Steps to Reduce Runoff From Fertilizer Applications in Maryland

Why fertilizer runoff matters in Maryland

Fertilizer runoff is a major source of nutrient pollution in Maryland, particularly in the Chesapeake Bay watershed. Nitrogen and phosphorus carried off fields, lawns, and construction sites stimulate algal blooms, reduce oxygen in bottom waters, harm aquatic life, and degrade water quality. Reducing fertilizer runoff is both an environmental necessity and a practical way to protect property values, recreational resources, and compliance with state and federal requirements.
Maryland’s landscape — from the Eastern Shore’s agricultural fields to suburban lawns and urban stormwater systems — creates many pathways for nutrients to reach streams, rivers, and the Bay. Managing fertilizer carefully at every scale (state, farm, homeowner, and developer) produces measurable benefits for water quality and can reduce regulatory risk for landowners.

Understand Maryland-specific rules and programs

Maryland implements a mix of regulations, incentive programs, and technical assistance targeted at nutrient reduction. Being aware of these frameworks helps you choose compliant and cost-effective practices.

• Know the basics: Maryland restricts phosphorus application on lawns unless a soil test indicates need, requires training for commercial applicators, and promotes nutrient management planning for farms and large properties.
• Use existing resources: University of Maryland Extension and local Soil Conservation Districts provide soil testing, technical guidance, and cost-share programs such as the Cover Crop Program and Conservation Reserve Enhancement Program (CREP).
• Incentives and cost-shares: Agricultural operations can often recover part of the cost of conservation practices (cover crops, riparian buffers, manure storage) through state and federal programs. Homeowners may qualify for local cost-share or rebates for installing green stormwater infrastructure.

Basic principles to reduce runoff

Before specifying techniques, adopt these guiding principles:

• Apply only what plants need. Base applications on soil tests and crop or turf demand.
• Time applications to match plant uptake. Avoid applying fertilizer when plants are dormant, during heavy rain forecasts, or on frozen ground.
• Keep fertilizer off impervious areas and out of storm drains. Sweep up any spilled product immediately.
• Maximize infiltration and retention. Vegetated buffers, rain gardens, and permeable surfaces trap and use nutrients before they reach streams.

On-farm practices: practical BMPs for agriculture

Agricultural operations have large potential for nutrient reductions. Implementing these practices lowers runoff and often improves yields or reduces input costs.

• Conduct regular soil testing and update nutrient management plans. Soil sampling every 2-3 years guides phosphorus and potassium management and sets realistic nitrogen targets.
• Use cover crops in fall and early spring to scavenge residual nitrogen, reduce erosion, and improve soil structure. Select species (rye, cereal rye, clover) appropriate to rotation and termination timing.
• Apply manure and fertilizer based on a written nutrient management plan. Spread manure when soils are not saturated, use injection or incorporation where appropriate, and avoid surface spreading before heavy rain.
• Use buffer strips and riparian plantings along streams. A 35- to 100-foot buffer of permanent vegetation dramatically increases nutrient uptake and reduces sediment delivery.
• Consider no-till or reduced-till systems to decrease erosion and runoff and increase soil organic matter.
• Adopt precision nutrient management: variable-rate application based on soil and yield maps, split applications of nitrogen, and use of slow-release or stabilized fertilizers to reduce leaching and denitrification.
• Maintain edge-of-field structures (grass waterways, terraces, filters) and routine equipment calibration to prevent over-application.

Homeowner and urban actions

Household lawns, landscapes, and municipal turf account for a significant portion of nonpoint nutrient loads when multiplied across many properties. Homeowners can make high-impact choices with simple actions.

• Perform a soil test before applying phosphorus or lime. University of Maryland Extension offers testing and interprets results for turf and garden needs.
• Reduce total fertilizer use. Many lawns require less fertilizer than labeled schedules suggest. Focus on one to two targeted applications when grass is actively growing.
• Use phosphorus-free lawn fertilizers unless a soil test shows deficiency. Switch to fertilizers with higher proportions of slow-release nitrogen.
• Mow high (3 to 3.5 inches) and leave clippings. Taller turf shades soil, reduces weeds, and slower growth reduces nutrient demand.
• Avoid application before rain or on frozen ground. Do not broadcast granular products on paved areas; sweep any material back onto the lawn.
• Calibrate spreaders and follow label rates. Overlap or mis-calibrated equipment is a common cause of over-application.
• Install rain gardens, bioswales, or permeable pavers to capture and infiltrate runoff from roofs, driveways, and patios.

