Animal. 2016 Nov;10(11):1911-1922. Epub 2016 May 11.
- 11INRA,UMR1213,F-63122 Saint-Genès-Champanelle,France.
Abstract
Crop-livestock
production is claimed more sustainable than specialized production
systems. However, the presence of controversial studies suggests that
there must be conditions of mixing crop and livestock productions to
allow for higher sustainable performances. Whereas previous studies
focused on the impact of crop-livestock interactions on performances, we
posit here that crop-livestock organization is a key determinant of
farming system sustainability. Crop-livestock organization refers to the
percentage of the agricultural area that is dedicated to each
production. Our objective is to investigate if crop-livestock
organization has both a direct and an indirect impact on mixed
crop-livestock (MC-L) sustainability. In that objective, we build a
whole-farm model parametrized on representative French sheep and crop farming systems in plain areas (Vienne, France).
This model permits simulating contrasted MC-L systems and their
subsequent sustainability through the following indicators of
performance: farm income, production, N balance, greenhouse gas (GHG)
emissions (/kg product) and MJ consumption (/kg product). Two MC-L
systems were simulated with contrasted crop-livestock organizations
(MC20-L80: 20% of crops; MC80-L20: 80% of crops). A first scenario -
constraining no crop-livestock interactions in both MC-L systems -
permits highlighting that crop-livestock organization has a significant
direct impact on performances that implies trade-offs between objectives
of sustainability. Indeed, the MC80-L20 system is showing higher
performances for farm income (+44%), livestock production (+18%) and
crop GHG emissions (-14%) whereas the MC20-L80 system has a better N
balance (-53%) and a lower livestock MJ consumption (-9%). A second
scenario - allowing for crop-livestock interactions in both MC20-L80 and
MC80-L20 systems - stated that crop-livestock organization has a
significant indirect impact on performances. Indeed, even if
crop-livestock interactions permit improving performances,
crop-livestock organization influences the capacity of MC-L systems to
benefit from crop-livestock interactions. As a consequence, we observed a
decreasing performance trade-off between MC-L systems for farm income
(-4%) and crop GHG emissions (-10%) whereas the gap increases for
nitrogen balance (+23%), livestock production (+6%) - MJ consumption
(+16%) - GHG emissions (+5%) and crop MJ consumption (+5%). However, the
indirect impact of crop-livestock organization doesn't reverse the
trend of trade-offs between objectives of sustainability determined by
the direct impact of crop-livestock organization. As a conclusion,
crop-livestock organization is a key factor that has to be taken into
account when studying the sustainability of mixed crop-livestock
systems.
KEYWORDS:
farm modeling; integration; livestock; organization; sheep