Long-term no-till integrated crop-pasture system as a strategy to enhanced rainwater productivity, food production stability, and profitability

Sustainable intensification in tropical agriculture requires production systems that improve soil fertility, stabilize yields, enhance rainwater use, and increase farm profitability over the long term. However, integrated evidence from long-term tropical no-till experiments remains scarce. This study evaluated the effects of four off-season strategies within a 12-year field experiment in Brazil (2006-2018): fallow, second crop, cover crop, and forage grass-based systems under no-till management. The experiment was conducted in a randomized complete block design with four replications. Soil chemical attributes were measured to 0.60 m depth in 2006 and 2018, while grain yield was assessed in all growing seasons from 2006/2007 to 2017/2018. Apparent rainwater productivity, yield stability, estimated animal stocking rate, meat production, and economic return were also determined. The systems differed consistently in agronomic, soil, and economic performance. Across soil parameters, the forage system outperformed all others; relative to fallow, it increased soil P, K, Ca, and Mg by 65%, 71%, 82%, and 86%, respectively, and reduced Al saturation by 52%. Grain yield followed the same ranking, with forage > second crop > cover crop > fallow. In the most recent season of each crop, soybean, maize, rice, and common bean yields were 1.51, 3.17, 0.83, and 0.93 Mg ha-1 higher, respectively, in the forage system than in the fallow system. When both spring-summer and fall-winter production were considered, the second crop system had the highest apparent rainwater productivity, exceeding the average of the other systems by 8.3 kg grain mm-1. The forage system also generated the highest economic return. Over 12 years, total net income reached US$12,803 in the forage system, compared with US$8,720 in the second crop system, US$7,131 in the cover crop system, and US$4,948 in the fallow system. These results show that, under tropical no-till conditions, replacing fallow with biologically active off-season systems, especially forage grasses integrated with livestock potential, simultaneously improves soil fertility, production stability, rainwater use, and profitability.热带农业可持续集约化需要能够长期提升土壤肥力、稳定作物产量、强化雨水利用效率并提高农场经济效益的生产体系。但目前针对热带免耕（no-till）长期试验的综合实证研究仍较为匮乏。本研究依托巴西2006至2018年开展的为期12年的田间试验，评估了4种季闲期管理策略的效果，分别为休闲制、复种制、覆盖作物制以及基于饲用禾草的免耕管理体系。该试验采用完全随机区组设计，设置4次重复。研究分别于2006年和2018年对0~0.60 m土层的土壤化学属性进行了测定，并在2006/2007至2017/2018年的所有生长季中测定了谷物产量。同时还测定了表观雨水生产力、产量稳定性、估算载畜量、肉类产量以及经济效益。各试验体系在农艺、土壤及经济表现上均存在显著且稳定的差异。在所有土壤指标中，饲用禾草体系表现最优：相较于休闲制，其土壤有效磷（P）、钾（K）、钙（Ca）、镁（Mg）含量分别提升65%、71%、82%和86%，铝饱和度降低52%。谷物产量也呈现相同的排序：饲用禾草体系 > 复种制 > 覆盖作物制 > 休闲制。在各作物的最后一个生长季中，饲用禾草体系下的大豆、玉米、水稻及普通菜豆产量分别较休闲制高出1.51、3.17、0.83和0.93 兆克每公顷（Mg ha⁻¹）。若同时考虑春夏与秋冬两季生产，复种制的表观雨水生产力最高，较其他体系的平均值高出8.3 千克谷物每毫米降雨量（kg grain mm⁻¹）。饲用禾草体系的经济效益同样最优。12年试验周期内，总净收入达12803美元，而复种制、覆盖作物制及休闲制的总净收入分别为8720美元、7131美元与4948美元。上述研究结果表明，在热带免耕种植条件下，以具备生物活性的季闲期管理体系替代休闲制，尤其是整合畜禽养殖潜力的饲用禾草体系，可同时提升土壤肥力、生产稳定性、雨水利用效率与经济效益。