Nitrous oxide emission from intensified maize-rice and rice-mungbean cropping systems

Date

4-2014

Degree

Bachelor of Science in Agriculture

Major Course

Major in Soil Science

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Pearl B. Sanchez

Abstract

Nitrous oxide (N2O) emissions and soil nitrate concentrations were measured on upland soils under different cropping systems. The two aerobic cropping systems observed were Maize-Rice and Rice-Mungbean on Block UD3 plots located at the Experimental Station of the International Rice Research Institute from May 2012 (dry season) to October 2012 (wet season). The cropping system, its environment and management, showed significant effect on N2O emission from Maize-Rice and Rice-Mungbean cropping systems. In the Maize-Rice cropping system, nitrogen fertilization of previous maize crop and occurrence of heavy rainfall significantly increased N2O emission to 503.3 μg N2O/m2-h. The nitrate that accumulated from the previous cropping, given favorable conditions was subject to N2O emission unless it is utilized by another crop. Basal application of 16-16-16 prior to sowing of wet season rice further increased N2O emission to 826.1 μg N2O/m2-h. The timing of planting of the wet season crops had implications on N2O emission. Earlier planting of wet season mungbean in the Rice-Mungbean cropping system along with low rate of N fertilization resulted in lower N2O emission (86.5 μg N2O/m2-h) and insignificant changes in N2O emission throughout the study.Soil moisture also had a critical effect on N2O emission since it was shown that alternate wetting and drying increased the emission of N2O. Peaks were subsequently observed on Maize-Rice plots after periods of strong rainfall. Prolonged soil submergence resulted in lower N2O emission, however, nitrogen losses may still have occurred in the form of nitrogen (N2) gas. Rice-Mungbean cropping system proved to be more beneficial due to the presence of a legume crop. Mungbean, with low nitrogen requirement, is able to fix atmospheric nitrogen and can be rotated with rice, which has a higher nitrogen requirement, under aerobic soil conditions. The benefits from this cropping system include the utilization of residual nitrogen from previous cropping, forgoing additional nitrogen application and more importantly, reduction of N2O emission.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2013 A3 /A24

Document Type

Thesis

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