Proteins constitute the single largest soil organic nitrogen (SON) reservoir and its decomposition drives terrestrial N availability. Protein cleavage by extracellular enzymes is the rate limiting step in the soil organic N cycle and can be controlled by extracellular enzyme production or protein availability/stabilization in soil. Both controls can be affected by geology and land use, as well as be vulnerable to changes in soil temperature and moisture/O₂. To explore major controls of soil gross protein depolymerization we sampled six soils from two soil parent materials (calcareous and silicate), where each soil type included three land uses (cropland, pasture and forest). Soil samples were subjected to three temperature treatments (5, 15, 25 °C at 60% water-holding capacity (WHC) and aerobic conditions) or three soil moisture/O₂ treatments (30 and 60% WHC at 21% O₂, 90% WHC at 1% O₂, at 20 °C) in short-term experiments. Samples were incubated for one day in the temperature experiment and for one week in the moisture/O₂ experiment. Gross protein depolymerization rates were measured by a novel ¹⁵N isotope pool dilution approach. The low temperature sensitivity of gross protein depolymerization, the lack of relationship with protease activity and strong effects of soil texture and pH demonstrate that this process is constrained by organo-mineral associations and not by soil enzyme content. This also became apparent from the inverse effects in calcareous and silicate soils caused by water saturation/O₂ limitation. We highlight that the specific soil mineralogy influenced the response of gross depolymerization rates to water saturation/O₂ limitation, causing (I) increasing gross depolymerization rates due to release of adsorbed proteins by reductive dissolution of Fe- and Mn-oxyhydroxides in calcareous soils and (II) decreasing gross depolymerization rates due to mobilization of coagulating and toxic Al³⁺ compounds in silicate soils.

蛋白质构成了最大的土壤有机氮（SON）库，其分解驱动了陆地氮的利用率。细胞外酶的蛋白质裂解是土壤有机氮循环中的限速步骤，可以通过细胞外酶的产生或土壤中蛋白质的可用性/稳定性来控制。这两种控制都会受到地质和土地利用的影响，并且容易受到土壤温度和湿度/O ₂变化的影响。为了探索土壤总蛋白解聚的主要控制因素，我们从两种土壤母质（钙质和硅酸盐）中取样了六种土壤，其中每种土壤类型包括三种土地利用（农田、牧场和森林）。土壤样品经过三种温度处理（5、15、25 °C，60% 持水能力 (WHC) 和有氧条件）或三种土壤湿度/O ₂处理（30 和 60% WHC，21% O ₂，在短期实验中，在 1% O _{2 、20 °C 下为 90% WHC。}样品在温度实验中孵育一天，在湿度/O ₂实验中孵育一周。通过新型¹⁵ N 同位素池稀释方法测量总蛋白质解聚率。总蛋白解聚的低温敏感性、与蛋白酶活性缺乏关系以及土壤质地和 pH 值的强烈影响表明，该过程受到有机矿物质关联的限制，而不是受到土壤酶含量的限制。_{这也从水饱和/O 2}限制引起的钙质和硅酸盐土壤的反向效应中变得明显。_{我们强调，特定的土壤矿物学影响了总解聚速率对水饱和度/O 2}限制的响应，导致（I）由于钙质土壤中 Fe-和 Mn-羟基氧化物的还原溶解释放吸附的蛋白质而导致总解聚速率增加，并且(II) 由于硅酸盐土壤中凝结且有毒的 Al ^{3+化合物的移动，总解聚率降低。}