Page 78 - Nutrient Management Planning Guide

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Chapter 3.1

The loss of nutrient-rich organic matter from eroded soils greatly reduces soil productivity. The addition of fertilizer and manure can enhance the productivity of these areas by adding nutrients and organic matter. Landscape-specific management strategies, such as variable rate technology and targeted manure application, can be used to improve productivity and soil quality in these areas.

Eroded soils typically have pH issues. Extremes in pH can affect the availability and risk of loss of some nutrients. For example, alkaline soil conditions reduce the availability of phosphorus, and promote higher losses of nitrogen (N) in the form of ammonia from fertilizer or manure.

Strategies for reclaiming eroded areas and improving soil structure include: the addition of manure, returning or maintaining crop residues, direct seeding, or the establishment of perennial forages. These areas should also be managed using erosion control measures to prevent further degradation.

Past and Current Site Management

Evaluating past and current management practices will help in identifying necessary changes to reduce environmental risk or improve site productivity.

Key Information on Site Management

Improved drainage: • The presence of tile drainage or ditching significantly increases the risk of nutrient loss or movement from a field.

Recent fertilizer application history: • Document application history including type, application rate, timing of application (e.g., fall versus spring) and method and timing of incorporation.

Manure application history: • Document manure source (e.g., beef, hog, etc.), manure

test information, application rate, timing of application (e.g., fall versus spring) and method and timing of incorporation. Account for residual nutrient availability when planning future nutrient applications, particularly if manure has been applied on the site within the last two years.

Tillage practices • : Fields under direct seeding or other reduced tillage systems have less risk of nutrient runoff losses. However, the incorporation of manure, particularly solid manure, on these sites may not be practical. Without adequate incorporation, volatile N losses from the manure could be substantial.

Crop rotation • : Short or long-term cropping plans for a site can reveal opportunities for reducing the risk of nutrient loss, building soil organic matter and determining expected nutrient removal by future crops. Account for anticipated nutrient release from past green manure crops in the rotation.

Issues relating to row crops • : Row crop

management increases the risk of runoff, erosion and soil compaction.

Presence of irrigation • : Fields under irrigation management have higher yield potential and can support a greater variety of crops, but are also at increased risk for nutrient leaching and runoff. Be aware of potential soil quality implications and the addition of nutrients present in irrigation water.

Past soil test information: • Historical soil test results can help identify chronic soil problems (e.g., salinity, acidity) that may affect crop selection.

Existing control structures or beneficial •

management practices : In some situations, structures or practices may already be in place to minimize erosion and nutrient loss. Evaluate these to identify any necessary improvements. In some cases, effective practices or structures may allow for manure applications that otherwise would have been restricted under AOPA.