Jonathan Vayssières

Pluri-energy analysis of livestock systems--a comparison of dairy systems in different territories.

This paper introduces a generic assessment method called pluri-energy analysis. It aims to assess the types of energy used in agricultural systems and their conversion efficiencies. Four types of energy are considered: fossil energy, gross energy contained in the biomass, energy from human and animal labor and solar energy. The method was applied to compare smallholder low-input dairy-production systems, which are common in developing countries, to the high-input systems encountered in OECD countries. The pluri-energy method is useful for analyzing the functioning of agricultural systems by highlighting their modes of energy management. Since most dairy systems in South Mali (SM) are low-input systems, they are primarily based on solar and labor energy types and do not require substantial fossil-energy inputs to produce milk. Farms in Poitou-Charentes (PC) and Bretagne (BR) show intermediate values of fossil-energy use for milk production, similar to that found in the literature for typical European systems. However, fossil-energy use for milk production is higher on PC than BR farms because of a higher proportion of maize silage in the forage area; grazing pastures are more common on BR farms. Farms on Reunion Island (RI) require a relatively large amount of fossil energy to produce milk, mainly because the island context limits the amount of arable land. Consequently, milk production is based on large imports of concentrated feed with a high fossil-energy cost. The method also enables assessment of fossil-energy-use efficiency in order to increase the performance of biological processes in agricultural systems. Comparing the low-input systems represented by SM to the high-input systems represented by RI, PC and BR, an increase in solar-energy conversion, and thus land productivity, was observed due to intensification via increased fossil-energy use. Conversely, though fossil-energy use at the herd level increased milk productivity, its effect on gross-energy conversion by the herd was less evident. Partitioning the total on-farm gross energy produced among animal co-products (milk, meat and manure) highlights the major functions of SM herds, which are managed to produce organic crop fertilizers.

Evaluating the ability of current energy use assessment methods to study contrasting livestock production systems.

Environmental impact assessment of agriculture has received increased attention over recent decades, leading to development of numerous methods. Among them, three deal with energy use: Energy Analysis (EA), Ecological Footprint (EF) and Emergy synthesis (Em). Based on a review of 197 references applying them to a variety of agricultural systems, this paper evaluates their ability to assess energy use. While EF assesses energy use as land use via a global accounting approach in which energy is only one component of the assessment, EA and Em are energy-focused and appear more appropriate to highlight ways to increase energy-use efficiency. EA presents a clear methodology via fossil energy use and its associated impacts but does not consider all energy sources. With inclusion of natural and renewable resources, Em focuses on other energy resources, such as solar radiation and energy from labour, but does not present impact indicators nor establish a clear link between activities and their environmental impacts. Improvements of the EA and Em methods could increase their ability to perform realistic and unbiased energy analysis or the diversity of livestock systems encountered in the world. First, to consider all energy sources, as Em does, EA could include solar radiation received by farm surfaces and energy expenditure by humans and animals to accomplish farm operations. Second, boundaries of the studied system in EA and Em must include draft animals, humans and communal grazing lands. Third, special attention should be given to update and locally adapt energy coefficients and transformities.

Managing nutrient cycles in crop and livestock systems with green technologies

The cycles of several key nutrients have been substantially altered by agricultural activities over the past century. It is urgent to better manage nutrient cycling in agro-ecosystems. In developing countries, it will contribute to soil fertility recovery and food production increase, and in industrial countries it will participate in environmental impact mitigation. To better access the gains associated with nutrient management, this chapter proposes a multiscale view of the nitrogen (N) cycle in agro-ecosystems: (A) At animal-manure-soil-plant levels, the literature review indicates the large range of observed N loss rates, the complexity of processes implicated and the multiple specific technical options existing for limiting these losses. (B) At farm-household levels, two integrated simulation models are used to analyze N cycling within low and high-input systems. With a well chosen combination of technical options, N use efficiency can be substantially improved in farming systems of both developing and industrialized countries

Livestock induces strong spatial heterogeneity of soil CO2, N2O and CH4 emissions within a semi-arid sylvo-pastoral landscape in West Africa

