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Intensive straw harvesting, fertilization, and fertilizer source affect nitrogen mineralization and soil labile carbon of a loblolly pine plantation

Informally Refereed

Abstract

Straw harvesting can supplement traditional revenues generated by loblolly pine (Pinus taeda L.) plantation management. However, repeated raking may alter soil properties and nutrition. In northcentral Louisiana, a study was conducted to evaluate the long-term effects of intensive straw raking and fertilizer source (inorganic or organic) on nitrogen (N) cycling and soil carbon (C) quality. Monthly in situ soil N mineralization, total N and C concentrations, and end-of-season soil labile C concentrations were measured in response to: (1) annual straw raking for 4 years, (2) annual straw raking and fertilization with inorganic fertilizer for 4 years, and (3) annual straw raking and fertilization with broiler poultry litter application for 4 years. Straw raking led to significant increases in N mineralization. Significant increases in N mineralization larger than those from straw raking alone occurred in response to both fertilization treatments, whereas N was immobilized in response to unfertilized treatments. Applying poultry litter annually to raked soil increased soil C, N, and labile C concentrations and thus reduced the soil C to N ratio. However, application of poultry litter did not raise N mineralization above that found in response to fertilization with inorganic fertilizer. Total soil N concentrations were highest in response to poultry litter application, suggesting that N applied with this fertilizer source was better retained within soil than with inorganic fertilizer. Application of inorganic fertilizer reduced the potential C turnover rate to levels below those of all other treatments. Poultry litter may be superior to inorganic fertilizer in maintaining nutrition of frequently raked loblolly pine plantations because it more readily increased soil N availability and labile C critical in soil nutrient turnover. Inorganic fertilizer, by contrast, increased the potential turnover of C in the soil.

Parent Publication

Citation

Ellum, K.; Liechty, H.O.; Blazier, M.A. 2013. Intensive straw harvesting, fertilization, and fertilizer source affect nitrogen mineralization and soil labile carbon of a loblolly pine plantation. In: Guldin, James M., ed. 2013. Proceedings of the 15th biennial southern silvicultural research conference. e-Gen. Tech. Rep. SRS-GTR-175. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 473-474.
https://www.fs.usda.gov/research/treesearch/43915