DeAnn Presley

Field evaluations on soil plant transfer of lead from an urban garden soil

Lead (Pb) is one of the most common contaminants in urban soils. Gardening in contaminated soils can result in Pb transfer from soil to humans through vegetable consumption and unintentional direct soil ingestion. A field experiment was conducted in 2009 and 2010 in a community urban garden with a soil total Pb concentration of 60 to 300 mg kg. The objectives of this study were to evaluate soil-plant transfer of Pb, the effects of incorporation of a leaf compost as a means of reducing Pb concentrations in vegetables and the bioaccessibility of soil Pb, and the effects of vegetable cleaning techniques on the Pb concentrations in the edible portions of vegetables. The amount of compost added was 28 kg m. The tested plants were Swiss chard, tomato, sweet potato, and carrots. The vegetable cleaning techniques were kitchen cleaning, laboratory cleaning, and peeling. Compost addition diluted soil total Pb concentration by 29 to 52%. Lead concentrations of the edible portions of vegetables, except carrot, were below the maximum allowable limits of Pb established by the Food and Agriculture Organization and the World Health Organization. Swiss chard and tomatoes subjected to kitchen cleaning had higher Pb concentrations than laboratory-cleaned plants. Cleaning methods did not affect Pb concentrations in carrots. Bioaccessible Pb in the compost-added soils was 20 to 30% less than that of the no-compost soils; compost addition reduced the potential of transferring soil Pb to humans via vegetable consumption and direct soil ingestion. Thorough cleaning of vegetables further reduced the potential of transferring soil Pb to humans.

Soil and crop response to stover removal from rainfed and irrigated corn

Excessive corn (Zea mays L.) stover removal for biofuel and other uses may adversely impact soil and crop production. We assessed the effects of stover removal at 0, 25, 50, 75, and 100% from continuous corn on water erosion, corn yield, and related soil properties during a 3‐year study under irrigated and no‐tillage management practice on a Ulysses silt loam at Colby, irrigated and strip till management practice on a Hugoton loam at Hugoton, and rainfed and no‐tillage management practice on a Woodson silt loam at Ottawa in Kansas, USA. The slope of each soil was <1%. One year after removal, complete (100%) stover removal resulted in increased losses of sediment by 0.36–0.47 Mg ha−1 at the irrigated sites, but, at the rainfed site, removal at rates as low as 50% resulted in increased sediment loss by 0.30 Mg ha−1 and sediment‐associated carbon (C) by 0.29 kg ha−1. Complete stover removal reduced wet aggregate stability of the soil at the irrigated sites in the first year after removal, but, at the rainfed site, wet aggregate stability was reduced in all years. Stover removal at rates ≥ 50% resulted in reduced soil water content, increased soil temperature in summer by 3.5–6.8 °C, and reduced temperature in winter by about 0.5 °C. Soil C pool tended to decrease and crop yields tended to increase with an increase in stover removal, but 3 years after removal, differences were not significant. Overall, stover removal at rates ≥50% may enhance grain yield but may increase risks of water erosion and negatively affect soil water and temperature regimes in this region.

Wheat and sorghum residue removal for expanded uses increases sediment and nutrient loss in runoff.

Crop residue removal for expanded uses such as feedstocks for cellulosic ethanol production may increase loss of sediment and nutrients in runoff. We assessed on-farm impacts of variable rates of residue removal from no-till winter wheat (Triticum aestivum L.) and plow till grain sorghum [Sorghum bicolor (L.) Moench] on sediment, soil organic carbon (SOC) and nutrient losses in runoff in western Kansas. Five treatments with three replications consisting of removing residues at 0, 25, 50, 75, and 100% after harvest under two tillage levels for wheat (no-till and freshly tilled) and grain sorghum (spring tilled and freshly tilled) were established on 1x2 m plots. Simulated rainfall was applied at 115+/-3 mm h(-1) for 30 min. Compared with plots without residue removal, complete removal increased runoff by 61% in freshly tilled wheat plots, 225% in spring-tilled sorghum plots, and 94% in freshly tilled sorghum plots. Residue removal at rates as low as 50% increased loss of sediment. Complete removal doubled the sediment loss to 14 Mg ha(-1) in tilled wheat, whereas it increased sediment loss from 0.9 to 7.2 Mg ha(-1) in no-till wheat. No-till with 100% residue removal lost as much sediment as freshly tilled wheat plots with 0 or 25% removal. Residue removal at 75 and 100% increased losses of total N, total P, and SOC associated with sediment. Overall, excessive residue removal led to large losses of sediment, sediment-bound SOC, and nutrients in runoff. Furthermore, erosion protection provided by no-till management is lost when residue removal exceeds 25%.

