The rules on amending the soil have changed over the years.
Part of the change relates to the fact that good soil is hard to come by in newly developed subdivisions where enormous earth moving equipment is used to level trees and land.
This equipment not only removes the valuable topsoil, it also compacts subsoil and kills the living organisms that make up a healthy soil system. The less we disturb the soil the better, but for many the reality is bleak so some sort of amendment is necessary in order to improve tilth, drainage and nutrition.
Typically, we want to avoid amending the soil for trees and other woody plants; we don’t want to create a false environment where once the root systems grow beyond their original amended hole they can’t quite compete.
The key here is to dig a large hole so the soil is loosened allowing for easier root growth, drainage and oxygen penetration.
When it comes to annual beds and vegetable gardens it is an entirely different story. Amend all you want to the great benefit of annual plants that give their best in one season, whether it is bloom or fruit.
The primary concerns when assessing soil condition should include texture, structure, fertility, pH, drainage, erosion probability and how wet the soil is at the time of working and planting.
Fertility, for example, may be high, but if the pH is too alkaline or too acid for certain plants then certain nutrients become bound to the soil and are unavailable to the plant.
For a vegetable garden we want to maintain a neutral to slightly acid pH (6-6.5) to ensure maximum availability of nutrients to the plants.
Drainage and erosion, of course, relate directly to soil structure and texture.
The greater the tilth the better drainage; the better the drainage, the greater chance your garden will be ready to work in the spring.
Do not work your soil if it is soggy-wet, you are effectively compacting the soil if you do so.
Nutrient rich soil that is alive with microorganism is all the fertilizer you need for your vegetable plants.
Treat the soil well and you will be rewarded. Composted organic matter and composted manure (from a vegetarian animal: cow, horse, chicken, etc.) should be staples added to vegetable gardens twice a season. You can supplement with fish emulsion, kelp, seed meals and other natural sources of micro and macronutrients during critical times for crops but consider the health of your soil as primary to plant health.
Use 2-4 inches of compost when preparing and planting the garden; add another inch or two as a side dressing or mulch halfway through the season.
This is one case where more is better, no need to worry about using too much compost because it is an excellent soil conditioner, fertilizer and mulch.
I think the most important part of its usefulness is how it is nature’s slow-release fertilizer.
We have all become so accustomed to using synthetic liquid and granular fertilizers we have forgotten how to feed the soil naturally.
Synthetic fertilizer is good practice for ornamentals in containers, but the vegetable garden can do with more permanent improvement.
Synthetic fertilizers high in nitrogen are known to kill earthworms, microorganisms and ultimately drain the soil of fertility. Too much nitrogen fertilizer can even reduce the amount of vitamin C in some green vegetables according to the USDA.
As nature’s slow-release fertilizer, compost feeds microorganisms in the soil as it feeds our plants. No burst of energy, just a constant source of nutrients for the soil and for the plant without disturbing other parts of the ecosystem.