Background and aims

Increased N deposition can break the coupled associations among chemical elements in soil, many of which are essential plant nutrients. We evaluated the effects of four years of N deposition (0, 10, 20, 50 kg N ha⁻¹ yr⁻¹) on the temporal dynamics of the spatial co-variation (i.e., coupling) among ten chemical elements in soils from a semiarid shrubland in central Spain.

Methods

Soil element coupling was calculated as the mean of Spearman rank correlation coefficients of all possible pairwise interactions among elemental cycles, in absolute value. We also investigated the role of atomic properties of elements as regulators of coupling.

Results

While N deposition impacts on nutrient bioavailability were variable, soil elemental coupling consistently increased in response to N. Coupling responses also varied among elements and N treatments, and four out of ten elemental cycles also responded to N in a season-dependent manner. Atomic properties of elements such as mass, valence orbitals, and electronegativity contributed to explain the spatial coupling of soil elements, most likely due their role on the capacity of elements to interact with one another.

Conclusions

The cumulative effects of N deposition can alter the spatial associations among chemical elements in soils, while not having evident consequences on the bioavailability of single elments. These results indicate that considering how multiple elements co-vary in topsoils may provide a useful framework to better understand the simultaneous response of multiple elemental cycles to global change.

中文翻译：

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半干旱灌木丛中氮沉降增加导致土壤元素循环变得更加耦合

背景和目标

氮沉降的增加可以打破土壤中化学元素之间的耦合关系，其中许多化学元素是植物必需的养分。我们评估了四年的氮沉降（0、10、20、50 kg N ha ^-1  yr ^-1）对土壤中十种化学元素之间空间共变（即耦合）的时间动态的影响。西班牙中部的半干旱灌木丛。

方法

土壤元素耦合计算为元素循环之间所有可能的成对相互作用的斯皮尔曼等级相关系数的平均值（绝对值）。我们还研究了元素原子性质作为耦合调节剂的作用。

结果

虽然氮沉降对养分生物有效性的影响是可变的，但土壤元素耦合随着氮的响应而持续增加。元素和氮处理之间的耦合响应也有所不同，十分之四的元素循环也以季节依赖性方式对氮做出响应。质量、价轨道和电负性等元素的原子特性有助于解释土壤元素的空间耦合，很可能是由于它们对元素彼此相互作用的能力的作用。

结论

氮沉降的累积效应可以改变土壤中化学元素之间的空间关联，同时对单一元素的生物利用度没有明显影响。这些结果表明，考虑表土中多种元素如何共同变化可能提供一个有用的框架，以更好地理解多种元素循环对全球变化的同时响应。