Modeling nitrate transport in soils under multiple cropping systems in Aurora, Isabela, Philippines

Issue Date

12-2019

Abstract

This experimental and modeling study was conducted to compare the nitrate transport behavior of conventionally-tilled (CT) and no-till (NT) soils under multiple cropping systems in the Philippines. This study also aimed to simulate the effects of soil organic carbon on nitrate transport. Undisturbed soil columns were obtained from both production systems. Miscible displacement experiments were performed to determine the dispersivity and retardation factor. The CXTFIT model was used to optimize the values of dispersivity and retardation factor in the Convection-Dispersion Equation (CDE). Results showed that the upper layer of CT soil exhibited the highest dispersivity of 14.55 cm and lowest retardation factor of 1.19 and showed the highest peak concentration of 0.69 C0 and shortest peaking time of 134 s. On the other hand, the upper layer of NT soil showed a lower dispersivity of 3.05 cm and higher retardation factor of 2.92 and exhibited the lowest peak concentration of 0.39 C0 and a longer peaking time of 12 min. The differences in solute transport behavior may be attributed to the relatively higher organic matter content in NT soils than in CT soils and the presence of macropores and possible compaction in CT soils. Model efficiency ranging from 81-93% indicates that the CDE satisfactorily modeled the nitrate transport in these soils with a high degree of accuracy. Simulation of the effects of varying fractions of organic matter on nitrate transport for a 10-yr period showed a 19.2% decrease in peak concentration and 15.4% increase in peaking time for a projected 30% increase in organic carbon in NT soils. For CT soil, a 3% decrease in organic carbon will result to a 6.8% increase in peak concentration while the time to peak will remain unchanged.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

44

Issue

3

Page

77-86

Document Type

Article

Physical Description

illustrations, tables, graphs

Language

English

Subject

nitrate transport, modeling, soils, multiple cropping systems, Aurora, Isabela, Philippines

Identifier

https://www.cabdirect.org/cabdirect/abstract/20203113785

Digital Copy

Yes

En – AGROVOC descriptors

NICOTIANA TABACUM; ZEA MAYS; SOLANUM MELONGENA; MULTIPLE CROPPING; NITRATES; TRANSPORT; MODELS; SOILS; PHILIPPINES

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