Sub-soil drainage, an overlooked agricultural technique
08 June 2013
TONY FLYNN
LOOK AS I MAY, I find no mention of sub soil drainage in the websites of development agencies and graduates inform me that it is not covered in Papua New Guinea tertiary institutes.
My 45 hectares of ex-lake bed farmland here in Wau has some 300mm of soil over clay which is about as permeable as a roofing sheet.
In all of Papua New Guinea there are no artisans capable of producing burnt clay bricks or drainage tiles to enable a sub soiling project.
“Agricultural drainage systems usually increase crop yields on poorly drained soils by providing a better environment for plants to grow, especially in wet years,” writes US Professor Gary Sands.
“The systems generally help improve field conditions for timely tillage, planting and harvesting. These two factors have improved agricultural production on nearly one-fifth of US soils."
If this is good enough for developed countries, why not in the Third World?
I know that there are villagers in Kaintiba who die from hunger caused by waterlogged gardens in periods of extended rainfall.
Reports from Kabwum say that waterlogging is causing problems there.
Unfortunately this type of drainage only works with permanent farms.
Our PNG government is good at giving away five million hectares to foreigners but cannot see its way clear to organize small 2-5 hectare farms for its own citizens 38 years after Independence.
Indeed, I have not come across such technique being used on the farms or discussed in any agricultural school in PNG. Many productive soils need to be protected and efficiently used. This is a useful drainage technique for small farms in growing annuals .
Posted by: John Palolen | 11 June 2013 at 01:48 PM
Errol, I talked to a senior expat soil scientist and made three points:
1 Deep drains lead to erosion.
2 They lead to extra labour costs to clean them.
3 Subsoil drains allow more efficient use of land.
Labour costs almost doubled in the last wage increase. This alone should make the adoption of labour saving technology attractive. He showed no interest.
I can only think he believes that agricultural labour is so cheap that improved technologies are not required.
Posted by: Tony Flynn | 08 June 2013 at 07:59 PM
The Murrumbidgee irrigation area and other irrigation areas in Australia would not survive without sub soil drainage. It is a common agricultural practice.
In PNG I have seen deep trenches in gardens for drainage. This works but also aids soil erosion.
The concept of sub soil drainage should be a subject of discussion in agricultural schools in PNG.
Posted by: Errol Gunn | 08 June 2013 at 10:14 AM