Effects of digestate from anaerobic digested cattle slurry and plant materials on soil microbiota and fertility and emission of CO2 and N2O

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Summary

Anaerobic digestion of animal manure and crop residues may be employed to produce biogas as a climate-neutral source of energy to provide fertilizers which allow recycling of plant nutrients on the farm. However, compared to fertilizing with the pristine input materials (e.g. raw animal slurry or plant residues), the effect on soil microbiota and soil fertility may be impacted due to the increased content of mineral nitrogen (N) and decreased amount of organic carbon (C); an issue of concern in especially organic farming systems. An incubation study was performed where 1) water, 2) raw cattle slurry, 3) anaerobically digested cattle slurry + maize, 4) anaerobically digested cattle slurry + grass-clover, or 5) fresh grass-clover was applied to soil at arable realistic rates. During the following 9 days experimental unites were sequentially sampled destructively and the soil assayed for content of mineral N, available organic C, microbial phospholipid fatty acids (community composition), catabolic response profiling (functional diversity) and emission of CO2 and N2O. Fertilizing with the anaerobic digested materials increased the soil concentration of NO3- ca. 30-40% compared to when raw slurry was applied. Grass-clover contributed with four times more readily degradable organic C than the other materials, causing an increased microbial biomass which depleted the soil for mineral N and probably also O2. Consequently, grass-clover also caused a ~10 times increase in emissions of both CO2 and N2O compared to any of the other treatments. Besides increasing the total microbial biomass, grass-clover also induced the largest changes in microbial diversity measures. Comparing to this, digested materials and raw cattle slurry only had little effect on the soil microbiota.

Available Versions of this Item

• Effects of digestate from anaerobic fermented cattle slurry and plant materials on soil microbiota and fertility. (deposited 28 Jun 2011 15:01)
  • Effects of digestate from anaerobic digested cattle slurry and plant materials on soil microbiota and fertility and emission of CO2 and N2O. (deposited 06 Feb 2012 10:53) [Currently Displayed]