Use of Soil Surveys in Precision Soil and Crop Management

Soil survey involves the mapping, classification, correlation, and interpretation of soils. The first soil survey in Iowa was in the Dubuque County area but did not include the entire county. The field work was done in 1902 and the report was published in 1903. Since that time, most Iowa counties have had at least two soil surveys completed and some have had three. The basic factors of soil formation have not changed but the use of the soils for intensive agriculture has resulted in changes in some soil properties, especially of the surface horizons. However, generally factors other than soil differences have been responsible for multiple soil surveys over one area. Over time, our concept of soil has changed. Early soil scientists with a background in geology considered the soil to be primarily that part of the earth\u27s surface that had been darkened by the addition of organic matter. Our concept of soil has evolved so that soil now is considered a natural body made up of several horizons or layers that are genetically related to the soil forming factors under which the soil has developed. Total analyses of soils for phosphorus and potassium was a common practice during the early 1900\u27s. Later, it was learned that it was not the total amount of a nutrient that was important for plant growth but the amount that was available to the plant. Other major factors in resurveys were the scale and the base map used

Variability of Soil and Landscape Properties Related to Precision Agriculture

Soil survey involves the mapping, classification, correlation, and interpretation of soils. The first soil survey in Iowa was in the Dubuque County area but did not include the entire county. The field work was done in 1902 and the report was published in 1903. Since that time, most Iowa counties have had at least two soil surveys completed and some have had three. The basic factors of soil formation have not changed but the use of the soils for intensive agriculture has resulted in changes in some soil properties, especially of the surface horizons. However, generally factors other than soil differences have been responsible for multiple soil surveys over one area. Over time, our concept of soil has changed. Early soil scientists with a background in geology considered the soil to be primarily that part of the earth\u27s surface that had been darkened by the addition of organic matter., Our concept of soil has evolved so that soil now is considered a natural body made up of several horizons or layers that are genetically related to the soil forming factors under which the soil has developed. Total analyses of soils for phosphorus and potassium was a common practice during the early 1900\u27s. Later, it was learned that it was not the total amount of a nutrient that was important for plant growth but the amount that was available to the plant. Other major factors in resurveys were the scale and the base map used

Potential for Use of Electrical Conductivity Measurements for Refinement of Soil Survey Information

Precision agriculture (PA) is concerned with understanding and managing variability. PA is made possible by the merging of several technologies--GPS-Global Positioning Systems, GIS-Geographic Information Systems, yield monitors, remote sensing, digital soil maps and databases, and variable rate applicators. Operators may be involved in only one or all these technologies and still be considered involved in PA. The ultimate goal is to improve the management of agricultural land. To achieve this goal data on soils, crops, pests, weather, etc., that will help in determining the best management practices for a field are needed. However, these technologies are only tools to aid our understanding, analyses, and conservation of sustainable agricultural ecosystems

Environmental effects of two contrasting farming systems in the Clarion-Nicollet-Webster soil association area

Growing interest in the environmental effects of agricultural practices has led to increased research about the relationships between land use, soil moisture, groundwater hydrology, and environmental quality. Soil properties and parent material stratigraphy (the sequence of deposits) are important factors affecting groundwater flow patterns and fertilizer and pesticide transport through the soil. However, the interactions among shallow groundwater systems, soil geomorphology (the study of land forms, their origin, and their development) and near-surface stratigraphy have not undergone detailed investigation. This lack of knowledge has hampered attempts to evaluate the environmental effects of differing agricultural systems

Soil carbon quality and interactions in Iowa wetlands

Most of Iowa\u27s wetlands have been drained, tiled, and cultivated. This project looked at how carbon sequestration has been affected and what might be done to help improve the situation. Researchers collected GPS coordinates of all the sites samples so that in the future someone can return to the sites and determine the amount of change in organic carbon or other properties that have occurred over time

Roosting Ecology and the Evolution of Pelage Markings in Bats

Multiple lineages of bats have evolved striking facial and body pelage makings, including spots, stripes and countershading. Although researchers have hypothesized that these markings mainly evolved for crypsis, this idea has never been tested in a quantitative and comparative context. We present the first comparative study integrating data on roosting ecology (roost type and colony size) and pelage coloration patterns across bats, and explore the hypothesis that the evolution of bat pelage markings is associated with roosting ecologies that benefit from crypsis. We find that lineages that roost in the vegetation have evolved pelage markings, especially stripes and neck collars, which may function in crypsis through disruptive coloration and a type of countershading that might be unique to bats. We also demonstrate that lineages that live in larger colonies and are larger in size tend not to have pelage markings, possibly because of reduced predation pressures due to the predator dilution effect and a lower number of potential predators. Although social functions for pelage color patterns are also possible, our work provides strong support for the idea that roosting ecology has driven the evolution of pelage markings in bats

The Impact of White Pine (Pinus strobus) on a Mollisol After Seven Decades of Soil Development

