In situ infiltration as influenced by cover crop and tillage management

Water is usually the most limiting factor in agricultural grain crop production. Various agricultural management practices such as tillage and use of cover crops have the potential to influence water infiltration into soil. This study was conducted on a Waldron silt loam (fine, smectictic, calcareous, mesic Aeric Fluvaquents) soil to evaluate the influence of cover crop and tillage management on in situ infiltration. The field site included three replicate blocks in a randomized complete block design with each plot measuring 21.3 m (69.9 ft) length and 12.2 m (40.0 ft) width. The two treatment factors included cover crop at two levels (cereal rye [Secale cereale] cover crop [CC] versus no cover crop [NC]) and tillage at two levels (moldboard plow tillage [Till] versus no-tillage [NT]). Continuous corn (Zea mays L.) was grown. Infiltration rates were measured in all the treatments using a Mariotte system with single ring infiltrometers during the 2014 and 2015 growing seasons. Water infiltration parameters were estimated using the Parlange and Green-Ampt infiltration equations. Parlange and Green-Ampt models appeared to fit measured data well with coefficient of variation ranging from 0.92 to 0.99. In 2014, the saturated hydraulic conductivity (KS) parameter value determined from the Parlange model was 30.4 mm h-1 for NT, about 42% greater than Till. The KS parameter value determined from the Green-Ampt model was 25.9 mm h-1 for NT, about 54% greater than Till. In 2015, the sorptivity (S) parameter value determined from the Parlange model was 38.6 mm h-0.5 for CC, about 82% greater than NC. The S parameter value determined from the Green-Ampt model was 34.0 mm h-0.5 for CC, about 90% greater than NC. Cover crop management can increase water infiltration, which can improve soil quality and enhance the sustainability of crop production systems

The Fate of Methylcyclohexane Methanol in Soil and Effect on Enzyme Activity

Methylcyclohexane methanol (MCHM) is the chemical that leaked into the Elk River, in Charlestown, West Virginia on the 9th of January, 2014, causing state of emergency called for use of drinking water contaminated with the chemical. Methylcyclohexane methanol is an organic compound classified as a saturated higher alicyclic primary alcohol. It is commonly used in air fresheners and as frothing agent for coal processing and cleaning. The full toxicity of this chemical to humans was unknown at the time of spill and there is still lack of information on exact toxic effects of the crude MCHM. In a recent study it was determined that the MCHM can cause damage to human DNA and potentially cause cancer and reproductive problems. Soils are ultimate recipient of all kinds of contaminates from different sources. There is a need to study and investigate the properties of the MCHM in water and soil especially with the crude MCHM. If released to soil, MCHM is expected to have very high mobility. Volatilization from moist soil surfaces is expected to be an important fate process. To determine toxicity of this chemical on soil biological properties, we measured beta-glucosidase activities in soil treated with different rates and incubated for periods of one hour to 4-weeks. Results indicated that in short term enzyme activity was inhibited by MCHM

Effect of Silver Nanoparticles on Select Soil Enzyme Activities Involved in Nutrient Cycling

Soils are being continuously exposed to large amounts of engineered nanoparticles (ENPs), especially silver nanoparticles (AgNPs). These materials can interact with microbial enzyme activity, stability and/or specificity affecting their role in nutrient cycling. Specific enzyme activity measurements have potential to serve as bioindicator in identifying major changes in the soil environment. Present study investigated the effect of AgNPs on soil enzymes known to play a critical role in mineralization of C, N, P and S in the soil. Soil samples were collected from surface layer (0-10 cm) of a Wrengart silt loam series. The study used two sizes (10 and 50 nm) and treatment included two rates (1.6 and 3.2 mg Ag/kg of dry soil) of silver nanoparticles and a control without AgNP application in a randomized complete design, replicated three times. The solution of AgNP was applied to the soil and mixed until homogeneously distributed. Acid Phosphatase, β-Glucosaminadase, β-Glucosidase and Arylsulfatase activities were measured after 1-hr, 1-week, and 1- month of incubation time. All four enzymes showed a decrease in activity after treatment with silver nanoparticles at 1-hr and 1-week incubation period compared to control. In this study there was some difference, though not highly significant, in the effect on enzyme activity between the two sizes used (10nm and 50nm)