Is Crop Residue Removal to Reduce N2O Emissions Driven by Quality or Quantity? A Field Study and Meta-Analysis

Lisa Essich,Moritz Schneider,Peteh Mehdi Nkebiwe,Reiner Ruser

doi:10.3390/agriculture10110546

Abstract

In order to quantify the reduction potential for nitrous oxide (N2O) release from arable soils through the removal of crop residues, we conducted an experiment after sugar beet (Beta vulgaris L.) harvest with three treatments: (i) ploughing of the crop residues (+CR:D), (ii) returning residues after ploughing on the surface (+CR:S), and (iii) removal of the residues and ploughing (−CR). N2O fluxes were measured over 120 days in south Germany. High positive correlations between N2O fluxes and the CO2 fluxes and soil nitrate contents suggested denitrification as the main N2O source. N2O emissions in +CR:D was higher than in +CR:S (2.39 versus 0.93 kg N2O−N ha−1 120 d−1 in +CR:D and +CR:S). Residue removal in −CR reduced the N2O emission compared to +CR:D by 95% and to +CR:S by 87%. We further conducted a meta-analysis on the effect of crop residue removal on N2O emissions, where we included 176 datasets from arable soils with mainly rain fed crops. The overall effect of residue removal showed a N2O reduction of 11%. The highest N2O reduction of 76% was calculated for the removal subgroup with C/N-ratio < 25. Neither the remaining C/N-ratio subgroups nor the grouping variables “tillage” or “residue quantity” differed within their subgroup.

Highlights

Nitrous oxide (N2 O) is one of the climate relevant trace gases, it accounts for 7.4% of the anthropogenically derived greenhouse effect [1]
We further conducted a meta-analysis on the effect of crop residue removal on N2 O
The overall result of our meta study showed that removal of crop residues lowered N2 O emissions from arable soils by approximately 11%

Summary

Introduction

Nitrous oxide (N2 O) is one of the climate relevant trace gases, it accounts for 7.4% of the anthropogenically derived greenhouse effect [1]. It has a long atmospheric lifetime of more than. Since all processes of N2 O production in soils rely on mineral N, the input of mineral or organic fertilization provides the substrates (nitrate (NO3 − ) and ammonium (NH4 + ) for these processes and fuels N2 O emission from soils (e.g., [9]). Crop residues constitute a substantial input of mainly organic bound N and, may contribute to N2 O emissions from arable soils after mineralization. Depending mainly on the chemical properties of these crops, the mineralization of the residues may affect the mineral N pool in soils. Decomposable crop residues like cauliflower can increase the N pool between 95 and 140 kg N ha−1 after harvest [11,12]

Methods

Results

Discussion

Conclusion