Changes in soil microbial communities as affected by intensive cattle husbandry

The present field study documents substantial changes in the soil microbial community (SMC) and organic matter (SOM) in an upland pasture soil resulting from 10 years of “cattle outdoor over-wintering practice”. Soils from a long-term investigated pasture area were compared under three different levels of cattle impact (SI – severe, MI – moderate, NI – no impact). Extended polar lipids analysis (PLA) confirmed a qualitatively new microbial community profile and a several-fold increase of the microbial biomass in the impacted soils (SI) compared to the control NI soil. The new SMC was derived from cattle intestine microorganisms, typical by increased content of archaeal phospholipid ether lipids and by new fatty acids indicative for bacterial and fungal fecal anaerobes. A quality of the SI-SOM, evaluated by the relative content of the pyrolytic fragments profile was more similar to the cattle excrements than to the MI and NI soils, and an organic carbon content of the SI soil was not more than three times higher in comparison to the control NI soil. The quality and quantity of the SOM as well as the SMC in both, the most impacted SI and the control NI soils, were stable in contrast to the moderately impacted MI soil. During the growing season, the MI soil lost 75% of the Corg and 65% of the soil microbial biomass that had accumulated during winter; its aromatic-rich-SOM showed transformation into SOM, enriched by N, P-organic derivates. This transformation was positively correlated to a significant recovery of the actinobacteria and reduction of anaerobic microorganisms during the vegetation season. Results in this study showed that the stability of the soil microbial changes due to the cattle outdoor over-wintering husbandry depended on the stability of the quantitative and qualitative changes of the SOM. © 2012 Published by Elsevier B.V.