Soil Chemistry Guidelines
December 12th, 2009 by shrimppopThis week saw the delivery of NOFA’s newspaper Natural Farmer, which is always chock full of amazingly useful information. The paper is quarterly and usually features a pull out section on a particular topic, this one being the topic of Nutrient Density. There’s a fabulous long interview with farmer and consultant Mark Fulford of Teltane Farms in Maine.
In talking about soil nutrients, Fulford offered a very concise useful nugget about soil chemistry, which I’ve tried to capture in the table below.
UPDATE: 20100115: Here’s a better version of the table with original following:
| Element | Aspect | Function | Form | Notes |
| Nitrogen (N) | Vegetative | Growth | Nitrate - N03 | |
| Nitrogen | Reproductive | Seed, fruit, root | Ammonia- NH3 | some plants switch from growth to reproductive, esp. tomatoes and potatoes |
| Carbon (C) | Energy storage, binding, nutrient availability, soil “digestion” | e.g. Calcium carbonate | ||
| Phosphorus (P) | Reproductive | Seed, fruit, root | Phosphate- many forms | called a “salt”; rock phosphate, bird and bat guano as a source |
| Sulphur (S) | Reproductive | Seed, fruit, root | Sulfate, many forms, x-SO4 | also called a “salt” |
| Manganese (Mn) | Reproductive | Seed embryo development and finishing | only need very small amounts | |
| Calcium (Ca) | Vegetative | Cell wall structure, critical for growth | Calcium carbonate- CaCO3 | Limestone, Dolomite, Gypsum |
| Potasium (K) | Vegetative | Growth | Potash, Green sand; bracken ferns recycle K | |
| Magnesium (Mg) | Vegetative | Key to chlorophyll and photosynthesis | ||
| Silicon (Si) | Vegetative | Structural; like the rebar in cell wall growth | needs organic matter to be made available |
Fulford talks about a lot of things in this lengthy article which I highly recommend. One way to assess soil chemistry is through soil testing of course, but another way is to analyze the weeds growing on a property. For example, dandelions and goldenrod indicate dry conditions, whereas buttercups indicate wet or anaerobic soils. Broadleaf weeds indicate high potassium, low phosphorus. Annual grasses indicate lack of calcium.
Fulford mentions a couple of good books on weeds:
Weeds: Why They Grow, by J. McCaman
Weeds: Control Without Poisons, by Charles Walters
