Effects of organic amendments with various nitrogen levels on arbuscular mycorrhizal fungal growth

TY - JOUR

T1 - Effects of organic amendments with various nitrogen levels on arbuscular mycorrhizal fungal growth

AU - Aleklett, Kristin

AU - Wallander, Håkan

PY - 2012

Y1 - 2012

N2 - Arbuscular mycorrhizal fungi (AMF) are plant symbionts capable of enhancing nutrient uptake and improving soil structure. These features have brought AMF into focus as a component of soil restoration practices in ecosystems with degraded or highly eroded soils. It has been suggested that increasing the levels of organic material in the soil will enhance the production of AMF biomass, and that organic amendments with high concentrations of nitrogen (N) generate the largest increases in AMF growth. We tested the effects of different organic amendments and N sources on AMF responses in a natural sand dune system and pot cultures of Zea Mays L. The in-growth of AMF was measured as relative biomass through analyses of signature phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA) from mesh bags with different treatments. In the field, results showed a significant positive effect in AMF growth from adding a naturally N-rich organic amendment (alfalfa). Amendments of the low-N organic amendment (barley straw) produced no positive effect, and the effect was negative when ammonium nitrate (NH4NO3) was added to the barley straw to simulate the N concentrations of alfalfa. Saprophytic fungi, on the other hand, were stimulated by additions of NH4NO3. In greenhouse conditions, alfalfa and yeast extract were found to have a similar effect on AMF growth when added proportionally to their N content, even though their mass and texture are distinct. These results suggest the N content in organic amendments does play a role in its effect on AMF growth. There are also indications that the organic or inorganic nature of the N could determine its effect on AMF growth, possibly through interactions with the surrounding microbial community. This aspect requires further investigation. (C) 2012 Elsevier B.V. All rights reserved.

AB - Arbuscular mycorrhizal fungi (AMF) are plant symbionts capable of enhancing nutrient uptake and improving soil structure. These features have brought AMF into focus as a component of soil restoration practices in ecosystems with degraded or highly eroded soils. It has been suggested that increasing the levels of organic material in the soil will enhance the production of AMF biomass, and that organic amendments with high concentrations of nitrogen (N) generate the largest increases in AMF growth. We tested the effects of different organic amendments and N sources on AMF responses in a natural sand dune system and pot cultures of Zea Mays L. The in-growth of AMF was measured as relative biomass through analyses of signature phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA) from mesh bags with different treatments. In the field, results showed a significant positive effect in AMF growth from adding a naturally N-rich organic amendment (alfalfa). Amendments of the low-N organic amendment (barley straw) produced no positive effect, and the effect was negative when ammonium nitrate (NH4NO3) was added to the barley straw to simulate the N concentrations of alfalfa. Saprophytic fungi, on the other hand, were stimulated by additions of NH4NO3. In greenhouse conditions, alfalfa and yeast extract were found to have a similar effect on AMF growth when added proportionally to their N content, even though their mass and texture are distinct. These results suggest the N content in organic amendments does play a role in its effect on AMF growth. There are also indications that the organic or inorganic nature of the N could determine its effect on AMF growth, possibly through interactions with the surrounding microbial community. This aspect requires further investigation. (C) 2012 Elsevier B.V. All rights reserved.

KW - AMF

KW - Organic amendments

KW - Nitrogen

KW - PLFA

KW - NLFA

U2 - 10.1016/j.apsoil.2012.03.007

DO - 10.1016/j.apsoil.2012.03.007

M3 - Article

VL - 60

SP - 71

EP - 76

JO - Applied Soil Ecology

JF - Applied Soil Ecology

SN - 0929-1393

ER -