Evaluating soil water content data monitored at different locations in a vineyard with regard to irrigation control

Knowledge on the water content of a certain soil profile and its temporal changes due to rainfall and plant water uptake is a key issue for irrigation management. In this regard, sensors can be utilized to monitor soil water content (SWC). Due to the characteristic spatial variability of SWC, a key question is whether the measurements are representative and reliable. This study focused on the assessment of SWC and its variability in a vineyard with subsurface drip irrigation. SWC was measured in profiles down to a 50 cm depth by means of multi-sensor capacitance probes. The probes were installed at six locations along vine rows. A temporal stability analysis was performed to evaluate the representativeness and reliability of each monitoring profile with regard to irrigation control. Mean SWC was within a plausible range compared to unsaturated hydraulic parameters determined in a laboratory. The measurements revealed a considerable variability, but standard deviations were comparable to values from literature. The main finding was that some monitoring profiles (probes) proved to be more suitable to monitor SWC with respect to irrigation control than the others. Considering temporal stability provided helpful insights into the spatio-temporal variability of SWC measurements. However, not all questions that are related to the concept of temporal stability could be answered based on the given dataset.

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Temporal stability of electrical conductivity in a sandy soil

International Agrophysics ◽

10.1515/intag-2016-0005 ◽

2016 ◽

Vol 30 (3) ◽

pp. 349-357 ◽

Cited By ~ 12

Author(s):

Aura Pedrera-Parrilla ◽

Eric C. Brevik ◽

Juan V. Giráldez ◽

Karl Vanderlinden

Keyword(s):

Electrical Conductivity ◽

Spatial Variability ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Precision Agriculture ◽

Temporal Stability ◽

Principal Component ◽

Model Parameters ◽

Soil Spatial Variability

Abstract Understanding of soil spatial variability is needed to delimit areas for precision agriculture. Electromagnetic induction sensors which measure the soil apparent electrical conductivity reflect soil spatial variability. The objectives of this work were to see if a temporally stable component could be found in electrical conductivity, and to see if temporal stability information acquired from several electrical conductivity surveys could be used to better interpret the results of concurrent surveys of electrical conductivity and soil water content. The experimental work was performed in a commercial rainfed olive grove of 6.7 ha in the ‘La Manga’ catchment in SW Spain. Several soil surveys provided gravimetric soil water content and electrical conductivity data. Soil electrical conductivity values were used to spatially delimit three areas in the grove, based on the first principal component, which represented the time-stable dominant spatial electrical conductivity pattern and explained 86% of the total electrical conductivity variance. Significant differences in clay, stone and soil water contents were detected between the three areas. Relationships between electrical conductivity and soil water content were modelled with an exponential model. Parameters from the model showed a strong effect of the first principal component on the relationship between soil water content and electrical conductivity. Overall temporal stability of electrical conductivity reflects soil properties and manifests itself in spatial patterns of soil water content.

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