氮量（90与180 kg N·ha⁻¹，施加于冬季牧场）、两种农牧综合系统（integrated crop-livestock systems, ICLS，分别设置有树木与无树木处理）以及树行间5个位置，对用于青贮与籽粒生产的玉米（Zea mays L.）品质与产量的影响。本研究采用随机完全区组设计（complete randomized block design），各处理设置3次重复。2006年，研究团队在12个牧场中的6个按14×3 m的株行距种植树木，当前树木密度为158株·ha⁻¹。两种农牧综合系统中，牛群均于前一个冬季在一年生牧场上放牧，而玉米种植则于2013/2014年夏季开展。用于青贮的玉米于R5物候期收获，籽粒用玉米则于播种后176天收获。青贮用玉米植株经粉碎后，装填至实验用微型PVC青贮筒仓中。树行间不同位置的青贮品质差异微弱。施氮水平间在干物质、粗蛋白（crude protein, CP）与籽粒产量上的差异，体现了冬季施肥的后效作用。遮阴效应可改善青贮品质：其降低了酸性洗涤纤维（acid detergent fiber）含量并提升了粗蛋白含量，但同时使青贮用玉米与籽粒玉米的产量降低了52%。本文还探讨了若干可缓解此类产量损失的可行技术手段。