Dig for Victory: Soil II

soil ph test

Dig for Victory is a primer for the kitchen gardener. Every few weeks or so we’ll publish a new post to build on our technical knowledge of gardening. You’re under the capable hand of Steve here. Let me know what you think and if you’d like anything in particular to be covered. Enjoy!

Part two
There’s no such thing as good or bad soil in the natural world, yet it makes a world of difference for us humans when we cultivate the land for food. Thus it pays to be observant. You want to ensure that your potential growing area receives at least six hours sunlight—that’s a given. Yet you should also note the type of plants already growing there; they impart information on soil acidity, the presence of—and the potential for—ground moisture and weeds. They can also indicate what has been previously grown there and what type of nutrients may be present in the soil.

If the area is full of annual weeds, there’s a good chance the soil is full of weed seeds and a lot of your time will be spent hand weeding. So having a strategic weed plan (even if it’s only in your head) is very important—more on this later. The presence of sedges and other aquatic species indicate that if the soil is not wet and boggy now, then it could become so after rain, and drainage may be a problem. It’s most likely though, that you‘ll have some type of grass in a highly disturbed urban or peri–urban environment with two common issues: compaction and pH.

Compaction
Soil should feel soft and springy. Compacted soil—where air pockets and soft organic elements in the soil are pushed together—makes root growth difficult. It may be caused by foot or vehicle traffic, or walking on soil while it‘s wet. Thus my rule is, if you’re going to grow on it: don’t walk on it, park the car on it, allow the kids to play on it or use it as a storage area!

To test for soil compaction, push a small, sturdy stick into the soil in a couple of places. If it penetrates with little resistance—great! If the stick has trouble breaking the surface, your soil is compacted and will need work.

A compacted soil needs to be broken up and something needs to be incorporated into it to prevent future compaction. This is where the different types of soils come into play; clay is inherently sticky and tends to compact easier, in contrast to sandy soil with fewer problems.

The solution is nearly always compost. Well-made and liberal applications of compost either placed directly onto the soil or incorporated through non-inversion tillage (i.e. forked through the soil) can have a dramatic impact on compaction and worm populations. These processes mimic nature, albeit in an accelerated fashion. The former replicates organic matter dying and falling onto a forest floor and the latter mimics the process that worms and other decomposers play in the production of soil. This will also improve drainage in clay soils to no end. In sandy soils, adding compost is essential to slow the leaching of nutrients, hold water and reduce the likelihood of erosion.

For clay soils, the application of gypsum is another option.

pH
A pH test is an important preliminary step as it relates to plant growth. It measures the acidity or alkalinity of soils, and is very important for how plants take up nutrients and use them, bacterial action in the soil and fungal growth. The pH ranges from 1 (extremely acid) to 14 (extremely alkaline). Garden plants prefer a range of 6.0 – 7.5.

You can buy inexpensive test kits from most garden centres; just follow the instructions. What you intend to grow will influence the desired result. For example, blueberries demand acid soils, 4.5 – 5.5 so they will need high levels of organic matter (which tend to be acidic). Pine mould (the mulch underneath pine trees) is a good way to prepare soils for blueberries.

To correct for acid soil, dolomite or gardener’s lime should be applied at a recommended rate for the improvement you require. To improve alkaline soil, you can apply sulphur.

Generally speaking, Australian soils are acidic and will benefit from the addition of some lime or dolomite.

Just remember to use gardener’s lime, not cement lime!

cc pic by Team Tanenbaum

In refusal of cheap fast food at university, Steve Fleischmann began growing vegetables. He is pragmatically organic with 20 years’ experience in Australia and overseas. Once a bush regenerator and project manager for youth environmental projects, he now works at Mamre Farm in Western Sydney with refugees, people with a disability and youths. Building soils, encouraging biodiversity and growing heritage varieties allows Steve the opportunity to feed his family, develop small scale enterprises and pass on knowledge and skills. Follow Mamre Farm on Facebook.

Dig for Victory
1. Soil I: soil type, improving soil and soil health test
2. Soil II: soil compaction and ph test
3. Soil III: Nutrients
4. Plants and naming
5. Adapting to a new climate
6. Dig for Victory: Planning for the win

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