Life Cycle Assessment: application to the agricultural mechanization
The LCA system measures the environmental impact of production activities and is based on rigorous protocols and methods shared at the international level. The LCA index can also be applied in agriculture by assessing the various production factors associated with mechanization. It makes it possible to objectively verify the improvements resulting from the use of environmentally friendly techniques
The concept of sustainability is increasingly used, regardless of its real meaning and how much it actually constitutes a decisive attribute in the choice between various products and services. "Limiting" the analysis to the agricultural sector, there is no doubt that consumer attention is increasingly directed towards products deriving from sustainable production processes, particularly regarding the environment.
To increase the environmental sustainability of an agricultural process reducing its impact, the first requirement is to have techniques capable of quantifying it: in fact, what cannot be measured can hardly be reduced. Although over the years various assessment methodologies have been developed, there are currently two viable alternatives to address the environmental impact of agricultural processes: limit the assessment to one aspect, knowing, however, that the result may not be exhaustive of the system studied; use particular analytical tools – the Life Cycle Assessment (LCA) is the best known and most widely applied – which, by “unpacking” sustainability in some of its aspects, measures (assesses) its different effects (impact).
Despite being developed for industrial processes where monitoring is relatively simple, LCA is increasingly used in farming. This contribution aims to present potentialities and still critical aspects concerning the application of LCA to agricultural processes and, specifically, to their mechanization.
LCA system
LCA is an impact assessment tool, standardized by international standards and technical documents that specify its application methods and seek to limit the analyst's freedom of choice in order to make the results as comparable as possible, at least for the same product categories.
LCA covers the entire life cycle of a product or service and considers all phases from the production of raw materials to the disposal of waste generated, including processes, transport, and use. The more complex the production chain, the more information will be needed to identify the inputs and outputs, in terms of both mass and energy, generated by the production phases. All this information defines the "inventory" of the life cycle, i.e., the list of everything that enters and exits the system, related to the functional unit, chosen as a study reference (example, 1 kg of product).
The structure of the LCA is set by ISO standards and consists of four distinct phases. It starts with defining the objective and purpose of the analysis, which determines the unit to which the impact is to be referred and the use of the results. The second phase involves the production and analysis of the inventory, while the third requires impact assessment, i.e., converting the information contained in the inventory table into impacts (climate change, resource consumption, eutrophication, acidification, human health, and ecosystem impacts). The fourth phase of the LCA is the interpretation of the results, by which the contributions of individual production steps on impacts are also assessed and "mitigation measures" identified.
The most critical phase is usually the inventory, which requires a lot of information, often difficult to find and of variable reliability. In technical terms, the term primary data refers to information specific to the system being analyzed (direct measurements, machinery specifications, data taken from records linked to quality certification). Secondary data is also used, which is not linked to the specific system but relates to similar systems and is provided by more or less reliable sources (scientific literature, LCA databases, technical documents). An LCA study typically contains an inventory based on a mix of primary and secondary data, and the significance of the final results is often closely tied to the quality of this information.
Inventory of procution factors
In our farming systems, the quantity-qualitative use of the various production factors (e.g., seeds, fertilizers, phytopharmaceuticals) is, in fact, connected to agricultural mechanization (tractors and machinery): seeds, fertilizers, phytopharmaceuticals) is, in fact, related to agricultural mechanization (tractors and operating machinery). Rationality in the choice (type of machinery) and the use (operation of machinery) is, on the one hand, the prerequisite for maximizing yields and, on the other, the primary way to minimize inputs (partial or indirect wear and tear; total or direct wear and tear) and outputs (direct and/or indirect emissions into the atmosphere, soil, surface, and groundwater).
In this regard, for the collection of some primary data, the support of the manufacturers is crucial (for example, to quantify the mass flows of materials and energy associated with the production of the machinery, the related maintenance-repairs and final scrapping, rather than mapping fuel consumption in different engine operating conditions). However, the experimental and site-specific survey of all the data associated with their selection (type and size of machinery, type, and power of tractors) and their operation in the field (working methods and times, actual consumption of materials used/distributed) is a specific task of those performing the assessment.
Application examples
Given the not negligible effort required to collect the data necessary to carry out a good inventory, it must be considered that the potential of LCA is manifold. The main one is undoubtedly to compare different technical solutions with the same result from an environmental point of view. For example, it is possible to compare the execution of a given field operation using different operating machinery and/or tractors that differ in their emission stage.
Below, the results of two applications of LCA in the agricultural mechanization sector are briefly reported.
In the first case (Fig. 2), the impact on climate change (kg of CO2 equivalent)) is compared for three different seedbed preparation sites (Tab. 1). The results, calculated assuming identical working depths and an optimal coupling between machinery and tractors, show how the choice of operating machinery can induce variations of 12-13% in the final impact with the same degree of amortization achieved.
The second case (Tab. 2) shows the absolute environmental impact for a hectare of ploughed land at a depth of 35 cm using the same implement (four-row plough) but employing two 4WD tractors with different emission stages: the first (152 kW), equipped with an EGR system, has a 3A emission rating, while the second (158 kW), with an SCR system, has a 4A emission rating. The use of AdBlue® leads to a reduction in emissions of pollutants in the engine's exhaust gases. These results show that, even with AdBlue® consumption, there is a substantial reduction in the impact categories that depend on the emission of pollutants in the exhaust gases (CO, PM, and NOx).
Conclusions
LCA applied to farm mechanization might be a valuable tool to define operational strategies to reduce the contribution in terms of emissions of herbaceous and tree productions.
From the manufacturer's point of view, the comparison allows reading the improvements introduced and/or the development of innovative solutions aimed at reducing the impact. For the farmer, LCA can support a more conscious and environmentally aware choice of mechanization to be adopted.
Briefly, the application of LCA can be perceived as an opportunity to validate the results pursued that can also be used for marketing purposes.
