As soil breaks down over time the race of bacteria must be noticed – the beneficial nitrogen-fixing type that live on the roots of legumes such as peas and beans. If you pull up a flourishing pea or bean plant, you will notice a number of little nodules or lumps on the roots. Here the bacteria are at work making more nitrogen than they need for themselves, and on this surplus nitrogen the plant depends for supplies.
Accordingly, if peas or beans are new to your garden, the seed should first be inoculated with a culture of the proper bacteria. This is a simple operation, since the inoculant can be bought as a black powder for a few cents and merely needs to be shaken through the seeds before they are sown.
Obviously, the soil is a highly complex body. Nature, which is not pressed for time, may have taken a million years making it fertile with plant food materials. Man comes along and quickly robs this fertility by intensive cultivation, so that it must be rebuilt yearly by the application of organic material such as manure and compost, supplemented by inorganic fertilizers which supply, in readily accessible form, some of the chemicals mentioned above, built up in the soil much more slowly by natural processes.
Even a casual observer will notice by the difference in the color of soils from black to red, that they vary considerably in their constituents. Whether these elements are in proper balance and in, sufficient supply for satisfactory plant growth cannot be determined by smell, sight or touch; a chemical test is necessary. This is one of the first things to be done in the early spring. A home soil-testing set is inexpensive and interesting, but samples will also be tested, usually free of charge, by your state agricultural experiment station. Your local seed store will give you the address and tell you just what to do. You should receive a report from the station within a week or two indicating what, if anything, your soil requires.
In sum, therefore, the A, B and C of successful vegetable gardening are good seed, good light and good soil. Given these, your plants should come up healthy and strong – but so will the weeds, often from seeds that have been deep in the soil for many years. They must be scuffled down when they are small, before they enter into competition with your vegetables. Afterwards, a mulch, or thick layer of grass clippings, leaves or straw, should be spread around. This will not only keep the pesky weeds from coming up, but will help to conserve essential moisture in the soil and to maintain an even soil temperature.