Assessment of PM10 emissions from agricultural field fertilization, comparison between mineral fertilizer and animal slurry spreading operations.

Particulate matter (PM) originating from agricultural practices poses a significant concern due to its potential adverse effects on the environment and human health. PM is typically categorized into two primary classes based on the particle size: PM10 (with an aerodynamic diameter of ≤ 10 µm) and PM2.5 (with an aerodynamic diameter of ≤ 2.5 µm).

The concentration of PM in the atmosphere is a crucial parameter determining air quality in both urban and rural areas. Numerous studies have demonstrated that short-term PM exposure is harmful to the respiratory and cardiovascular systems, highlighting a relationship between air particle pollution and hospital admissions due to respiratory and cardiovascular diseases.

In Italy, PM concentration is monitored daily, and public administrations have set a specific atmospheric concentration threshold equal to 40 µg m^-3 and 25 µg m^-3 for PM10 and PM 2.5 respectively.

PM pollution is also highly present in rural and agricultural areas. Estimates suggest that agricultural activities contribute approximately 17% and 3% to global PM10 and PM2.5 emissions, respectively. Primary PM emissions from agricultural activity arise from animal husbandry and open-field crop operations, including land preparation, field fertilization, and crop management.

In this context it is of crucial importance to understand and quantify PM emissions from agricultural activity, directing efforts towards the choice of a proper micrometeorological model to assess reliable emission rates.

This study aimed to measure PM10 emissions from three different field fertilization strategies: liquid slurry injection and two types of synthetic fertilizer spreading (potassium chloride - KCl and superphosphate - P₂O₅). The experiment was carried out on a farm located in Carmagnola (Province of Turin, Northern Italy) in a maize-cultivated soil. The selected field was divided into two main plots, which differed in the soil tillage technique, having one ploughed and one strip-tilled plot. The main plots were divided into three sub-plots, corresponding to the different fertilization strategies.

PM10 concentration was measured during each tractor passage using a PM monitor (TSI, DustTrack^TM II model 8530), and emission factors (EFs) were assessed with the backward Lagrangian stochastic model, by using a 2D sonic anemometer to monitor the wind field.

Experimental results revealed significant variations in PM10 emission among the different field fertilization strategies. The average EFs were significantly (P<0.05) higher for liquid slurry injection (72.63 mg m^-2) compared to KCl (0.43 mg m^-2) and P₂O₅ (2.6 mg m^-2) spreading.