Thermal infrared research: Where are we now?

The use of infrared temperatures in agriculture and hydrology is based on the energy balance equation which is used to estimate evapotranspiration and crop stress over small areas within a field as well as large areas. For its full utilization, this measurement must be combined with other spectral data collected at a time resolution sufficient to detect changes in the agricultural or hydrological systems and at a spatial resolution with enough detail to sample within individual fields. The most stringent requirement is that the data be readily available to the user. The spatial resolution necessary for IR measurements to be incorporated into evapotranspiration models to accurately estimate field and regional transpiration or measure crop stress; methods to estimate crop stress and yield over large areas and different cultivars within a species; the temporal resolution adequate for detecting crop stress or inclusion in evapotranspiration models; and ancillary parameters for estimating thermal IR measurements must be investigated

Soil Tilth and Sustainable Agriculture

Soil tilth is defined as the physical condition of soil as related to its ease of tillage, fitness as a seedbed, and its impedance to seedling emergence and root penetration. Sustainable agriculture has been defined in Iowa as the appropriate use of crop and livestock systems and agricultural inputs supporting those activities which maintain economic and social viability while preserving the high productivity and quality of Iowa\u27s land. Thus, it is not possible to discuss sustainable agriculture without considering soil tilth. Development of a sustainable agricultural system requires a viable and stable soil resource, so we will explore linkages between the two concepts

Climate Change and the Potential Impact on the Soil Resource

Climatic change will lead to changes in the carbon dioxide C02, temperature, and precipitation. There have been many predictions of the effect of climatic change on plant growth but none on the soil parameters or water use. To fully understand the implications on soil management from climate change the expected changes in soil temperature, water use, and water and nutrient use efficiency need quantification

Factors Affecting Agricultural Chemical Losses to Surface and Ground Water Resources

The major chemical factors determining concentrations and losses of agricultural chemicals from cropland are their persistence and adsorption to soil. The major hydrologic factors are rate and route of infiltration. The major management factors are the rate, method, timing, and choice of applied chemicals; cropping; and tillage system. To determine the Best Management Practices (BMPs) to reduce chemical losses, their mechanisms of interactions with the soil and management practices must be understood. Depending on soil adsorption, pesticides and nutrients can be mostly lost with surface runoff water, sediment, or water percolating out of the root zone (water which may return to the surface through base flow or artificial subsurface drainage). Erosion control is a BMP for strongly adsorbed chemicals. For moderately adsorbed chemicals, soil incorporation is a BMP that reduces the amount of chemical in the thin surface soil mixing zone and reduces surface runoff losses. BMPs that enhance infiltration also reducesurface runoff losses. The route of infiltration (e.g., through macropores ) can allow chemicals to percolate through the root zone more quickly than normally expected, resulting in concentration spikes . However, for moderately adsorbed chemicals, leaching losses are usually much lower than with surface runoff. For weakly or non-adsorbed chemicals, primarily nitratenitrogen (N03-N), increased infiltration may increase losses. BMPs that reduce the rate or improve the timing of nitrogen (N) applications relative to crop requirements can reduce leaching losses. N03-N concentrations are usually much lower in surface runoff than in drainage from the root zone; however, if root zone drainage dominates surface water resources, concentrations in excess of the drinking water standard are likely. In the following sections, using atrazine and N03-N as main examples, the importance of chemical, hydrologic, and management factors on concentrations and losses with surface runoff and shallow subsurface drainage will be further discussed. A major new project underway to further our understanding and develop and refme additional BMPs will be discussed

Multilevel measurements of surface temperature over undulating terrain planted to barley

A ground and aircraft program was conducted to extend ground based methods for measuring soil moisture and crop water stress to aircraft and satellite altitudes. A 260ha agricultural field in California was used over the 1977-78 growing season. For cloud free days ground based temperature measurements over bare soil were related to soil moisture content. Water stress resulted from too much water, not from lack of it, as was expected. A theoretical examination of the canopy air temperature difference as affected by vapor pressure deficit and net radiation was developed. This analysis shows why surface temperatures delineate crop water stress under conditions of low humidity, but not under high humidity conditions. Multilevel temperatures acquired from the ground, low and high altitude aircraft, and the Heat Capacity Mapping Mission (HCMM) spacecraft were compared for two day and one night overpasses. The U-2 and low altitude temperatures were within 0.5 C. The HCMM data were analyzed using both the pre- and post-launch calibrations, with the former being considerably closer in agreement with the aircraft data than the latter

