Birl Lowery

Identification of the spatial distribution of soils using a process-based terrain characterization

Abstract A simple process-based terrain characterization model was developed to identify the occurrence of soils over a complex landscape. Its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological, geomorphological, and pedological processes occur. The proposed model is a three-dimensional extension of the nine-unit soil landscape model. The two-dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes, and is implemented in a geographical information system (GIS) through the analysis of a raster digital elevation model (DEM). The application of this model at the Empire Prairie in southern Wisconsin, USA, shows a good agreement with the results of a soil investigation. The difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation, however, remain unsolved. This model can consider the spatial variability of soils both at the continuous and discrete scales, and is easily transferable to other slopes in a predictive manner. It is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey, and also a priori information for spatially distributed ecological and environmental models.

Effect of high axle-load traffic on subsoil compaction and crop yield in humid regions with annual freezing

Abstract The weight of agricultural machines is steadily increasing, and this leads to higher axle load and deeper subsoil compaction. As an international joint effort, the effects of high axle load traffic on subsoil compaction and crop yield are being studied in 26 field experiments in Europe and North America. Results at present available, applicable to humid areas with annual freezing, show that crop yield losses normally become larger and more persistent with increasing soil clay content. The results indicate that restrictions upon axle loads are required.

A fast method for determining soil particle size distribution using a laser instrument

The sieve-pipette is the standard method for determining soil particle size distribution (PSD) because it is precise and reproducible. However, this method requires considerable time. Light diffraction methods for determining PSD are fast, but there is no standard procedure and often, results do not agree precisely with the pipette. The objective of this study was to develop a simple and fast procedure for sample handling and treatment of light diffraction method. A commercially available laser-light diffraction instrument was used. Soil samples were loaded dry into the instrument for ease and speed. A combination of chemical and physical dispersion within the instrument was found to be convenient and effective. Time required to analyze a sample was at most 15 min. Reproducibility between different operators was good, with S.E. ranging from 0.2% to 3.6%. Furthermore, we attempted to identify optimal values for the real refractive index and imaginary refractive index used in the optical model for light diffraction. Values of 1.42 and 0.001 for real refractive index and imaginary refractive index, respectively, were found to give acceptable results when compared with the pipette method. The light diffraction method was not significantly different from the pipette method for sand (P = 0.084), silt (P = 0.743), and clay (P = 0.052). Correlation between the light diffraction and pipette method for sand, silt, and clay was acceptable (R2 = 0.88, 0.80, and 0.69, respectively). The light diffraction technique does not have a perfect agreement with the pipette method, but it provides data rapidly and was reproducible. This method can be very valuable when a large number of samples need to be analyzed for relative comparisons between different sites.

SOIL PHYSICAL PROPERTIES AND CROP PRODUCTIVITY OF AN ERODED SOIL AMENDED WITH CATTLE MANURE

Erosion changes soil properties, especially physical properties, mainly because it removes surface soil rich in organic materials and exposes lower soil layers. In 1988, a study was established to determine the effects of soil erosion and long-term manure applications on selected soil physical properties and corn (Zea mays L.) production. After 10 years of annual manure applications, soil core samples were collected in 7.6-cm increments at three depths, 0 to 7.6, 15 to 22.6, and 30 to 37.6 cm, to determine soil bulk density (&rgr;b), hydraulic conductivity of saturated soil (Ks), and water retention. Bulk density and Ks increased slightly with erosion level. Water retention did not change in the surface 7.6 cm, but it did decrease with increasing erosion level at deeper depths. Long-term application of manure decreased &rgr;b by 10%, whereas Ks was doubled in the top 7.6 cm of soil. Manure increased soil-water retention capacity and decreased differences in water retention between erosion levels, especially at low suctions (0 to 20 kPa). Soil carbon content correlated well with water retention and &rgr;b. Corn grain yields in 1997, 1998, and 1999 were 15, 6, and 14% less, respectively, in the severe than in the slight erosion phase. Long-term manure additions increased corn grain yields by 19% in 1998 and by 25% in 1999. Increased yield from manure additions was likely related to an enhancement in water retention. Results from this study show that long-term manure application is a possible management alternative for restoring the physical properties and crop productivity of eroded soil.

