Mole drainage, also called undermining, is a simple and low-cost farm management practice that reduces waterlogging problems, hence improving the soil quality and structure. Mole drainage provides a solution for high rainfall areas and abandoned fields that are affected by the accumulation of water. Undermining involves deep plowing at a depth of 50-70 cm (19,6-27,6 in) that creates unlined channels, the mole drains.
How Does It Work?
Theoretically, undermining sounds like a very simple farm management practice. Still, the question remains: How is it done?
The basic principle of forming mole drains is to pull the mole plow through the soil. In this way, the riper blade, with a cylindrical foot or torpedo, creates unlined channels. In looking at plow technology, there are the two main types of mole plows:
- Basic mole plow
- Gravel mole plow
The Formation of the Typical Mole Plow
The mole plow is comprised of a steel cylindrical foot or torpedo. The foot is attached to a narrow leg (blade) and followed with the cylindrical expander. First, the narrow leg creates a narrow slot with associated soil cracks that extend the water to the mole channel. The cracks produced with the mole plow are vertical and their number depends on the soil structure. While the narrow leg creates a narrow slot, the foot and expander form the mole drain channels.
A typical mole plow consists of the following measurements:
- Foot: 7-8 cm (2,8- 3 in) in diameter
- Expander: 8-10 cm (3-4 in) in diameter
- Narrow leg: adjustable to depths up to 70 cm (27,5 in)
The Formation of the Gravel Mole Plow
A gravel plow is a special mole plow required for the creation of mole drains filled with gravel. Gravel mole drains are required for soils with lower clay content, where simple mole drains would have too short a life span. The main characteristic of the gravel plow is its hopper, which carries the gravel. The flow of gravel is managed with a hydraulically operated shutter. Additionally, an adjustable door on the gravel chute manages the height of gravel in the mole drain. The hopper may be filled with gravel by using a loading shovel or conveyor belt.
Along with the basic mole plow and gravel plow, there is also a Dual mole plow. This plow is created through the merging of the two basic mole plows.
At first sight, each plow is very different. However, they all have the one common purpose: to create mole drain channels that will reduce waterlogging problems and improve the soil porosity and structure.
After all, farmers must make the final decision of which of aforementioned plows is the most suitable for their specific field and mole drain.
Text sources: Teagasc