Ammonia Volatilization from Pig Slurries in a Semiarid Agricultural Rainfed Area

Abstract

Slurries are one of the main NH3 emission sources. Nitrogen losses impact air quality, and they constrain the sustainability of farming activities. In a rainfed Mediterranean agricultural system, the aim was to quantify NH3 emissions at a time when plants do not yet cover the soil surface and according to fertilization practices. One treatment was slurry from fattening pigs (PSF) applied before cereal sowing and incorporated into the soil; two treatments were PSF or from sows (PSS) applied at the cereal tillering stage (topdressing); and two more treatments received slurries twice, before sowing and as topdressing. Ammonia emissions were quantified with semi-static chambers during 145 h (before sowing) and 576 h (at cereal tillering) after slurry application. Before sowing, tillage after slurry application controlled NH3-N emissions, but they accounted for 14% of the total NH4-N applied. At tillering, average NH3-N emissions also accounted for ca. 14% of total NH4-N applied as PSF or PSS, respectively. Slurry dry matter from 84 kg m−3 (PSS) up to 127 kg m−3 (PSF), combined with low soil moisture content (below 30% of water holding capacity) at application time, helped in NH3 emission control. Slurry applications before sowing did not enhance later NH3-N emissions at topdressing.