Kenneth R. Olson

Impacts of tillage and no-till on production of maize and soybean on an eroded Illinois silt loam soil

In the United States, millions of hectares of highly erodible cropland have been in the Conservation Reserve Program (CRP) for the past 10 years. Any conversion of CRP land back to maize (Zea mays L.) and soybean (Glycine max L. Merr.) production could require the use of conservation tillage systems, such as NT and CP, to meet federal and state soil erosion control standards. Evaluations of yield response of these conservation tillage systems such as NT and CP, over time are needed to assess the return of this land to crop production. An eight-year study was conducted in southern Illinois on land similar to that being removed from CRP to evaluate the effects of conservation tillage systems on maize and soybean yields and for the maintenance and restoration of soil productivity of previously eroded soils. Soils had been in tall fescue (Festuca arundinacea L.) sod for more than 10 years prior to the study. In 1989, no-till (NT), chisel plow (CP), and moldboard plow (MP) treatments were replicated six times in a Latin Square Design on sloping, moderately well-drained, moderately eroded phase of a Grantsburg soil (Albic Luvisol) (fine-silty, mixed, mesic Typic Fragiudalf). Starting with maize, maize and soybean were grown in alternate years. Surface crop residue levels were higher with the NT system than with the CP and MP systems. Soil temperature at 20 cm was lower (1.18C) with NT than with the other systems in 1996. Plant-available water was slightly higher with NT and CP systems than with the MP system. In 1995, maize was taller with the NT system than with the MP and CP systems. The MP system plots had higher plant populations in 1995 and 1996, but crop yields were higher with the NT system than with the MP system. The four-year average maize yields were equal (9.81, 9.74, and 9.80 Mg ha ˇ1 ) for NT, CP, and MP systems, respectively, as a result of a significantly higher yield with the MP system in the first year which offset the higher yields with the NT and the CP systems during the last two years. The four-year average soybean yield with NT (2.90 Mg ha ˇ1 ) was 15% higher than with the MP (2.55 Mg ha ˇ1 ) system. Crop yields for eight years (four years maize and four years soybean) appear to show improved long-term productivity of NT compared with that of MP and CP systems. # 1999 Elsevier Science B.V. All rights reserved.

Erosion patterns on cultivated and uncultivated hillslopes determined by soil fly ash contents

The severity of accelerated erosion is affected by slope gradient, slope shape, slope length, and tillage practices. Fly ash, the product of high temperature coal combustion, has been used previously as a sedimentation marker, but it has never been used on the upland as an indicator of soil loss fro

Spatial variability of soil properties in selected Illinois Mollisols.

We investigated two areas of contrasting spatial variability in east-central Illinois using grid sampling to determine the composition of soil map units and the variability of significant soil properties within map units. We also evaluated the effectiveness of the modern soil survey legend and maps in addressing the soil variability in the two different landscapes. The surface characteristics of the sample sites showed extremely high variability, especially in slope and aspect with CVs of 93.5% and 83.6%, respectively. The depth of the A horizon showed high variability with CV of 35% for both areas. The depth to reducing conditions was highly variable with a CV of 34.6%, while the depth to discontinuity was 48.4%. Characteristically the degree of color variability increased in the order, hue, value, and chroma, regardless of where in the profile it occurred. The A horizon showed very high variability in sand content with a CV of 74.4%, but silt content and clay content both showed moderate variability with CVs of 22.9% and 23.6%, respectively. Organic C content showed moderate variability with CV of 15% and was more variable in the highly undulating landscape, probably due to redistribution by erosion. Soil reaction in the B horizon showed a low degree of variation with CV of 9.5%. Although the variability of each soil property within the eight map units measured by coefficient of nondetermination showed less variance than the total variance present in both sample areas, most of the variation of soil properties was still left within map units. Tolerance limits of 75% set for the various map units indicate that some of the map units contained less variation of soil properties than others. This approach should help in refining the cartographical separations by identifying potential units that need reduction in variation of selected properties. Based on evaluation of soil property variability, we found that although the existing soil survey legend and maps are good, they could be improved substantially by considering the within-map unit variability of significant soil properties. We recommend that in future soil surveys, an initial soil property variability study be conducted using grid sampling to aid in a comprehensive development of the soil survey legend which will help reduce the within-map unit variation.

Tillage effects on selected chemical properties of grantsburg silt loam

Abstract The objective of this research was to determine the effects of tillage systems on selected chemical properties of a sloping and eroded soil which had previously been in sod. A tillage project was initiated in the spring, 1989 in southern Illinois on a soil with a root‐restricting fragipan. Corn (Zea mays L.) and soybean [Glycine max (L.) Mem] were grown on the plot area on a yearly rotation system. Prior to the application of lime or tillage treatments the 0–15 cm Ap horizon had a pH of 6.3, organic carbon (C) of 1.4 g/100g, and CEC equal to 17 meq/100g. Lime had been surface applied early in the spring of 1989 prior to moldboard (MP) and chisel (CP) plowing. Moldboard plowing had lower pH than the other treatments in the 0–5 cm layer in 1989 due to the moldboard plow mixing low pH subsoil material into the 0–5 cm layer and mixing surface applied lime into the 5–15 cm layer. During the 4th year, organic C was lowest for MP (1.28 g/100g) and highest for no tillage (NT) (1.65 g/100g), with CP havin...