Effect of nitrogen fertilization and cover cropping systems on sorghum grain characteristics.

Cover crop treatments and nitrogen (N) fertilization rates were investigated for their impact on sorghum grain quality attributes. Sorghum was planted in field plots treated with differing cover cropping systems and fertilization rates. The size (weight and diameter) and hardness of the kernels were influenced by both the cover crop and N rates. The protein content increased as the N rate increased and also with the addition of cover crops to the system. The protein digestibility values and starch granule size distributions were not affected by N rate or the cover cropping treatments. Soil properties were tested to determine relationships with grain quality attributes. The utilization of cover crops appears to increase the protein content without causing a deleterious effect on protein digestibility. The end-product quality is not hampered by the use of beneficial cropping systems necessary for sustainable agriculture.

Effects of Flue Gas Desulfurization Gypsum on Crop Yield and Soil Properties in Kansas

Flue gas desulfurization (FGD) gypsum was recently approved for use in Kansas as a sulfur (S) fertilizer and as a soil amendment. Gypsum has been known as an effective product used in remediation of sodic soils, as the calcium (Ca) can exchange with sodium (Na) on the cations on clay particles. Marketing efforts have promoted the use of FGD gypsum on non-sodic soils as a means of improving soil health. Two 3-year study sites were established in Kansas in 2013, and no yield effects were observed for any of the site years. Treatment differences for grain quality and soil chemical properties had consistently greater sulfate-sulfur (SO4-S) with increasing FGD application rates. Soil electrical conductivity (EC) had instances where it was greater with increasing gypsum rates. There were no treatment differences for the selected soil physical and biological parameters. During this project, FGD gypsum did not cause changes in soil health at the two sites.

Soil Erodibility, Phosphorous, and Microbial Biomass within a Switchgrass Stand

Switchgrass (Panicum virgatum L.) is a native, warm season perennial that may be suitable for advanced renewable bioenergy feedstock production in semi-arid regions, where year-round soil cover is desirable as the primary environmental concern related to vegetation harvest is wind erosion. One objective of this project was to explore potential effects of two switchgrass varieties, Blackwell and Kanlow, on both abiotic and biotic soil quality indicators. No significant differences were detected in soil erodibility parameters, but numerically the cultivar with the lesser biomass and fewer plants per unit area had soil properties that had greater potential for wind erosion. Regardless of cultivar, soil P was enriched in the wind-erodible fraction compared with the bulk soil samples. Biological properties did not differ for the two switchgrass varieties, but microbial biomass and dehydrogenase enzyme activity was greater for samples collected <15 cm from the base of a plant than for samples >15 cm from the nearest switchgrass plant. No significant differences were detected between the two switchgrass varieties in this study, despite differences in the density of plants within the stand. Enrichment of soil P in the wind-erodible fraction and decreased microbial life in bare areas between plants highlight the importance of dense soil cover in a perennial switchgrass stand if it is to be considered as a feedstock for advanced bioenergy production.

Growth, Forage Quality, and Economics of Cover Crop Mixes for Grazing

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Crop residue harvest impacts wind erodibility and simulated soil loss in the Central Great Plains

