If ever there was a truism, this is the truism of all truisms. I have gardened on a variety of soils including soot, gravel, clay, sand and loam. Without a doubt, loam is the best for high production tasty vegetable and fruit. The question is, can you make soot, gravel, clay and sand more like loam and can you make loam better? The answer is undoubtedly YES and the METHOD is ADD COMPOST.
Sometimes you may be able to get well rotted horse manure from a nearby stable. I was once lucky enough to get ten cubic yards of four plus year old horse dung and rotted straw. It was as black as the Ace of Spades and very crumbly. I dug it all into a cleared sandy border which I then planted up. The plants absolutely bombed away. Unfortunately I did not keep up the treatment and each year the plants became weaker as the goodness was leached away.
You can become independent of luck and good fortune and make your own compost. You can then regularly add your own "top up" to your soil, whatever type it is.
The first source of compost material is your own garden. Grass cuttings, annual weeds, prunings, autumn leaves can all be collected and recycled. Pernicious weeds should be set to one side and burned.
The second source is your kitchen and home. Vegetable waste, old flowers (cut and potted) and shredded news papers can all help.
But most important of all is METHOD. It has taken me thirty (untutored) years to discover these "secrets".
The first requirement is to control your MIX of potential compost material between Green and Brown. How many of us have piled grass clippings in a heap to be encouraged by early heat and composting activity only to end with a half rotted and layered sludge?
You need to aim for a mix of materials with about 1/5th being Green and 4/5ths Brown.
Green/ Nitrogen
Grass Cuttings
Kitchen Waste
Farm Manure
Brown/Carbon
Dead Leaves
Straw/Wood shavings
Wood Ash/ Newsprint
I save my leaves in plastic bags to feed into my compost over the following year.
Secondly you need MOISTURE. Your pile should be neither too wet nor too dry. Brown material is often dry and needs to be watered in after mixing. If you take a handful of your mix and squeeze it you want it to ball in your hand without a runoff of water and not being flaky. In rainy periods it can pay to cover your compost to stop it getting sodden
Thirdly you need AERATION. Oxygen is essential as composting is a burning process. You need to turn your heap on a regular basis to ensure this happens. It is possible to achieve temperatures as high as 70 degrees centigrade and 60 degrees should be a minimum peak norm. Having two adjacent bins makes this easier as you turn one into the other. It is also useful exercise for your heart!
Fourthly control particle SIZE. Breaking up, cutting down, shredding the potential compost is very helpful. The greater the wounding and the smaller the particle size, the greater the surface area and the quicker the rotting.
Finally you need VOLUME. The more the merrier. Given the above four steps you will find that 2 cubic yards rots better than 1, 3 cubic yards better than 2 and so on.
So get out there, get on with it and GOOD COMPOSTING.