A Newly Practice to Mitigate N2O Emission from Winter Wheat Soil by Intercropping Isatis indigotica

Hong-Sheng Wu,Lu-Ji Yu,Joshua Kendall,Ke-Ke Wang,Shun-Yi Li,Su-Yun Chen,Ji Li,Dong-Yang Liu,Xiao-Xia Shang,Xiao-Hang Fang,Ya Xu,Ya-Dong Liu,Dong-Yang Wei

doi:10.5539/jas.v8n7p7

Abstract

Greenhouse gas (GHG) emitted from agricultural field was received considerable attention worldwide, depending on differed land use and cropping system. An innovative strategy to mitigate agricultural N2O by intercropping traditional Chinese medicinal herb Isatis indigotica in winter wheat field was assessed. By exogenously applying root exudates of I. indigotica in a lab incubation study, we testify and quantify whether N2O emission was inhibited.Results demonstrated great reduction of N2O emission from winter field soil intercropping I. indigotica (NPKWR-N+P+K+wheat+I. indigotica) compared to CK (NPKW-N+P+K+wheat but no I. Indigotica) was found. N2O emission in treatment of NPKWR was decreased by 32% than that in CK during the whole winter wheat growth season, among which the best decreasing N2O emission was obtained in the stage of grain filling of winter wheat, N2O emitting from NPKWR was reduced by 60% than that in CK. The N2O emission intensity per kg of harvested wheat grain treated with I. indigotica was declined to 0.15 g N2O/kg grain from 0.24 g N2O/kg grain in CK.qPCR (quantitative fluorescent polymerase chain reaction) analysis indicated nitrifying microbial population in wheat soil was severely suppressed by I. indigotica. The number of qPCR gene copy in both soil intercropping I. indigotica and exogenously applying root exudates of I. indigotica was lower than in CK. Such trend of decreased microbial population number was in agreement with that of N2O emission from winter wheat field. This suggested that intercropping I. indigotica was a practical and simple technique to reduce N2O emission from winter wheat field which was an effective strategy for mitigating and adapting global change worldwide in agriculture.

Highlights

Nitrous oxide (N2O) is a powerful greenhouse gas which contributes to ozone depletion in the stratosphere (IPCC, 2007), and one of the most important non-CO2 greenhouse gases (GHGs) with a global warming potential 298 times higher than that of carbon dioxide (CO2) (IPCC 2001; Reay et al, 2012)
N2O emission in treatment of NPKWR was decreased by 32% than that in CK during the whole winter wheat growth season, among which the best decreasing N2O emission was obtained in the stage of grain filling of winter wheat, N2O emitting from NPKWR was reduced by 60% than that in CK
The N2O emission intensity per kg of harvested wheat grain treated with I. indigotica was declined to 0.15 g N2O/kg grain from 0.24 g N2O/kg grain in CK

Summary

Introduction

Nitrous oxide (N2O) is a powerful greenhouse gas which contributes to ozone depletion in the stratosphere (IPCC, 2007), and one of the most important non-CO2 greenhouse gases (GHGs) with a global warming potential 298 times higher than that of carbon dioxide (CO2) (IPCC 2001; Reay et al, 2012). Emissions of nitrous oxide (N2O) from agricultural soils contribute to global warming and stratospheric ozone depletion. Most soil-evolved N2O is produced by nitrification and denitrification processes (Bremner, 1997), where the soil microbes like nitrifying and denitrifying bacteria oxidize organic nitrogen compounds to release amino base and transforms into nitrous oxide (Massimiliano et al, 2014). N2O emissions from nitrification of ammonium based fertilizers can be substantial and is considered as a by-product of nitrification and may occur by denitrification of nitrite by denitrifying organisms under oxygen stress (Mosier, 1994). N2O emission flux could be seriously associated to the activity of nitrifying and denitrifying bacteria in soil

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