The chemical convergence and decomposer control hypotheses explain solid cattle manure decomposition in production grasslands

Abstract

Recently, we reported for the first time that home field advantage (HFA) of litter decomposition also exists in agricultural production systems, in addition to earlier reports from natural ecosystems. Here, we provide evidence that adaptation of the soil decomposer community to differences in the chemical composition of solid cattle manure (SCM) explains the HFA. Two dairy farms were selected which differed in type of home-produced SCM (high-quality stacked or low-quality composted SCM) and soil type (sand or peat). Manure was exchanged between these two farms. Also, manure was incubated in fields of two neighbouring non-SCM farms. Using litterbags with three different mesh-sizes (125 μm, 1.5 mm, and 4 mm), we investigated the contribution of microbiota, mesofauna and macrofauna, to SCM dry matter (DM) and nitrogen (N) disappearance after 60, 120 and 240 days of litterbag placement. Home field advantage was estimated after accounting for effects related to structural differences in manure quality (quality index) and grassland soil biota communities (ability index). We found HFA in meso- (14–34%) and macro-mesh (19–31%) size litterbags. In micro-mesh litterbags, the HFA for dry matter and nitrogen disappearance was significant only after 120 days (18 and 26%, respectively). With time, trends of initial increase and then decrease in HFA of both aforementioned parameters were observed, but these were not significant. The quality index indicated that the composted manure had a lower dry matter and nitrogen disappearance rate compared to the stacked manure, irrespective of the location of incubation. The difference between the two manure types for N disappearance had vanished at day 240. Also, the chemical composition of the manure that remained in the litterbags changed over time. After 120 days, the C:N ratio of SCM at home was significantly higher compared to the translocated SCM (P