N2O emission from soil following combined application of fertiliser-N and ground weed residues

Abstract

Emissions of N 2 O and CO 2 were measured following combined applications of 15 N-labelled fertiliser (100 μg N g −1 ; 10 atom % excess 15 N) and organic olive crop weed residues (Avena sativa, Ononis viscosa, Ridolfia segetum and Olea europea; 100 μg N g −1 ) to a silt loam soil under controlled environment conditions. The objective was to determine the effect of varying combinations of inorganic fertiliser and plant residues on these emissions and soil mineral N dynamics. Emissions were generally increased following application of residues alone, with 23 ng N 2 O-N g −1 soil (2 ng N 2 O-N g −1 soil mg −1 biomass) and 389 μg CO 2 -C g −1 soil (39 μg CO 2 -C g −1 soil mg −1 biomass) emitted over 28 days after addition of the Ridolfia residues in the absence of fertiliser-N. N 2 O emissions from these residue-only treatments were strongly negatively correlated with residue lignin content (r = −0.91; P < 0.05), total carbon content (r=−0.90; P<0.05) and (lignin + polyphenol)-to-N ratio (r=−0.70; P<0.1). However, changes in the net input of these compounds through application of 25:75, 50:50 and 75:25 proportional mixtures of Avena and Ononis residues had no effect on emissions compared to their single (0:100 or 100:0) applications. Addition of fertiliser-N increased emissions (by up to 30 ng N 2 O-N g −1 28 days −1 ; 123%), particularly from the low residue-N treatments (Avena and Ridolfia) where a greater quantity of biomass was applied, resulting in emissions above that of the sum from the unfertilised residue and fertilised control treatments. In contrast, fertiliser application had no impact on emissions from the Olea treatment with the highest polyphenol (2%) and lignin (11%) contents due to strong immobilisation of soil N, and the 15 N-N 2 O data indicated that residue quality had no effect on the denitrification of applied fertiliser-N. Such apparent inconsistencies mean that before the potential for manipulating N input (organic + inorganic) to lower gaseous N losses can be realised, first the nature and extent of interactions between the different N sources and any interactions with other compounds released from the residues need to be better understood.

Does incorporation of cowpea-maize residue mixes influence nitrous oxide emission and mineral nitrogen release in a tropical luvisol?

“…N 2 O emission from soils amended with crop residue has often been reported to be influenced by initial N content, C:N ratio, lignin content, polyphenol content, and lignin:N ratio, polyphenol:N ratio or (lignin ? polyphenol):N ratio (Constantinides and Fownes 1994;Garcia-Ruiz and Baggs 2007;Palm and Rowland 1997). In this experiment, however, the lignin and extractable polyphenol contents of the cowpea and maize residues were lower than the 15% lignin and 3-4% polyphenol threshold levels proposed in the Organic Resources Database (Palm et al 2001) and by other authors (Constantinides and Fownes 1994;Palm et al 2002;Palm and Rowland 1997) to retard residue N mineralization.…”

“…Gas sampling and analysis were done following the procedures described in and Garcia-Ruiz and Baggs (2007). Gas samples for N 2 O and CO 2 analysis were collected from the Kilner jar headspaces on day 0, (6 h after addition of fertiliser and residues), and on days 1, 2, 3, 5, 7, 10, 14 and 30 after addition.…”

Influence of different manuring systems with and without biogas digestion on soil organic matter and nitrogen inputs, flows and budgets in organic cropping systems

“…Gaseous N losses are not only important in terms of the absolute N losses from the Nutr Cycl Agroecosyst (2009) 84:179-202 193 cropping system, compared for example to the total productive N losses (Table 6), but also, due to ammonia volatilization and denitrification, the most limiting fraction of N in organic farming systems, the readily available inorganic-N, was lost. Any gaseous N loss has a double negative effect: it reduces the absolute amounts of available N, and it reduces simultaneously the N availability of the organic N remaining in the manure, as the N availability in organic manures also depends on their total N concentration (Kyvsgaard et al 2000;Garcia-Ruiz and Baggs 2007). For example, in FYM 380 kg N were lost due to gaseous N losses.…”

An assessment of factors controlling N2O and CO2 emissions from crop residues using different measurement approaches

“…With regard to the crop residue characteristics, the most important property is its C/N ratio that determines organic N dynamics in the soil (Heal et al 1997;Baggs et al 2003;Al-Kaisi and Yin 2005;Garcia-Ruiz and Baggs 2007). In particular, it has been shown that higher N 2 O emissions occur from soil after the incorporation of residues with low C/N ratio, such as legumes, rather than after cereal straw as a result of mineralization processes (Baggs et al 2000;Huang et al 2004;Raiesi 2006).…”