Mineralization of carbon and nitrogen from freeze- and oven-dried plant material added to soil
1988
Moorhead, K.K. | Graetz, D.A. | Reddy, K.R.
Drying organic material before soil incorporation is a common procedure used in mineralization or decomposition studies. A laboratory study was conducted to determine the effect of drying methods on plant C and N and associated mineralization patterns in soil. Freeze- and oven-dried water hyacinth (Eichhornia crassipes [Mart] Solms) was added to a Kendrick soil (loamy, siliceous, hyperthermic Arenic Paleudults) at a rate of 5 g kg-1 and incubated in the dark at 27 degrees C for 90 d. Oven drying in paper bags significantly increased the lignin content and decreased the mineral content of the plant material compared to freeze drying. The total C and N was not significantly different for the two materials. The mineralization of C from freeze-dried plant material was more rapid during the initial stage of decomposition and remained significantly higher throughout the incubations. At 90 d, 50 and 41% of the plant C had evolved as CO2 for the freeze- and oven-dried plant material, respectively. Mineralization of 15N from the plant material accounted for 33% of the applied N of the freeze-dried material and 23% of the applied N of the oven-dried material. Nitrogen mineralization and CO2 evolution were linearly correlated (r = 0.998) for the oven-dried plant material, but less correlated (r = 0.770) for the freeze-dried material.
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