Douglas M. Stone

Soil properties and aspen development five years after compaction and forest floor removal

Forest management activities that decrease soil porosity and remove organic matter have been associated with declines in site productivity. In the northern Lake States region, research is in progress in the aspen (Populus tremuloides Michx. and P. grandidentata Michx.) forest type to determine effects of soil compaction and organic matter removal on soil properties and growth of aspen suckers, associated woody species, herbaceous vegetation, and on stand development. Four treatments: (1) total tree harvest (TTH); (2) TTH plus soil compaction (CPT); (3) TTH plus forest floor removal (FFR); and (4) TTH plus CPT + FFR were applied after winter-harvest of a 70-yr-old aspen stand growing on a loamy sand with a site index(age50) of 20.7 m. The CPT treatment significantly increased bulk density and soil strength of the surface 30 cm of soil and neither have recovered during the 5 yr since treatment. The CPT plots had 19.6 thousand (k) suckers ha−1, less than half that of the TTH and FFR treatments; mean diameter...

Sorption of hexazinone, sulfometuron methyl, and tebuthiuron on acid, low base saturated sands

The objective of this research was to determine the sorption of hexazinone, sulfometuron methyl, and tebuthiuron on six acid, low base saturated sands as a function of depth. Sorption Kd values for tebuthiuron on these soils ranged from 0.002 to 3.6 L kg−1 with greatest sorption on soils from the surface 0–5 cm depth and least on soils from depths > 65 cm. Sorption is correlated to OC content of the soil; mean Koc = 39 ± 22 L kg−1. Hexazinone Kd values ranged from 0.0011 to 1.10 L kg−1. Sorption is correlated to soil OC; mean Koc = 19 ± 13 L kg−1. Kd for sulfometuron methyl sorption to soils of 0–20 cm depths ranged from 0.04 to 0.6. Sorption of sulfometuron methyl on soil from depths 65–95 cm was less than in the surface soils and was approximately equal to that of tebuthiuron at the same depth. In contrast to tebuthiuron and hexazinone, using data for all soils and from all depths, sorption did not correlate to OC content. It appears that factors affecting sorption change with soil depth. For instance, sorption is correlated to OC for surface soils (0–20 cm depths), Koc = 5.4 ± 3.4, and for subsurface soils (65–95 cm depths), Koc = 44 ± 22. It appears that once these three herbicides leach past the top 10 cm of these soils, retardation of the herbicides would be slight.

Using column lysimetry to evaluate acid precipitation effects.

Describes methodology for collecting, instrumenting, and measuring acid soils using soil columns as lysimeters and reports the effects of varying acid precipitation and litter-humus treatments.

Ion movement in acidified, low base saturated sand soils.

Describes factors causing cation export in leachate in low base saturated forested sand soils. Reports the effects of varying acid precipitation and litter-humus treatments on ion movement and interaction.

Curly needle syndrome of loblolly pine seedlings

Curly shaped needles developed on loblolly pine (Pinustaeda L.) seedlings grown in lysimeters in two greenhouse studies. Nearly 80% of the seedlings from five half-sib families developed curly needles when watered weekly with one of four acid rain solutions. No abnormal needles developed on seedlings from the same seed lots growing on an adjacent bench and watered daily. In a second study, curly needles developed within 2 weeks after seedlings were transplanted into the lysimeters. Weekly misting of the foliage significantly reduced the proportion of fascicles with curly needles. Results indicate that curly needle syndrome is induced by water stress during needle elongation and suggest that wetting the foliage decreases the strength of the fascicle sheaths.