Arbuscular mycorrhizal fungi (AMF) provide many benefits in agroecosystems including improved soil tilth, carbon sequestration, and water and nutrient transfer to plants. AMF are known to affect plant nitrogen (N) dynamics and transfer N to plants, but there have been few studies addressing whether the amount of N transferred to plants by AMF is agronomically relevant. We used δ15 N natural abundance methods and δ15 N mass balance equations to estimate the amount of plant N derived from AMF transfer in perennial grasses managed for bioenergy production under different N addition treatments (0, 56, and 196 kg N/ha). Differentiation of δ15 N among plant, soil N, and AMF pools was higher than anticipated leading to calculations of 34-55% of plant N transferred by AMF in the treatments receiving no N addition to 6-22% of plant N transferred to plants in high-N addition treatments. AMF extra-radical hyphae biomass was significantly reduced in the high-N (196 kg N/ha) addition treatments, which was negatively correlated to enriched plant δ15 N. Our results suggest that N addition decreases AMF N transfer to plants. When N was limiting to plant growth, AMF supplied agronomically significant amounts of plant N, and a higher proportion of overall plant N. Because differentiation between N pools was greater than expected, stable isotope measurements can be used to estimate N transfer to AMF plant hosts.

中文翻译：

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无机氮的添加替代了丛枝菌根真菌提供给柳枝（（Panicum virgatum）的氮。

丛枝菌根真菌（AMF）在农业生态系统中提供了许多好处，包括改善土壤倾倒性，碳固存以及水和养分向植物的转移。已知AMF会影响植物氮（N）的动力学并将N转移到植物上，但是很少有研究解决AMF转移到植物上的N量是否在农学上相关的问题。我们使用δ15N自然丰度方法和δ15N质量平衡方程式，估算了在不同氮素添加处理（0、56和196 kg N / ha）下，多年生草丛中从AMF转移获得的植物N的数量，这些草用于生物能源生产。植物，土壤氮，土壤中δ15N的分化 而AMF池比预期的要高，这导致计算得出在不接受氮添加的处理中AMF转移的植物N占34-55％，而在高氮添加处理中转移到植物中的植物N占6-22％。在高氮（196 kg N / ha）添加处理中，AMF自由基菌丝的生物量显着减少，这与富集植物的δ15N呈负相关。我们的结果表明，氮的添加会降低AMF N向植物的转移。当氮限制植物生长时，AMF在农艺上提供了大量的植物N，并且提供了更高比例的整体植物N。由于N库之间的差异大于预期，因此可以使用稳定的同位素测量来估算N向AMF植物宿主的转移。在高氮（196 kg N / ha）添加处理中，AMF自由基菌丝的生物量显着减少，这与富集植物的δ15N呈负相关。我们的结果表明，氮的添加会降低AMF N向植物的转移。当氮限制植物生长时，AMF在农艺上提供了大量的植物N，并且提供了更高比例的整体植物N。由于N库之间的差异大于预期，因此可以使用稳定的同位素测量来估算N向AMF植物宿主的转移。在高氮（196 kg N / ha）添加处理中，AMF自由基菌丝的生物量显着减少，这与富集植物的δ15N呈负相关。我们的结果表明，氮的添加会降低AMF N向植物的转移。当氮限制植物生长时，AMF在农艺上提供了大量的植物N，并且提供了更高比例的整体植物N。由于N库之间的差异大于预期，因此可以使用稳定的同位素测量来估算N向AMF植物宿主的转移。