Greenhouse gas (GHG) emissions from the surface soils and surface water receiving animal excreta may be important components of the GHG balance of terrestrial ecosystems, but the associated processes are poorly documented in tropical environments, especially in tropical arid and semi-arid areas. A typical sylvo-pastoral landscape in the semi-arid zone of Senegal, West Africa, was investigated in this study. The study area (706 km² of managed pastoral land) was a circular zone with a radius of 15 km centered on a borehole used to water livestock. The landscape supports a stocking rate ranging from 0.11 to 0.39 tropical livestock units per hectare depending on the seasonal movements of the livestock. Six landscape units were investigated (land in the vicinity of the borehole, natural ponds, natural rangelands, forest plantations, settlements, and enclosed plots). Carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) fluxes were measured with static chambers set up at 13 sites covering the six landscape units, and the 13 sites are assumed to be representative of the spatial heterogeneity of the emissions. A total of 216 fluxes were measured during the one-year study period (May 2014 to April 2015). At the landscape level, soils and surface water emitted an average 19.8 t C-CO2 eq/(hm²•a) (CO2: 82%, N2O: 15%, and CH4: 3%), but detailed results revealed notable spatial heterogeneity of GHG emissions. CO2 fluxes ranged from 1148.2 (±91.6) mg/(m²•d) in rangelands to 97,980.2 (±14,861.7) mg/(m²•d) in surface water in the vicinity of the borehole. N2O fluxes ranged from 0.6 (±0.1) mg/(m²•d) in forest plantations to 22.6 (±10.8) mg/(m²•d) in the vicinity of the borehole. CH4 fluxes ranged from–3.2 (±0.3) mg/(m²•d) in forest plantations to 8788.5 (±2295.9) mg/(m²•d) from surface water in the vicinity of the borehole. This study identified GHG emission “hot spots” in the landscape. Emissions from the surface soils were significantly higher in the landscape units most frequently used by the animals, i.e., in the vicinity of the borehole and settlements; and emissions measured from surface water in the vicinity of the borehole and from natural ponds were on average about 10 times higher than soil emissions.

Livestock Farming Constraints in Developing Countries—From Adaptation to Mitigation in Ruminant Production Systems

The livestock sector’s relationship with climate change is complex. The sector is a major contributor to agricultural greenhouse gas emissions, whereas it is subject to climate change and must adapt to ensure its survival. The diverse range of livestock farming systems worldwide provides a range of greenhouse gas emission mitigation options. Moreover, livestock production contributes to a significant and increasing extent to food systems and to agricultural systems in developing countries (manure, transportation, savings, income). In this sense, their integration in climate-smart agricultural systems is essential, especially since these regions are undergoing major changes in their demographic, environmental and consumption patterns. Livestock farming is thus a crucial adaptation mechanism for poor and vulnerable people living in changing environments who are subject to a range of risks.

Modelling crop-livestock integration systems at a farm scale in a Highland region of Madagascar: a conceptual model

Introduction Malagasy Highland region of Vakinankaratra (19°51’S; 47°01’E) is the heart of the Madagascar dairy basin and generates 90% of the national dairy production. Farms are based on diverse crop rotations, where rise is the main crop, and livestock activities (dairy cows, zebus, pigs, poultry, etc.). The milk is produced by a multitude of smallholders (with less than five cows in average) which commonly feed animals with crop residues and natural vegetation. This region knows critical erosion problems and soil fertility degradation (Douzet et al., 2008) which increased with cover-crop and land over-using for agriculture and livestock feeding. In these complex traditional farming systems, integrative and interdisciplinary modelling tools are needed for better understanding crop-livestock interactions and identifying a compromise between resources allocation for livestock production and soil fertility improvement. The purpose of this work is to build a biophysical whole-farm computer model (milk and crop yields) for simulating at the farm scale the various flows of biomass occurring between the different compartments (cattle, crops, stocks of organic plant material, soil, organic fertilizers, etc.) in these mixed farming systems.

Agricultural Organic Waste Recycling to Reduce Greenhouse Gas Emissions

Organic waste recycling in agriculture can enhance the efficiency of nutrient cycles and directly or indirectly reduce major and increasing sources of greenhouse gas emissions. It can also boost soil fertility and agricultural resilience to climate change. There is considerable potential for improving recycling that has been studied from the farm to the territorial scale. We present research results concerning the improvement and introduction of recycling practices on several scales and concerning associated biophysical processes allowing more reliable assessment of greenhouse gas emission balances. Whether concerning the resilience of agricultural systems or the mitigation of emissions, the agricultural waste recycling potential is highest on the territorial scale, especially when the spatial concentration of various wastes is high, e.g. in periurban areas around fast-growing megacities in developing countries. CIRAD has developed recycling management methods and support tools and is enhancing knowledge on processes that determine the climate footprint of recycling. The aim is to fill the many knowledge gaps regarding greenhouse gas emission factors and determinants of organic matter bioprocessing in tropical conditions.