Abstract Plant-available N in soil originates both from fertilizer N amendments and from mineralization of soil organic matter and crop residues. This study compared the N mineralization potential of soil in five biofuel cropping systems in Iowa (continuous corn [Zea mays], continuous corn with a winter rye [Secale cereale] cover crop, perennial prairie, N-fertilized perennial prairie, and corn-soybean [Glycine max] rotation). Net N mineralization potential was measured by a 4-week incubation and leaching method. To evaluate the impact of plant residues on mineralization, net N mineralization potential was measured with and without macroscopic in situ residues. To explore the effect of freezing and thawing on net N mineralization, some soil samples were frozen and thawed before incubation. Cropping systems had a significant effect (P < 0.05) on net N mineralization rate, in the following order: N-fertilized perennial prairie ≈ continuous corn with winter rye ≥ corn-soybean rotation ≥ continuous corn ≥ perennial prairie. The freezing and thawing treatment increased the 30-day net N mineralization rate approximately two-fold. The presence of plant residues alone did not affect the N mineralization rate, but N mineralization was significantly and positively correlated with the amount of plant residue N in the soil.

中文翻译：

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生物燃料种植系统土壤中的短期氮矿化潜力

摘要 土壤中植物有效氮来源于肥料氮的添加以及土壤有机质和作物残留物的矿化。本研究比较了爱荷华州五种生物燃料种植系统（连续玉米 [Zea mays]、连续玉米与冬季黑麦 [Secale creame] 覆盖作物、多年生草原、施氮肥多年生草原和玉米-大豆）土壤的氮矿化潜力[甘氨酸最大值] 旋转）。净氮矿化潜力通过 4 周的培养和浸出方法测量。为了评估植物残留物对矿化的影响，在有和没有宏观原位残留物的情况下测量了净 N 矿化潜力。为了探究冻融对净氮矿化的影响，一些土壤样品在孵化前进行了冻融。种植系统有显着影响（P < 0。05）关于净氮矿化率，依次为：施氮肥的多年生草原≈连续种植冬黑麦≥玉米-大豆轮作≥连续种植玉米≥多年生草原。冷冻和解冻处理使 30 天净氮矿化率增加了大约两倍。单独存在植物残体不影响氮矿化速率，但氮矿化与土壤中植物残体氮含量呈显着正相关。