Sustainability assessment of agro-bioenergy land use: Industrial agriculture vs. Ecological Agriculture

Abstract:

Bioenergy from agricultural sources (agro-bioenergy production) has often been heavily criticized and tagged unsustainable, especially within the context of transition to a bio-economy. Previous studies sharing this position were however based on the assumptions that (i) energy inputs are essentially fossil-fuel based, (ii) fossil-fuel resources will remain infinitely available and (iii) bioenergy-cropping must be ran on an industrial scale (i.e. as intensive mono-cultures) to be profitable. Conversely, if viewed from an ecological agriculture (agro-ecology) perspective, as a small-scale, family/community owned or rural-cooperative based enterprise, that is ran on organic farming principles, its long-term sustainability may be guaranteed. Bearing in mind, that food sovereignty (i.e. farming systems’ capacity to produce enough food locally/regionally to sustain its teaming population) and energy sovereignty (i.e. farming systems’ capacity to source enough energy locally or regionally to sustain continuous food production for its teaming population) are non-negotiable cornerstones for the sustainability of agro-ecological systems, this study considered the effects of often ignored local and regional agro-ecological factors such as alternative farm power (fossil-fuel powered tractor vs. human vs. animals), tillage (conventional vs. reduced vs. no-till), irrigation (rain-fed vs. surface vs. sprinkler vs. drip), pesticides (organic vs. synthetic), fertilizer (synthetic vs. animal manure vs. biogas digestate) and seed-sowing options (organic vs. hybrid vs. transgenic) on agro-bioenergy sustainability indicators (net-energy, energy-return, carbon-savings, water-savings, biomass-appropriated etc.) within a transport distance of not more than 20 km, using maize ethanol and maize biogas production systems as case studies.

We found that a lot more than accounted for under conventional (industrial) agriculture is accounted for by considering these agro-ecological factors (43.7-71.6% net-energy and 18.2-30.4% energy-returns from maize ethanol production systems; 27.4-49.5% net-energy and 43.1-47.6% energy-returns from the maize biogas production system). Consequently, it was concluded that organic farming principles (e.g. adoption of rain-fed/surface irrigation as against sprinkler/drip, animal manure/biogas digestate as against synthetic fertilizers, organic pesticides and seeds as against synthetic pesticides and transgenic/hybrid seeds, no-till/reduced tillage as against conventional tillage, crop rotation/mixed cropping/cover cropping as against intensive mono-cultures etc.) espoused by agro-ecology do not only take us closer to nature and promote social equity through reduction of farmland grabbing and rural livelihood loss incidences (which industrial agriculture promotes), but also has the potential to sustainably support agro-bioenergy production with higher energy-returns and carbon-savings, as well as better biomass-appropriation than those reported by conventional (industrial) agriculture.