Spatial and temporal patterns of soil water content in an agroecological production system

Ole Otto Wendroth,Daniel Fonseca De Carvalho,Marcos Bacis Ceddia,Hugo Hermsdorff Das Neves,Maria Gabriela Ferreira Da Mata,José Guilherme Marinho Guerra

doi:10.1590/1678-992x-2016-0213

Abstract

Spatial and temporal patterns of soil water content (SWC) can not only improve the understanding of soil water processes but also the water management in the field. The spatial distribution of SWC depends on the spatial variability of soil attributes, vegetation and landscape features. The aim of this study was to evaluate: i) the spatial and temporal variability pattern in an agroecological system; ii) understand the factors affecting the spatial variations of SWC; iii) determine if wet and dry zones conserve their spatial position; iv) evaluate the possibility of using this information to reduce the number of SWC measurements. The experiment was carried out in an area of 2,502 m2, where a regular grid with spacing of 10 m was laid out. At each point, time domain reflectometer sensors were installed at depths of 0.05, 0.15, 0.30 m to monitor the SWC for 18 days in 2014 (Jan, Feb and Mar) and 9 days in 2014/2015 (Dec and Jan). The SWC, at the three soil depths, followed a similar and systematic pattern, being highest in the deepest layers, and exhibited temporal stability. The correlation between SWC and clay content varied both with the depth and the magnitude of SWC. During the wet season it is necessary to intensify the sampling density to estimate the SWC, while during the dry season the Spearman rank correlation remained high indicating the need for a small sampling effort only. The driest zones tend to conserve their spatial position more for a longer period than compared to wettest zones.

Highlights

Soil water content (SWC) is the main limiting factor for plant growth (Letey, 1985) and knowledge about the spatial and temporal variability of soil water in the field is critical to the improvement of water management
The aim of this study was to evaluate: i) the spatial and temporal variability pattern in an agroecological system; ii) understand the factors affecting the spatial variations of soil water content (SWC); iii) determine if wet and dry zones conserve their spatial position; iv) evaluate the possibility of using this information to reduce the number of SWC measurements
Considering the importance of the spatial and temporal variability on the soil water, the aims of this study were: i) improve the understanding about the factors affecting the spatial variability of SWC; ii) evaluate the spatial variability of SWC persisting over time; iii) evaluate the possibility of using the spatial and temporal stability of SWC to both reduce the number of SWC sensors in the field and increase the measurement intervals

Summary

Introduction

Soil water content (SWC) is the main limiting factor for plant growth (Letey, 1985) and knowledge about the spatial and temporal variability of soil water in the field is critical to the improvement of water management. Based on temporal stability it would be possible to reduce the number and the frequency of observations in time to monitor the SWC (Vachaud et al, 1985) This methodology is used so as to understand soil water dynamics in the field (Kachanoski and Jong, 1988; Pachepsky et al, 2005; Wang et al, 2013). Measuring SWC at these points would allow for estimating the mean of the SWC and the magnitude of its variance Sensors located at these strategic points could be used for managing the soil water (Van Pelt and Wierenga, 2001; Starr, 2005)

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