Soil moisture and temperature are two important soil parameters that influence many vital agronomic, environmental, engineering processes within the soil. Due to the difficulties arising when measuring these parameters in the field as well as the cost of instrumentation, many models that yield accurate and timely estimation of these parameters on a large scale have been developed as reliable and efficient alternatives. The Versatile Soil Moisture Budget model can be used to stimulate the vertical, one dimensional, water balance in a soil profile. Originally the model was designed to use air temperature and precipitation data to simulate soil water content within the root zone of a cereal crop. It has since undergone modifications and the model can now output, potential evapo-transpiration, actual evapo-transpiration, and surface temperature. The temperature algorithm simulates temperature at the soil surface and has not been rigorously tested for cropping systems. In this study, a simple empirical equation that simulates soil temperature at depth of up to 90 cm was introduced into the model. The model was evaluated and the accuracy of predicted soil moisture and temperature under both perennial and annual cropping systems were tested using two years of data collected at the University of Manitoba Research Station at Carman using soil water and temperature probes. The model’s accuracy in simulating soil moisture was also tested. Observed R2 comparing modelled temperature with observed was greater than 0.90 at the soil surface but decreased to about 0.40 at soil depth greater than 30-45 cm layer. The model was shown to be better at estimating soil temperature than soil moisture. The accuracy of the model was also shown to decrease with depth. These results can be used to improve soil temperature modeling at depth as well as improve farm management planning, irrigation schedules, nutrient management, fertilizer application and drought monitoring. / October 2015

Thesis (MSc)--Stellenbosch University, 1983. / ENGLISH ABSTRACT: No abstract available / AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar

Thesis (M.S.)--Ohio State University, 1955. / Includes bibliographical references (leaves 41-42). Available online via OhioLINK's ETD Center

Thesis (M.S. - Soil and Water Science)--University of Arizona, 1984. / Includes bibliographical references (leaves 63-66).

<p> During the spring and summer months of 1967, measurements of the temperature and moisture regimes under a control, and lamp black, white talc, and straw mulch surface treatments, on a fine sandy loam, and a sandy clay loam, were undertaken. The sites were the McMaster University campus, and the Arboretum of the Royal Botanical Gardens in Hamilton, Ontario.</p> <p> A description of the experimental procedures is presented in Chapter II. Chapter III discusses the regimes of soil temperature and moisture - content; and also the effects of clear and cloudy skies, and rain on soil temperatures.</p> / Thesis / Master of Arts (MA)

No description available.

No description available.

Soybean (Glycine max L. Merr.) planting date and plant density are agronomic decisions made simultaneously at the beginning of the growing season that can be used to maximize yield and economic return. Research on these basic soybean agronomic decisions must be conducted to support the expansion of soybean production in northern growing regions of the Northern Great Plains (NGP). The objectives of this study were to evaluate the effects of planting dates based on soil temperature on soybean emergence, maturity, and yield for short and long season varieties in Manitoba, and to determine optimum soybean plant density for early to very late planting dates in northern growing regions of the NGP. In the first experiment, calendar date had a greater influence than soil temperature at planting on soybean yield. Soybean yield declined with later planting rather than increasing soil temperature at planting. The earliest planting dates resulted in the greatest soybean yields. In the second experiment, soybean yield-density relationships were responsive to planting date. Yield-density relationships formed early/mid (May 4 to 26) and late/very late (June 2 to 23) planting date groups for combined site years. Early/mid planting dates resulted in greater maximum yields. According to the yield-density model, true yield maximization did not occur for any planting dates and site years within the range of plant densities tested in this field study. Soybean economic optimum seed densities (EOSDs) were much lower than predicted plant densities that maximized yield. Soybean EOSDs were identified as 492,000 and 314,000 seeds ha-1 by marginal cost analysis for early/mid and late/very late planting, respectfully. These values were sensitive to changes in soybean grain price and seed cost. Thus, growers need to adjust EOSDs for changes in price and cost. A combined analysis of soybean yields from both experiments using similar target plant densities determined that a significant negative linear relationship existed between soybean yield and planting date. The greatest soybean yields resulted from early planting and declined by 16 kg ha-1 for each one-day delay in planting from Apr 27 to June 16. However, yield responses varied among site years. The overall recommendation from this study would be to plant soybeans during the month of May at a profit-maximizing seed density, accounting for fluctuating grain price and seed cost. / May 2017

This research tested the hypotheses that (a) suboptimal root-zone temperatures (RZT) limit the soybean-Bradyrhizobium N$ sb2$-fixing symbiosis primarily through an inhibition of symbiosis establishment and (b) this inhibition is modified by the genotype of micro- or macrosymbiont. Controlled environment and field experiments were conducted utilizing two soybean genotypes and six B. japonicum strains. At 19$ sp circ$C RZT fixed nitrogen levels decreased by 30-40%, predominantly due to a restriction in the latter stages of nodule development. Reductions of 10% and 30% in specific nodule activity rates at 19$ sp circ$C and 15$ sp circ$C RZT respectively, indicated nodule function to be comparatively insensitive to low RZT. Soybean genotypes did not differ in seedling nodulation or N$ sb2$-fixation under cool-soil, field or controlled environment, conditions. At all temperatures, commercial B. japonicum strain 532C was more efficient, but not effective, than strains obtained from the cool-soils of Northern Japan. Under cool-soil field conditions, two of the latter strains increased seedling nodulation and N$ sb2$-fixation.

Thesis (M.S. - Soils, Water and Engineering)--University of Arizona, 1985. / Includes bibliographical references (leaves 127-132).