Legumes are used in crop rotations by both large‐scale and smallholder farmers alike to increase soil fertility, especially before high‐nitrogen‐demanding crops such as corn (maize). Legume crop residues and green manures are rich in nitrogen due to mutualistic rhizobia, bacteria that live in their roots and convert atmospheric nitrogen into a biologically available form. Growers can obtain recommendations from local extension offices about how much less inorganic nitrogen fertilizer needs to be added to a subsequent crop following different legume break crops for the predominant soil type (the nitrogen fertilizer replacement value, or NFRV). Due to the intimate relationship between legumes and rhizobia, conditions that affect plant health can also affect the rhizobia and how much nitrogen they provide. We use a combination of empirical data and previously published values to estimate reductions in nitrogen inputs under outbreaks of plant viruses of varying severity. We also use historical fertilizer prices to examine the economic impacts of this lost fertilizer for farmers. We find that fertilizer losses are greatest for crops that fix large amounts of nitrogen, such as clover and alfalfa as opposed to common bean. The economic impact on farmers is controlled by the proportion of plants with viral infections and the price of synthetic fertilizer. In a year of high disease prevalence, attention is normally focused on the yield of the diseased crops. We suggest that farmers growing legumes as break crops should be concerned about yields of subsequent crops as well. Viral diseases can be difficult to diagnose in the field, so the easiest way for farmers to prevent unexpected yield losses in subsequent crops is to test their soil when it is feasible to do so.

中文翻译：

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病毒感染可以减少豆科作物和覆盖作物的净氮输入

大农户和小农户都在轮作中使用豆类来提高土壤肥力，尤其是在玉米（玉米）等高氮需求作物之前。豆科作物残留物和绿肥由于共生根瘤菌而富含氮，根瘤菌是生活在根部的细菌，可将大气中的氮转化为生物可利用的形式。种植者可以从当地推广办公室获得关于在主要土壤类型（氮肥替代值，或 NFRV）的不同豆类破碎作物之后需要向后续作物添加多少无机氮肥的建议。由于豆科植物和根瘤菌之间的密切关系，影响植物健康的条件也会影响根瘤菌及其提供的氮量。我们结合经验数据和先前公布的值来估计在不同严重程度的植物病毒爆发下氮输入的减少。我们还使用历史化肥价格来检查这种损失的化肥对农民的经济影响。我们发现，与普通豆类相比，三叶草和苜蓿等固氮作物的肥料损失最大。对农民的经济影响受病毒感染植物的比例和合成肥料的价格控制。在病害高发的一年，人们的注意力通常集中在病害作物的产量上。我们建议种植豆类作物的农民也应该关注后续作物的产量。病毒性疾病在现场很难诊断，