Daily Maximum Soil Temperatures Research Articles

Weed Suppression by Live and Desiccated Hairy Vetch (Vicia villosa)

Hairy vetch was grown as a winter annual cover crop and evaluated for weed suppression when desiccated by paraquat or left alive until natural senescence in a 3-yr field experiment. Total weed density and biomass were variable in the desiccated hairy vetch treatment relative to a bare soil treatment but were consistently lower in the live hairy vetch treatment relative to the desiccated or bare soil treatments. An average of 87% of sites under live hairy vetch compared to 8% of sites under desiccated hairy vetch transmitted less than 1% of unobstructed sunlight. The red (660 nm) to far-red (730 nm) ratio of transmitted light was reduced by 70% under live hairy vetch compared to 17% under desiccated hairy vetch. Daily maximum soil temperature and diurnal soil temperature amplitude were reduced by live hairy vetch > desiccated hairy vetch > bare soil. Soil moisture content was greater under both live and desiccated hairy vetch compared to bare soil during droughty periods. Changes in light extinction, red to far-red ratio, and diurnal soil temperature amplitude were sufficient to explain greater weed suppression by live than desiccated hairy vetch.

Ammonia Volatilization from Urea as Influenced by Soil Temperature, Soil Water Content, and Nitrification and Hydrolysis Inhibitors

AbstractResidue cover influences temperature and water gradients in the soil profile. Changes in the physical environment of the soil influence NH3 volatilization from urea‐containing fertilizers. Field and laboratory experiments were conducted to investigate the influence of residue‐cover‐induced changes in soil water and temperature on NH3 volatilization as impacted by urea treatment with a nitrification and urease inhibitor. Fertilizer treatments were urea, urea plus dicyandiamide (DCD), urea plus N‐(n‐butyl)thiophosphoric triamide (NBPT), and urea plus NBPT and DCD. Following fertilizer application, the soil was either left bare or covered with corn (Zea mays L.) residue. Every 3 h over a 4‐d period, water potential, soil temperature, CO2 production, and NH3 volatilization were measured. The influence of fertilizer treatments on soil pH was determined in a laboratory incubation experiment conducted over 8 d under controlled environmental conditions. Treatments were similar to the field experiment, with NH3 volatilization, pH, and CO2 production measured daily. The NH3‐volatilization rate in the field was highest 2 d after urea application at a time that corresponded with daily maximum soil temperature and decreasing soil water content. Residue cover reduced NH3 volatilization. Volatilization of NH3 as a result of urea application was not increased when urea was treated with DCD. Ammonia volatilization as a result of urea treatment with NBPT was reduced by 100 times over untreated urea. During an incubation experiment, soil pH increased from 6.5 to 7.2 in the urea‐NBPT, and from 6.5 to 9.0 in the urea and urea‐DCD treatments. Associated with the pH increase in the urea‐NBPT treatment was a reduction in CO2 production when compared with the untreated soil.

Drainage - tillage effects on crosby-kokomo soil association in Ohio II. Soil temperature regime and infiltrability

Effects of subsurface drainage on soil temperature regime and water infiltrability were evaluated for four tillage methods: ridge till, permanent beds, conventional tillage and no-till. Soils of the experimental site near Columbus, Ohio belong to the Crosby-Kokomo Association, and are classified as fine, mixed, mesic, Aeric Ochraqualf and fine, mixed, mesic, Typic Argiaquall, respectively. The mean daily maximum soil temperature, measured in early spring, was highest on top of the undrained ridges. The mean daily maximum soil temperature was significantly higher at a distance 27 m away from the drain than in the vicinity of the drainline. Ridge-tillage and raised beds farther away from the drain had higher maximum temperature than plow-till or no-till methods of seedbed preparation. The minimum soil temperature was not affected by drainage. Infiltrability, measured in terms of accumulative infiltration; infiltration rate; sorptivity and transmissivity was significantly affected by tillage but not by drainage. The least value of these infiltration parameters was observed for the conventional plow-till system.

