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Rapid indices of potential nitrogen mineralization for intensively managed hardwood plantations

Informally Refereed

Abstract

Short-rotation hardwood plantations generally require repeated applications of nitrogen (N) fertilizer to maintain desired growth and are being installed on two previous land uses: agricultural fields and cutover forest lands. Because the soil organic matter chemistry is different between agricultural field and cutover soils, indices of N availability developed for one land use or the other may not work well across both land use types. The standard aerobic incubation index is time consuming and costly. Therefore, three rapid methods were tested for estimating it on six converted agricultural fields and seven cutover pine sites currently in intensively managed sweetgum plantations on the eastern coastal plain of the United States. Two procedures (anaerobic incubation and hot KCl extract) were not useful for estimating mineralizable N in either agricultural field soils or cutover pine soils. The third index, a 3-day incubation of rewetted soils previously dried, was linearly correlated to mineralizable N (p , 0.0001, R2 = 0.88). This method, which had not been tested in forest soils previously, worked best for the cutover soils (p , 0.002, R2 = 0.82) and less so for the agricultural field soils (p , 0.097, R2 = 0.66). However, none of the procedures estimated potentially mineralizable N better, across all sites, than total N (p , 0.0001, R2 = 0.93). Total N was not effective, however, in estimating mineralizable N within the agricultural field sites (p , 0.220, R2 = 0.44). Further work will be needed to assess if potentially mineralizable N, total N, or the drying-rewetting index can be used to help predict fertilizer rates and timings in intensively managed hardwood plantations, especially on cutover forest lands.

Keywords

Nitrogen availability indices, nitrogen mineralization potential, land-use history, short-rotation woody crops

Citation

Scott, D. Andrew; Norris, Alixanna McLearen; Burger, James A. 2005. Rapid indices of potential nitrogen mineralization for intensively managed hardwood plantations. Communications in Soil Science and Plant Analysis, 36: 1421–1434, 2005
https://www.fs.usda.gov/research/treesearch/20512