Effects of digestate from anaerobic fermented cattle slurry and plant materials on soil microbiota and fertility

Summary

Soil from the Højbakkegård experimental (BioConcens) field was amended with nothing (control), each of two anaerobic digested (AD) materials (mixture of AD cattle manure and maize, mixture of AD cattle manure and cut off grass-clover material), raw cattle manure, and grass-clover in five individual treat-ments. The materials were incorporated homogeneously into the soil and sampled destructively at 0, 1, 3 and 9 days after incorporation. Besides, experiments were performed to follow the turnover of these materials, measured as accumulated respiration over a longer period. Measures included available organic soil carbon (cold- and hot-water extractable), soil mineral nitrogen concentration, soil pH, accumulated respiration over a two-week period, emission of CO2 and N2O (flux and total), microbial biomass development estimated from soil total phospholipid fatty acid (PLFA) content, soil microbial genetic diversity pattern measured by PLFA profiling, soil microbial functional diversity pattern measured by catabolic response profiling (MicroResp), and estimation of functional diversity evenness indicies from MicroResp data.
The results showed that the grass-clover amended soil contained much more readily available organic carbon (cold-water extractable) than in the other treatments. The soil mineral N concentration completely depleted after GC at any time during the experiment, where the AD materials resulted in the highest levels and manure intermediate levels. Additionally, the level of N2O emission was about 50 times higher in the grass-clover treatment (~40 µg N2O-N g-1 dry soil) compared to the other treatments. All the amendments were followed by increases in microbial biomass, although highest in the grass-clover treatment. However, nine days after the material application, the microbial biomass was roughly the same in all treatments. The two diversity measures (PLFA and CRP/MicroResp data) showed that in both cases, the dominating trends were that it was the individual materials. In other words, it is the nutritional composition (quantity and quality) of the individual fertilizer material which governs how the microbial community react regarding population size, and genetic and functional diversity. Using the MicroResp data for calculating an index of functional diversity (Simpson-Yule index of similarity) revealed similarity indices close to maximum in all treatments. Hence, the functional diversity of the soil microbial community seemed not to be impaired by the amendment with the de-gassed waste materials.

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) [Currently Displayed]
  • 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)