Surface Amendment Application - Alum
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The application of amendments to the pen surface in order to decrease ammonia volatilization has been widely researched in the literature, but is rarely done on true operations. We looked at the application of liquid and granular alum on feedlot pen surfaces to evaluate its effectiveness in a real-world situation.
The Problem
The greatest ammonia emissions from feedlots occur from the surface of open drylot pens. Bierman et al. (34) reported that 57 to 67% of the total nitrogen excreted is volatilized by the time that feedlot pens are cleaned. Application of surface amendment compounds (i.e. alum) to pen surfaces has shown potential to decrease the rate of ammonia volatilization in laboratory studies.
Background
Successful surface ammonia reduction amendments are usually acidic compounds that decrease the pH of the soil surface and inhibit ammonia (NH3) volatilization by favoring the formation of ammonium (NH4+) ion (the more stable, soil bound form of ammonia). If the soil is acidic, a pH below 6, ammonia will primarily be found in its ionic form ammonium, and volatilization will be low. At a higher pH, above 8, ammonia will volatilize rapidly from the soil surface. Different types of surface amendments to reduce soil pH have been tested on feedlot pen surfaces to assess their ability to decrease ammonia emissions. Aluminum sulfate (alum) has been shown in laboratory evaluations to be the most effective additive in reducing the surface pH and subsequent ammonia emissions (35, 36). Laboratory studies have found that alum reduced cumulative ammonia emissions by 98% over a 21 day period from simulated feedlot surfaces (35). However, while surface amendment studies are successful in laboratory settings, they often times have less success in field application, losing effectiveness over a short period of time and showing variable results. This is likely due to the continual deposition of manure on treated pen surfaces and animal hoof action breaking and removing the treated pen surface crust.
Experimental Methods
Method. The treatments used in this study were chosen based on current literature information and laboratory proven results. Aluminum sulfate (alum) was chosen as the surface treatment for this study. Typical application is with a liquid solution, which was tested, as well as a granular application of alum.
For liquid alum application, a 15% solution was mixed at a rate of 1.04 lb dry matter per gallon of water, and applied at a rate of 0.011 gal per ft2 (0.001 gal/m2) with a calibrated pump sprayer. To achieve the same application rate, the dry granular alum treatment was applied with a calibrated broadcast applicator at a rate of 0.011 lb per ft2 (0.001 lb/m2) of corral surface. We tested each treatment (liquid, granular, control) on three pens, which had as average size of 25,833 ft2 (2400 m2). Ammonia measurements were taken at the surface level before application, 30 minutes after application, and 24 hours after application using methods described in the field studies section of Our Study.
Results and Cost Analysis
Results. Coming Fall 2008......
Cost Analysis. Coming Fall 2008.....
The Solution
Coming Fall 2008.....
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