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Emissions of carbon dioxide, methane and nitrous oxide from soil receiving urban wastewater for maize (Zea mays L.) cultivation

Fernández-Luqueño, Fabián, Reyes-Varela, Verónica, Cervantes-Santiago, Fernando, Gómez-Juárez, Concepción, Santillán-Arias, Amalia, Dendooven, Luc
Plant and soil 2010 v.331 no.1-2 pp. 203-215
Zea mays, aquifers, carbon dioxide, corn, crops, global warming, greenhouse gas emissions, irrigation, leaching, methane, mineralization, nitrates, nitrogen fertilizers, nitrous oxide, nutrients, oxidation, salt content, soil, soil amendments, urea, wastewater
We investigated how amending maize with wastewater at 120 kg N ha⁻¹ affected crop growth, soil characteristics and emissions of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) compared to plants fertilized with urea. Maize growth response was similar when fertilized with urea or wastewater despite a delayed release of nutrients upon mineralization of the organic material in the wastewater. Applying wastewater to soil significantly increased the mean CO₂ emission rate 2.4 times to 1.74 µg C kg⁻¹ soil h⁻¹ compared to the unamended soil (0.74 µg C kg⁻¹ soil h⁻¹), and cultivating maize further increased it 3.2 times (5.61 µg C kg⁻¹ soil h⁻¹). Irrigating soil with wastewater, cultivating it with maize or applying urea had no significant effect on the emission of N₂O compared to the unamended soil (1.49 × 10⁻³ µg N kg⁻¹ soil h⁻¹). Adding urea to soil did no affect the CH₄ oxidation rate (0.1 × 10⁻³ µg C kg⁻¹ soil h⁻¹), nor did cultivating maize in the urea-amended soil, but adding wastewater to soil resulted in a significant production of CH₄ (128.4 × 10⁻³ µg C kg⁻¹ soil h⁻¹). Irrigating soil with wastewater increased the global warming potential (GWP) 2.5 fold compared to the urea amended soil, while in soil cultivated with maize GWP increased 1.4 times. It was found that irrigating crops with wastewater might limit the use of N fertilizer and water from aquifers, but the amount applied should be limited because nitrate (NO ₃ ⁻ ) leaching and emissions of CO₂, N₂O and CH₄ will be substantial and the increased soil salt content will limit crop growth.