Quantitative Relationship Between Nitrous Oxide Emissions and Nitrogen Application Rate for a Typical Intensive Vegetable Cropping System in Southeastern China

Abstract

To explore the mechanism underlying the relationship between nitrous oxide (N 2 O) emissions and different nitrogen (N) application rates, we conducted a 2-year-round field experiment comprising seven vegetable crop seasons by using static chamber-gas chromatographic techniques in a continuously cultivated vegetable cropping system in Southeastern China. The results showed that N application significantly affected the N 2 O emissions. The cumulative N 2 O emissions amounted to 16.9 AE 1.9, 25.2 AE 2.2, 30.0 AE 1.9, 36.7 AE 1.5, and 48.1 AE 2.2 kg N ha À1 y À1 for the five N application rates at 0, 370, 740, 1110, 1480 kg N ha À1 y À1 , respectively. Both linear and exponential relationship was observed between cumulative N 2 O emissions and N application rates. The emission factors ranged from 1.8 AE 0.1 to 2.3 AE 0.6% and averaged 2.0 AE 0.3%. The treatment receiving 2/3 of the conventional N fertilizer amount led to the lowest yield-scaled N 2 O emissions. Therefore, according to this study the recommended N application rate should be reduced by one-third for N 2 O mitigation while enhancing vegetable production in Southeastern China.

Dynamic responses of nitrous oxide emission and nitrogen use efficiency to nitrogen and biochar amendment in an intensified vegetable field in southeastern China

“…In our study, N application significantly increased total cumulative N 2 O emissions in nine consecutive vegetable growing periods in relation to the treatments without N (Fig. , P < 0.01), which agreed well with previous studies (IPCC, ; Zhang et al ., ). This was supported by the high soil and concentrations under high N inputs in the vegetable soils (Figs and ).…”

“…Moreover, the effects of biochar amendment on N 2 O emissions from acidic vegetable field (Wang et al ., ) seem to be distinct as compared to other croplands (Cayuela et al ., ) since the surplus N inputs probably mask the beneficial effect of biochar addition on N transformation, such as inorganic N absorption and microbial immobilization (Clough et al ., ). So far, however, as limited by trial temporal extent and crop species, N 2 O emissions and NUE from biochar‐amended agricultural ecosystems were typically estimated on a whole‐trial scale (Zhang et al ., , ; Li et al ., ), complicating mechanistic insight into the dynamic effects of N and biochar amendment in agricultural ecosystems.…”

“…() demonstrated that substantially increased yields can be achieved with reduced inputs of N fertilizer and so lower environmental costs by a set of integrated soil–crop system management practices based on a modern understanding of crop ecophysiology and soil biogeochemistry. However, a nonlinear (accelerating) relationship between N 2 O emissions and increasing N inputs was observed for a wide range of N inputs (Zhang et al ., ), thus indicating a disproportionately high risk of N 2 O emissions in vegetable production systems, where up to 1217 kg N ha −1 yr −1 may be applied (Li et al ., ). Considering both environmental issues and economic profits, reasonable N application rate and reduction should be given high priority in intensified vegetable production.…”

“…As a result, the intensified vegetable fields usually had low nitrogen use efficiency (NUE; Ju et al, 2009) and high nitrous oxide (N 2 O) emissions (Xiong et al, 2006;He et al, 2009;Jia et al, 2012;Zhang et al, 2015a) as compared to other croplands. Moreover, long-term high N input results in negative effects including soil acidification and soil nitrate accumulation on agriculture soil (Guo et al, 2010;Zhang et al, 2015b), which have a feedback on the N transformation processes in vegetable fields (Zhu et al, 2011;Cheng et al, 2015). Therefore, agricultural management strategies must be optimized to meet the joint challenges of high production and acceptable environmental consequences (Zhang et al, 2013) and thus to achieve the improvement in NUE and soil quality in intensified vegetable agriculture.…”

Impact of Different Nitrogen‐Horizontal Placements on Greenhouse Gas Exchange in an Apple Orchard

“…However, research interest has grown in increasing NUE while reducing GHG emissions. Current research on N fertilizer management practices that reduce GHG emissions from agriculture soil mostly focuses on the effects of the N fertilizer application rate, the N fertilizer source, and N fertilizer application timing . There have been few reports on the impact of different N fertilizer placement on GHG emissions .…”