Impacts of Tillage, Slope, and Erosion on Soil Organic Carbon Retention

The objective of this 20-year tillage study was to quantify the amount and rates of soil organic carbon (SOC) storage and retention as a result of a conversion to no-till (NT) or chisel plow (CP) tillage systems using the comparison method with moldboard plow (MP) tillage SOC data as baseline. The NT and CP plots did store and retain 8.4 Mg C ha−1 and 0.6 Mg C ha−1 more SOC in the soil than MP. That SOC amount was retained in the soil and not decomposed and re-emitted to the atmosphere as a result of cultivation or in the transported sediment moved off of the plots. However, no SOC sequestration occurred in the NT, CP, and MP plots because the SOC level of the plot area was higher at the start of the experiment than at the end of the study. Pretreatment SOC baseline of the plot area was used to determine NT, CP, and MP SOC sequestration or loss. The NT plots actually lost a total of −6.8 Mg C ha−1, the CP lost −15.1 Mg C ha−1, and the MP lost −15.2 Mg C ha−1 during the 20-year study. Soil erosion and transport of SOC rich sediment off of the sloping plots contributed substantially (29%-39%) to these SOC losses. These findings suggest that determination of a pretreatment SOC baseline is essential in all tillage comparison studies to determine the amount and rate of SOC sequestration or loss.

Cover Crop Effects on Crop Yields and Soil Organic Carbon Content

An 8-year cover crop study was conducted in southern Illinois to evaluate the effects of conservation tillage systems on corn and soybean yields and for the maintenance and restoration of soil organic carbon (SOC) and soil productivity of previously eroded soils. In 2001, the no-till (NT), chisel plow, and moldboard plow (MP) treatment plots, which were replicated six times in a Latin square design, were split (with cover crop and without) on sloping, moderately well-drained, moderately eroded soil. The average corn and average soybean yields were similar for NT, chisel plow, and MP systems with and without cover crops. By 2009, the tillage zone, subsoil, and rooting zone of all treatments had similar SOC on a volume basis for the cover crop treatments as for the same tillage treatment without a cover crop. However, using the baseline 2000 SOC contents only, the NT with cover crops maintained most of the SOC levels in the topsoil and subsoil during the 8-year study, when the sediment was high in SOC and retained in the upland landscape by soil conservation practices, including border and filter strips and sod waterways adjacent to the plots, with and without cover crops. Soil carbon creation retention in the upland landscape was greatest for the MP treatments when sediments were retained by the soil conservation practices, which should reduce soil erosion and sediment rich in SOC being transported by overland flow into water and the eventual release of methane and carbon dioxide to the atmosphere.

FIELD EVALUATION OF METHODS TO ESTIMATE SOIL EROSION

The objective of this study was to evaluate alternative methods of estimating the postsettlement soil erosion from hillslopes in a small watershed in Bureau County, northwestern Illinois. Methods used include: (i) estimation of the soil erosion using total organic C balance or enrichment ratio, (ii) selected soil property comparisons between the cultivated, sloping, and eroded soils of the watershed and uncultivated, sloping, and uneroded reference soils of the same taxa occurring in the area cemeteries, and (iii) Universal Soil Loss Equation (USLE). Previously measured sediment remaining in the sediment basin and calculated sediment delivery were used as the bases for evaluating the effectiveness of proposed methods to estimate soil erosion from the surrounding hill-slopes. Differences in thickness of the A horizon consistently underestimated soil erosion by 64% relative to the estimates made by the total sediment remaining in basin and delivered to the stream. This suggests erosion classes which are based on erosion of topsoil underestimate the extent of erosion from both the topsoil and subsoil, particularly where soils have been severely truncated. Organic C redistribution was highly correlated to sediment delivery method and appear to be related directly to the quantity of soil eroded and could provide an alternative to A horizon thickness differences as a basis for quantifying soil erosion. The soil erosion estimated by the USLE was 80% of the soil erosion estimated by the sediment delivery method. This difference can be accounted for by the fact that the sediment delivery method assumed all the sediment came from the sideslopes and USLE is not designed to include erosion resulting from concentrated overland flow (gully erosion). The comparison between cultivated and uncultivated sites of the depth to carbonates and the lowest part of the Bt horizon containing 27% clay between eroded and uneroded phases of Tama soils each produced an estimate of soil erosion within 17% of the soil erosion estimated by sediment delivery method and could be used to estimate soil erosion.