Design and deploy landscape BMPs

Strategically placed landscape practices reduce nutrient loads from developed areas.

Riparian buffers and vegetative strips

• Plant native grasses, shrubs, and trees in a multi-tiered buffer adjacent to water features. Trees provide shade and long-term stability; shrubs and grasses filter sediments and nutrients.
• Design buffer width to space and slope; larger widths are needed on steeper slopes.

Rain gardens and bioretention

• Size rain gardens to capture the expected runoff from a drainage area (common design: 1 to 8 percent of the impervious area depending on soil infiltration rates).
• Use engineered soil mixes and underdrains only when native soils have poor infiltration.

Permeable surfaces and green infrastructure

• Replace some impervious surfaces with permeable pavers or porous asphalt. Combine with subgrade storage and pretreatment to prevent clogging.
• Use tree pits and structural soils in urban streetscapes to increase infiltration and reduce stormwater flow velocity.

Implementation steps: step-by-step plans for different audiences

Below are focused action plans for homeowners, farmers, and municipalities. These can be adapted to different scales.

• Homeowner action plan:
• Get a soil test and follow recommendations.
• Reduce or eliminate phosphorus unless required by soil test.
• Time fertilizers during active growth; avoid rainy forecasts.
• Calibrate spreader and follow label rates.
• Install a rain barrel or rain garden to capture roof runoff.
• Consider lawn alternatives (native planting beds) on slopes or near streams.
• Farmer action plan:
• Update your nutrient management plan and soil tests.
• Adopt cover crops and split nitrogen applications.
• Implement buffer strips and maintain grassed waterways.
• Use manure storage and plan for weather-sensitive spreading.
• Pursue cost-share for conservation practices and document implementation.
• Municipal/Developer plan:
• Review and adopt stricter fertilizer ordinances for public lands.
• Retrofit stormwater ponds with enhanced nutrient removal features.
• Require riparian buffers and stormwater BMPs in site plans.
• Train public works crews on sweep-up protocols and proper turf fertilization.

Practical calculations and examples

Being able to calculate application amounts helps prevent over-application. Use the following approach:

1. Determine area to be fertilized in square feet.
2. Choose an application rate recommended for the species (for example, “x pounds of nitrogen per 1,000 square feet” — follow extension guidance or soil test).
3. Read the fertilizer label to determine percent nitrogen (for example, a 20-10-10 product is 20 percent N by weight).

Calculation example (method, not a prescriptive rate):

• If you need 1 pound of nitrogen per 1,000 square feet on a 5,000 sq ft lawn, total needed = 5 pounds of nitrogen.
• For a 20-10-10 fertilizer (20% N), amount of product = total N required / 0.20 = 5 / 0.20 = 25 pounds of product.

Always cross-check with local extension recommendations and avoid multiple applications that exceed annual recommended totals.

Monitoring, recordkeeping, and measuring success

Track changes and demonstrate progress:

• Keep records of soil test dates and results, fertilizer products and amounts, application dates, and weather conditions.
• Monitor vegetation in buffers and infiltration features for plant health and sediment accumulation.
• Use local water quality data or community monitoring groups to observe trends in stream clarity or algal presence.
• For farms, maintain documentation required for nutrient management compliance and for cost-share audits.

Policy and community engagement

Reducing fertilizer runoff is most effective when individuals act within a supportive policy environment.

• Support local ordinances that restrict phosphorus use, require training for fertilizer applicators, and limit winter applications where appropriate.
• Engage neighborhood associations and homeowner groups in education and demonstration projects (rain gardens, native habitat plantings).
• Work with Soil Conservation Districts and Extension to access technical assistance and cost-share.

Practical takeaways

• Test soil first; apply nutrients only to meet documented needs.
• Time fertilizer applications to plant uptake windows and avoid rain and frozen ground.
• Use slow-release nitrogen and limit phosphorus to soil-test demonstrated deficiencies.
• Implement vegetated buffers, cover crops, rain gardens, and permeable surfaces to intercept and treat runoff.
• Calibrate equipment, sweep spills, and maintain records.
• Leverage Maryland technical assistance and cost-share programs to implement larger-scale practices.

Reducing fertilizer runoff in Maryland is a combination of sound agronomy, careful timing, thoughtful landscape design, and community-level engagement. With targeted actions by homeowners, farmers, and municipal managers, nutrient loads to the Chesapeake Bay can be substantially reduced while maintaining productive landscapes and healthy watersheds.