Written by Angus Stewart
Building better garden soils for free – improving your soil’s water holding capacity with home-made compost or worm castings.
What if I told you that you can create the means to grow a huge amount of highly nutritious food in your garden for next to no cost? And, while you are doing that you are also reducing your personal carbon footprint and thereby demonstrating how much more sustainable you can be in your everyday life. Creating your own compost is one of the very best things you can do for your soil. Not only are you recycling essential nutrients such as nitrogen, potassium and phosphorus from your kitchen to the soil, you are also putting carbon back into the soil where it belongs and also where it can do a power of good. Depending on the type of compost and how it is made, as a bare minimum you will be building your soil’s water and nutrient holding capacity, something that will help your garden to be far more resilient and productive. With a tiny bit more effort you can create composts that also provide your plants with all the nutrients they need as well.
It is important to make the distinction between building up your soil’s capacity for storing water and nutrients (also known as soil conditioning) versus adding nutrients and water (i.e., fertilizing). This is a big issue if you want to make your garden more productive, and equally importantly, sustainable. The trick is to use relatively high nutrient ingredients to create your compost and then making sure that it is mature and ready to use, so it is not too strong in nutrients when it is applied. Compost and worm castings are such a powerful option because they can do both things if made to a high standard.
One of the best composting methods to achieve all the above is worm farming using kitchen scraps and/or manure as the high nutrient source and adding chopped straw or cardboard to provide a carbon rich balance. Generally speaking, the nutrients within the kitchen scraps will replace in your soil what you are taking out of the soil when you harvest vegetables or cut the lawn and take away the grass clippings. The high carbon materials break down to create humus, a dark-coloured material that does the soil conditioning part of the process that boosts the water and nutrient holding capacity of your soil.
A compost heap can also provide the same sort of dual-purpose soil fertilizer and conditioner if you use the same sorts of inputs. However, with home-made compost, especially if the compost bin sits on the soil, a great deal of nutrients will leach through the pile the longer it is left. Nutrients such as nitrogen are also lost to the air as gases like ammonia. Using such composts as soon as they are ready is the key to getting maximum benefit. This can be tested by germinating some quick growing seeds (such as radishes) in a sample of what you believe to be ready to use compost.
Using compost that has been sitting in a pile for a long time is usually still beneficial from the point of view of conditioning the soil but you will likely need to add fertilizer to keep your plants growing satisfactorily. In any case, do the seed germination test as described previously to ensure the compost is not going to do any harm.
Your choice of a composting system will come down to what sort of organic materials you have available, how big your garden is, and also how much time you have to manage it. Tumbleweed provides an impressive array of composting systems and tools to suit just about any circumstance, from an indoor worm farm to a 400-litre outdoor compost bin. Have a look through their video collection to educate yourself as to the best option to grow your garden and show the world that we can live so much more sustainably.