Agriculture Reference
In-Depth Information
Fig. 3.5
Changes in the con-
centrations of ammonium ion
(filled circles and left-hand
axis) and nitrate ions (open
squares and right-hand axis)
during the course of compost-
ing. (Data replotted from
Wang et al. 2011)
3.5.2
Lignocellulosic Material and the Processing of Nitrogen
Relative to the fertility of soils, conditions affecting the processing of nitrogen
during composting are especially critical (Hubbe et al.
2010
). Under favorable cir-
cumstances, the nitrogen content of compost can displace the need to use synthetic
fertilizers (Hermann et al.
2011
). Recent studies have shown that, when compost-
ing conditions are well chosen, the content of fixed nitrogen tends to rise dur-
ing the course of composting (Amira et al.
2011
; Bikovens et al.
2012
). Work by
Doublet et al. (
2011
) showed that lignocellulosic materials had little effect on ni-
trogen processing under the studied conditions; rather they mainly affected the
rates of chemical changes. However, the same authors noted that a high C:N ratio,
achieved by the addition of lignocellulosic materials, tends to favor the beneficial
transformation of nitrogen compounds and to limit the production and volatiliza-
tion of ammonia gas. Likewise, Orrico et al. (
2012
) found that addition of various
lignocellulosic materials tended to reduce losses of nitrogen during composting.
Leconte et al. (
2011
) found that addition of the more easily degraded rice hulls was
better able to inhibit the release of ammonia, in comparison to sawdust. Particle
sizes also could be optimized to help maximize levels of nitrogen and phosphorous
in the final compost. Serramia et al. (
2010
) and Luz Cayuela et al. (
2012
) showed
that nitrogen processing in compost also depends on the nature of the N-containing
organic material employed. For instance, urea was found to be a good promoter for
composting (Serramia et al.
2010
). Wang et al. (
2011
) found that higher ammoni-
um contents in compost were achieved following inoculation by white-rot fungus.
Yang et al. (
2011
) reported related results for compost piles inoculated with a pair
of thermophilic bacteria.
Figure
3.5
shows how the levels of different nitrogen-containing species can
change during the course of compositing (Wang
2011
). Wheat straw was compos-
ted with manure from cattle and chickens. The observed increase in the content of
ammonium ions is consistent with the breakdown and transformation of proteins in
