County-Level Nitrogen Fertilizer Application for US Croplands

County-level data estimates nitrogen fertilizer application for 21 major crops across the contiguous United States. The dataset was assembled by SCIOPS for driving the DNDC agro-ecosystem model to assess greenhouse gas production from US agriculture. It is based on 1990-1992 crop area statistics from the National Agricultural Statistical Service and typical fertilization rates derived from USDA NASS bulletins.

Use Cases

• Model county-level greenhouse gas emissions from agriculture using crop-specific nitrogen application rates and cropland area.
• Analyze spatial patterns of nitrogen fertilizer use across US counties for environmental policy assessment.
• Estimate total national fertilizer consumption for major crops by aggregating county-level 'typical N Fert. Rate' and area data.
• Compare fertilizer application intensity between crops like Corn (125 kg N/ha) and Soybean (0 kg N/ha) at a county scale.

Strengths

• Covers 21 distinct crop types with specific 'typical N Fert. Rate' values provided.
• National total estimate of 8.5 million tonnes N/yr for 1990 is validated against sales data (83% match).
• Data is geospatially explicit at the county level for the contiguous United States.

Limitations

• Data is temporally stale, based primarily on 1990-1992 crop area statistics.
• Methodology estimates typical rates, not actual measured application, and excludes crops like vineyards and orchards.
• The 1990 national total is 17% lower than reported fertilizer sales, indicating incomplete coverage of all nitrogen uses.

Provenance

Source

National Agricultural Statistical Service (NASS) crop area data and USDA NASS state agricultural statistics bulletins for fertilization rates.

Collection Method

County crop areas were multiplied by crop-specific typical nitrogen fertilization rates to calculate total annual application.

Time Range

1990-1992

Geography

Counties in the contiguous United States.