CO2, CH4 and N2O fluxes in an Ultisol treated with sewage sludge and cultivated with castor bean

Jonas Jacob Chiaradia,Marcio Koiti Chiba,Claudeir De Oliveira,Cristiano Alberto De Andrade,Arquimedes Lavorenti,Janaína Braga Do Carmo

doi:10.1590/s0100-06832009000600035

Abstract

Organic residue application into soil alter the emission of gases to atmosphere and CO2, CH4, N2O may contribute to increase the greenhouse effect. This experiment was carried out in a restoration area on a dystrophic Ultisol (PVAd) to quantify greenhouse gas (GHG) emissions from soil under castor bean cultivation, treated with sewage sludge (SS) or mineral fertilizer. The following treatments were tested: control without N; FertMin = mineral fertilizer; SS5 = 5 t ha-1 SS (37.5 kg ha-1 N); SS10 = 10 t ha-1 SS (75 kg ha-1 N); and SS20 = 20 t ha-1 SS (150 kg ha-1 N). The amount of sludge was based on the recommended rate of N for castor bean (75 kg ha-1), the N level of SS and the mineralization fraction of N from SS. Soil gas emission was measured for 21 days. Sewage sludge and mineral fertilizers altered the CO2, CH4 and N2O fluxes. Soil moisture had no effect on GHG emissions and the gas fluxes was statistically equivalent after the application of FertMin and of 5 t ha-1 SS. The application of the entire crop N requirement in the form of SS practically doubled the Global Warming Potential (GWP) and the C equivalent emissions in comparison with FertMin treatments.

Highlights

The scientific community has paid considerable attention to the study of the balance of greenhouse gas (GHG) emissions (Lal et al, 1995)
There was no significant correlation between GHG fluxes and soil moisture considering the five gas collections together (Table 2)
A positive correlation is generally expected between N2O and CH4 emission and soil moisture since the production of this gas is favored in anaerobic environments

Summary

Introduction

The scientific community has paid considerable attention to the study of the balance of greenhouse gas (GHG) emissions (Lal et al, 1995). Increases in GHG concentrations in the atmosphere caused by human activity have led to a greater retention of solar radiation on the planet surface, reducing atmospheric losses and resulting in an increase in temperature or global warming. In this context, agricultural activities are responsible for around 30 % of the global GHG emissions (Norse, 2003), though this value increases to 50 % when considering only developing countries, mostly located in tropical and subtropical regions (IPCC, 2007). The degradation rates of organic C may be higher (Oliveira, 2000) as a result of high temperature and moisture

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