Effect of water and residue management during fallow period on nitrogen dynamics in lowland rice soils.

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

A field experiment was conducted to investigate the effect of water and residue management during fallow period on NH4+-N and NO3--N dynamics in lowland rice soils. Ammonium-N and NO3--N concentrations were determined from the start of the 2011 DS-WS fallow until the establishment of WS rice crop. Experimental treatments consisted of 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 - straw removed (S0) and straw returned (S1). Water management was found to have a significant effect on concentration of soil NH4+-N and NO3--N. Highest concentration of NH4+-N (14.75 mg kg-1) was obtained from continuously flooded (W1) plots. Soil drying and aerobic tillage (W3) resulted in higher NH4+-N concentration than soil drying alone (W2). Plots that were kept dry (W2 and W3) for the entire fallow period had higher NO3--N concentrations as compared to plots that were subjected to alternate wetting and drying (W4) and continuous flooding (W1). Leaching and denitrification losses contributed to lower NO3--N concentration in W4 plots. The incorporation of rice straw (S1) which has high C/N ratio markedly reduced NH4+-N concentrations particularly in W3 plots as well as NO3--N concentration in W2 and W3 plots. Soil submergence during fallow period can lead to conservation of NH4+-N and consequently to increased N availability for plant uptake. This water management practice can also minimize leaching and denitrification losses of N and has the potential to mitigate emission of nitrous oxide which is a greenhouse gas.

Language

English

Location

UPLB Main Library Special Collections Section

Call Number

Thesis

Document Type

Thesis

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