Arbuscular Mycorrhizal Fungi Mitigate Nitrogen Leaching under Poplar Seedlings

Abstract

The leaching of soil nitrogen (N) has become one of the most concerning environmental threats to ecosystems. Arbuscular mycorrhizal (AM) fungi have important ecological functions, however, their influence on soil N leaching and the mechanism of action remain unclear. We conducted a two-factor (N application level × AM inoculation) experiment on poplar, and for the first time, comprehensively analyzed the mechanism by which AM fungi influence soil N leaching. The results showed that, under optimum (7.5 mM) and high (20 mM) N levels, the nitrate (NO3−) and ammonium (NH4+) concentrations of leachate in the AM inoculated treatment (+AM) were lower than in the non-inoculated treatment (−AM), with significant reductions of 20.0% and 67.5%, respectively, under high N level, indicating that AM inoculation can reduce soil N leaching and that it is more effective for NH4+. The arbuscular and total colonization rates gradually increased, and the morphology of spores and vesicles changed as the N level increased. Under optimum and high N levels, +AM treatment increased the root N concentration by 11.7% and 50.7%, respectively; the increase was significant (p < 0.05) at the high N level, which was associated with slightly increased transpiration and root activity despite reductions in root surface area and root length. Additionally, the +AM treatment increased soil cation exchange capacity (CEC), soil organic carbon (SOC), and significantly (p < 0.05) increased the proportions of macroaggregates (but without significant change in microaggregates), causing soil total nitrogen (TN) to increase by 7.2% and 4.7% under optimum and high N levels, respectively. As the N levels increased, the relative contributions of AM inoculation on N leaching increased, however, the contributions of plant physiological and soil variables decreased. Among all of the variables, SOC had important contributions to NH4+ and total N in the leachate, while root N concentration had a higher contribution to NO3−. In conclusion, AM fungi can mitigate soil N leaching and lower the risk of environmental pollution via enhancing N interception by the inoculated fungi, increasing N sequestration in plant roots, and by improving soil N retention.

Recovering Soil Quality of Elephant Grass-Cultivated Suboptimal Land Through Mycorrhizae and Organic Fertilizer

“…The highest CEC value found at the highest dosage (45 Mg ha −1 of manure) could be reduced leaching, and there were more exchangeable cations such as Na + , Ca 2+ , Mg 2+ , and K + incorporated by soil organic matter and manure itself. Similar findings on changes in soil CEC with AMF and manure are also reported by Fang et al [44] and Shi et al [43], respectively.…”

Effects of poplar intercropping systems on reducing the concentration of different forms of inorganic nitrogen in the soil profile

“…Gikas et al (2016) obtained a similar result in poplar intercropping systems. The mobile ability of is lower than that of and ; thus, the root system interception effect possibly plays a dominant role in the 20–40 cm soil layer (Fang et al, 2020; Thorup‐Kristensen et al, 2009). Therefore, root direct absorption is the main mechanism for inorganic nitrogen reduction in the upper soil layers.…”

A Review on Bacteria, Fungi and Dual Inoculation Towards Nitrogen Fixation in Oil Palm Plants

“…Previous research has shown that AM fungus inoculation can boost plant root activity, which is a comprehensive indication of root nutrient absorption [46]. Furthermore, due to their large mycelia, which effect soil aggregation and absorb nutrients from the soil, AM fungus have been found to enhance soil quality [47]. As pointed out by studies, inoculation with AMF boosts dry matter build up, water moisture and nutrient absorption, hence boosting plant tolerance to stressors such as drought [48].…”