Nitrogen losses following application of pig slurry to arable land

Abstract

Emissions of ammonia (NH 3 ) and nitrous oxide (N 2 O), and nitrate (NO À 3 ) leaching were measured in two field experiments following application of pig slurry at rates corresponding to 83^96 kg NH 4^N ha 71 before sowing. In spring and in autumn1994, slurry was applied by four methods: trenching (T), shallow injection (S), band spreading immediately followed by harrowing (BaH) and band spreading (B). NH 3 emission measurements were made during the first week after application in both experiments. In the spring experiment N 2 O emissions and NO À 3 leaching were measured during 6 and 52 weeks after spreading respectively, and during 11 and 33 weeks after spreading in the autumn experiment. In spring, the increased N 2 O emissions (i.e. control subtracted) ranged from 0.27% (T) to 0.45% (BaH), and in the autumn study from 0.92% (T) to 1.14% (BaH), of applied NH 4^N , although showing no statistically significant differences. In order to validate the chamber measurements, a`megachamber' (21m 2 ) was used together with an infrared spectrometer.The emissions agreed well for (BaH), while (B) resulted in lower emissions compared with the smaller chambers. Emissions of NH 3 were about one order of magnitude higher. In spring, (B) gave the highest emission, reaching 19.5% of applied NH 4N , whereas (S), and (BaH) gave the lowest emissions, reaching 1.2 and 3.5% of applied NH 4^N , respectively. NH 3 emissions in autumn were 15^20% lower compared with spring. In spring the increased nitrate leaching ranged from 10.1 (T) to 24.9 kg ha 71 (BaH) and from 29.5 (B) to 37.8 kg ha 71 (T) in the autumn experiment, showing no statistically significant differences. Estimations of indirect N 2 O emissions due to ammonia deposition and nitrate leaching, suggested that the N 2 O contribution from NH 3 deposition was relatively small, while the indirect N 2 O emissions from NO À 3 leaching were of the same order of magnitude or higher than the direct N 2 O emissions.

Inclusion of the variability of diffuse pollutions in LCA for agriculture: the case of slurry application techniques

“…Emission factors for NO 3 leaching and indirect N 2 O emission. Concerning nitrate leaching, only Weslien et al (1998) studied the effect of the application technique but could not conclude on a significant effect. Thus, we took into account the effect of the application technique by assuming that nitrate leaching was a fixed ratio, noted C leached , of the total amount of applied nitrogen minus NH 3 and direct N 2 O losses.…”

“…(Hansen et al, 2003;Huijsmans et al, 2003;Dosch and Gutser, 1996;Smith et al, 2000;Misselbrook et al, 2006;Wulf et al, 2002a,b;Weslien et al, 1998;Søgaard et al, 2002;Velthof et al, 2003;Clemens et al, 1997;Vandre et al, 1997;Rodhe et al, 1995;Svensson, 1994;Sommer et al, 1996;Flessa and Beese, 2000). N 2 O fluxes measured in these experiments are considered to be ''direct emissions'' (noted N 2 O d ), i.e.…”

“…The analysis was also restricted to experiments where N losses could be expressed as a percentage of losses for band spreading, which was chosen as the reference technique, for it was the most represented in the reviewed studies. Finally, data from seven studies were used to calculate the relative loss factors (Dosch and Gutser, 1996;Smith et al, 2000;Wulf et al, 2002a,b;Weslien et al, 1998;Clemens et al, 1997;Vandre et al, 1997;Rodhe et al, 1995). They are noted k N,Tech , where N designates the emission (NH 3 or N 2 O d ) and Tech designates the application technique (BAND, BROAD, HARR, INJ) respectively.…”

“…Furthermore, there is concern that NH 3 reduction may result in greater losses via other pathways, e.g. N 2 O, NO 3 , and not necessarily lead to greater N uptake (Dosch and Gutser, 1996;Misselbrook et al, 2006;Wulf et al, 2002a,b;Weslien et al, 1998;Rodhe et al, 2006;Mkhabela et al, 2009). Most results in the literature are in agreement regarding the effect of the application technique on NH 3 , for which average emission factors have been quantified (EMEP/CORINAIR, 2007;CORPEN, 2006;Søgaard et al, 2002;Sommer and Hutchings, 2001), but studies on the effect of application technique on N 2 O are contradictory, probably because this emission is the most influenced by interacting environmental variables (Peoples et al, 2004;Velthof et al, 2003).…”

Manure management for greenhouse gas mitigation

“…Apparently, N 2 O emissions increase curvi-linearly when N application rates exceed crop N requirements (Van Groenigen et al, 2004;Cardenas et al, 2010). Similarly, proper timing of application has been shown to influence both direct and indirect N 2 O emissions after land spreading of manures (Weslien et al, 1998; Chambers et al, 2000;Thorman et al, 2007). These various observations suggest that, by optimising application method, rate and timing of manure application relative to the need of growing crops, N 2 O emissions from land spreading may be kept to a minimum.…”