Effects of Biochar Addition on CO2 and N2O Emissions following Fertilizer Application to a Cultivated Grassland Soil.

Jingjing Chen,Gayoung Yoo,Hyunjin Kim,R Michael Lehman

doi:10.1371/journal.pone.0126841

Abstract

Carbon (C) sequestration potential of biochar should be considered together with emission of greenhouse gases when applied to soils. In this study, we investigated CO2 and N2O emissions following the application of rice husk biochars to cultivated grassland soils and related gas emissions tos oil C and nitrogen (N) dynamics. Treatments included biochar addition (CHAR, NO CHAR) and amendment (COMPOST, UREA, NO FERT). The biochar application rate was 0.3% by weight. The temporal pattern of CO2 emissions differed according to biochar addition and amendments. CO2 emissions from the COMPOST soils were significantly higher than those from the UREA and NO FERT soils and less CO2 emission was observed when biochar and compost were applied together during the summer. Overall N2O emission was significantly influenced by the interaction between biochar and amendments. In UREA soil, biochar addition increased N2O emission by 49% compared to the control, while in the COMPOST and NO FERT soils, biochar did not have an effect on N2O emission. Two possible mechanisms were proposed to explain the higher N2O emissions upon biochar addition to UREA soil than other soils. Labile C in the biochar may have stimulated microbial N mineralization in the C-limited soil used in our study, resulting in an increase in N2O emission. Biochar may also have provided the soil with the ability to retain mineral N, leading to increased N2O emission. The overall results imply that biochar addition can increase C sequestration when applied together with compost, and might stimulate N2O emission when applied to soil amended with urea.

Highlights

Biochar application to agricultural soils is a promising management practice that has the potential to mitigate climate change and increase soil quality [1,2,3,4,5]
Soluble C measured by hot water extractable C (HWC) from compost was hypothesized to stimulate the microbial community, resulting in higher CO2 evolution, and extractable organic C showed a high correlation with CO2 evolution (Table 3, r = 0.586ÃÃÃ).unlike the consistent trend in HWC with CO2 emission, the patterns in fluorescein diacetate (FDA) activity and MBC were not consistent with that of CO2 emission (Fig 2) and the correlations of them with CO2 emission rate were not significant
Soil C sequestration was highest in the COMPOST soil with biochar addition, consistent with the pattern of CO2 evolution

Summary

Introduction

Biochar application to agricultural soils is a promising management practice that has the potential to mitigate climate change and increase soil quality [1,2,3,4,5]. It is not yet widely used in agricultural fields as a common practice, because the effects of biochar appear to be dependent on the characteristics of the soil and the biochar [6,7,8,9]. The addition of biochar to soils can affect the physical, chemical, and biological aspects of the soil, thereby influencing C and N cycles in the soil [10,11,12,13,14]

Methods

Results

Conclusion