Long-term nitrogen fertilization imparts significant effects on the soil environment and soil microbial communities relevant to nutrient cycling. Understanding the complex interactions between soil biology, management practices, and the soil environment is an important step toward improving soil health. The Crop Residue study of the Long-Term Plots at Pendleton, Oregon USA demonstrate declines in soil quality with acidification and reduced soil carbon under a wheat-fallow cropping system. Soil enzyme activity (β-glucosidase, β-glucosaminidase, acid and alkaline phosphatase, arylsulfatase, and arylamidase) and ammonia oxidation was measured in plots managed with three different fertilizer treatments (no fertilization, urea-ammonium nitrate, and manure) at two stages of crop growth. The fertilizer treatments had a strong impact on total carbon and nitrogen and produced a broad range of soil pH from 4.8 (urea-ammonium nitrate) to 5.7 (no fertilizer) and 6.7 (manure). Overall, potential nutrient cycling activity (hydrolytic enzymes and ammonia oxidation) was enhanced in manure-fertilized soils except for acid phosphatase which was greater in the low pH soil. Treatment trends in the proportional geometric mean (an index of soil nutrient cycling capacity) were generally consistent over a 32-year transect excluding acid phosphatase. All activities were highly correlated to total carbon, nitrogen, and sulfur. Except for β-glucosaminidase, all enzymes were also highly correlated to pH. The only enzyme to vary by crop phase was β-glucosidase which was greater at boot than tillering. Soils remaining after the analyses were oven-dried at 40 °C and stored in a non-climate-controlled warehouse for archiving. After 2-years of storage, the oven-dried soils were re-assessed for hydrolytic enzyme activity to determine whether the ability to distinguish treatment differences is retained in archived soils. The oven-dried archived samples showed similar contrasts as the soils analyzed moist between manure and the other fertilizer treatments, although the level of activity was significantly reduced. Overall, long-term fertilization with manure slowed the decline in soil acidity and enhanced soil function relevant to nutrient cycling and organic matter dynamics in the wheat-fallow cropping system.

长期施氮肥对土壤环境和与养分循环相关的土壤微生物群落具有显着影响。了解土壤生物学、管理实践和土壤环境之间复杂的相互作用是改善土壤健康的重要一步。在美国俄勒冈州彭德尔顿的长期地块的作物残留研究表明，在小麦休耕制度下，土壤质量随着酸化和土壤碳减少而下降。土壤酶活性（β-葡萄糖苷酶、β-氨基葡萄糖苷酶、酸性和碱性磷酸酶、芳基硫酸酯酶和芳基酰胺酶）和氨氧化在使用三种不同肥料处理（不施肥、尿素-硝酸铵和粪肥）管理的两个阶段进行测量的作物生长。施肥处理对总碳和氮有很大的影响，产生的土壤 pH 值范围很广，从 4.8（尿素-硝酸铵）到 5.7（不施肥）和 6.7（肥料）。总体而言，在施肥的土壤中，潜在的养分循环活性（水解酶和氨氧化）得到了增强，但酸性磷酸酶在低 pH 土壤中更强。在不包括酸性磷酸酶的 32 年样带中，比例几何平均值（土壤养分循环能力指数）的处理趋势总体上是一致的。所有活动都与总碳、氮和硫高度相关。除β-氨基葡萄糖苷酶外，所有酶也与pH高度相关。唯一随作物阶段而变化的酶是β-葡萄糖苷酶，它在启动时比分蘖时更大。分析后剩余的土壤在 40°C 下烘干并储存在非气候控制的仓库中存档。储存 2 年后，重新评估烘干土壤的水解酶活性，以确定区分处理差异的能力是否保留在归档土壤中。尽管活性水平显着降低，但在粪便和其他肥料处理之间分析土壤潮湿时，烘干的存档样品显示出相似的对比。总体而言，长期施肥减缓了土壤酸度的下降，增强了与小麦休耕系统中养分循环和有机质动态相关的土壤功能。重新评估烘干土壤的水解酶活性，以确定区分处理差异的能力是否保留在归档土壤中。尽管活性水平显着降低，但在粪便和其他肥料处理之间分析土壤潮湿时，烘干的存档样品显示出相似的对比。总体而言，长期施肥减缓了土壤酸度的下降，增强了与小麦休耕系统中养分循环和有机质动态相关的土壤功能。重新评估烘干土壤的水解酶活性，以确定区分处理差异的能力是否保留在归档土壤中。尽管活性水平显着降低，但在粪便和其他肥料处理之间分析土壤潮湿时，烘干的存档样品显示出相似的对比。总体而言，长期施肥减缓了土壤酸度的下降，增强了与小麦休耕系统中养分循环和有机质动态相关的土壤功能。尽管活动水平显着降低。总体而言，长期施肥减缓了土壤酸度的下降，增强了与小麦休耕系统中养分循环和有机质动态相关的土壤功能。尽管活动水平显着降低。总体而言，长期施肥减缓了土壤酸度的下降，增强了与小麦休耕系统中养分循环和有机质动态相关的土壤功能。