Agriculture Reference
In-Depth Information
Fig. 1.2
Graphical representation of minimum's law applied to ecosystem services. In the exam-
ple, 'soil quality' service is considered the limiting factor (
a
). The farm residues recycling and
composting practices improve several ecosystem services (Kremen and Miles
2012
). The case pre-
sented in (
b
) assume that those services are 'nutrients management' and 'pest control'. It results in
a partial reduction of off-farm input needs (Ecological Services Replacement) however it doesn't
increase the yield that it is limited always by 'soil quality'. On the medium/long-term the same
practices ameliorate also soil quality (
c
) leading to yield increasing (Ecological Services Enhance-
ment) by ecological intensification strategy
The Liebig's law (Liebig
1840
) could be applied to the ecological services con-
sidering each service level a possible limiting factor for the yield (Fig.
1.2
). Kremen
and Miles (
2012
) presented a relationship between agroecological practices and the
provisioning of ecosystem services showing that compost amendment and cover
crops practices enhance, in terms of ecosystem services, biodiversity, soil quality,
nutrient management, water holding capacity, pest and disease control, C seques-
tration and energy use efficiency. It is unsatisfactory to implement agroecological
practices to intensify the crop production shrinking the environmental impact but
also how appropriately these practices are used (Francis
2003
). Effective applica-
tion of the eco-efficiency concept requires an understanding of the production func-
tions that relate agricultural outputs to the level of resource and other inputs (Dillon
and Anderson
1990
). Accordingly, the microbial metabolism of decomposer should
be well understood to make the most of composting and farm residues recycling.
1.5.1
Feed Microorganism to Feed the Soil
Many microbial processes are essential for the long-term sustainability of agricul-
tural systems (Wardle and Ghani
1995
). Microbes grow on plant residues and utilize
plant-derived C to build their biomass, then after cell death, part of microbial de-
rived C is transformed into non-living SOM. The bacterial residues after cell death
were recorded about 40 times as high as the living microbial biomass (Miltner et al.
2012
). Assuming microbial C in soil is 2 % of the SOM, the 80 % of the SOC might
have a microbial origin.
In the organic farming systems soil microorganism are: (i) taking benefit of
the organic matter management based on compost amendment and crop residues
incorporation; (ii) utilizing the available C more efficiently as indicated by a
lower metabolic quotient qCO2 (Fließbach and Mäder
2000
); (iii) contributing to
