Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Florida dairies face challenges managing nitrogen (N) from waste effluent sprayfields to prevent groundwater contamination.
• Excessive N loss to groundwater poses environmental risks and impacts water quality.

Purpose of the Study:

• To quantify nitrogen removal by two different forage systems.
• To monitor nitrate nitrogen (NO3(-)-N) concentrations in soil water below the rooting zone.
• To compare the effectiveness of bermudagrass-rye (BR) and corn-forage sorghum-rye (CSR) systems in preventing N leaching.

Main Methods:

• Two forage systems, bermudagrass-rye (BR) and corn-forage sorghum-rye (CSR), were evaluated over four 12-month cycles (1996-2000).
• Nitrogen loading rates of effluent varied (500, 690, 910 kg ha(-1) per cycle).
• Forage N removal and soil water NO3(-)-N concentrations were measured in Kershaw sand, an excessively drained soil.

Main Results:

• The BR system removed significantly more N per cycle (465-585 kg ha(-1)) than the CSR system (320-378 kg ha(-1)) across loading rates.
• Higher N concentrations in bermudagrass contributed to its greater N removal capacity compared to corn and forage sorghum.
• The BR system was more effective at preventing NO3(-)-N leaching, maintaining lower concentrations in soil water below the rooting zone.

Conclusions:

• The bermudagrass-rye (BR) forage system is superior to the corn-forage sorghum-rye (CSR) system for nitrogen removal from dairy effluent sprayfields in Florida.
• BR system effectively minimizes nitrate nitrogen (NO3(-)-N) leaching into groundwater, safeguarding water resources.
• Year-round forage systems like BR are crucial for sustainable dairy farming and environmental protection in sandy soil conditions.