Selected chemical, physical, and macro and micromorphological properties in two pedons of a Clarion soil (Fine-loamy, mixed, superactive, mesic Typic Hapludolls) formed in till parent material, one planted to white pines (Pinus strobus) for the past 75 years and the other to grass, were compared. The most obvious difference between the two was the increased biological activity under pines; the variety and quantity of excrements suggested the activity of soil microfauna and variability of species resulted in finer and better aggregation of biological origin (crumbs and granules), numerous excrements in voids, and higher total porosity under pines. The matrix was lighter colored in the upper horizons under pines. The soil under pines seemed to be drier and to have more expressed water oscillations in the middle part of profile. There was some evidence of higher groundmass activity in the soil under pines and the groundmass b-fabric was slightly better expressed. The soil under the pines exhibited evidence of stronger weathering (weathered biotite at a shallower depth, more iron-rich fine fraction, common amorphous iron impregnation and frequent amorphous iron coatings related to grains or pores together with abundant iron nodules) than the soil under grass. Analytical and micromorphology methods showed only slight changes in the Clarion soil under pines. That means 75 years, at least under the prevailing climate, is too short a period for the formation of pronounced morphological and physico-chemical differences

Site evaluation, design, operation, and installation of home sewage systems in Iowa

The demand for on-site waste treatment systems for dwellings not served by sewer systems continues to grow in Iowa. On-site systems, when properly designed and maintained, provide a viable means of treating septic tank effluent. A research project was initiated at Iowa State University to provide information for solving problems associated with design, location, and maintenance of on-site systems in Iowa. This publication is designed to report the results of the interdisciplinary research and provide information for sanitarians, extension personnel, and contractors on waste treatment systems.https://lib.dr.iastate.edu/specialreports/1083/thumbnail.jp

1RXS J232953.9+062814: A Dwarf Nova with a 64-minute Orbital Period and a Conspicuous Secondary Star

We present spectroscopy and time-series photometry of the newly discovered dwarf nova 1RXS J232953.9+062814. Photometry in superoutburst reveals a superhump with a period of 66.06(6) minutes. The low state spectrum shows Balmer and HeI emission on a blue continuum, and in addition shows a rich absorption spectrum of type K4 +- 2. The absorption velocity is modulated sinusoidally at P_orb = 64.176(5) min, with semi-amplitude K = 348(4) km/s. The low-state light curve is double-humped at this period, and phased as expected for ellipsoidal variations. The absorption strength does not vary appreciably around the orbit. The orbital period is shorter than any other cataclysmic variable save for a handful of helium-star systems and V485 Centauri (59 minutes). The secondary is much hotter than main sequence stars of similar mass, but is well-matched by helium-enriched models, indicating that the secondary evolved from a more massive progenitor. A preliminary calculation in which a 1.2 solar-mass star begins mass transfer near the end of H burning matches this system's characteristics remarkably well.Comment: accepted to Astrophysical Journal Letters; 14 pages, 3 eps figures + 1 jpg greyscale figur

A sub-field scale critical source area index for legacy phosphorus management using high resolution data

AbstractDiffuse phosphorus (P) mitigation in agricultural catchments should be targeted at critical source areas (CSAs) that consider source and transport factors. However, development of CSA identification needs to consider the mobilisation potential of legacy soil P sources at the field scale, and the control of (micro)topography on runoff generation and hydrological connectivity at the sub-field scale. To address these limitations, a ‘next generation’ sub-field scale CSA index is presented, which predicts the risk of dissolved P losses in runoff from legacy soil P. The GIS-based CSA Index integrates two factors; mobile soil P concentrations (water extractable P; WEP) and a hydrologically sensitive area (HSA) index. The HSA Index identifies runoff-generating-areas using high resolution LiDAR Digital Elevation Models (DEMs), a soil topographic index (STI) and information on flow sinks and effects on hydrological connectivity. The CSA Index was developed using four intensively monitored agricultural catchments (7.5–11km2) in Ireland with contrasting agri-environmental conditions. Field scale soil WEP concentrations were estimated using catchment and land use specific relationships with Morgan P concentrations. In-stream total reactive P (TRP) concentrations and discharge were measured sub-hourly at catchment outlet bankside analysers and gauging stations during winter closed periods for fertiliser spreading in 2009–14, and hydrograph/loadograph separation methods were used to estimate TRP loads and proportions from quickflow (surface runoff). A strong relationship between TRP concentrations in quickflow and soil WEP concentrations (r2=0.73) was used to predict dissolved P concentrations in runoff at the field scale, which were then multiplied by the HSA Index to generate sub-field scale CSA Index maps. Evaluation of the tool showed a very strong relationship between the total CSA Index value within the HSA and the total TRP load in quickflow (r2=0.86). Using a CSA Index threshold value of ≥0.5, the CSA approach identified 1.1–5.6% of catchment areas at highest risk of legacy soil P transfers, compared with 4.0–26.5% of catchment areas based on an existing approach that uses above agronomic optimum soil P status. The tool could be used to aid cost-effective targeting of sub-field scale mitigation measures and best management practices at delivery points of CSA pathways to reduce dissolved P losses from legacy P stores and support sustainable agricultural production