Easy steps to great soil health (or how to fix your soil and keep it fixed!)
By growing food (and eating it!) you are taking away a lot of nutrient from the soil. You need to replenish this, or over time your crops will become weaker and weaker. Since many people ask me how to improve their soil ready for growing, here’s a short, simple “how to” guide for you to use.
If you already have good soil
Assuming your soil is good, protected by mulch or groundcover to stop erosion, and you have been adding compost or manures recently, you only need to add extra organic matter, fertilizers or any enrichments to your soil if you take away any part of the plant.
What do I mean by that? This could be something like removing a tomato from a tomato bush, picking a flower from a rose bush, or pruning a tree and taking away the branches, just as examples. Imagine what would happen if there was no human intervention. These things would drop to the ground below the plant, decompose and reintegrate into the soil. If you change this cycle, you need to compensate somehow.
If you were to never take away a rose flower and when pruning the rose bush you left the prunings underneath the bush to decompose naturally (rather than taking them away from the site) your rose bush would not need any additional enrichment. I am careful to chop up my prunings as I go and drop them below the plant to save some extra nutrients. It doesn’t take much longer and saves me time and energy in the long-run.
A prime example of people removing nutrient from the soil (and in most cases not even realizing it) would be by mowing a lawn, taking away the clippings and dumping them. The lawn will get unhealthier and unhealthier over time unless you give back to it. The most simple and effective way to care for a lawn is to cut the grass with the mower set high (3/4 or maximum height) and remove the catcher to allow the grass to fall on the lawn. If you mow regularly then you will only be trimming the grass and what falls to the ground fertilises the lawn without looking messy.
(Weeding is also removing things from the soil. This is a good reason to stay on top of your weeds so that you only need to take out the odd blade of grass.)
If you need to improve your soil quality and nutrient levels
- Apply 5kg of compost or manure per square metre every year.
- Mulch your garden with an organic mulch such as straw, sugar cane or lucerne (around your veggies). You can use wood chips around trees. As well as retaining moisture and heat, mulch is extra organic matter in itself. It makes your soil progressively better over time as it breaks down.
Compost is crucial, but the benefits only last about 2 years. For great soil, you also need trace elements. For example, if you fill a pot with potting mix alone, it will last you about 1 year before you need to replace it. If you mix it 50-50 with potting mix and sand, you’ll double its life because of all the extra minerals and trace elements in the sand. (This is why no-dig beds in confined spaces tend to have problems. They should always be bottomless to access the soil minerals.)
- Your soil needs phosphorus for root growth and potassium for flower and fruit development. You can purchase potash from most hardware shops, but wood ash can be used an alternative to potash, gives you calcium too, and is far cheaper. Interestingly, to get phosphorous, some people use diluted urine and water their plant with it! Urine is considered safe as long as it comes from a healthy person, however there is much debate about using human manure or ‘hu-manure’. Although there is no doubt it is a great manure, there is still much argument about the safety issues.
- Most of the required minerals you need are available deep in the subsoil. You can draw them up by growing deep rooted (or tap-rooted) plants, sometimes known as accumulators (because they store minerals). A couple of examples of these plants are dandelion (which adds calcium to the soil) and comfrey (adding potash). Once grown, these plants can be chopped down and used as mulch, or added to compost and re-applied to the soil. They also have the added bonus of de-compacting the spoil with their roots.
However, the soil does not have an endless supply of these minerals and nutrients. Some things still need to be added over time. In nature, animals come by and graze, poop, pee and die around plants, adding the necessary nutrients and organic matter. We need to reproduce that effect.
- Some ways of replenishing minerals and micro-nutrients in the soil are by using volcanic rock dust or kelp meal. I sell kelp meal in 400g jars for $5 each. This is enough to cover 8 square metres. Larger amounts are also available by request. Please contact me if you would like to buy some. A very cost-effective way of using it is to make a compost tea by brewing the rock dust or kelp meal for a few days and then spraying it onto your plants. This is similar to the seaweed solution available commercially, but much cheaper! Alternatively, you can also mix the volcanic rock dust or kelp meal into the top 10 cm of your soil using something like this three-tined cultivator from Allsun Farms.
The world of minerals and soil health is a complex and fascinating one. If you are interested in finding out more, you might like to check out the Soil Foodweb site which has lots of interesting information on the topic.
Please let me know if you have any questions or want some help improving your soil or food garden. Happy growing!