Soil catena formation and erosion of two Mississippian mounds at Cahokia archaeological site, Illinois

About 1000 years ago, Mississippian Indians built what are now designated Mounds 69 and 70 at Cahokia near Collinsville, Illinois. Loamy soil materials were placed on the mounds by Mississippian Indians before A.D. 1100, and the site was inhabited until approximately A.D. 1300. The general objective of this study was to determine the potential of using archaeological mounds or sites to obtain information on soil development and erosion processes. Our specific objectives were to determine: (i) the extent of soil formation during the past 900 years, (ii) the time period and extent of disturbance by human activities, including tillage and digging by treasure hunters and looters, and (iii) the erosion phase of soils on mound sideslopes and the amount of soil loss from accelerated erosion. The vegetation and distribution of organic C in soil profiles suggests there has been no tillage since the 1970s and little soil erosion of either the summit or the sideslope of Mound 69. The adjacent alluvial plain is still being cultivated. Fly ash, particulate matter resulting from high-temperature coal combustion, was used as a time marker in soil and sediment. Fly-ash distributions in the upper 20 cm of Mound 69 support the theory that cultivation occurred between the 1850s and the 1970s. Based on the fly ash data, approximately 55% of the original surface soil layer remains on the sideslope of Mound 69 (compared with the uncultivated sideslope of Mound 70). There has been substantial deposition of sediment rich in fly ash onto the footslope of Mound 69 (from the cultivated sideslope) and the toeslope of Mound 70 (from the cultivated footslope). The fly ash and organic C data for the summit soil profile on Mound 70 suggest treasure hunters and looters disarranged the soil profile completely. The uncultivated sideslope with a 23% slope had a 40-cm surface layer rich in fly ash. The fly-ash content and thickness of the footslope soil surface layer was reduced as a result of tillage and erosion from the 1850s to the 1970s. Fly ash-enriched sediment accumulated on the toeslope and created a 60-cm surface layer. The current vegetation and the decrease in organic C with depth on the footslope and toeslope of Mound 70 suggest that no tillage has occurred since the 1970s. Fly ash presence within soil layers indicates which layers have been exposed at the soil surface since the 1850s and the extent of soil mixing. Archaeological mounds with known dates of construction can be used to obtain information on soil development and erosion processes.

Recovery rate of organic C in organic matter fractions of Grantsburg soils.

Abstract Walkley‐Black method is a simple and rapid method for organic carbon analysis. Because of incomplete oxidation of organic carbon (C), the recovery of organic C is low with this method. Assuming the 77% recovery of organic C with Walkley‐Black method, the results are corrected with a correction factor of 1.30. The objective of this study is to determine the soil organic C recovery rate and appropriate correction factor for Walkley‐Black (wet combustion) method for tilled soils in southern Illinois. Soil samples were collected in 1995 and 1996 from a trial established in southern Illinois on a moderately well drained, Grantsburg (fine‐silty, mixed, mesic Oxyaquic Fragiudalf) soil. Organic C contents with the Leco analyzer (dry combustion) were significantly higher as compared to the Walkley‐Black method in different tillage systems (no‐till, chisel plow and moldboard plow), soil organic matter fractions (whole soil and mineral fraction) and soil depths (0–5 and 5–15 cm). The recovery percentage of organic C was lower than the assumed percentage with the Walkley‐Black method. No significant differences in organic C recovery percentage were found due to differences in tillage systems and depths, whereas the recovery percentage was lower in mineral fraction as compared to the whole soil. The lower organic C recovery percentage was due to the more stable organic C compounds in the mineral fraction. On the basis of these findings, correction factors of 1.35 and 1.41 are proposed for whole soil and mineral organic C analysis with Walkley‐Black method, respectively for tilled Grantsburg and other similar soils in southern Illinois.

Effects of 24 Years of Conservation Tillage Systems on Soil Organic Carbon and Soil Productivity

The 24-year study was conducted in southern Illinois (USA) on land similar to that being removed from Conservation Reserve Program (CRP) to evaluate the effects of conservation tillage systems on: (1) amount and rates of soil organic carbon (SOC) storage and retention, (2) the long-term corn and soybean yields, and (3) maintenance and restoration of soil productivity of previously eroded soils. The no-till (NT) plots did store and retain 7.8 Mg C ha−1 more and chisel plow (CP) −1.6 Mg C ha−1 less SOC in the soil than moldboard plow (MP) during the 24 years. However, no SOC sequestration occurred in the sloping and eroding NT, CP, and MP plots since the SOC level of the plot area was greater at the start of the experiment than at the end. The NT plots actually lost a total of −1.2 Mg C ha−1, the CP lost −9.9 Mg C ha−1, and the MP lost −8.2 Mg C ha−1 during the 24-year study. The long-term productivity of NT compared favorably with that of MP and CP systems.