SALCA’s Own Emission and Impact Assessment Models

Agroscope developed its own emission models for use in life cycle assessments to calculate the direct emissions from arable and forage production as well as livestock husbandry. These models describe the probable environmental impact of individual agricultural activities, taking site conditions into account wherever necessary.

The emission models for nitrate, phosphorus, heavy metals, pesticides and animal emissions provide results at the life cycle inventory level, i.e. for individual substances such as methane or nitrous oxide. Characterisation factors are then used to translate these into environmental impacts such as global warming potential or eutrophication.

We have developed models at the impact assessment level to evaluate soil quality and biodiversity on agricultural land. Agroscope maintains and continuously improves these models.

SALCA Nitrate: The SALCAnitrate model quantifies...

...the leaching of excess nitrate from the root zone into groundwater and flowing waters.

Nitrate leaching is defined as the surplus between supply to (mineralisation and fertilisation) and uptake by the plant. The SALCAnitrate model accounts for the ploughing-in of green manure and the ploughing-up of meadows. Furthermore, and for the sake of consistency, leaching is not calculated for any crops during months with low precipitation but high growth rates. The nitrate remaining at the end of this period is considered to be at risk of leaching. The method is applicable for the Swiss Central Plateau and can be adapted for other regions as well as neighbouring countries.

SALCA Phosphorus: The emission of phosphorus from agricultural...

...land contributes substantially to the accumulation of phosphorus in water bodies.

The SALCAfieldP model takes into account phosphorus emissions from soil erosion, surface run-off and leaching into groundwater. For each emissions pathway, the model specifies a start value which is then adjusted to the given site conditions or fertilisation regime using various correction factors. In addition to soil structure, soil water balance and vegetation type, these correction factors also account for topographic factors such as slope gradient or slope shape as well as distance to the nearest water body.

SALCA Heavy Metals: Agriculture can lead to an accumulation of...

...heavy metals with a potentially toxic impact in soils and water bodies. The SALCAheavymetal model compiles heavy-metal balances and calculates emissions into the water and soil.

The SALCAheavymetal model considers the following heavy metals: cadmium, copper, zinc, lead, nickel, chromium and mercury. In a first step, a mass balance is used to calculate livestock excreta and the metal concentrations in the farmyard manures. In a second step, the mass balance is conducted at plot level, including inputs from seeds, fertilisers and plant-protection products, as well as depositions and emissions from harvest products. Emissions into surface waters are caused by erosion or tile drainage, and emissions into groundwater by leaching. The balance yields the inputs into the agricultural soil. An allocation factor is used to distinguish between diffuse and agriculture-related inputs.

SALCA Pesticides: Pesticides have potentially toxic impacts...

...on aquatic and terrestrial ecosystems as well as on humans. The large number of active substances as well as changes in the list of authorised substances are a particular challenge. This calls for efficient operationalisation, which was achieved with the international project ‘Operationalising Life Cycle Assessment of Pesticides (OLCA-Pest)’.

The aim of the ‘OLCA-Pest’ project was to implement a consensus method to operationalise and harmonise the effects of pesticides in life cycle assessments. The PestLCI Consensus calculation tool developed in this context (https://pestlciweb.man.dtu.dk/) estimates the distribution of the active substances across different environmental compartments. For use in life cycle inventory (LCI) databases, we calculated default values for this distribution and developed recommendations for implementation. Missing characterisation factors for a number of active substances were also calculated. We tested the methods and tools in various case studies in field-crop production, vegetable production and viticulture.

SALCA Animal Emissions: The emissions from animal production lead to...

...high environmental impacts such as climate change, nutrient enrichment in sensitive ecosystems (eutrophication) and acidification. The SALCAanimal model calculates the animals’ excreta and the ammonia, nitrous oxide and methane emissions from animal production.
SALCAanimal uses a mass balance to calculate animal excreta and the nitrogen, phosphorus, potassium and heavy-metal content in farmyard manure. Consumed feed and animal purchases are calculated as inputs, while animal products and animal sales are calculated as outputs, yielding the excreta and concentrations in the farmyard manure. The model then calculates ammonia, nitrous oxide, nitric oxides, nitrate and methane in the barn and outdoor exercise area as well as on the meadow using IPCC, EMEP and Agrammon emission factors.

SALCA Biodiversity: The method calculates the impact of agricultural...

...activities on biodiversity. It accounts for 11 indicator species groups and calculates a score for the overall rating of a crop. The scores can be extrapolated to farm level.

The impact category ‘biodiversity’ encompasses 11 indicator species groups: ‘grassland flora’, ‘arable flora’, ‘birds’, ‘mammals’, ‘amphibians’, ‘molluscs’, ‘bees’, ‘spiders’, ‘ground beetles’, ‘butterflies’ and ‘grasshoppers’. The potential impact of agricultural activities on biodiversity is determined in two steps: first, the agricultural activities are rated according to their effects on biodiversity and the species composition of each indicator species group: the lower the score, the more negative the effect of an activity on biodiversity. In a second step, a weighting based on trophic connections and species richness of the indicator species groups can be used to calculate an overall score from these scores. This can be extrapolated to a crop, plot, production branch or farm.

SALCA Soil Quality: The SALCAsoilquality method assesses the impact...

...of agricultural activities on soil quality. The method covers aspects of soil physics, soil chemistry and soil biology.

The impact of agricultural activities on soil quality is assessed at plot level using nine indicators. Three indicators are calculated for each of the three categories ‘soil physics’ (depth of soil, macropore volume, aggregate stability), ‘soil chemistry’ (organic C content, heavy-metal input, organic pollutants) and ‘soil biology’ (earthworm biomass, microbial biomass and microbial activity). The model aggregates the results at plot level into a single indicator which serves to estimate the impact of a cultivation system or farm on soil quality. The results are currently being supplemented to allow the entire value chain to be evaluated. This requires the linking of the existing detailed model with a generic model used to evaluate the upstream chains. These methodological expansions are intended to enable an improved assessment of value chains by accounting for imports and exports.