A Simple Drainage Test

heavy claggy clay is best left alone until it dries outtion

Winter is a telling time in your soil health journey – from now through early spring you get to see your drainage in action. Those of you at the basemap phase of gathering info and learning your land – perk your ears on up! How wet are your soils?

Drainage is absolutely key for plant health. Our edible gardens must have oxygenated soil to be at peak performance. Water displaces air, you see, so if your soil is soggy, it is also airless. It’ll feel heavy, sticky, be pale or grey-ish in colour and most likely be sour smelling. Soil life thumbs it’s nose at conditions such as these, and herein lies the deep reason for the drainage – without soil life, there cannot be above ground abundance.

There are, of course, degrees of wetness. From vegie patches that are underwater for long periods – a loud cry for drainage to be resolved, to soil that’s simply a heavy clay – awaiting transformation to a delicious vegie-growing loam.

Lets begin at the beginning, with a simple drainage test. It’s great to do this when soils are at their wettest so you can understand your worst case scenario and shape your land to cope with it.

A simple drainage test

measuring the drainage test to assess how fast the water is draining

Do this test in a few different spots about your garden/ land, each in a distinctly different environment – top of slope, mid slope, bottom of slope, deep shade etc.

  • Dig a 30cm by 30cm (or there abouts) hole.
  • Fill with water and let it empty.
  • Fill with water again right to the top, as soon after the first empty as poss.
  • Pop a stick in so it sits proud of the water, and rest on the bottom of the hole. You’ll use for measuring later.  
  • After 15minutes, measure against the stick, how much water has drained away. Times this by 4, to find your hourly rate.

If your hourly rate is less than 2.5cm – you’ve got drainage issues that need sorting. Sorry about that my friend. Its not ideal, but at least you know and can now surge forward + get set up for success.

If its 2.5cm through 7.5cm, your soil gets the gold star! You are good to grow.

More than 10cm an hour is too quick and your soil will need to be built up with lots of compost and organic matter before growing vegies or fruit trees successfully.

You’ll have different drainage times in different parts of your land. Mark them all down on your basemap and where possible, use the well drained areas for food and the poorly drained/ dry areas for plants that suit those conditions. Working with is always the easiest road, and the first option to explore. Its not always possible though – there are times when we need to muck in and change things up a bit.