Methane and nitrous oxide emissions from lowland rice soils under different fallow management.Methane and nitrous oxide emissions from lowland rice soils under different fallow management.Methane and nitrous oxide emissions from lowland rice soils under different fallow management.

Date

12-2011

Degree

Bachelor of Science in Agriculture

Major Course

Major in Soil Science

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Sanchez, Pearl B.

Abstract

Methane (CH4) and nitrous oxide (N2O) emissions were simultaneously measured in lowland rice soils under different fallow management practices using a manual closed chamber method for eleven weeks covering the period from dry season (DS) – wet season (WS) fallow until transplanting of the WS rice. This field study which included four water management namely, continuous flooding (W1), soil drying for at least three weeks (W2), soil drying for at least three weeks with aerobic tillage (W3), and alternate wetting and drying (W4) and two rice straw management namely, straw removed (S0) and straw returned (S1), was set up at the International Rice Research Institute (IRRI) experimental farm station. Modifying water and rice straw management during fallow period had significantly influenced CH4 and N2O emissions. Continuous flooding of the soil (W1) resulted in the highest CH4 emission (5.41 mg m-2 h-1) but corresponded to the lowest N2O emission (1.03 mg m-2 h-1). Maintaining a dry fallow (as in W2 and W3) markedly reduced CH4 and N2O emission as compared to keeping the soil under prolonged submergence (W1). Combining dry fallow with aerobic tillage (W3) was found to have a potential in reducing emission of both gases. It should however be recognized that management options should not have any significant trade-off effect such as decreasing yield or increasing environmental impact of CH4 and N2O. Although N2O emissions were relatively lower than CH4 emissions, the Global Warming Potentials (GWP) of the two greenhouse gases should also be considered in reducing their emission to the atmosphere. Rice straw application during the fallow period enhanced CH4 emission particularly in continuously flooded soils. N2O emission was however reduced by incorporation of rice straw. Rice plants played an important role in the transfer of CH4 to the atmosphere as shown by the increased CH4 fluxes after the establishment of the WS rice crop.

Language

English

Location

UPLB College of Agriculture-Agricultural Systems Cluster

Call Number

Thesis

Document Type

Thesis

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