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Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/1/2004 Publication Date: 8/23/2005 Citation: Adler, P.R. 2005. Effect of a temporal carbon gradient on nitrogen and phosphorus dynamics and decomposition during mesophilic composting. Communications in Soil Science and Plant Analysis. 36:2047-2058. Interpretive Summary: A layered compost system was previously developed that eliminated the need for excess carbon to compost liquid manure. As compost stabilizes, nitrogen and phosphorus can be converted to forms that are more easily lost to surface and ground water. Excess carbon has been used to reduce the potential for loss of nitrogen and phosphorus. Short-term conditions of excess carbon were tested as a way to reduce nitrogen and phosphorus loss without the requirement of excess carbon in the long-term, but it did not appear to be effective. However, the rate of conversion to forms that could be lost were determined and this knowledge could be used to develop a carbon buffer to more effectively control the loss of nutrients from compost systems and reduce the amount of carbon required to be effective. This information could be used by fish farmers and others using compost systems for liquid manure to design effective strategies to control nutrient loss. Technical Abstract: Excess carbon (C) can immobilize inorganic nitrogen (N) and phosphorus (P) when composting manure and has been used to reduce the moisture content of liquid manure so they can be composted. A mesophilic composting strategy was previously developed and shown to be an effective method to manage liquid manure without the need for excess C. The objective of this study was to determine if a temporal C gradient would sequester more N and P without the need for excess C. The experiment was conducted in bags. All treatments had arctic char manure applied at the same rate (1.28g N), every 14 days for 112 days. The C source, ground corn stover, was applied in 3 batch sizes. The 1X treatment applied 70g corn stover every 14 days, the 4X treatment applied 280g corn stover at day 0 and 56, and the 8X treatment applied 560g corn stover once at day 0. All bags had the same amount of C and N added to them by the end of the experiment at a C:N ratio of 30:1. As the C to N or P ratio decreased below 20 and 30, respectively, net mineralization occurred and the time of this occurrence was similar for all C treatments. The concentration of N and P were relatively low until day 91 when NH4-N and P and day 105 when NO3-N started to increase, after which point mineralization occurred at a rate of about 60 mg N and 4 mg P/kg mass/day. Although the temporal C gradient did not appear to reduce the net rate of N and P mineralization, this information could be used to design a C buffer that could capture any leached N or P from the layered mesophilic compost system based on N and P dynamics and weather statistics. |
