Building a raised bed garden helps aid in water drainage and aeration. It is also beneficial to keep some good quality mulch on the surface of your garden. It is important to make sure that the mulch isn’t packed too tight. It’s also important to note that soil is like a fine wine in that it gets better with time. When using a raised bed, you will notice that the level of your soil will go down over time. This drop in your level of soil will leave room to add compost and other organic matter for your next planting season. The longer your soil is around, the better it gets, so don’t shovel out your old soil at the beginning of each planting season.
The earth upon which we live has passed through great deal of changes throughout its existence. Much of the soil that we use today was formed due to the disintegration of rocks, which, through the influence of rain, frost, and air, have gradually crumbled to pieces. The diversity of soils we depend on is due to the diverse character of the primitive rock from which they have been derived. Soil is largely made up of small particles of pulverized rock and this substance, when mixed with decaying vegetation, forms a nutrient rich soil capable of growing plants. The elements taken from the soil in its virgin condition were returned to it on the decay of the plants which it had nourished, or on the death of the animals which fed upon the plants produced.
Each year, vegetation reaches the end of its life cycle and dies. Leaves and branches fall and portions of the roots decay. This causes the surface soil to become rich in carbon and nitrogen. Due to the breakdown of organic matter, the top spoil becomes highly charged with carbonic acid, which decomposes the mineral substances contained in the soil and in this manner year by year more and more of the nitrogen collected by each generation of plants becomes available for the generation that succeeds it. I typically mix my soil with around 40% organic matter, preferably compost. When using manure, it’s important to make sure that it has sufficient time to breakdown before you add it to your garden.
In order to start with definite notions on the inherent quality of soils, let us take, as an example, some ordinary arable soil, of a clayey nature, in fair cultivable condition. Such a soil, when all roots and vegetable debris have been removed, will contain in the first nine inches of the surface soil a quantity of organic matter containing about 3,000 lbs. of nitrogen and 30,000 lbs. of carbon per acre. This nitrogenous organic matter of the soil has been derived either entirely from the decay of vegetable growth, left in the land by preceding generations of plants, or possibly, to some extent, also from past applications of organic manure. In a fertile soil the formation of nitrates is always in progress, and it is very important for gardeners to bear in mind that the nitrogenous capital of a soil, which represents to a considerable extent its fertility, depends, as a rule, on the bulk and composition of the previous plant residues.