A flexible flight display research system using a ground-based interactive graphics terminal

Requirements and research areas for the air transportation system of the 1980 to 1990's were reviewed briefly to establish the need for a flexible flight display generation research tool. Specific display capabilities required by aeronautical researchers are listed and a conceptual system for providing these capabilities is described. The conceptual system uses a ground-based interactive graphics terminal driven by real-time radar and telemetry data to generate dynamic, experimental flight displays. These displays are scan converted to television format, processed, and transmitted to the cockpits of evaluation aircraft. The attendant advantages of a Flight Display Research System (FDRS) designed to employ this concept are presented. The detailed implementation of an FDRS is described. The basic characteristics of the interactive graphics terminal and supporting display electronic subsystems are presented and the resulting system capability is summarized. Finally, the system status and utilization are reviewed

The environment and host haloes of the brightest z~6 Lyman-break galaxies

By studying the large-scale structure of the bright high-redshift Lyman-break galaxy (LBG) population it is possible to gain an insight into the role of environment in galaxy formation physics in the early Universe. We measure the clustering of a sample of bright (-22.7<M_UV<-21.125) LBGs at z~6 and use a halo occupation distribution (HOD) model to measure their typical halo masses. We find that the clustering amplitude and corresponding HOD fits suggests that these sources are highly biased (b~8) objects in the densest regions of the high-redshift Universe. Coupled with the observed rapid evolution of the number density of these objects, our results suggest that the shape of high luminosity end of the luminosity function is related to feedback processes or dust obscuration in the early Universe - as opposed to a scenario where these sources are predominantly rare instances of the much more numerous M_UV ~ -19 population of galaxies caught in a particularly vigorous period of star formation. There is a slight tension between the number densities and clustering measurements, which we interpret this as a signal that a refinement of the model halo bias relation at high redshifts or the incorporation of quasi-linear effects may be needed for future attempts at modelling the clustering and number counts. Finally, the difference in number density between the fields (UltraVISTA has a surface density ~1.8 times greater than UDS) is shown to be consistent with the cosmic variance implied by the clustering measurements.Comment: 19 pages, 8 figures, accepted MNRAS 23rd March 201

A qualitative pilot study of food insecurity among Maasai women in Tanzania

Background: Food insecurity is an ongoing threat in rural sub-Saharan Africa and is complicated by cultural practices, the rise of chronicconditions such as HIV and land use availability. In order to develop a successful food security intervention program, it is important to be informed of the realities and needs of the target population. The purpose of this study was to pilot a qualitative method to understand food insecurity based on the lived experience of women of the Maasai population in the Ngorongoro Conservation Area of Tanzania.Methods: Short semi-structured qualitative interviews with 4 Maasai women.Results: Food insecurity was present in the Maasai community: the participants revealed that they did not always have access to safe and nutritious food that met the needs of themselves and their families. Themes that emerged from the data fell into three categories: Current practices (food sources, planning for enough, food preparation, and food preservation), food Insecurity (lack of food, emotions, coping strategies, and possible solutions), and division (co-wives, food distribution, and community relationships).Conclusion:This pilot study suggested the presence of food insecurity in the Maasai community. Larger sample studies are needed to clarify the extent and severity of food insecurity among this population. Having a detailed understanding of the various aspects of the food insecurity lived experience could inform a targeted intervention program.Key words: Food security, food supply, human rights, qualitative research, Eastern Afric

Chapter 1. The Nitrogen Cycle, Historical Perspective, and Current and Potential Future Concerns

Nitrogen (N) along with carbon and oxygen is the most complex and crucial of the elements essential for life. Supplementing grain and grass forage crops with organic and inorganic N fertilizers has long been recognized as a key to improving crop yields and economic returns. Globally. N fertilizer is largely used for cereal grain production and accounts for an estimated 40(1r of the increase in per capita food production in the past 50 years (Mosier et al.. 200 I). Smil (200 I) estimates that N fertilizer supplies up to 40% of the world\u27s dietary protein and dependence on N from the Haber-Bosch process will increase in the future. Nitrogen compounds also have been recognized for their many potential adverse impacts on the environment and health (Keeney. 2002)