Abstract Transferring liquid manure from dairy farms to nearby cash-grain farms has the potential to support high grain yields at reduced cost, while making use of animal wastes that might otherwise cause environmental hazards if not utilized appropriately. Yet, empirical evidence of the legacy of long-term liquid manure application, and its interaction with crop rotation management on grain yield and soil properties is scarce. Here we evaluate the benefits and legacy of repeated liquid dairy manure (115 Mg ha−1 yr−1) over 12 years (2003–2014) on corn yield, soil organic matter (SOM) content, and soil nutrient availability in three annual cash grain cropping systems under different crop rotation management in southern Wisconsin. The three systems include: continuous corn (CC); minimum-till corn-soybean (CS); and an organically managed corn-soybean-wheat/oat-clover rotation (CSW). Results showed that, liquid manure application increased corn yield, soil test phosphorus (STP), and soil test potassium (STK) content across the three systems, and soil pH and nitrate (0–90 cm) in CC over the 12 years. The lack of significant impact of manure on SOM content suggested that the liquid manure application was insufficient to build SOM on these fertile Mollisols. The legacy benefit of liquid manure application on corn yield was significant in 2015, but no longer detectable in 2017, three years after the last application, while STP and STK content remained higher in manure treated plots than no manure plots. In 2017, cation exchange capacity (CEC), soil pH, and soil nitrate content were also greater in manured plots, but the effect was crop rotation specific. We show that manure is an equivalent or superior substitute for synthetic fertilizers providing a potential win-win scenario for both grain and dairy farms in the North Central US, where synthetic fertilizer is costly (cash-grain farms) and land for manure spreading is often limited (dairy farms). Our study suggest that liquid dairy manure application is beneficial for agroecosystem productivity but continual applications are needed to sustain its benefit in the crop production systems in the region.

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液态奶粪对粮食生产系统的遗留影响

摘要 将液态粪便从奶牛场转移到附近的现金粮农场有可能以较低的成本支持高谷物产量，同时利用动物粪便，如果使用不当可能会对环境造成危害。然而，关于长期施用液体肥料的遗产及其与作物轮作管理对谷物产量和土壤特性的相互作用的经验证据很少。在这里，我们以三个年度现金形式评估了 12 年（2003-2014 年）重复使用液态乳粪（115 Mg ha−1 yr−1）对玉米产量、土壤有机质 (SOM) 含量和土壤养分可用性的益处和遗产威斯康星州南部不同作物轮作管理下的粮食种植系统。这三个系统包括：连续玉米（CC）；最少耕作玉米-大豆（CS）；以及有机管理的玉米-大豆-小麦/燕麦-三叶草轮作（CSW）。结果表明，在 12 年的时间里，液体肥料施用增加了三个系统的玉米产量、土壤测试磷 (STP) 和土壤测试钾 (STK) 含量，以及 CC 中土壤的 pH 值和硝酸盐 (0-90 cm)。粪肥对 SOM 含量没有显着影响，这表明施用液体粪肥不足以在这些肥沃的 Mollisol 上构建 SOM。2015 年施用液体肥料对玉米产量的遗留效益显着，但在最后一次施用三年后的 2017 年不再检测到，而经过粪便处理的地块中的 STP 和 STK 含量仍然高于未施肥地块。2017 年，施肥地块中的阳离子交换能力 (CEC)、土壤 pH 值和土壤硝酸盐含量也更高，但影响是作物轮作特有的。我们表明，粪肥是合成肥料的等效或更好的替代品，为美国中北部的谷物和奶牛场提供了潜在的双赢局面，那里合成肥料成本高（现金谷物农场），而且肥料撒播的土地通常是有限（奶牛场）。我们的研究表明，液态乳粪施用有利于农业生态系统生产力，但需要持续施用以维持其在该地区作物生产系统中的效益。