Spatial variability of soil solute and saturated hydraulic conductivity affected by undrained water table conditions


Akis R.

PRECISION AGRICULTURE, vol.16, no.3, pp.330-359, 2015 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 3
  • Publication Date: 2015
  • Doi Number: 10.1007/s11119-014-9379-0
  • Journal Name: PRECISION AGRICULTURE
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.330-359
  • Bursa Uludag University Affiliated: Yes

Abstract

Spatial information of soil solute and saturated hydraulic conductivity under undrained water table conditions can provide explicit knowledge to better manage soil and water than nonspatial management practices. This research was conducted to determine spatial structure of soil saturated hydraulic conductivity and salt content, as influenced by undrained water table conditions in the Amik Plain of Turkey. Using grid sampling, the General Directorate of Turkish State Hydraulic Works sampled the Amik Plain soils at approximately 1 600 locations, 254 of which were examined through undisturbed soil core sampling for land drainage evaluation. Geostatistical analyses revealed that the 30-60 and 90-120 cm soil layers had a shift in the particle size and were exposed to two different alluvial soil forming processes. Mean soil Ksat steadily decreased from 1.05 to 0.99 cm h(-1) and mean salt content increased from 0.307 to 0.335 % below the 30 to 60-cm layer. Correlation distance varied from 710 to 1 130 m for soil Ksat and 1 000-1 130 m for soil salt content for horizontal variograms. Nugget values of the models for soil Ksat ranged from 0.031 to 0.036, while the range of nugget was from 0.002 to 0.18 for soil salt content. Sill variance was the highest for Ksat (0.201) from 30 to 60 cm layer and soil salts (1.18) from 60 to 90 cm layer. Soil profile was moderately to heavily saline (1.69-7.73 dS m(-1)). For the vertical variograms, correlation distance was approximately 75 cm for soil Ksat and 136 cm for soil salt content. Results showed that an 1 130 m x 1 130 m subfield with 75 cm and/or deeper depth could be used for the layout of drain tiles. Further studies of long-term spatial variability of these properties under drained and undrained conditions with anisotropy are needed for sound surface and subsurface drainage system implementations in the Amik Plain.