Soil Water Storage in Soybean Crop Measured by Polymer Tensiometers and Estimated by Agrometeorological Methods

A P Schwantes,Klaus Reichardt,Angélica Durigon,Victor Meriguetti Pinto,Durval Dourado Neto

doi:10.5539/jas.v8n7p30

A P Schwantes, Klaus Reichardt + Show 3 more

Open Access

https://doi.org/10.5539/jas.v8n7p30

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Abstract

<p>The estimation of soil water status in cropped areas continues to be challenging for soil and climate scientists. This study contributes to this issue estimating soil water storage by the water balance of Thornthwaite and Mather, Rijtema and Aboukhaled, and Dourado and de Jong van Lier, combined with crop potential evapotranspiration estimated by Penman-Monteith, to compare them with soil water storage values calculated from polymer tensiometer data of a soybean crop field experiment. The experiment was conducted in Piracicaba, SP, with tensiometers installed at 0.05, 0.15 and 0.3 m depths. Results show that the tensiometers presented good performance to measure soil water pressure head in the whole range of the available water capacity for the crop. The tensiometer presents the advantage of allowing measurements of soil water storage in layers, in contraposition to climatologic water balance calculations which assume one single layer. Rijtema and Aboukhaled presented the best correlation with the water storage estimated from tensiometer data.</p>

Highlights

The estimation of soil water storage S is of great importance for the management of agricultural crops
This study contributes to this issue estimating soil water storage by the water balance of Thornthwaite and Mather, Rijtema and Aboukhaled, and Dourado and de Jong van Lier, combined with crop potential evapotranspiration estimated by Penman-Monteith, to compare them with soil water storage values calculated from polymer tensiometer data of a soybean crop field experiment
The time course of daily averages of the matric potential head h measured by the polymer tensiometer for the whole soybean crop period at the three depths (Figure 1b) shows that the lowest values of h, of -186.2 m and -160.8 m were observed on February 9 and April 7, respectively, both below the PWP, which is a novelty in field measurements of h

Summary

Introduction

The estimation of soil water storage S (mm) is of great importance for the management of agricultural crops. Calculation of soil water storage is commonly based on soil water content θ (m3m-3) measurements, for which several laboratory and field methods are available. A novel method is the use of polymer tensiometers capable of measuring the soil water pressure head h (m) within the whole range of soil water contents prevailing in agriculturally used soils (Bakker et al, 2007; Van Der Ploeg et al, 2008). Measured values of h can be transformed to θ when the h(θ) relation (water retention curve) is known. Polymer tensiometer data have been used by Durigon et al (2011) and Durigon and de Jong van Lier (2013) polymer for laboratory observations; Durigon et al (2012) reported data from field measured values with this tensiometer

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