Many quick field tests exist for evaluation of soil pH. With our increase in cropping intensity and no-till, and more frequent N fertilization, some of our surface soils are beginning to acidify, and may require addition of limestone to avoid a decrease in production. The SOM content, and its direction of change over time, can be diagnostic of the health of the soil. Generally, high SOM content is associated with good soil physical properties and good productivity. Quick field tests exist for relative comparisons among different cultural practices or rotations. The level of soil SOM, however, is sometimes used as a surrogate for sulfur needs and nitrate contribution, and its exact quantification once every three to five years is recommended.
Crop residue is a direct function of cropping intensity, fertilization, tillage, and sanitation.
The significance of the SOM levels is realized more fully in conjunction with the soil texture. An Ascalon sandy loam will never reach the organic matter levels of a Promise clay. Presence of Earthworms and Macropores Residue and organic matter are the food earthworms need to proliferate. Their presence is rarely found in dryland conventional wheat summer fallow systems. After seven years of intensive cropping and more residue production, our plots are finally showing the presence of earthworms.