SUSTAINABLE CROPPING SYSTEMS FOR IRRIGATED SPECIALTY CROPS AND BIOFUELS
Location: Vegetable and Forage Crops Production Research
Title: Mineralization of nitrogen from biofuel byproducts and animal manures amended to a sandy soil
Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2009
Publication Date: April 26, 2010
Citation: Moore, A.D., Alva, A.K., Collins, H.P., Boydston, R.A. 2010. Mineralization of nitrogen from biofuel byproducts and animal manures amended to a sandy soil. Communications in Soil Science and Plant Analysis. 41:1315-1326.
Interpretive Summary: Rapid increases in fertilizer costs during the recent years have contributed to an increased interest in use of alternative nutritional products as soil amendments. Byproducts of biofuel industry, such as mustard meal (MM) and distillers grain (DG), are of interest for evaluation of their nutrient release characteristics. Similarly, organic growers need nutrient sources that can be used for certified organic production. Poultry litter (PL), dairy manure compost (DMC), anaerobically digested fiber (ADF), and perfect blend 7-2-2 (PB) are alternative nutrient sources that can be used for organic farming. For optimal management of these products, it is important to know the rate of release of plant available forms of nitrogen (ammonium and nitrate forms) from the above organic products; when applied to a typical agricultural soil. An incubation study was conducted using a Quincy fine sand with application of the above alternate nutrient products at 200 mg/kg with field capacity water content. The temperature was adjusted every two weeks (for a total of 210 days) in the range of 55 to 74 degrees F to mimic the changes in temperature from April through October (potato growing season) in the major potato-growing region in the US Pacific Northwest (PNW). The cumulative releases of plant available forms of nitrogen at the end of incubation period ranged from 2 to 61 percent of the total nitrogen applied as the above described different sources. The high nitrogen releases were (56-61%) from MM, PB, and DG; while the low nitrogen releases (2%) were from DMC and ADF. The latter products have high carbon : nitrogen ratio thus, result in immobilization of available nitrogen during the initial period (up to about 80 days), followed by release of available nitrogen. For potato production, these products are not advisable since they decrease the availability of nitrogen during the early growing season, which is critical period for adequate nitrogen availability.
In Washington, 1.3 million tonnes of distillers grains and 78.5 million tonnes of oilseed meals are expected to be produced in the upcoming years as byproducts of the biofuel industry. These byproducts contain plant nutrients, similar to other byproducts such as manures and composts. It is important to understand the kinetics of nitrogen (N) transformations from these byproducts to estimate plant available N to determine the optimal rate and timing of N. Transformations of N from poultry litter (PL), dairy manure compost (DMC), anaerobically digested fiber (ADF), Perfect Blend 7-2-2TM (PB), a compost/litter mixture (C/L), dried distillers grains (DG), and mustard meal (MM) applied to a Quincy fine sand were investigated in an incubation experiment over 210 days. Amendments were applied at a rate of 200 mg total N/kg and the incubation temperature was adjusted biweekly to represent the soil temperature in the Pacific Northwest (PNW) region of the U.S. The soil was sampled regularly to measure the concentration of ammonium and nitrate extractable in 2 M KCl. Mineralization of organic nitrogen was rapid from PL and PB, while relatively slow from MM and DG. The cumulative release of available N for 210 days accounted for 61 and 56 percent of total N in MM and DG, respectively, in contrast to 44 percent for PL. With application of MM and DG, NH4-N accumulated in the soil with very little nitrification, due to possible inhibition of nitrification due to the compounds present in these amendments. Nitrogen mineralization was negligible from DMC, thus suggesting that this amendment is in effective as a source of plant available N for most annual crops growing period.