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Tuesday, January 6, 2009

Soil Test

Gardeners and farmers, when they even bother with soil testing, usually look at 4 things, pH, N,P, and K. The assumption is one should add enough lime to bring the soil close to neutral pH and add the right blend of N,P, and K, and everything will be brilliant. Even in Organics practices follow these rules. They use different things, like compost to get there, but it's the same model. What you find if you keep your focus on NPK and pH is that you have to add more and more fertilizer each year, and you get increasingly poorer results. Why? Balance. You can bring soil to neutral pH and still have soil that doesn't promote healthy life. Calcium, Magnesium, Potassium, and Sodium have a lot to do with pH management, maintenance of balanced hormone and enzyme systems, healthy plants, protection against insect, bacterial and fungal attack, weed control, and nutrient availability. You can have a pH of 6.5 or 7 and still be way out of balance in these 4 elements. If you are, you can feed your plants as much N as you want and they will grow, but they will be continually stressed, highly susceptible to disease and drought, and they will produce fruit low in nutritional quality.

Our first order of business in building fertility in the pasture is to get our soil into balance. Here's our soil test and the recommendations.

We are going to use a high calcium lime on the pasture this spring. Picking the right lime is important to archiving equilibrium in the big four. Common limes are Dolomite, which is 21% calcium and 12% magnesium; Gypsum, which is 21% calcium and 16 % sulfur; and Hi-calcium lime which is 30% calcium and 4 % magnesium. Since our sulfur and magnesium levels are about where we want them we don't want to add more as we bring the calcium level up. After we let this work in for a season we will retest and see what else we need to adjust.

1 comment:

Craig Dick said...

Alan,
Great article and blog, though I wanted to share with you that in our experience gypsum does not act as a liming agent, though it can help to reduce subsoil acidity over time.

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