Certified Crop Advisor Practice Exam

In a typical row crop production system, the primary source of organic matter comes from crop residues. After harvest, the leftover parts of the crops, such as stalks, leaves, and roots, contribute significantly to the organic matter in the soil. These residues decompose over time, enhancing soil structure, improving moisture retention, and providing essential nutrients for subsequent crops.

While animal manure, cover crops, and green manure also contribute to soil organic matter, crop residues are generally the most abundant source in conventional row cropping systems. Manure adds organic matter but is not as prevalent in quantity compared to the vast amount of crop residues produced annually. Cover crops and green manure are often utilized for their benefits in improving soil health but do not match the volume of organic matter contributed by crop residues from the harvested crops. Thus, crop residues stand out as the primary source that most directly influences soil organic matter levels in row crop systems.