In tropical agroecosystems, intercropping crops and including perennial forages can increase crop system diversity and sustainability. However, adequate management of cash crops in crop rotation under no-till requires an understanding of the release of nutrients by surface mulch. This study evaluated the effects of two sowing times and nitrogen (N) management of palisade grass [Urochloa brizantha (A. Rich.) Stapf Marandu] and guinea grass [Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs Tanzania] on forage production, nutrient accumulation, and decomposition rates; soybean [Glycine max (L.) Merrill] yield; and soil chemical properties over three growing seasons. Palisade and guinea grasses were sown for intercropping with sorghum [Sorghum bicolor (L.) Moench] in the growing season or after sorghum silage harvest (hereafter succession) and subjected to N fertilization management (urea − 0 and 70 kg N ha⁻¹ cut⁻¹, totalling 210 kg N ha⁻¹ per season) during the off-season. Nitrogen fertilization increased nutrient accumulation in surface mulch in all cropping systems. Regardless of cropping system, N rates, or growing season, palisade and guinea grass provided an adequate plant biomass production, soil cover throughout the year, soybean nutrient use efficiency, and soil quality. Soybean was positively influenced by N fertilization of grasses sown in succession to sorghum. Guinea grass had the greatest effect on soybean grain yield, with an improvement of 0.8 Mg ha⁻¹. Sowing grasses in succession to sorghum positively affected soil pH, Ca, Mg, and base saturation.

在热带农业生态系统中，间作作物和包括多年生草料可以增加作物系统的多样性和可持续性。然而，在免耕下轮作经济作物的充分管理需要了解地表覆盖物释放养分。本研究评估了栅栏草 [ Urochloa brizantha (A. Rich.) Stapf Marandu] 和几内亚草 [ Megathyrsus maximus (Jacq.) BK Simon & SWL Jacobs Tanzania]的两次播种时间和氮 (N) 管理对牧草生产的影响，养分积累和分解率；大豆 [ Glycine max (L.) Merrill] 产量；和三个生长季节的土壤化学性质。种植栅栏草和麦地草用于与高粱间作[双色高粱(L.) Moench] 在生长季节或高粱青贮收获后（以下称为连续）并进行施氮管理（尿素 - 0 和 70 kg N ha ^-1削减^-1，总计 210 kg N ha ^-1每季节）在淡季。在所有种植系统中，施氮增加了地表覆盖物中的养分积累。无论种植系统、施氮量或生长季节如何，栅栏和几内亚草都能提供充足的植物生物量生产、全年土壤覆盖、大豆养分利用效率和土壤质量。继高粱后播种的禾本科植物施氮肥对大豆有积极影响。几内亚草对大豆籽粒产量的影响最大，提高了 0.8 毫克公顷^-1。继高粱后播种草对土壤 pH、Ca、Mg 和碱饱和度有积极影响。