Daniela Lovarelli

Anaerobic digestion and milking frequency as mitigation strategies of the environmental burden in the milk production system.

The aim of the study was to assess, through a cradle to farm gate Life Cycle Assessment, different mitigation strategies of the potential environmental impacts of milk production at farm level. The environmental performances of a conventional intensive dairy farm in Northern Italy (baseline scenario) were compared with the results obtained: from the introduction of the third daily milking and from the adoption of anaerobic digestion (AD) of animal slurry in a consortium AD plant. The AD plant, fed only with animal slurries coming also from nearby farms. Key parameters concerning on-farm activities (forage production, energy consumptions, agricultural machines maintenance, manure and livestock management), off-farm activities (production of fertilizers, pesticides, bedding materials, purchased forages, purchased concentrate feed, replacement animals, agricultural machines manufacturing, electricity, fuel) and transportation were considered. The functional unit was 1kg fat and protein corrected milk (FPCM) leaving the farm gate. The selected environmental impact categories were: global warming potential, acidification, eutrophication, photochemical oxidation and non-renewable energy use. The production of 1kg of FPCM caused, in the baseline scenario, the following environmental impact potentials: global warming potential 1.12kg CO2 eq; acidification 15.5g SO2 eq; eutrophication 5.62g PO4(3-) eq; photochemical oxidation 0.87g C2H4 eq/kg FPCM; energy use 4.66MJeq. The increase of milking frequency improved environmental performances for all impact categories in comparison with the baseline scenario; in particular acidification and eutrophication potentials showed the largest reductions (-11 and -12%, respectively). In anaerobic digestion scenario, compared to the baseline one, most of the impact potentials were strongly reduced. In particular the most important advantages were in terms of acidification (-29%), global warming (-22%) and eutrophication potential (-18%). The AD of cow slurry is confirmed as an effective strategy to mitigate the environmental impact of milk production at farm level.

A new tool for life cycle inventories of agricultural machinery operations

The interest in environmental assessments about agricultural processes is fast growing and asking for new tools for accurate impact evaluations. The methodology commonly used to go through these studies is the life cycle assessment, of which the inventory phase (life cycle inventory, LCI) is an essential step. For studies focusing on agricultural productions, the completion of LCI is particularly complex: taking into account the pedo-climatic and mechanical operative variability is evidently difficult. However, the prediction of the environmental impact of mechanical operations caused by the agricultural sector is essential to quantify the impact categories for which it is responsible. A new tool, ENVIAM, was developed to complete LCI to guarantee the availability of local data that describe the mechanical and pedo-climatic conditions occurring in the Po Valley area and widely applicable as well. It calculates mechanical power requests, directly consumed inputs ( i.e ., fuel, lubricant) and material consumption of a productive system by taking into account soil texture, specific machinery operations and coupling solutions as defined by the user. A subdivision of working time and defined engine load have been considered to calculate fuel consumption; with regard to outputs, exhaust gases emissions from internal combustion engines have been assessed by evaluating the emissive stages of belonging as stated by the EU Directive. A case study was also performed to highlight the differences that occur when an analysis is fulfilled in a context with features different from the average, and resulted in significant variations for the inventory. In more details, a comparison was carried out both with Ecoinvent database and within ENVIAM. With regard to fuel consumption, by changing the soil texture, the analysis showed a range between 64%-184% for sandy and clay soils, respectively, if compared with medium texture ones. With this tool, local contexts defined either as real or as optimised coupling solutions can be investigated to assess their environmental impact.

Fuel consumption and exhaust emissions during on-field tractor activity: A possible improving strategy for the environmental load of agricultural mechanisation

Abstract Agricultural machinery plays an important role on the environmental sustainability assessments of the agricultural sector and, in particular, a prominent part of its impact is due to fuel consumption and engine exhaust gases emissions. In order to adopt trustworthy data on agricultural machinery operations for fulfilling reliable local inventories in Life Cycle Assessment (LCA) studies, field tests were performed. During the trials several operations were monitored (i.e. ploughing, spike harrowing, rotary harrowing, sowing and rolling) and the measured data with CAN-bus (among which the fuel consumption) and with the engine exhaust gases emissions analyser (CO 2 , CO and NO X ) were attributed to the field working states of effective work, turns at headlands and stops that were identified thanks to GPS. Moreover, data during the farm-field transfers were also collected. In addition to data processing from the field trials, a model for predicting fuel consumption and engine exhaust gases emissions was adopted and its reliability was studied for further future uses. From the results, specific considerations about the tested tractor (Valtra N101, 82 kW maximum power, IIIA emission stage) and the studied working conditions (e.g., engine speed, torque, working speed and depth) can be performed to get information valid for the engine and the operations.