Douglas A. Wysocki

Predicting ECe of the saturated paste extract from value of EC1:5

He, Y., DeSutter, T., Hopkins, D., Jia, X. and Wysocki, D. A. 2013. Predicting ECeof the saturated paste extract from value of EC1:5. Can. J. Soil Sci. 93: 585-594. Many laboratories appraise soil salinity from measurement of electrical conductivity of 1:5 soil to water extract (EC1:5) due to its simplicity. However, the influence of salinity on plant growth is mainly based on electrical conductivity of saturated paste extract (ECe), so it is necessary to convert EC1:5 to ECe in order to assess plant response. The objectives of this research were to develop models relating EC1:5 and ECe under four different 1:5 equilibration methods: (1) shaking, (2) shaking plus centrifuging, (3) stirring, and (4) a United States Department of Agriculture-Natural Resources Conservation Service (2011) equilibration method. One hundred soil samples, which were all derived from glacial parent materials in North Dakota, USA, were selected for this study. Non-transformed, non-transformed separated, ln-transformed, and exponential models were developed between EC1:5 and ECe. Non-transformed, simple linear regression models had obvious segments for all equilibration methods and the residual distributions varied. Therefore, data were separated at EC of 4 dS m-1 and a quadratic curvilinear model was developed for relating EC1:5 and ECe (r2 values ranged from 0.87 to 0.93) when ECe values were less than 4 dS m-1. Although the linear model was significant (P<0.05), soils having ECe greater than 4 dS m-1 had r2 values less than 0.61. Across all soils, the ln-transformed model had r2 values greater than 0.85, which was greater than the non-transformed or exponential models. By comparison of r2, RMSE, and relative percentage difference, the separated curvilinear model that was established when salinity is less than 4 dS m-1, and ln-transformed models were superior at predicting ECe from EC1:5 data compared to non-transformed and exponential models. These results indicate that across all equilibration methods ECe can reliably be predicted from EC1:5 data for soils from this region.

Drought drove forest decline and dune building in eastern upper Michigan, USA, as the upper Great Lakes became closed basins

Current models of landscape response to Holocene climate change in midcontinent North America largely reconcile Earth orbital and atmospheric climate forcing with pollen-based forest histories on the east and eolian chronologies in Great Plains grasslands on the west. However, thousands of sand dunes spread across 12,000 km 2 in eastern upper Michigan (EUM), more than 500 km east of the present forest-prairie ecotone, present a challenge to such models. We use 65 optically stimulated luminescence (OSL) ages on quartz sand deposited in silt caps (n = 8) and dunes (n = 57) to document eolian activity in EUM. Dune building was widespread ca. 10–8 ka, indicating a sharp, sustained decline in forest cover during that period. This decline was roughly coincident with hydrologic closure of the upper Great Lakes, but temporally inconsistent with most pollen-based models that imply canopy closure throughout the Holocene. Early Holocene forest openings are rarely recognized in pollen sums from EUM because faint signatures of non-arboreal pollen are largely obscured by abundant and highly mobile pine pollen. Early Holocene spikes in nonarboreal pollen are recorded in cores from small ponds, but suggest only a modest extent of forest openings. OSL dating of dune emplacement provides a direct, spatially explicit archive of greatly diminished forest cover during a very dry climate in eastern midcontinent North America ca. 10–8 ka.

Nonpoint source of nitrogen contamination from land management practices in Lost River basin, West Virginia.

Poultry production in Hardy County, West Virginia, has increased considerably since the early 1990s. The Lost River basin contains the highest density of poultry facilities in the county. Most of the N-rich poultry litter produced is land applied, and concerns over water quality are widespread. The objective was to apply the Natural Resources Conservation Service exploratory technique on two watersheds (Cullers Run and Upper Cove Run) in the Lost River basin to estimate the loss of nitrate-N from soils by runoff and leaching and to predict the impact on water quality. The predicted annual nitrate-N loss by runoff was 192 Mg, whereas that by leaching was 764 Mg, and their combined amount represented the annual loading for the Lost River. The predicted averages of nitrate-N concentration in runoff and leaching water were 2.57 and 45.1 mg/L, respectively. These data would give an estimated average nitrate-N concentration of 10.4 mg/L in the Lost River. The observed nitrate-N concentration in 12 monthly samples collected from the Lost River ranged from 2.41 to 19.9 mg/L, with an average of 7.11 mg/L (S.D., 4.68 mg/L). The relatively low nitrate-N concentrations observed in the river could be attributed to assimilation by algae, weeds, and aquatic plants, as well as denitrification in stream water under anaerobic conditions. When factors affecting N concentration in streams are considered, the technique could estimate the impact on water quality. We concluded that the exploratory technique could provide a quick estimation and identify hot spots for large areas of agricultural land. Thus, lengthy and site-specific studies could be focused on certain areas of high risk.

Effects of Land Use on Selected Properties and Heavy Metal Concentration for Soil in the US Great Plains

ABSTRACT There is increasing interest in the current conditions of dynamic soil properties and element concentration in the US Great Plains as well as the nature and magnitude of change due to land use and management practices. The study was conducted on Pawnee soil, a major U.S. benchmark soil in the Great Plains. The objectives were to investigate the effects of four common land uses [NoTill (NT), Conventional Till (CT), Grass (G), and Conservation Reserve Program (CRP)] on: i) selected soil properties [total organic carbon (TOC), bulk density (BD), pH, cation exchange capacity (CEC), and electric conductivity (EC)] and ii) water-soluble concentration of 14 heavy metals and micronutrients. The analysis of variance (ANOVA test) indicated that the land use had significant effects on the TOC, CEC, and EC, whereas no relation was detected for BD and pH. Irrespective of land use, the mean element concentration in soil could be arranged in the order: Si (Silicon) > Al (Aluminum) > Fe (Iron) > Mn (Manganese) > B (Boron) > Zn (Zinc) > Cr (Chromium) > Ni (Nickel) > Cu (Copper) > As (Arsenic) > Pb (Lead) > Co (Cobalt) > Mo (Molybdenum) > Cd (Cadmium). Silicon, Al, and Fe which are usually form the major components of soil minerals were present in much higher levels (91 to 308 mg/kg) than other elements in soil. Essential plant micronutrients such as B, Cu, Mn, Mo, and Zn, generally presented moderate levels in soil (7 to 698 µg/kg), whereas toxic heavy metals such as As, Cd, Co, Ni, and Pb were present in the lowest values (0.7–96.2 µg/kg). The ANOVA test indicated land use had significant effects on As, B, Cd, Co, Cu, Ni, and Si concentration in soil while effects were insignificant for other elements. The data proved the important effects of land use on dynamic soil properties as well as nutrient and heavy metal for a major benchmark soil. Thus, more studies on other major soils are warranted. The information is needed to modify and adapt management practices to improve and sustain soil health and water quality in the US Great Plains.