Water Vapor, Temperature and Wind Profiles within Maize Canopy under in-Field Rainwater Harvesting with Wide and Narrow Runoff Strips

Weldemichael Tesfuhuney,Sue Walker,Leon Van Rensburg,Colin Everson

doi:10.3390/atmos4040428

Abstract

Micrometeorological measurements were used to evaluate heat and water vapor to describe the transpiration (Ev) and soil evaporation (Es) processes for wide and narrow runoff strips under in-field rainwater harvesting (IRWH) system. The resulting sigmoid-shaped water vapor (ea) in wide and narrow runoff strips varied in lower and upper parts of the maize canopy. In wide runoff strips, lapse conditions of ea extended from lowest measurement level (LP) to the upper middle section (MU) and inversion was apparent at the top of the canopy. The virtual potential temperature (θv) profile showed no difference in middle section, but the lower and upper portion (UP) had lower in narrow, compared to wide, strips, and LP-UP changes of 0.6 K and 1.2 K were observed, respectively. The Ev and Es within the canopy increased the ea concentration as determined by the wind order of magnitude. The ea concentration reached peak at about 1.6 kPa at a range of wind speed value of 1.4–1.8 m∙s−1 and 2.0–2.4 m∙s−1 for wide and narrow treatments, respectively. The sparse maize canopy of the wide strips could supply more drying power of the air in response to atmospheric evaporative demand compared to narrow strips. This is due to the variation in air flow in wide and narrow runoff strips that change gradients in ea for evapotranspiration processes.

Highlights

The growing interest in the application of the integrated studies of plant water use and micrometeorological parameters for alternative evaluations is a noteworthy experience in tillage management
In both runoff strip lengths (RSL) treatments, the basin leaf area ratio (BLAR) increased with the plant growth during 35–55 days after planting (DAP) and reached a plateau after 65 DAP (Figure 2)
The vegetation characteristics of plant density and BLAR have an effect on the processes of heat and water vapor within the maize canopy at different growth stages

Summary

Introduction

The growing interest in the application of the integrated studies of plant water use and micrometeorological parameters for alternative evaluations is a noteworthy experience in tillage management. Basic understanding of the micrometeorological variable profiles and their relationships within the canopy surface is an essential step to quantify and evaluate the heat and water vapor exchange processes between the atmosphere and canopy. Conservation tillage techniques, such as alternate basin and runoff area of in-field rainwater harvesting systems (IRWH) affect the momentum and heat transfer inside the canopy. Much research has been done on the soil and crop parameters within IRWH [2,3]

Methods

Results

Conclusion