A Blueprint for Feeding Your Lawn and Garden:
Healthy gardens and lawns have one major component in common, that is healthy soil. Healthy soil is soil that breathes, and is alive. Healthy soil has twenty to forty percent organic content (composted material, peat moss, etc). Healthy soil is alive with fungi, microbes, and worms that feed on the organic material and convert it into a form that plant life can absorb. Healthy soil both absorbs moisture and drains once saturated. It is made up of inorganic materials of varying densities ranging from fine particles like clay and silt, to sand, and even some gravel/aggregate (but not too much, and not much denser than 1/8th of an inch.
Though you can engage in extensive and expensive testing to find out exactly what your soil is made up of, including live microbial activity for example, it is simpler to stick with basic soil testing (through the Cornell Co-Operative Extension) to find out how acid/alkaline your soil is and what the ratios of Phosphorous, Nitrogen, and potassium are. The results of this testing will tell you what special amendments you need to add to get the right nutrient balance which is your baseline.
Soil density, organic and microbial content should be amended regularly throughout the year. In a basic program, compost tea (a tea brewed using live compost as the base material) should be applied at least 3 times a year, in April, June, and August. Compost tea is rich in trace minerals, live microbes, and beneficial fungi and will help re-invigorate your soil. The soil should also be fed with corn gluten in March/April to both give it a nitrogen boost and inhibit weeds from germinating. In soil that needs more vigorous attention, compacted soil with low organic content, aeration and addition of composted material is highly recommended. In a lawn this is also an excellent time to over seed, making sure the seed is lightly covered with the composted material.
With the presence of certain weeds, diseases, and insects, it becomes evident that the soil may be low in calcium, or over acidic. Liquid kelp, and/or fish emulsion are very high in calcium and will nurture the soil and the lawn, as well as reduce the occurrence of certain infestations.
Stay away from chemical fertilizers, fungicides and pesticides whenever possible. Though these will yield short term results, in the long run, they kill every living organism in the soil and weaken the root systems of your lawn and plants.