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Project Details:
Methodology
Justification
This draft proposes that a fertilizer trial (3 to 4 replications in a randomized complete block design) using NP, NPCu, NPKCu, and NPKSCu and an untreated control be installed in one of Chuck Leavell's thinned loblolly pine stands that has marginal fertility. The major objectives: (1) quantify the magnitude and duration of wood volume response to the fertilizer combinations, (2) determine changes in product class distribution and (3) the cash flow and rate of return for each fertilizer combination compared to unfertilized control plots, and (4) discern when fertilizers are to be re-applied to maintain wood volume gain.
The proposed project duration is 5 years. Seven thinned loblolly pine stands have been located on Chuck Leavell's property that are NP, NPCu, NPKCu or NPKSCu deficient.
Gross treated plots (147.6 x 147.6 feet, or 0.5 acres) and internal permanent measurement plots (104.5 x 104.5 feet or 0.25 acres) will be installed in the delineated soil series area. Forty feet of untreated buffer will be between each gross treated plot. Replications (blocks) will be laid out on the contour to minimize soil moisture differences. Baseline soil (10 to 20 samples to make a composite sample, with one composite sample /plot @ 0-8") and foliar samples will be taken in each plot prior to treatment. Initial stand and plot leaf area index (LAI) will be estimated using the NCSU protocol in midsummer. Foliage samples (3 dominants/plot, upper 1/3 crown, south side, first flush of previous year’s growth to represent each composite sample/plot) will be taken each dormant season. Soil and foliage analysis will include N (foliage only), P, K, Ca, Mg, S, Cu, Mn, Zn, and B. Soil pH for each plot will also be determined. All living crop trees in each plot will be aluminum tagged, numbered and measured for dbh and total height prior to treatment. Live crown ratio of all living trees/plot will be measured prior to treatment.
Randomly assigned to each plot will be a NP, NPCu, NPKCu, or NPKSCu fertilizer treatment. Untreated control plots will serve reference plots. The one-time fertilizer application levels in the thinned loblolly pine stand will be 200 lbs N/acre + 40 lbs elemental-P + 80 lbs elemental-K + 60 lbs S and 5 lbs Cu/acre. Application timing of fertilization will be targeted for late winter (February-March) to minimize N losses. Forest soil and foliage sampling will occur each subsequent winter following treatment, and LAI estimated at peak expression in midsummer following treatment. Total height and dbh will be remeasured every other winter to determine diameter class distribution, volume/tree, and volume/acre by product class. Live crown ratio of all trees/plot will also be measured every other winter.
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