Ridge tillage for corn and soybean production: environmental quality impacts

Abstract Tillage practices are needed to increase agronomic stability and productivity while enhancing the environment. Ridge tillage has been demonstrated as an effective agronomic practice; some have described it as a miniature precision agriculture. Environmental impacts have generally been positive but the results vary, depending upon soil and climatic factors. Ridge tillage changes soil temperature and water patterns compared to no-till and full width – moldboard/chisel plowing or disking for primary tillage. These changes lead to an improved soil environment for crop emergence and early growth, because of warmer soil temperatures in cool climates and better water relations in both poorly-drained and moderately well-drained soils. While increased soil water infiltration in the interrow can lead to increased leaching and greater loading of nitrates and herbicides at the bottom of the root zone, controlled studies suggest that ridge tillage with precise agrichemical placement in the ridge can provide a favorable environmental impact. Moreover, the combined herbicide and cultivation for weed control reduces the treated area and overall application for herbicides. Ridge tillage was evaluated at a number of field locations of the Management Systems Evaluation Areas program to assess both agronomic and environmental impacts. A special effort in these ridge tillage evaluations was to trace agrichemical movement from the site of application within the soil and into the surficial aquifer. In most instances, ridge tillage decreased agrichemicals leaching and the negative environmental impact.

Nest structure of ant Lasius neoniger Emery and its implications to soil modification

Abstract The ant Lasius neoniger Emery is one of the most abundant ant species found in the temperate regions of North America and has been studied primarily from an entomological standpoint. This study was conducted to characterize its nest structure and implications to soil modification. To study the structure, development, and micromorphological characteristics of the ant nests, we constructed three-dimensional models of the nests from excavated nest castings made with dental gypsum and ant farms with Plexiglas, and made thin sections ( ≈30 μm thick) from undisturbed field soil samples that contained the nests. We assessed the effect of the ant on soil chemical properties by comparing the composition of ant crater rim and nest materials with that of associated bulk soil. The ant nests consisted of underground branched networks of galleries and chambers concentrated in the upper 0.3 m of the soil, with a few vertical galleries penetrating to about 0.7 m. The galleries tended to be circular tubes (channels) 1.5 to 5.0 mm in diameter, whereas the chambers, connected by the galleries, bulged to diameters of 10 to 20 mm and were 30 to 50 mm in length. The volume of the nests ranged from 20 to 250 cm 3 . Walls of the nests ( ≈1 μm thick) were more consolidated and contained larger amounts of fine sand, silt, and colloidal material than adjoining bulk soil. The primary effect of the ants was mixing of the upper 0.7 m of soil. Estimated soil turnover time ranges, for upper 0.3 m soil, from approximately 1000 years for the grass border areas of a corn field to 2800 years inside the field. For soils between 0.3 and 0.7 m depths, estimated soil turnover time ranges from approximately 9000 years for the grass border areas to 24,000 years inside the corn field. Selective mining by ants of fine-particles, which concentrate in the upper tier of the soil, may also counter balance processes such as clay translocation and nutrient leaching that tend to degrade physical and chemical attributes of sandy soil surfaces forming in humid environment.

Duration and effects of compaction on soil and plant growth in Wisconsin

Abstract Compaction by 8 and 12.5 Mg farm equipment caused significant subsoil compaction that persisted after 4 years in a silty clay and a silt loam soil in Wisconsin, USA. Hydraulic conductivity of saturated soil cores showed a general trend of decreasing with increasing levels of compaction. Bulk density values increased with increasing levels of compaction. Penetration resistance dramatically increased with increasing levels of compaction. Corn growth (plant height) was also a good indicator of compaction. Plant height was smaller in the compacted plots in all years. Corn grain yields were reduced in the compaction treatments the first year after compaction at both sites and the second and fourth years at the silt loam site and silty clay site, respectively.

