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ARS Home » Research » Publications at this Location » Publication #167526

Title: On the significance of transients in soil temperature series

item Belesky, David

Submitted to: Pedosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2006
Publication Date: N/A
Citation: N/A

Interpretive Summary: Compost materials, including waste bedding material removed from poultry production operations, used as a soil amendment could affect soil physical properties and, in turn, plant growth and nutrient availability. Poultry litter is a compost material applied to pasture in the Appalachian Region without clear knowledge of how this affects soil physical properties associated with soil temperature. Understanding this could help design application strategies to improve plant growth and nutrient use efficiency. We investigated how litter application influenced soil temperature and transfer of heat in soil and examined various methods to measure the response. Litter increased soil organic matter and decreased heat transfer in the soil. Short-term changes in soil temperature were easier to measure at certain times of the year but required complex mathematical approaches to do so. High rates of poultry litter application suppressed movement of heat in the soil the most and could be caused by plant cover of the soil surface as well as the high amount of applied organic matter.

Technical Abstract: Studies indicate that composted poultry litter application can affect soil physical properties and processes, suggesting that it may also induce changes in internal soil heat transfer. Our objective was to determine whether quantifiable effects of composted turkey litter treatments on internal soil heat transfer in a grazed sward could be determined from analysis of soil temperature observations over a one-year period at two soil depths. Turkey litter treatments were 3 and 6 Mg ha-1. Control treatments were NPK fertilizer with and without N. Data-logged temperatures at 10-minute intervals were automatically time-averaged every four hours to obtain time series of 2190 observations at 10 and 25 cm depths for the four treatments. The apparent soil thermal diffusivity (D- value) was taken as the primary indicator of treatment effects on internal soil heat transfer. It was hypothesized that D-values extracted from the annual patterns in these series would reflect overall time averages, and therefore less likely to capture treatment effects. Rather, if such effects existed, they should be more strongly manifested in patterns over shorter time scales. Various methods were used to analyze the series to obtain D-values at various time scales. Results indicated that treatment effects were more obvious in D-values calculated from monthly and daily partial series. Application of turkey litter increased soil organic matter content and tended to lower the apparent soil thermal diffusivity. Diurnal soil temperature amplitudes, needed to calculate mean D-values over a given period, were more effectively obtained using a temperature change rate method. The more commonly used Fourier analysis tended to be effective for this purpose when the partial series presented reasonably well-defined diurnal patterns of increasing and decreasing temperatures.