Visual drainage assessment: land drainage design on the farm
2015
Tuohy, P., Teagasc, Animal and Grassland Research and Innovation Centre, Cork (Ireland) | Humphreys, J., Teagasc, Animal and Grassland Research and Innovation Centre, Cork (Ireland) | Holden, N., University College Dublin (Ireland). UCD School of Biosystems Engineering | O’ Loughlin, J., Teagasc, Animal and Grassland Research and Innovation Centre, Cork (Ireland) | Reidy, B., Teagasc, Environment Research Centre, Wexford (Ireland) | Fenton, O., Teagasc, Environment Research Centre, Wexford (Ireland)
The objectives of the current study were to compare designs developed using a) the VDA methodology criterion b) optimal criterion and c) generic criterion for six dairy farms in south-west Ireland. For the VDA methodology nine indicators (water seepage, texture (sand/silt/clay %), absence or presence of pan layers, structure, porosity, consistence, stone content, colour/mottling and root development) were chosen to permit inference of soil permeability or to identify characteristics that inhibit or promote particular drainage techniques. Multiple soil test pits were excavated on each site and examined with respect to each of the indicators. A classification of each was provided in relation to depth below ground level. Discrete soil horizons in each profile were delineated in light of distinctions between indicators with increasing depth. Then, using the indicators, these horizons were classified as highly, moderately or poorly permeable. Groundwater drainage systems were prescribed if highly permeable layers, which can be exploited by field drains, were overlain by moderately permeable layers, which could facilitate percolation of surface water through the profile. Shallow drainage systems incorporating disruption techniques were prescribed where poorly permeable profiles were uncovered.
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