A. J. Turgeon

Microbial activity in soil and litter underlying bandane- and calcium arsenate-treated turfgrass

Abstract Microbial abundance and activity were examined in soil and litter under Kentucky bluegrass turf that received four annual applications of 39.2 kg ha −1 of bandane (polychlorodicyclopentadiene) or 439 kg ha −1 of calcium arsenate. No consistent effect of either herbicide on bacterial numbers was observed and fungal numbers were unaffected compared to control plots that received no herbicide. Amylase and invertase activities were significantly higher in undecomposed residues from treated plots. The rates of glucose utilization, nitrification of ammonium, and amylase synthesis were significantly lower in soil underlying treated turf than in control soil. The amount of undecomposed plant material was greatest in arsenate-treated plots in which microbial activity was most severely affected, suggesting that the increased residue accumulation was the direct consequence of a reduction in soil microbial activity.

Determination of Soil Separates with near Infrared Reflectance Spectroscopy

The use of near infrared (NIR) reflectance spectroscopy to evaluate soil properties has started to receive more attention in recent years. The technology is evolving and research on NIR spectroscopic analysis using natural state samples is increasing. There is no method available today, besides NIR spectroscopy, that could simultaneously evaluate physical and chemical properties of a soil sample without processing the sample and affecting the visual quality of the site. More samples can be scanned in their natural undisturbed form resulting in a variety of particle sizes. Research on the effect of scanning products with different particle sizes is essential. The differences in the particle size of the soil separates may lower the prediction accuracy of NIR spectroscopy. In this study, we evaluated the ability of NIR spectroscopy to predict soil separates from artificial soil samples. Feldspar and silica sands and silts, kaolinite and montmorillonite clays, and reed sedge and Canadian sphagnum peat moss organic matters were used as separates. They were scanned alone, and in different mixture percentages, from 400 to 2500 nm with a total of 116 samples. The absence of linearity in the binary mixtures, preventing accurate calibration, was noticed and required the development of a transformation model to generate new laboratory values from a laboratory weight scaling factor generated for each soil separate. The adjustment of the laboratory values improved the prediction accuracy of the mixtures. The coefficient of determination ranged from 0.95 to 0.99. The standard error of cross-validation ranged from 2.09 to 5.82%.

Composition of turfgrass thatch

Abstract In many intensively cultured turfs, thatch, an organic layer of leaves, stems, and roots, that develops above the soil surface, is recognized as a potentially serious problem. This study evaluated the constituents of turfgrass thatch in terms of organic matter (OM), cellulose, and lignin content. Ten samples were analyzed containing two or three layers of 2‐cm thick for a total of 30 layers. As thatch layers may often include mineral matter, a technique was developed to separate the OM from any mineral particles in the samples. An important loss of OM was observed during the separation process. Despite problems encountered during the constituent analyses due to the heterogeneity of the samples and the presence of mineral matter, results showed a significant increase in lignin content with depth.

Vertical soil water retention in newly‐sodded, drained turfgrass sites a

Abstract Drained golf greens, athletic fields, and various other turfgrass planting sites are frequently backfilled with specially‐prescribed coarse or very coarse‐textured root growth media to compensate for the effects of the shallow (20 to 50 cm deep), perched water table which forms at the drainage level. These areas are often planted with sod grown on much finer‐textured soils. This study examined the water retention in such nonhomogenous soil profiles following irrigation and drainage. Water retention in such a drained soil profile was predicted from moisture characteristics of a backfill medium (5 parts very coarse‐textured river sand plus 1.25 parts silty clay loam soil), a muck soil, and Drummer silty clay loam and confirmed by water content measurements on laboratory columns duplicating drained, sodded turfgrass sites where the sod was grown on a muck or silty clay loam soil. Both the muck and silty clay loam sod‐soil layers remained essentially saturated following irrigation and 48 hours draina...