Once again yesterday and today I spent hours amending the soil in my garden. The health of the soil is crucial to being able to grow strong and healthy plants. This sounds like a simple concept to us these days. However, less than a century ago people thought that soil was an infinite resource that could never be depleted. It was upon this foundation that the United States agriculture policies were based. It led to the greatest ecological disaster in our history. The rich top soil that it had taken Mother Nature thousands of years to perfect was plowed up and turned into farm land. Crops were planted, grown, and harvested year after year with the belief that they could do this in perpetuity. Then drought struck the nation in the early 1930s. Nothing could grown on these lands since irrigation was also largely unknown. Dry winds picked up the depleted soil and blew it across the country, creating what became known as Black Blizzards. They would often rage for days on end. Killing humans and livestock alike by clogging lungs with the dirt. People lived, ate, and slept with the dirt of the Dust Bowl, as the affected region became known. This occurred in conjunction with the financial collapse of the world economy.
It would take years of soil conservation, including things like crop rotation, fallow fields, and soil amendment to bring back the richness of the farm lands. So you little garden or urban farm may not seem to rate on the same scale, but your soil is just as vulnerable as if you were working the north forty.
Since I live in a mobile home park, much of my urban farming is done in pots, more than thirty-five of them. Growing depletes the soil, as does watering in being able to wash away the nutrients with the pot drainage. So amending my soil is crucial. I start each year by emptying all of the pots and remixing the soil. This is because some of the plants are heavy eaters, while others are fairly light eaters. There are some plants that are also known as caterers. These plants actually deposit nutrients into the soil. Most notably this comes from peas and beans. So by remixing the soil I am basically "rotating my crops" by planting different things in different "fields." At the same time I generously mix in additional organic material in the form of manure and compost. I generally buy this locally. If you can get fertilizer direct from someone with cows, horses, or sheep, the manure needs to be aged for several months before it can be added to the soil. Raw manure it too "hot" to use right away.
I also tend to buy the cheaper amendments, which often come loaded with wood chips in them that have not been completely composted. I take the time to sift the material through a colander and save the wood chips to use as mulch on top of my pots and raised beds. There are supposed to be some more expensive brands that are less prone to wood chips, but I have yet to come up with them.
Of course, keeping your own compost heap is a great way to recycle yard waste and vegetable scraps into lovely organic material that your garden will love. Many people refer to it as "black gold." However, that is a subject for another time.
You can also purchase hay or straw to use as mulch to conserve moisture.
In arid and semi-arid climates like Colorado, moisture conservation is
also crucial. The organic matter added to the soil also helps maintain moisture around the plants roots. On some of the hotter, drier days of the year, I will need to water twice.
Once the soil is completely remixed and refreshed, it is time to start planting.