Nitrogen Removal and Nitrate Leaching for Forage Systems Receiving Dairy Effluent

Abstract

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.

North Florida Dairy Farmer Perceptions Toward the Use of Seasonal Climate Forecast Technology

“…Dairy farmers, on the other hand, may find this management change infeasible because they need to maintain certain milk production levels that they think can only be reached with high protein levels. Another example is a researcher's recommendation based on model outcomes, to plant Bermudagrass in lieu of another species (Woodard et al, 2002). A dairy farmer might recognize the change as good for reducing N leaching, but may not be able to make the change because it is economically or financially infeasible.…”

“…Consequently, N leaching, the difference between N in the soil and N uptake, is also impacted by ENSO climatic changes. More specifically, N losses from forage crop rotations on a dairy farm in the study area have been shown to be influenced by inter-annual climatic variability (Woodard et al, 2002). Woodward's study lasted four years (1996)(1997)(1998)(1999), and even though it included one El Niño phase (1997)(1998), one La Niña phase (1999)(2000) and two Neutral years, it does not provide enough information to generalize results according to ENSO phases.…”

“…By using baseline information from Woodard et al (2002), biophysical crop models of the Decision Support System for Agrotechnology Transfer (DSSAT v4.0;Jones et al, 2003), and a whole dairy farm model, Cabrera (2004) was able to simulate the most common forage rotations in the study area, categorize N leaching according to ENSO phases, and propose ENSO-based dairy management strategies to reduce N leaching. Overall results from Cabrera (2004) indicate that dairy farmers could decrease N leaching mostly by selecting adequate forage rotations in the sprayfields and pastures.…”

The Influence of Bahiagrass, Tillage, and cover crops on Organic Vegetable Production and Soil Quality in the Southern Coastal Plain

“…2; added N availability. Cover cropping (Jackson et al, 1993;Wyland et al, 1996;Constantin et al, 2010) and perennial grass (Woodward, 2002) also reduced the potential of nitrate leaching. Soil organic N has also been found to increase with perennial grass (Giddens et al, 1971).…”

The treatment performance and nutrient removal of a garden land infiltration system receiving dairy farm wastewater

“…Forage vegetation can substantially improve the potential of land treatment system for nutrient removal because, unlike grain production systems, nearly all aboveground biomass is removed during harvest (Paranychianakis et al, 2006;Woodard et al, 2002). For instance, 465, 528, and 585 kg N/ha per cycle were removed by a Bermuda grass-rye system for the low, medium, and high rates of dairy effluent, respectively, during a study of four 12-month cycles (Woodard et al, 2002).…”