In tropical regions, one of the primary difficulties in the sustainability of no-till systems is the maintenance of soil cover throughout the year. Intercropping corn (Zea mays L.) with tropical perennial grasses is an innovative approach to overcome this difficulty. However, the use of sidedress nitrogen (N) fertilization in this intercropping system remains incompletely studied. The effects of using sidedress N application rates (0, 50, 100 and 200 kg ha⁻¹ N) on monocropped corn or corn intercropped with palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R. Webster ‘Marandu’] or guineagrass [Megathyrsus maximum (Jacq.) R. Webster ‘Mombaça’] with respect to leaf nutrient concentration, agronomic characteristics, revenue and land use efficiency were investigated over three growing seasons in the Brazilian Cerrado region on a clay soil, kaolinitic, thermic Typic Haplorthox. In general, the intercropping systems of corn with palisade or guineagrass did not cause reductions in the leaf nutrient concentration, agronomic characteristics, kernels attributes, shoot dry matter and corn yield compared to that observed in the monocropped system. High sidedress N application rates promoted higher concentrations of nutrients in leaves (primarily N and P), corn yield, forage production and crude protein concentration in the off-season. Corn monocropped or intercropped with palisadegrass and guineagrass using 113, 156 and 187 kg ha⁻¹ N resulted in the highest corn yields (9.2, 8.8 and 9.7 Mg ha⁻¹, respectively). In addition, using these N application rates, corn intercropped with palisadegrass and guineagrass and subsequent meat production estimated on pastures resulted in the highest net profits (US$ 1196 and 1093 ha⁻¹, respectively), whereas monocropped corn without N addition resulted in the lowest net profits (US$ 304 ha⁻¹). Thus, forage produced during the off-season can be used for animal grazing or fodder during the dry season, increasing revenue. Corn intercropped with palisade grass with the addition of 200 kg ha⁻¹ N resulted in a higher land equivalent ratio and relative N yield (1.21 and 123%, respectively). In summary, sidedress N fertilization in intercropped systems can increase crop and forage yields and revenue, improving land-use efficiency in tropical agriculture.

中文翻译：

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夏施氮肥对玉米和热带多年生禾草的影响

在热带地区，免耕系统可持续性的主要困难之一是全年保持土壤覆盖。间作玉米（Zea mays L.）和热带多年生草是克服这一困难的一种创新方法。但是，在间作系统中使用追施氮肥的方法仍未完全研究。使用单施氮肥（0、50、100和200 kg ha ^-1 N）对单种玉米或间作有木栅草的玉米[ Urochloa brizantha（Hochst。ex A. Rich。）R. Webster'Marandu']或豚鼠[ Megathyrsus最大（Jacq。）R. Webster'Mombaça']在巴西Cerrado地区三个高生长季节的黏土，高岭土，热型Typic Haplorthox上研究了叶片养分浓度，农艺特性，收入和土地利用效率。通常，与单作系统相比，玉米与木栅或豚草的间作系统不会引起叶片养分浓度，农艺特性，籽粒特性，枝干物质和玉米产量的降低。氮肥的高施用量促进了淡季叶片中养分浓度（主要是氮和磷），玉米产量，牧草产量和粗蛋白浓度的升高。使用113、156和187 kg ha ^-1单季或间作的木瓜和豚草氮导致最高的玉米产量（分别为9.2、8.8和9.7 Mg ha ^-1）。此外，使用这些氮肥施用量，玉米与木瓜和豚草的间作以及随后在牧场上的肉类产量估计产生了最高的净利润（分别为1196美元和1093公顷^-1），而没有添加氮的单作玉米导致玉米的净利润最高。最低净利润（304公顷^-1美元）。因此，淡季产生的草料可在干旱季节用于动物放牧或饲料，增加了收入。玉米和栅栏草间作，增加200 kg公顷^-1氮导致更高的土地当量比和相对氮产量（分别为1.21和123％）。综上所述，间作系统中的施氮肥可以增加作物和牧草的产量和收成，提高热带农业的土地利用效率。