Context or problem

Soil acidity limits crop growth and yield all over the world. Low grain yields is usually associated with poor soil fertility; however, little attention has been given to the nitrogen-based fertilizer use efficiency in soils managed with lime.

Objective

Given the current scenario of uncertainties regarding the availability and prices of fertilizers, our study aimed to understand how maize intercropped with ruzigrass and soybean plants develop in long-term soils managed with lime rates, and what the fate of the ¹⁵N–labeled ammonium sulfate [(¹⁵NH₄)₂SO₄] applied in the soil-plant system.

Methods

The treatments consisted of four dolomitic lime rates applied to the soil surface [control, half the recommended lime rate (½ RLR), full recommended lime rate (1 RLR) and double the recommended lime rate (2 RLR)].

Results

The higher lime rate (2 RLR) improved fertility, carbon and nitrogen stocks in the soil profile, and grain and/or stover production of maize, ruzigrass and soybean. As a consequence, maize and ruzigrass recovered a high amount of ¹⁵N-fertilizer. On the other hand, soybean recovered less ¹⁵N-fertilizer, regardless of treatment, but a greater amount was found in acidic soils. At the end of the maize and soybean growth cycles, our results showed that in 2 RLR-amended soil, the ¹⁵N unrecovered was 71% lower than control. Finally, our results suggested that the use of low lime rates (½ RLR) may increase the ¹⁵N losses potential to deep layers, whereas low amounts of ¹⁵N were found in the subsoil when higher lime rates were applied.

Conclusions and implications

Soil acidity management through higher lime rates leads, over time, to increased soil fertility, resulting in a favorable environment for plant growth and the use of nitrogen fertilizers. In this way, it is possible to obtain a more productive and less costly agricultural system, and with less potential to pollute the environment.

中文翻译：

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更高的石灰用量可实现更高的氮回收率：标有 15N 的长期免耕实验

上下文或问题

土壤酸度限制了全世界的作物生长和产量。粮食产量低通常与土壤肥力差有关；然而，很少有人关注用石灰管理的土壤中氮基肥料的使用效率。

客观的

^{鉴于目前肥料的可用性和价格存在不确定性，我们的研究旨在了解玉米与芸香草和大豆植物间作如何在长期用石灰率管理的土壤中生长，以及15} N 标记的硫酸铵的命运如何[( ¹⁵ NH ₄ ) ₂ SO ₄ ]应用于土壤-植物系统。

方法

处理包括施用于土壤表面的四种白云石石灰用量 [对照、推荐石灰用量的一半 (½ RLR)、完全推荐用石灰用量 (1 RLR) 和推荐用石灰用量的两倍 (2 RLR)]。

结果

较高的石灰用量 (2 RLR) 提高了肥力、土壤剖面中的碳和氮储量，以及玉米、芸香草和大豆的谷物和/或秸秆产量。因此，玉米和芸香草回收了大量的¹⁵ N-肥料。另一方面，无论处理如何，大豆回收的^{15 N 肥都较少，但在酸性土壤中发现了更多的 15 N 肥。}在玉米和大豆生长周期结束时，我们的结果表明，在 2 种 RLR 改良土壤中，未恢复的¹⁵ N 比对照低 71%。最后，我们的结果表明，使用低石灰率 (½ RLR) 可能会增加¹⁵ N 向深层流失的可能性，而少量的¹⁵当施加较高的石灰用量时，会在底土中发现 N。

结论和启示

随着时间的推移，通过提高石灰用量来管理土壤酸度会增加土壤肥力，从而为植物生长和氮肥的使用创造有利的环境。通过这种方式，可以获得更高产和成本更低的农业系统，并且污染环境的可能性更小。