Soil Moisture Regimes of Three Conservation Tillage Systems

ABSTRACT COMPARISON of three conservation tillage systems, chisel plowing (CH), till-plant (TP) and no-till (NT), to conventional moldboard plowing (CN) indicates soil moisture advantages with conservation tillage vary. Volumetric water content (3-year average, 0-76 mm depth) at planting was 0.324, 0.279, 0.267 and 0.246 m^m-^ for NT, CH, TP, and CN, respectively. Average 3-year water content in the 0-0.25 m zone for weekly measurements during the growing season was 0.320, 0.309, 0.300, and 0.297 m^m^ for NT, CH, CN and TP, respectively. Soil moisture was higher in the NT treatment during most of the growing period. However, during a heavy rain period (93 mm), profile recharge in the CN, TP and NT treatments was 34, 34 and 44% less than for the CH treatment, respectively. Less water was removed from the 0.50-1.0 m zone of NT during extensive water depletion. For this soil with a 6-% slope, the NT treatment displayed the least water fluctuation during drying periods.

Profile cone penetrometer data used to distinguish between soil materials

In young glaciated landscapes the variability of soil materials imparts a major control on crop growth and yield and environmental quality associated with production agriculture. Two common soil materials found on these glaciated landscapes are glacial till and reworked loess. Soil materials can be characterized by a combination of physical and morphological soil attributes. We hypothesized that penetration resistance is the response signal to a complex of multiple soil attributes and can be used as an integrating indicator to map soil materials. Our objective was to test the ability of a profile cone penetrometer to map soil materials at landscape-scale. The study site was located in southern Wisconsin, USA, on soils developed in reworked loess material overlying glacial till, which are classified as Typic or Mollic Hapludalfs and Typic Argiudolls. We collected a dense data set of cone index profiles from a 2.73 ha area on a 10 m grid up to depths of 1.3 m. Additionally, we collected soil cores randomly at 21 penetration locations and analyzed these by layer for texture, bulk density, and water content. We utilized point elevation data collected with a differential global positioning system to create a digital elevation model and derive slope and compound topographic index to subdivide the study area into landform element classes. We used expert knowledge to characterize soil materials and subsequently measured soil attributes to identify soil materials. A hierarchical cluster analysis was used to group cone index profiles. Combining the sparse soil material data with the dense cone index and landform element data resulted in soil material information covering the entire study area. The spatial distribution of soil materials was visualized using a three-dimensional soil layer model. The proposed method is associated with large uncertainties in some areas and can be recommended only for coarse mapping of contrasting soil materials such as glacial till and reworked loess at landscape-scale, when used in combination with landform element data.

Development of pedotransfer functions for a profile cone penetrometer

In this study, we illustrate how profile cone penetrometers PCP , can be used to measure . penetration resistance rapidly to define zones similar in cone index CI , which can be related to u , and ii to evaluate the sensitivity of parameters used in these functions. The data set represented soils formed in reworked silty loess overlying glacial till and ror lacustrine sediments. The global data set were grouped into subsets in terms of similar CIs. A horizontal hierarchical cluster analysis and a vertical point inflection method were used to derive cone index layer . profiles CILP1 to CILP5 . Variability of CI within CILPs was small and variability of CI among CILPs was large. Within each group, CI was regressed with soil physical properties to develop 2. pedopedotransfer functions. These were evaluated using the coefficient of determination R.A sensitivity analysis was executed to evaluate the relative importance of different parameters in the regression models. For the total data set, R 2 ranged from 0.35 to 0.48. Pedotransfer functions for the CILPs showed largest R 2 with 0.62 for CILP1, 0.76 for CILP2, 0.70 for CILP3, 0.63 for CILP4 and 0.98 for CILP5. Depth, r , clay content and u were variables with large predictive b power. Textural variables had strong predictive power in the top layers, CILP1 and CILP2. In CILP4, clay contents along with r and u were variables with large predictive power. In contrast, b the predictive power of r and u was strong in layers CILP3 and CILP5, whereas soil textural b