Nitrogen, biochar, and mycorrhizae: Alteration of the symbiosis and oxidation of the char surface
Nitrogen, biochar, and mycorrhizae: Alteration of the symbiosis and oxidation of the char surface
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DOI：
10.1016/j.soilbio.2012.11.023
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发表时间：
2013-03-01
影响因子：
9.7
通讯作者：
Silberg, Jonathan J.
中科院分区：
文献类型：
--
作者：
LeCroy, Chase;Masiello, Caroline A.;Silberg, Jonathan J.
在某些情况下，用生物炭改良土壤可以提高肥力，尽管生物炭改变土壤过程的确切机制还不是很清楚。然而，在其他情况下，生物炭改良剂可能对植物生长没有影响，或者可能产生负面影响。当作物受益时，同时使用生物炭和矿质营养进行改良，结果不是相加的，这表明生物炭可能能够提高植物吸收养分的效率，但这种协同作用的机制尚不清楚。一种尚未被充分研究的可能机制是植物-菌根真菌互惠关系的改变，这种关系发生在大多数陆地植物中。在为期4周的温室试验中，我们研究了生物炭、菌根真菌和氮肥对高粱幼苗生长的可能影响。结果表明，与菌根和高氮处理相比，生物炭、菌根真菌和高氮联合处理使植株地上生物量减少了42%，同时促进了菌根的定植。这是在我们的实验的4周时间尺度内，在氮气和生物炭存在的情况下诱导菌根真菌寄生的证据。使用X射线光电子能谱，我们发现在我们的试验的4周内，生物炭颗粒上的表面氧化增加，这与通过生物或非生物过程对不稳定的、植物来源的溶解有机物或炭氧化的吸附一致。在含有菌根但没有足够氮素的土壤中，生物炭表现出比其他处理组合更多的表面氧化，并显示出显著更多的表面碳以羰基(-C=0)形式存在。我们的结果表明，土壤氮作为一个开关，控制炭素影响菌根共生的能力，进而影响真菌对炭素表面的氧化程度。(C)2012爱思唯尔有限公司。保留所有权利。
In some cases amending soil with biochar improves fertility, although the exact mechanisms through which biochar alters soil processes are not well understood. In other cases, however, biochar amendment can have no effect on plant growth, or can have negative effects. When crop benefits occur, simultaneous amendment with biochar and mineral nutrients causes results that are not additive, suggesting that biochar may be capable of improving the efficiency of nutrient uptake by plants, but the mechanisms of this synergy remain unknown. One possible mechanism that has not been fully explored is alterations to the plant-mycorrhizal fungus mutualism, a relationship that occurs in most land plants. In a 4 week greenhouse experiment, we investigated possible effects of the presence of biochar, mycorrhizal fungi, and nitrogen fertilizer on sorghum seedling growth. Results indicated that the combined treatment of biochar, mycorrhizal fungi, and high nitrogen decreased aboveground plant biomass by 42% relative to the mycorrhizae and high nitrogen treatment, while simultaneously promoting mycorrhizal root colonization. This is evidence for an induced parasitism of the mycorrhizal fungus in the presence of nitrogen and biochar within the 4 week timescale of our experiments.Using x-ray photoelectron spectroscopy, we found evidence of increased surface oxidation on biochar particles over the 4 weeks of our trial, consistent with sorption of labile, plant derived dissolved organic matter or char oxidation, either via biotic or abiotic processes. Biochar in soils with mycorrhizae but without sufficient nitrogen showed more surface oxidation than other treatment combinations, and showed a significantly greater fraction of surface carbon present in carbonyl (-C=0) functionalities. Our results suggest that soil nitrogen acts as a switch controlling the ability of char to influence the mycorrhizal symbiosis and, in turn, the degree to which the fungi oxidize the char surface. (C) 2012 Elsevier Ltd. All rights reserved.