Soil temperature effects of biomass burning in windrows after clearing a tropical rainforest

Measurements of soil temperature at several depths were made during and after biomass burning in windrows following clearing of a primary rainforest in southern Nigeria. The dried biomass was collected in four windrows 10 m wide and 50 m long in a 1-ha plot. Each windrow contained 494 ± 60 kg m −2 of fuel that formed a 30–50-mm-thick layer of ash on the surface after burning. Visible flames and smouldering lasted for 2 h followed by 24 h of combustion of big logs. During burning, the maximum soil temperatures rose to 218, 150, 104, and 70°C at 1, 5, 10, and 20-cm depths, respectively. Daily maximum soil temperatures measured at 1-cm depth 10 months after burning (during the dry season) were higher at the burnt than the unburnt site in a bare plot. During periods of low soil-moisture content, differences in the maximum soil temperatures at these two sites decreased. Soil temperatures measured 18 months after burning (during the rainy season) were nearly similar at the two sites.

Soil Physical Properties of Tied Ridges in the Sudan Savannah of Burkina Faso

SUMMARYThe soil physical properties of tied ridges were measured in a trial, established in 1983, comparing three treatments: handhoe cultivation and planting on the flat; planting directly without any cultivation on tied ridges constructed the previous year; and handhoe cultivation and remoulding of tied ridges constructed the previous year. Two maize varieties and two management levels were used. The soil properties monitored were particle size distribution, penetro-meter resistance in the surface 20 mm, bulk density, water infiltration, soil water retention and soil temperature.Soil physical properties were affected mainly by the type of seedbed. Clay content in the surface 0.05 m was greater with tied ridging, with that in the furrows being higher than that in the ridge slopes. Daily maximum soil temperature was greatest in the flat planted plots and in the ridge slopes of the tied ridged plots. Penetrometer resistance at a soil water content of 0.05 kg kg−1 was greater in the tied ridged plots. Cumulative infiltration after 2 h was greatest with flat planting. The bulk density of ridge slopes in tied ridged plots was less than that in the furrows and in the flat planted plots. Soil water retention was greatest in the furrows of the tied ridged plots. Clay content was the major factor determining all the soil physical properties measured.

A mathematical model of the population dynamics of the lesser cornstalk borer, Elasmopalpus lignosellus

A simulation model was developed for the population dynamics of the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Leipdoptera: Pyralidae), in sandy loam soil. The model includes: temperature-dependent growth of E. lignosellus eggs, larvae, pupae, and adult age; temperature and age-dependent oviposition; and soil moisture-dependent mortality of eggs and larvae. Egg, larval, pupal and adult survivorship are also incorporated. Analyses were conducted to determine the model's sensitivity to changes in selected parameters. Sensitivity analysis simulations without rainfall indicated the model was most sensitive to the interaction of the proportion of adult females in each of three age classes by the oviposition and developmental thresholds, indicating adult biology must be very accurately estimated for model predictions to be accurate. One main effect (degree-day requirements for E. lignosellus eggs, larvae, pupae, preoviposition, and longevity) ranked in the four most influential effects. Two main effects were highly ranked in the sensitivity analyses with simulated rainfall: (a) parameters in the sixth-order polynomial for calculation of the oviposition rate; and (b) parameters in the two-independent-variable polynomial used to calculate the daily maximum soil temperature for degree-day computation. Thus, adult biology and soil temperature parameters must be accurately estimated for the model to function under rainy conditions. Both of these effects ranked ⩽ 3rd in the analyses with rainfall.

A note on the effect of bitumen mulch on soil temperature and forage maize production

Bitumen mulch sprayed over maize drills in 15 to 20 cm bands 1 to 2 mm thick increased average daily maximum soil temperatures at 10 cm depth in May and June 1975 by 0.7°C and 1.3°C, respectively. There was no significant effect of bitumen mulch on either seedling emergence, silking date or final yield and dry matter percentage.