How To Create Healthy, Fertile Soil

In your organic garden it is very important to have fertile soil to create the best possible growing conditions for healthy, tasty vegetables and great yields. Soil fertility is best when essential nutrients are available to your plants and when the humus levels are at 5% or more.

Humus is the stable decomposed remains of plant tissue. It is a product of composted vegetable matter, or if you like, your mature compost. The cellulose in humus acts like

a sponge and holds moisture in the garden soil, making it available for growing plants, creating better drought tolerance. It has a water-holding capacity of up to five times its own weight.

It helps prevent water-soluble nutrients from being leached from

the soil via watering or rainfall by binding itself to the nutrients, but at the same time making them available to plant roots.

It helps bring about a loose, crumbly structure in heavy clay soils, while allowing free drainage during excessive rain; and provides cohesion in sandy soils.

So you see that humus is really the best way to overcome whatever problems you may have with your soil. Humus is also necessary to maintain healthy levels of essential soil organisms, fungi, bacteria and earthworms.

Making your own compost is an integral part of organic gardening.

 

Sandy soils

Sandy soil has large, freely draining particles. Any nutrients present are quickly leached by watering and / or rainfall.

If you have sandy soil you will need to apply to the surface, or dig in, large amounts of humus to retain water and provide nutrients. All organic matter breaks down over time, so sandy soils will benefit from a large amount of compost, which will need replacing regularly.

Always mulch well to reduce evaporation. Did you know that a 20cm (4 inch) layer of mulch can reduce evaporation by up to 70%?

Sandy soils can become non-wetting soils, where any amount of irrigation will just run across the surface. If your soil is like this, you will need to add copious amounts of organic matter to correct this nasty problem.

Some organic soil wetting agents include vegetable soaps, plant and seaweed extracts and microbial wetting agents. When you’re buying a wetting agent, just check to see if it’s certified organic. Then you know that it’s safe to use on your garden.

 

Clay soils

Clay soils are made up of tiny particles. It will hold water well, but the spaces between the soil particles are so small, there’s little room for air, or space for water to escape. Clay soils tend to become boggy in wet weather, and dry out and crack in hot, dry weather. Clay soils often have high reserves of mineral elements, but roots are unable to mine them from the clay.

Gypsum is a well known clay breaker. Dig it into the soil for good effect. The clay will become friable and can then be made more workable by incorporating river sand and organic matter. You may want to construct raised beds to increase drainage.

 

Testing Your Soil

So what kind of soil do you have? Most soils are somewhere between the two extreme soil conditions above. A very simple, but effective way to test your soil is to use a glass jar. Add a handful of your soil, fill it with water and shake vigorously. Let it stand untouched for a few hours (or overnight) until all the suspended materials have settled. You will see quite distinct layers.

Course sand will be the lowest layer, then finer sands, silts, clays and lastly organic matter.

A good garden loam will have approximate equal proportions of clay, sands and silt, with a good percentage of humus or organic matter.

These jars are samples from my own yard. The sample on the left is from my vegetable plot, which has been built up with compost and organic matter. The layers are not so clear in the photo, but it is very good soil.

The sample on the right is the soil I started with here on this property – taken from an area where I haven’t made any improvements. You can clearly see the bottom layer is very distinct and is mostly course sand, the rest being a small amount of clay and organic material. This is very difficult soil to work with as any watering just runs over the surface, without penetrating the soil.

If you have this type of soil I would recommend creating raised beds and bringing in loam with a generous top layer of compost. That way you’ll have excellent drainage and fertile soil for your plants to thrive in.

 

Soil pH

The acidity or alkalinity of your soil is also an important consideration. The measuring of the acid / alkaline balance is called pH. The scale is from 1, being very acid, to 14, being very alkaline. 7 on the pH scale is considered neutral.

Most vegetables need a neutral to slightly acidic soil for optimum growth, with a pH of about 6.5. If your soil pH isn’t right, then some nutrients will be unavailable to your plants. It really is a good idea to find out the pH of your soil so that you can correct it if necessary.

You can buy a pH testing kit at your local nursery or hardware store – they are cheap, very easy to use and can be used over and over. They come with full instructions. You will need to test your vegetable patch every year. Plus it will come in handy when you include other food plants with specific pH preferences.

If you discover that your soil is particularly acidic, say around pH5, you can add lime or dolomite (lime and magnesium) to bring up the pH. If your soil is too alkaline, around pH8 or higher, you will need to add iron sulphate or flowers of sulphur. You can also reduce alkalinity by adding leaf-mould, peatmoss or old pine needles.

If you’re starting with bare soil just follow the instructions on the whatever product you are using. But if there are already plants growing where you need to amend your soil, you will need to do it in stages so that you don’t shock the existing plants.

The really great news is that no matter what kind of soil you are starting with, the continued addition of humus and other organic materials will correct nearly ever problem kind of soil. Even your pH levels will balance out over time.

 

Preparing Your Soil Before Planting

Organic fertilizer and soil conditioning materials can take a while to be effective. To make sure they are doing the job you want them to, they should be mixed into the soil at least three weeks ahead of planting.

Another thing to be aware of, is that any organic materials that are not properly composted can actually absorb nutrients from the soil as they continue to break down, robbing your young seedlings of precious and essential nutrients. This can sometimes result in nutrient deficiency and possible soil-borne diseases problems such as “damping-off” of your young seedlings.

So make sure your compost is mature before adding it to your garden. You can do this by grabbing a handful (yes, it’s wonderful).

If it feels quite hot in your closed hand it needs to be turned over and allowed a little longer to “cook”. Mature compost won’t be hot in your hand. It will smell sweet and earthy and have a fairly even texture.