While a soil test involves many important nutrients, the pH level is critical in optimizing the microbial activity in the root zone. This is especially important for organic gardeners because a proper pH will allow critical nutrients to be released as the plants mature.
Nutrient availability for soil pH levels University of Missouri Extension Service
As you can see in the chart, there’s a fall off of phosphorus availability as pH declines (or becomes more acidic – moving to the left on the chart). Root growth is dependent on adequate levels of phosphorus. We can also see how acidity affects other critical metals such as calcium and magnesium when pH drops below neutral (pH 7). These are among the macronutrients frequently cited as deficient in soil tests.
But altering pH can be difficult. Clay soils generally have a high degree of buffer capacity, meaning that the soil is resistant to change. Adding organic matter to the soil also increases both the buffer capacity and the acidity of the soil. While plants do well in soils ranging from a pH of 6 to 6.5, peak microbial activity occurs when the pH is between 6.3 and 6.8.
So why is this important? Continue reading →
Plants require a root system that is equal in mass to the top growth, and vice versa. So without a good “understanding” your plants can never reach their potential and provide a harvest worthy of your efforts.
Here in the Ozarks we’re usually faced with a clay soils of marginal fertility that’s more appropriate to pines and oaks rather than corn and tomatoes. The standard recommendation for improving the soil is to add organic matter in the form of manure or compost. In truth this doesn’t actually improve the soil – which technically can only be comprised of sand, silt, and clay – but organic matter, or humus, does make the soil more friable and increases its ability to hold nutrients.