Gaseous Emissions after Soil Application of Pellet Made from Composted Pig Slurry Solid Fraction: Effect of Application Method and Pellet Diameter

Abstract

The study aimed at determining ammonia and GHG emissions from soil fertilized with pellets made from composted pig slurry solid fraction and to evaluate the effects of pellet diameter and pellet application method on gaseous emissions. A laboratory scale experiment was carried out investigating two composts: pig slurry solid fraction compost (SSFC) and pig slurry solid fraction mixed with wood chips compost (WCC). The two composts were pelettized in two different diameters—6 and 8 mm—by means of mechanical pelletizer. In total, eight fertilized treatments plus one unfertilized control were included in the experiment. The investigated pellets were applied at the same nitrogen rate (equivalent to 200 kg ha−1) using two different methods (on soil surface and incorporated into the soil). Ammonia (NH3) emission was monitored immediately after pellet application, while nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) were measured on a 57-day incubation period. As expected, ammonia volatilization was not detected from any of the treatments investigated. At the end of the experiment, the cumulative amounts of N2O, CO2 and CH4 ranged from 2.70 mg N-N2O m−2 to 24.30 mg N-N2O m−2, from 601.89 mg C-CO2 m−2 to 1170.34 mg C-CO2 m−2 and from 1.22 mg C-CH4 m−2 to 1.31 mg C-CH4 m−2, respectively. The overall results of the investigation highlighted that application on the soil surface reduced nitrous oxide emission, while the carbon dioxide emission increased significantly with smaller pellet diameter.

Pellets from Biogas Digestates: A Substantial Source of N2O Emissions

“…Furthermore, these results are in the range reported by Pampuro et al [30,33], who found N 2 O emissions of about 30-240 g N 2 O-N ha −1 at a fertilizer level of 200 kg N ha −1 . Although the period of measurements in their work was considerably longer, most emissions were also registered during the first week after application [30,33].…”

“…Within a measuring period of one month, Cabrera et al [31,32] reported nitrous oxide (N 2 O) emissions from soils after pellet utilization between 0.2 and 3.9% of applied N. The N 2 O flux rates depended on the soil water regime and on physical characteristics of the pellets. Pampuro et al [33] measured N 2 O emissions between 0.05 and 0.12% of applied N, depending on pellet size and application method. For CH 4 and NH 3 , negligible release was reported [33].…”

“…Pampuro et al [33] measured N 2 O emissions between 0.05 and 0.12% of applied N, depending on pellet size and application method. For CH 4 and NH 3 , negligible release was reported [33].…”

Recycling Agricultural Wastes and By-products in Organic Farming: Biofertilizer Production, Yield Performance and Carbon Footprint Analysis

“…There are few data available on farm-composting in Europe, despite this technology has the advantage of saving transport costs and reducing emissions [47]. Conversely, there are different studies on composting processes for animal wastes and their GHG emissions, especially after soil application of these materials [38,57]. The amount of CO 2 emissions associated to the composting process (excluding the materials collection phase) were comparable with the values in Pergola et al [45].…”

Organic Matter Composition of Digestates Has a Stronger Influence on N2O Emissions than the Supply of Ammoniacal Nitrogen

“…Previous studies (e.g., [13,[16][17][18][19][20][21][22][23][24]) mainly focused on the effect of feedstocks in combination with management practices. However, no evaluation of the single steps within an entire processing chain could be found.…”