Stefano Monaco

Assessing agro-environmental performance of dairy farms in northwest Italy based on aggregated results from indicators.

Dairy farms control an important share of the agricultural area of Northern Italy. Zero grazing, large maize-cropped areas, high stocking densities, and high milk production make them intensive and prone to impact the environment. Currently, few published studies have proposed indicator sets able to describe the entire dairy farm system and their internal components. This work had four aims: i) to propose a list of agro-environmental indicators to assess dairy farms; ii) to understand which indicators classify farms best; iii) to evaluate the dairy farms based on the proposed indicator list; iv) to link farmer decisions to the consequent environmental pressures. Forty agro-environmental indicators selected for this study are described. Northern Italy dairy systems were analysed considering both farmer decision indicators (farm management) and the resulting pressure indicators that demonstrate environmental stress on the entire farming system, and its components: cropping system, livestock system, and milk production. The correlations among single indicators identified redundant indicators. Principal Components Analysis distinguished which indicators provided meaningful information about each pressure indicator group. Analysis of the communalities and the correlations among indicators identified those that best represented farm variability: Farm Gate N Balance, Greenhouse Gas Emission, and Net Energy of the farm system; Net Energy and Gross P Balance of the cropping system component; Energy Use Efficiency and Purchased Feed N Input of the livestock system component; N Eco-Efficiency of the milk production component. Farm evaluation, based on the complete list of selected indicators demonstrated organic farming resulted in uniformly high values, while farms with low milk-producing herds resulted in uniformly low values. Yet on other farms, the environmental quality varied greatly when different groups of pressure indicators were considered, which highlighted the importance of expanding environmental analysis to effects within the farm. Statistical analysis demonstrated positive correlations between all farmer decision and pressure group indicators. Consumption of mineral fertiliser and pesticide negatively influenced the cropping system. Furthermore, stocking rate was found to correlate positively with the milk production component and negatively with the farm system. This study provides baseline references for ex ante policy evaluation, and monitoring tools for analysis both in itinere and ex post environment policy implementation.

Laboratory assessment of ammonia emission after soil application of treated and untreated manures

Ammonia (NH 3 ) volatilization from soil-applied manure not only causes environmental pollution but also reduces the fertilization value of the manure. Anaerobic digestion and solid/liquid separation alter the physical and chemical characteristics of slurry, which affect NH 3 emissions after application. The present study measured potential laboratory NH 3 losses from different manures, untreated pig slurry and the liquid fractions of each untreated and digested slurry, after their application to two different soil types. The experiment was carried out in dynamic chambers using a photoacoustic infrared gas analyser to determine the NH 3 concentration in the air stream directly. The estimated values of nitrogen (N) emitted for surface-applied, untreated pig slurry were 0·26±0·064 mg per mg of applied total ammoniacal nitrogen (TAN). For the liquid fractions of pig slurry and digested pig slurry, results were 0·13±0·064 and 0·16±0·064 mg/mg, respectively. Initial NH 3 –N emission rates from surface-applied, untreated pig slurry were higher than those measured for either liquid fraction; in the case of the untreated pig slurry, half was emitted in the first 4·9 h of measurement. Silty-loam soil showed a higher N emission than loam soil with surface-applied slurries. This result was probably due to the higher infiltration rate of loam soil, even offsetting the effect of its high soil pH. Immediate manure incorporation into the soil was shown to reduce NH 3 emissions by 82%. Results demonstrated that a method combining dynamic chambers with a photoacoustic gas analyser was as reliable as the widely used acid traps method. Moreover, direct measurement with the gas analyser permits an increasing temporal resolution that gave a high-quality description of the NH 3 emission dynamic.

Comparison of ammonia emissions from animal wastes and chemical fertilizers after application in the soil

BackgroundApplication of different chemical fertilizers and manures is a major source of ammonia (NH3) emission. The rate and total amount of NH3 emission are related to different parameters such as climatic conditions, soil characteristics and kind of fertilizer. The current study has indicated the NH3 emission from bovine slurry, pig slurry and ammonium nitrate fertilizer after application on two soils. Two different methods were used to measure NH3 emissions: the method that use acid traps and the method that use photoacoustic infrared gas analyzer.ResultsIn both soils the rate of NH3 emission was the greatest from the denser bovine slurry, declined in the pig slurry followed by the ammonium nitrate treatment and the control. The rate of soil infiltration could be the main factor that explained these differences. For all treatments the amount of total NH3 losses reduced in the more acidic soil. For all fertilizers the highest NH3 fluxes were measured in the first hours after spreading. A good agreement observed between the two methods is used for determining of NH3 emission. The use of a multi-gas monitor (MGM) is simple and accurate and produces a continuous series of NH3 concentration in time.ConclusionThe rate and amount of NH3 emission was related to the kind of fertilizers and interaction of these treatments with soils. The results of current study confirmed that comparison of chemical fertilizers and slurry for NH3 emission is difficult because the reaction of these two groups of fertilizer is totally different.