Soil acidity is one of the major drivers of yield-limited crop productivity, particularly when combined with dry spells during crop development. Liming is a widely used strategy for alleviating the negative effects of soil acidity, ensuring greater crop root development to assist the plant in periods of low water availability, promoting full photosynthetic activity and, consequently, increasing crop yield. Here, we investigated the long-term effects of surface liming on soil chemical properties as well as soybean root growth, nutrition, photosynthetic parameters and grain yield during three growing seasons (2016–2019) in a region prone to dry spells. The long-term liming experiment was established in 2002. We evaluated the long-term effects of four surface lime rates: control, soil not treated with lime; ½ RLR, soil treated with half the recommended lime rate; 1 RLR, soil treated with the full recommended lime rate; and 2 RLR, soil treated with twice the recommended lime rate. The last lime application occurred in 2016. Our results revealed that increasing lime rates applied to soil surface up to 2 RLR increased soil fertility and root growth, besides to enhance the root distribution along soil profile. These changes contributed to boost soybean leaf photosynthetic pigments and gas exchange, leading to better growth, nutrition and grain yields, despite periods of dry spells. Our results suggested that in tropical agricultural systems with intensive cultivation throughout the agricultural year, higher lime rates can be applied without nutritional imbalances in the soil and plants. Our study provided important clues on how long-term liming changes soil fertility and triggers the cascading effects in improving root growth and distribution, as well as soybean photosynthetic metabolism and yield.

土壤酸度是限制产量的主要农作物生产力的主要驱动力之一，特别是在作物生长过程中与干旱相结合时。撒石灰是一种广泛使用的策略，可减轻土壤酸度的负面影响，确保更大的作物根系发育，以在水分缺乏的时期为植物提供帮助，促进充分的光合作用，从而提高作物的产量。在这里，我们调查了在干旱季节三个生长季节（2016-2019年），表面石灰对土壤化学特性以及大豆根系生长，营养，光合参数和谷物产量的长期影响。长期灰泥实验建立于2002年。我们评估了四种表面石灰比率的长期影响：对照，未用石灰处理的土壤，未使用石灰处理的土壤和未使用石灰处理的土壤。½RLR，用建议的石灰量的一半处理过的土壤；1个RLR，以建议的最大石灰量处理过的土壤；和2个RLR，用建议的石灰量的两倍处理过的土壤。上一次施用石灰是在2016年。我们的结果表明，增加土壤表层的石灰用量至2 RLR可以提高土壤肥力和根系生长，此外还可以提高根系在土壤剖面中的分布。这些变化有助于促进大豆叶片光合色素和气体交换，尽管经历了干旱期，但仍可改善生长，营养和谷物产量。我们的研究结果表明，在整个农业年度中进行精耕细作的热带农业系统中，可以采用较高的石灰用量，而不会在土壤和植物中造成营养失衡。