Slurry 15NH4-N recovery in herbage and soil: effects of application method and timing

Abstract

The effects of slurry application method and weather conditions after application on ammonia volatilisation are well documented, however, the effect on slurry N recovery in herbage is less evident due to large variability of results. The objective of this field experiment was to determine the recovery of cattle slurry NH 4 -N in herbage and soil in the year of application as affected by application method (trailing shoe versus broadcast) and season of application (spring versus summer), using 15 N as a tracer. In 2007 and 2008, 15 N enriched slurry was applied on grassland plots. N recovery in herbage and soil during the year of application was determined. Both spring and trailing shoe application resulted in significantly higher herbage DM yields, N uptake and an increased recovery of 15 NH 4 -N in herbage. Additionally, the recovery of slurry 15 NH 4 -N in the soil at the end of the growing season was increased. Spring and trailing shoe application reduced the losses of slurry 15 NH 4 -N by on average 14 and 18 percentage points, respectively, which corresponded closely to ammonia volatilisation as predicted by the ALFAM model. It was concluded that slurry N recovery in temperate pasture systems can be increased by adjusting the slurry application method or timing.

The fate of slurry-N fractions in herbage and soil during two growing seasons following application

“…After 6 and 62 weeks, <1% of slurry 15 N was recovered in the inorganic soil N pool (KCl-extract), which is in line with previous work (Hoekstra et al 2010;Morvan et al 1997) and is due to the rapid uptake into herbage and immobilisation of mineral N in soil.…”

“…As expected, the 15 NR in herbage 6 weeks after application was highest for the urine fraction (18.3%) followed by the FR (12.3%) and FS (2.7%), reflecting the plant availability of the three slurry fractions. The 18% recovery from the urine fraction is similar to recoveries reported for broadcast summer applied slurry by Hoekstra et al (2010) using slurry of which the NH 4 -N pool was labelled with 15 N. There was a large difference between the recovery of the slow and the rapid faecal fractions, confirming that the two N pools had distinctly different N availabilities.…”

“…Even though there have been many studies using 15 N labelling to trace the fate of manure N in arable systems (Dittert et al 1998), we have not been able to identify any studies on grassland, with the exception of studies that focussed on the fate of 15 N labelled NH 4 -N Dittert et al 2001;Hoekstra et al 2010;Morvan et al 1997). Therefore, the objective of the present experiment was to trace the fate of three slurry-N fractions (urine-N, rapid faecal-N and slow faecal-N) in herbage and multiple soil layers in the first 62 weeks after a single slurry application on a permanent grass sward, using 15 N labelling techniques.…”

Recovery of 15N-labeled urea and soil nitrogen dynamics as affected by irrigation management and nitrogen application rate in a double rice cropping system

“…The percentage of plant N uptake derived from the applied N (% 15 N dfan ) (Asagi and Ueno 2009), total N uptake, N apparent recovery (NAR) and 15 N-labeled N balance (Hoekstra et al 2010) were analyzed using the following equations: …”

Volatilização de amônia e emissão de óxido nitroso após aplicação de dejetos líquidos de suínos em solo cultivado com milho

“…Para reduzir tais perdas, é importante identifi car a intensidade com que elas ocorrem e também, como variam em função do método, a época e a taxa de aplicação, da composição dos dejetos, do tipo do solo e das condições ambientais (HOEKSTRA et al, 2010). Embora as emissões de NH 3 e de N 2 O já tenham sido avaliadas após a aplicação dos DLS no Sul do Brasil (BASSO et al, 2004;GIACOMINI et al, 2006), o efeito da aplicação dos DLS na presença ou na ausência de resíduos culturais na superfície do solo sobre tais emissões ainda não é bem conhecido.…”