Crop residue removal can affect the susceptibility to soil wind erosion in climates such as those of the Central Great Plains, United States. Six on‐farm trials were conducted in Kansas from 2011 to 2013 to determine the effects of winter wheat (Triticum aestivum L.), corn (Zea mays L.), and grain sorghum (Sorghum bicolor (L.) Moench), residue removal at 0, 25, 50, 75, and 100% of initial height on soil wind erosion parameters. Those parameters include soil surface random roughness (RR), and wind erodible fraction (EF; aggregates <0.84 mm), geometric mean diameter (GMD) and geometric standard deviation (GSD), stability of dry aggregates (DAS). Complete (100%) residue removal decreased the surface RR, increased EF, and decreased GMD. Overwinter EF values increased for five of six sites from fall 2011 to spring of 2012, particularly for the uppermost removal height (≥75%). Measured EF, GMD, GSD, DAS, and RR were also input into the Single‐event Wind Erosion Evaluation Program (SWEEP) to determine the effect of these parameters on simulated soil loss. The SWEEP simulated the wind velocity needed to initiate wind erosion as well as soil loss under each residue removal height at a wind velocity of 13 m s−1 for three hours. Threshold wind velocity required to initiate wind erosion generally decreased with increasing crop residue removal height, particularly for >75% removal. Total estimated soil loss over the three‐hour event ranged from ≈2 to 25 Mg ha−1, depending on EF, GMD, GSD, RR, and percent crop residue cover. Removing 75% residue increased simulated wind erosion at three of six sites while removing 50% appears sustainable at all six study sites. Findings reinforce the need for site‐by‐site consideration of the potential amount of crop residue that may be harvested while mitigating wind erosion. Study results indicate the value of maintaining residue at >75% of original height.

Human Land-Use and Soil Change

Soil change refers to the alteration of soil and soil properties over time in one location, as opposed to soil variability across space. Although soils change through natural processes (pedogenesis), this chapter focuses on human-caused soil change. Soil change can occur with human land use and management over long or short time periods and small or large scales. While change can be negative or positive, often soil change is observed when short-term or narrow goals overshadow soil’s other ecosystem services. Assessing soil change depends upon the ecosystem services and soil functions being evaluated. The interaction of soil properties with the type and intensity of management and disturbance determines the changes that will be observed. Many soils have been changed in their chemical, physical, or biological properties through agricultural activities, including cultivation, tillage, weeding, terracing, subsoiling, deep plowing, manure and fertilizer addition, liming, draining, and irrigation. Tillage of cropland disrupts aggregates and decreases soil organic carbon content, which can lead to decreased infiltration, increased erosion, and reduced biological function. Improved agricultural management systems can increase soil functions including crop productivity and sustainability. Forest management is most intensive during harvesting and seedling establishment. Most active management in forests causes disturbance of the soil surface, which may include loss of forest floor organic materials, increases in bulk density , and increased risk of erosion. In grazing lands, pasture management often includes periods of biological, chemical, and physical disturbance in addition to the grazing management imposed on rangelands. Grazing animals have both direct and indirect impacts on soil change. Hoof action can lead to the disturbance of biological crusts and other surface features impairing the soil’s physical, biological, and hydrological functions. There are clear feedbacks between vegetative systems and soil properties; when vegetation is altered because of grazing or other disturbances, soil property changes often follow. Some soils are very sensitive to management and disturbance and can undergo rapid change; for example, cropping led to massive gully formation in the southeastern USA, exposure of acid sulfate soils leads to irreversible changes in soil mineralogy, and thawing of cold soils has created thermokarst features. These soil changes alter soil properties and functions and may impact soil ecosystem services far into the future.

Morphology, Provenance, and Decomposition of a 19th Century Hybrid Dugout and Sod House in Nicodemus, Kansas

During the summer of 2009, researchers and students traveled to Nicodemus, Kansas to investigate a settlement home of African American pioneers. In the late 19th century, new arrivals in the Midwest often constructed dugouts and sod houses to quickly build shelters. Although sod structures began to disappear in the 1900s, their decomposed remains left clues in the soil that would tell us the story of their existence. Our team sought to identify and define sod remains that were once a part of an early home. Specifically, we studied the remains of one hybrid dugout and sod home and our goal was to collect data that would support the identification of materials used and how the structure has decomposed over time. Soil color, particle size analysis data, and micromorphology were used to compare and contrast the sod blocks from with other soil materials at the site. Generally, there is now a thin mantle of soil that has eroded from an upper landscape position and that now buries the site; dark rectangular blocks of soil, thought to be the sod; a lighter colored, structureless soil that outlined the darker blocks (henceforth referred to as “mortar”); and light colored soil underlying the section of the sod block wall. The properties of the blocks were generally more similar to the overlying soil - a strong indicator that the composition of the blocks was derived from sod cut from the surrounding area. Similarly, the particle size distribution of the mortar resembled the underlying native subsoil of the site. Based on the evidence, this paper identifies sod blocks within a geoarchaeological context and describes insights gained from the macro and micro-analysis of the soil.