Which management practices boost organic matter most effectively?
Written by
Kiana Okafor
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.To effectively build soil carbon with the appropriate management of organic matter, management techniques must be employed over time. Cover crops allow for continued organic inputs between cash crops. The application of compost gives nutrients in proper balance with humus in a stable form. Reduced tillage maintains the existing soil structure and organizes habitats for organisms. These techniques will work in combination to increase organic matter levels over time.
Cover Cropping is one of the best practices for increasing soil fertility. Leguminous cover crops such as clover naturally fix nitrogen from the atmosphere into the soil. Grass cover crops provide a significant amount of valuable biomass for soil building. At the same time, brassicas penetrate hard pans with their deep taproots, plant cover crops 4-6 weeks before the first frost for optimal establishment and growth. Terminate cover crops once flowering begins, allowing the nutrients to be available for the crops they will replace.
Compost Application
- Apply 10-20 tons/acre annually before planting
- Ensure carbon-to-nitrogen ratio around 20:1
- Spread evenly and incorporate lightly
- Moisten compost before application
Tillage Reduction
- Limit depth to 6 inches maximum
- Use strip-till for row crops
- Adopt no-till for perennial systems
- Time tillage when soil moisture is optimal
Crop rotation increases organic matter storage through the diverse roots produced. Alternate deep-rooted crops, such as alfalfa, with various kinds of vegetables that have shallow roots. This adds organic matter at different depths in the soil. Rotating species disrupts the life cycles of pests and naturally enhances soil structure. Twenty-five percent more organic matter has been recorded in rotated fields compared to monocultures.
Integrating manure requires the use of proper nutrient-balancing techniques to ensure optimal utilization. Apply 5-8 tons of composted manure/acre before planting. Test manure for nutrient analysis to avoid over-application. Incorporate manure immediately to prevent nitrogen loss. Combine with cover crops to buffer excess nutrients and reduce the potential for leaching.
Seasonal timing has a significant impact on the effectiveness of practices that rely on timing. For example, apply compost when the soil reaches 50% of its field capacity in terms of moisture. Cover crops should be planted sufficiently early to allow for adequate growth before cold weather arrives. Tillage operations should be performed during moderate moisture conditions. The effective scheduling of agricultural operations results in the greatest retention of organic matter.
Read the full article: Soil Organic Matter: The Essential Guide
