Effect of dolomite and biochar addition on N2O and CO2 emissions from acidic tea field soil.

Aung Zaw Oo,Tomohito Sano,Akira Shibata,Akinori Yamamoto,Shigeto Sudo,Hiroko Akiyama,Khin Thuzar Win,Yuhei Hirono,Jorge Paz-Ferreiro

doi:10.1371/journal.pone.0192235

Abstract

A laboratory study was conducted to study the effects of liming and different biochar amendments on N2O and CO2 emissions from acidic tea field soil. The first experiment was done with three different rates of N treatment; N 300 (300 kg N ha-1), N 600 (600 kg N ha-1) and N 900 (900 kg N ha-1) and four different rates of bamboo biochar amendment; 0%, 0.5%, 1% and 2% biochar. The second experiment was done with three different biochars at a rate of 2% (rice husk, sawdust, and bamboo) and a control and lime treatment (dolomite) and control at two moisture levels (50% and 90% water filled pore space (WFPS)). The results showed that dolomite and biochar amendment significantly increased soil pH. However, only biochar amendment showed a significant increase in total carbon (C), C/N (the ratio of total carbon and total nitrogen), and C/IN ratio (the ratio of total carbon and inorganic nitrogen) at the end of incubation. Reduction in soil NO3--N concentration was observed under different biochar amendments. Bamboo biochar with the rates of 0.5, 1 and 2% reduced cumulative N2O emission by 38%, 48% and 61%, respectively, compare to the control soil in experiment 1. Dolomite and biochar, either alone or combined significantly reduced cumulative N2O emission by 4.6% to 32.7% in experiment 2. Reduction in N2O production under biochar amendment was due to increases in soil pH and decreases in the magnitude of mineral-N in soil. Although, both dolomite and biochar increased cumulative CO2 emission, only biochar amendment had a significant effect. The present study suggests that application of dolomite and biochar to acidic tea field soil can mitigate N2O emissions.

Highlights

Nitrous oxide (N2O) is a potent greenhouse gas and the single most important ozone depleting compound currently emitted to the atmosphere [1]
Significant differences in soil pH was observed under biochar amendment, only 0.09 units pH increased was observed in soil treated with N 300 and 0.07 units treated with 600 kg (N 600) and N 900
The NO3--N concentration decreased with increasing rate of biochar amendment by 7.1%, 11.5% and 15.9% averaged over all N treatments

Summary

Introduction

Nitrous oxide (N2O) is a potent greenhouse gas and the single most important ozone depleting compound currently emitted to the atmosphere [1]. Reducing agricultural N2O emissions would reduce the GHG induced radiative forcing [4] and improve the stability of the stratospheric ozone layer [1]. Tea is a leaf-harvested crop, and nitrogen is the most important nutrient for improving the yield and quality of tea leaves [5]. To meet these criteria, tea fields in Japan tend to receive higher rates of N fertilizer than other crops, sometimes exceeding 1,000 kg N ha-1 year-1 [6], resulting in problems such acidification of soil and high rates of N2O emissions [5]. Since tea fields account for 16% of the total N2O emissions from agricultural soils in Japan [8], reducing N2O emissions from tea fields will greatly reduce N2O emission from agriculture in Japan

Methods

Results

Discussion

Conclusion