In Europe they refer to organic growers as biological growers, which is probably a more appropriate and descriptive term. While all aspects of soil analysis and management are critical, the twin engines of soil biology and organic matter inputs coupled with the appropriate style and frequency of cultivation drive the system of a biological-ecological approach to soil management.
Although it makes up only 3–5% of the soil, organic matter has a pronounced influence on all soil properties. When added to the soil, it yields: • A sufficient nutrient supply • An open, permeable soil surface that allows air/gas exchange to replenish the soil’s oxygen content, and makes it easy for water to enter, percolate through, and drain out of the root zone
Once added to the soil, phosphorus is relatively immobile—that is, it doesn’t readily leach downward as does nitrogen. But it is quickly “locked up” by both aluminum and calcium in the soil, and thus unavailable for plant growth.
As a biological soil manager you can grow phosphorus-concentrating crops such as brassicas, legumes, and cucurbits, then use them for compost or as green manure to work the phosphorus in their plant parts into the organic fraction of the soil, where it will be available to crops. Another strategy is to add a dusting of colloidal rock phosphate powder to manure layers in a compost pile.
Nitrifying bacteria proliferate in manure and they also consume and immobilize the phosphorus, then “give it up” as they die and decompose. Again, it becomes available in the organic matter fraction of the soil when the finished compost is applied.