Background and Aims

Soil acidity and tillage methods negatively affect crop yields in tropical and subtropical ecosystems. The goal of this study was to evaluate the long-term (32-year) impact of different soil tillage and liming strategies on crop yields, yield stability, and the residual effects on soil acidity properties of a subtropical Oxisol.

Methods

The experiment, established in 1987, included the following management combinations: (i) conventional tillage (CT) without lime, (ii) CT with incorporated lime, (iii) no-tillage (NT) without lime, (iv) NT with surface lime, and (v) NT with incorporated lime. Five lime applications were performed throughout the experimental period. Regional recommended fertilization and crop rotations were maintained, with yields monitored over 32 years for 55 harvests (24 soybean, 8 maize, 9 wheat, 8 barley, and 6 white oat crops). Soil samples were collected in 2019 between 0 to 40 cm depth.

Results

The highest yields for all crops were obtained in the treatments under NT and lime application. Additionally, the highest yield stability was observed in the liming treatments for soybean, maize, wheat, barley, and white oat crops. The stability index that showed the best fit was the adjusted coefficient of variation (aCV), as it eliminates the potential dependence of the standard coefficient of variation (CV) on the mean. Surface lime in no-till soil increased soil pH, exchangeable Ca²⁺ and Mg²⁺, saturation of Ca²⁺ + Mg²⁺ + K⁺, and decreased of that of Al³⁺ and exchangeable Al³⁺ compared to treatments without lime until 40 cm depth.

Conclusion

In soil with liming before NT beginning, surface lime reapplications effectively sustain optimal soil acidity in surface layers up to 10 cm and subsurface layers up to 40 cm, thereby maintaining high and stable crop yields over extended periods under NT in subtropical Oxisols.

中文翻译：

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耕作和施石灰对作物产量和土壤酸度校正的影响：来自巴西南部 32 年实验的见解

 背景和目标

土壤酸度和耕作方法对热带和亚热带生态系统的作物产量产生负面影响。本研究的目的是评估不同土壤耕作和施石灰策略对作物产量、产量稳定性的长期（32 年）影响，以及亚热带 Oxisol 对土壤酸度特性的残留影响。

 方法

该实验于 1987 年建立，包括以下管理组合：（i） 无石灰的常规耕作 （CT），（ii） 含掺入石灰的 CT，（iii） 无石灰的免耕 （NT），（iv） 含表面石灰的 NT，以及 （v） 含掺入石灰的 NT。在整个实验期间进行了五次石灰施用。维持了区域推荐的施肥和作物轮作，在 32 年内监测了 55 次收获（24 种大豆、8 种玉米、9 种小麦、8 种大麦和 6 种白燕麦作物）的产量。2019 年收集了 0 至 40 厘米深度的土壤样本。

 结果

在 NT 和石灰施用下的处理中，所有作物的产量最高。此外，在大豆、玉米、小麦、大麦和白燕麦作物的石灰处理中观察到最高的产量稳定性。显示最佳拟合的稳定性指数是调整后的变异系数 （aCV），因为它消除了标准变异系数 （CV） 对平均值的潜在依赖性。与不施用石灰至 40 cm 深的处理相比，免耕土壤中的表层石灰增加了土壤 pH 值、可交换的 Ca²⁺ 和 Mg²⁺、Ca²⁺ + Mg²⁺ + K⁺ 的饱和度，降低了^{Al 3}⁺ 和可交换的 Al³⁺ 的饱和度。

 结论

在 NT 开始前有石灰的土壤中，地表石灰再施用有效地维持了高达 10 厘米的表层和高达 40 厘米的地下层的最佳土壤酸度，从而在 NT 下亚热带氧化溶胶中长期保持高而稳定的作物产量。