Project Number: 6227-21310-007-27
Project Type: Reimbursable

Start Date: Aug 25, 2004
End Date: Sep 24, 2006

Objective:
To determine if nitrate and other nitrogen compounds from the application of animal waste effluent can move beyond the rooting depth of plants when applications are made in accordance with the properly configured CNMP (comprehensive nutrient management plan).

Approach:
The ARS will collaborate with the EPA to select site(s) to be characterized in this study. Site selection criteria will include a CAFO with a CNMP adhering to NCRS' guidelines and operation/farm records to verify adherence to CNMP. Site should be located such that the agricultural practices are the overwhelming source of nitrates. An ideal site would be one with sandy soils conducive to leaching. To characterize the site, 4 to 8 plots measuring 10 x 10 m will be delineated within the field receiving animal waste effluent. The relative topography of the field and each site will be assessed using conventional survey equipment. Soil type will be verified by actual field observations using a 2 m long soil auger. The appearance of roots as a function of soil depth will be noted, when soil type is being assessed. A stainless steel suction lysimeter will be installed to a depth of at least one meter in the center of each plot. A soil core will be collected from each plot at each sampling date. The soil core will be made using a truck mounted soil-coring device. The minimum depth of soil cores will be at least 1 m. This depth may need to be increased to 2 m depending on the rooting depth. The soil core will be divided into 6 to 8 discrete samples by depth, including soil from depths of 0-5, 5-10, and 10-20 cm. Soil cores will be collected approximately 20 times throughout a calendar year. However, the bulk of the samples will be collected just prior to and after swine effluent applications. Major root tissue will be removed from the soil particles by careful hand manipulation, tweezers and fine nylon brushes. The root tissue will be dried to determine dry weight. Soils will then be air-dried, and ground to pass 2 mm sieve prior to analyses. Ground water samples will be collected when soil moisture is sufficient. Leaf tissue will be collected from vegetation growing at each plot. Leaf tissue will be dried at 60o C for 48 h, ground to pass a 40-mesh screen and total N and nitrate-N will be determined. Soil ammonium and nitrate will be extracted from soil samples using 1 M KCl. Ammonium will be determined with the salicylate-nitroprusside technique, and nitrate (+nitrite) will be determined by the Cd reduction method. Soluble reactive phosphate (SRP) will be determined colorimetrically from water extracts of soils using the ascorbic acid technique. Lysimeter samples will be analyzed for total N, total C, total P, ammonium, nitrate, and SRP. Total N and C will be analyzed utilizing a Skalar total N and C analyzer. Total P will be analyzed following acid digestion. Several collection containers (at least 4) will be placed throughout each plot during a animal waste effluent application. The volume of effluent will be recorded. Samples from each plot will be bulk and analyzed for SRP, total N and P, ammonium and nitrate, as described above. Temperature and rainfall data will be collected from an on-site station with a data logger.

Project Team

Brauer, David - Dave Moore, Philip Pote, Daniel - Dan

Related National Programs

Food Animal Production (101)   Rangeland, Pasture, and Forages (205)