Mycorrhiza and farming

Research papers and other publications which do not fit comfortably into the above headings but inform the subject.
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Mycorrhiza and farming

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The impact of farming practice on soil microorganisms and arbuscular mycorrhizal fungi: Crop type versus long-term mineral and organic fertilization

Christopher Ngosong, Mareike Jarosch, Joachim Raupp, Elke Neumann, Liliane Ruess

This study investigates an arable field soil with long-term (27 and 28 years) mineral (NPK) and organic
(cattle manure, cattle manure with biodynamic preparations) fertilizer amendments at low, medium and
high amounts. Arbuscular mycorrhizal (AM) fungi host plant wheat was cultivated in the first vegetation
period and non-host amaranth in the second. Phospholipid fatty acids (PLFA) were used to assess
soil microbial biomass and community structure. AM fungi were quantified using the marker fatty acid
16:1 5, with its occurrence in soil PLFAs representing hyphae and in neutral lipid fatty acid (NLFA)
spores. Soil microbial biomass was enhanced by the addition of manure and at higher amounts for both
fertilizers. AM fungal hyphae and spore biomass responded positively to manure application. The soil
microbial community under both crops was dominated by bacteria. The ratio of fungal to bacterial (f/b)
PLFAs increased with higher fertilizer amounts but decreased in amaranth plots with the application of
manure. Meanwhile the ratio of Gram+/Gram− bacteria indicating environmental conditions (e.g. pH,
temperature) was higher in amaranth plots with the addition of manure as compared to wheat plots. Soil
PLFA revealed distinct effect of crop type displayed by changes in the occurrence of saturated fatty acids
and biomarkers for Gram-negative bacteria and saprotrophic fungi. The latter additionally accounted
for the dissimilarity between fertilizer treatments. In sum, the soil PLFA pattern distinctively separated
wheat from amaranth plots at 0–5cm soil depth, indicating a stronger effect of crop rotation and crop
identity on soil microorganisms than long-term fertilizer practice.