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Effects of contrasting catch crops on nitrogen availability and nitrous oxide emissions in an organic cropping system

Li, Xiaoxi; Petersen, Søren O.; Sørensen, Peter and Olesen, Jørgen E. (2015) Effects of contrasting catch crops on nitrogen availability and nitrous oxide emissions in an organic cropping system. Agriculture, Ecosystems & Environment , 199, 382- 393.

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Online at: http://www.sciencedirect.com/science/article/pii/S0167880914004794

Summary

Abstract Legume-based catch crops (LBCCs) may act as an important source of nitrogen (N) in organic crop rotations because of biological N fixation. However, the potential risk of high nitrous oxide (N2O) emissions needs to be taken into account when including LBCCs in crop rotations. Here, we report the results from a one-year field experiment, which investigated N availability and N2O emissions as affected by three LBCCs, i.e., red clover (CL), red clover–ryegrass mixture (GC) and winter vetch (WV), two non-LBCCs, i.e., perennial ryegrass (GR) and fodder radish (FR), and a control (CO) without catch crops. The effect of two catch crop management strategies was also tested: autumn harvest of the catch crop versus incorporation of whole-crop residues by spring ploughing. LBCCs accumulated 59–67 kg N ha−1 in their tops, significantly more than those of the non-LBCC, 32–40 kg N ha−1. Macro-roots accounted for >33% of total N in the catch crops. In accordance with this, LBCCs enhanced the performance of the succeeding unfertilised spring barley, thus obtaining a grain yield of 3.3–4.5 Mg ha−1 compared to 2.6–3.3 Mg ha−1 grain yield from non-LBCC and the fallow control treatments. Autumn harvest of catch crops, especially LBCCs, tended to reduce crop yield. The annual N2O emissions were comparable across treatments except for fodder radish, which had the highest N2O emission, and also the highest average yield-scaled N2O emission, at 499 g N2O-N Mg−1 grain. Although the sampling strategy employed in this study introduces uncertainty about the spatial and temporal variability, differences in seasonal emission patterns among catch crops were captured and harvest of catch crops in late autumn induced significantly higher emissions during winter, but lower emissions after residue incorporation in spring. In comparison with non-LBCC, LBCCs have the potential to partly replace the effect of manure application in organic cropping systems with greater crop production and less environmental footprint with respect to N2O emissions. However, harvest of the catch crops may reduce crop yield unless the harvested N is recycled as fertiliser to the crops in the rotation.


EPrint Type:Journal paper
Keywords:Legume-based catch crop; Nitrous oxide; Crop N uptake; Organic farming; Management strategy
Subjects: Crop husbandry > Production systems > Cereals, pulses and oilseeds
Soil > Nutrient turnover
Environmental aspects > Air and water emissions
Farming Systems > Farm nutrient management
Research affiliation: Denmark > Organic RDD 1 > HighCrop
Denmark > AU - Aarhus University > Faculty of Science and Technology > Department of Agroecology
H2020 or FP7 Grant Agreement Number:245216
Deposited By: Li, Xiaoxi
ID Code:28131
Deposited On:28 Jan 2015 08:32
Last Modified:02 Feb 2015 10:40
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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