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Nutrient Management: Split Manure and Fertilizer Application

alternative practice names:

Topdress; Split Application; Side Dressing

Split nitrogen application involves applying fertilizer partway through the growing season, typically during critical crop growth stages when nutrient demand is highest. This practice is common in corn production, where nitrogen is often applied at stages V4 to V8. By splitting the application, nitrogen is provided in sync with the crop’s uptake needs, reducing the risk of nitrogen loss from leaching or volatilization. Nitrogen can be applied using liquid or dry nitrogen fertilizers, as well as manure, and is adaptable to different systems, including irrigated and fertigated management systems. 

When used, in what regions in the U.S. is the practice found: 

Northwest, West, Upper Midwest, Southwest, Northeast, Southeast

FARM SIZE 

When used, typically found on farms of the following sizes:

All Sizes

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Practice Benefits 

Improved nitrogen use efficiency: By applying nitrogen in stages, you match nutrient availability with the crop’s growth stages, reducing the risk of nitrogen losses and improving overall efficiency.


Enhanced yield potential: Side-dressing provides a timely nutrient boost when the crop's nitrogen needs are greatest, which can lead to higher corn yields compared to a single, pre-plant application.

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Implementation Insights

Site-specific or Farm-specific requirements 

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In most cases, there are no specific site or farm requirements.

Required Capital Expenditures (CapEx)

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  • Sidedressing equipment: Specialized equipment is required to apply nitrogen fertilizers during the growing season. This could include a nitrogen applicator, which injects liquid or granular nitrogen into the soil alongside growing crops. In cases where manure or liquid nitrogen is applied via fertigation, an injection system is necessary to introduce nitrogen into the irrigation water. Farms can side-dress manure using Manure injectors or slurry applicators and draglines.

Required Operational Expenditures (OpEx)

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  • Labor: Additional labor will be required for the extra pass on the field needed to apply nitrogen during sidedressing, increasing the overall time and labor costs associated with crop management.

  • Custom applicators: If the farm does not apply the fertilizer themselves, equipment rental costs or fees for hiring custom applicators will be incurred, adding to the operational costs.

  • Soil and tissue samples can be valuable tools in determining how much additional nitrogen to apply during sidedressing. A Pre-Sidedress Nitrate Test (PSNT) measures the amount of nitrate already available in the soil and helps farmers assess how much additional nitrogen the crop needs. This test is typically conducted just before sidedressing, allowing for more precise nitrogen management and minimizing over-application, which can lead to nitrogen losses and environmental issues.

Implementation Considerations

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  • Sidedress timing: The timing of split nitrogen applications in corn largely depends on planting dates and growing conditions. Typically, side-dressing occurs between mid-June and early July which can sometimes interfere with other crop management tasks. Weather and field conditions may also delay nitrogen application causing nitrogen deficiency and reduced reduces yield potential. 

  • Crop damage: Sidedress equipment can damage corn if the plants are too tall. Draglines and equipment may temporarily flatten corn, and older plants at V3 or beyond may struggle to recover from such damage.

  • Risk of crop injury: Sidedress applications of UAN (urea ammonium nitrate) solutions can result in crop injury, such as foliar burn, leaf loss, and stunted early growth. These risks are heightened during hot, dry weather, which can exacerbate the damage. Proper management of nitrogen application rates and timing is essential to minimize potential crop injury under these conditions.

  • Crop injury with anhydrous ammonia: Sidedressing with anhydrous ammonia poses its own risks, including vapor damage to corn leaves and ammonia escape if applicator knives are not properly sealed, particularly in wet soil. Dry soil provides better sealing, reducing the likelihood of ammonia loss. Although minor leaf damage typically does not significantly affect plant growth, applying early is recommended to avoid root pruning, as corn roots can extend into the row middle early in the growing season.

  • Sidedressing with manure: Modified manure tankers are often used for sidedressing in emerged corn, delivering yields comparable to commercial fertilizers. Manure application can be timed later in the season due to the taller corn. Drag hose systems, which apply manure by flattening the corn, have shown the potential for increased yields compared to commercial fertilizers. However, drag hoses are best suited for firm fields, commonly in no-till systems, and generally cause minimal damage until the corn reaches the V4 stage or later.

Financial Considerations and Revenue Streams

There are no federal cost-share programs or conservation funding for this practice.

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Environmental Impacts

MAY REDUCE FARM GREENHOUSE GAS EMISSIONS

Split nitrogen applications can potentially reduce greenhouse gas (GHG) emissions compared to single pre-plant applications. By splitting nitrogen applications, the amount of nitrogen available in the soil at any given time is reduced, which minimizes the excess nitrogen in the soil that can be converted into nitrous oxide through microbial processes. However, studies on the impact of split applications on nitrous oxide emissions have mixed results; in some cases, it can even increase emissions depending on environmental conditions like rainfall and soil moisture. This inconsistency is influenced by factors such as timing, soil type, and weather conditions.


See research highlights below:

  • Venterea and Coulter (2015) found that split N fertilizer applications did not reduce cumulative N₂O emissions compared to a single application and, in some cases, actually increased emissions, particularly following a dry period and subsequent heavy rainfall, indicating that split applications may not always be effective in reducing N₂O emissions.

  • Ma et al. (2012) found that split N application systems increased total GHG emissions compared to continuous maize monoculture.

  • Zebarth et al. (2008) evaluated the impact of N fertilizer application rate and timing on N₂O emissions in commercial corn fields over two years. While side-dress application at lower rates reduced nitrate loading in the soil, there was no significant reduction in cumulative N₂O emissions.


IMPROVES WATER QUALITY

Applying nitrogen in smaller amounts at different growth stages helps minimize the risk of nitrogen leaching, particularly in regions with high rainfall or sandy soils.

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Alignment with FARM Program

FARM Environmental Stewardship (ES) V2-V3 Alignment

FARM ES Version 2 and Version 3 ask if the farm has a nutrient management plan (NMP), if it is maintained and implemented. FARM ES Version 3 also includes an optional crop module, allowing users to enter their unique management practices. Users can specify that they sidedress both manure and fertilizer.

Contents

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We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

Contents

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Practice Overview

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Practical Insights.png
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Research Results.png
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Split nitrogen application involves applying fertilizer partway through the growing season, typically during critical crop growth stages when nutrient demand is highest. This practice is common in corn production, where nitrogen is often applied at stages V4 to V8. By splitting the application, nitrogen is provided in sync with the crop’s uptake needs, reducing the risk of nitrogen loss from leaching or volatilization. Nitrogen can be applied using liquid or dry nitrogen fertilizers, as well as manure, and is adaptable to different systems, including irrigated and fertigated management systems. 

Practices and technologies

Nutrient Management: Split Manure and Fertilizer Application

alternative practice name:

Topdress; Split Application; Side Dressing