Illinois Soils Research Articles

The effect of tire inflation pressure and tillage systems on soil properties, growth and yield of maize and soybean in a silty clay loam soil

AbstractSoil compaction causes adverse effects on soil structure and the performance of crops. There is significant literature supporting the hypothesis that reducing tire inflation pressure can help to minimize compaction, but there is no data on the potential benefits of high flexion tires operating at reduced tire pressures in Midwestern United States agriculture. Hence, a field‐scale study was established in Illinois to determine the potential benefits of high flexion tires at low tire pressure (LTP) in comparison with those operated at standard tire inflation pressure (STP) on soil condition, crop growth and yield of maize and soybean for three tillage systems; deep tillage (450 mm), shallow tillage (100 mm) and no‐till. Two adjacent experiments were established in typical maize/soybean and soybean/maize rotations, respectively. The experiment used a 2 × 3 factorial design with five completely randomized blocks. The results showed that the use of LTP tires resulted in lower soil penetrometer resistance for three tillage systems in 2017 and 2018 in the maize field and 2018 in the soybean field. This improved plant establishment and the number of plants per hectare of maize in both 2016 (*p ≤ .05) and 2018 (**p ≤ .01) and plant establishment (***p ≤ .001) and the number of plants per hectare (***p ≤ .001) of soybean in 2018. The penetrometer resistance was higher in the no‐till plots compared to deep and shallow tillage plots in maize and was higher in the deep tillage plots compared to the shallow tillage in the soybean field. The use of LTP tires resulted in an increased grain yield of maize by 4.31% (15.02 Mg ha−1) and 2.70% (14.76 Mg ha−1) in 2017 (**p ≤ .01) and 2018 (*p ≤ .05), respectively, and soybean by 3.70% (4.25 Mg ha−1) in 2018 (*p ≤ .05). The depth of tillage had a significant effect on soybean and maize yields in 2017 (***p ≤ .001) and 2018 (***p ≤ .001), respectively, with higher yields of both soybean and maize in the deep and shallow tillage compared to no‐till plots. The study concludes that the use of the LTP systems can be a potential means of addressing soil compaction and maintaining soil porosity while increasing crop productivity in silty clay loam soils in Central Illinois.

Mehlich III predicts that soils in Wisconsin and Illinois may cause nickel deficiency in crops

Mehlich III predicts that soils in Wisconsin and Illinois may cause nickel deficiency in crops

Long‐term yields in annual and perennial bioenergy crops in the Midwestern United States

AbstractMany yield predictions in perennial bioenergy species have been made based on data collected during the establishment phase of growth or a limited number of long‐term studies. Few studies compare multiple perennial crops with the dominant agricultural vegetation of the landscape over long time periods. Here, we present the results of 11 years of perennial crop management on fertile agricultural soils in central Illinois, compared with conventional row crop maize/soybean (Zea mays L., Glycine max L.) production. We examined the long‐term productivity and drought susceptibility of Miscanthus x giganteus Greef et. Deu. ex. Hodkinson et Renvoize (miscanthus), Panicum virgatum L., Cave‐in‐Rock cultivar (switchgrass), and a native prairie mix, in contrast to annual maize/soybean agriculture. Long‐term yields for miscanthus and switchgrass failed to reach initial predictions made during the establishment phase; however, in miscanthus, the 11th year of production shows little progressive yield loss with age, exceeding the modeled limit for the onset of age‐related decline. Harvest timing and differences in yields from hand and machine harvests in perennial crops likely contribute to overestimates of potential yields. Application of fertilizer to mature miscanthus resulted in significant increases in yield after a severe drought, though modeled effects of management and drought in miscanthus point to a more complex mechanism for yield response.

Predicting soil organic matter nitrogen mineralization

AbstractThe objectives of this study were to develop a model for soil organic matter (SOM) N mineralization that required minimal inputs, to test the model using independent datasets, and to determine if the results could be used in adjusting commercial N fertilizer recommendations. A first‐order model was adjusted monthly for differences in soil temperature and moisture. A daily time step was used to allow N mineralization estimates from one date to another. Simulations began in the month where temperature exceeded 10 °C. Model predictions were compared with those in published studies in northern California and Illinois. In the first California study, model predictions were near observed values in four of five locations. In the second California study, model predictions were within the 95% confidence interval of those based on laboratory incubation corrected for field temperature and moisture regimes. In a third study, unfertilized corn (Zea mays L.) yields were compared with seasonal N mineralization predictions plus N from the prior crop for 15 Illinois soils. The result was 32.0 kg corn kg−1 seasonal available N as compared with the typical value of 67.5 kg corn kg−1 commercial N fertilizer. Nitrogen mineralization predictions for Illinois soils were related to total N, suggesting that an equation could replace simulation modeling for a given soil–location combination. It is proposed that the N mineralization model, which has readily obtainable inputs (total N, bulk density, monthly weather), could be used in conjunction with field studies to refine commercial N fertilizer recommendations.

Immobilization of agricultural phosphorus in temperate floodplain soils of Illinois, USA

Nutrient losses from Mississippi watersheds degrade downstream water bodies. As forested floodplains intercept agricultural drainage waters, a limiting nutrient like phosphorus (P) could potentially be sequestered in forest soils, reducing P loss to the Gulf of Mexico. Thus far, the role of temperate deciduous floodplain soils for P has not been extensively investigated in the Midwestern United States. The objective of this study was to investigate the buffering capacity of P in floodplain soils using soil biochemical chemical assays, 31P nuclear magnetic resonance spectroscopy (NMR) and P K-edge X-ray absorption near edge structure spectroscopy (XANES). Phosphorus reaction dynamics were compared between floodplains and surrounding upland soils in east-central Illinois, USA. Total organic P was significantly greater in the floodplain (277.27 ± 159.51 mg kg−1) than that in the upland (113.04 ± 74.88 mg kg−1), illustrating its buffering capacity. Notably, microbial biomass P (averaged 13.08 mg kg−1) was greater in the floodplain than that in the upland. The results of 31P NMR analysis showed the presence of organic P (e.g., orthophosphate monoesters) and orthophosphate. The P K-edge XANES analysis shows that these inorganic and organic P species are predominantly adsorbed in calcite and precipitated as calcium phosphate in floodplain soils. These findings suggest that temperate deciduous floodplain soils have a great potential to immobilize agricultural P in the Upper Mississippi watershed.

Continuous Corn and Corn–Soybean Profits over a 45‐Year Tillage and Fertilizer Experiment

Core Ideas Cumulative profit (1970–2014) in no‐till was similar to other tillage types with NPK. Relative profits were more sensitive to changes in machinery than herbicide cost. Return on fertilizer ranged from 56 to 251% for P and K and 69 to 434% for N. Studies comparing profitability of tillage systems often examine narrow historic windows or exclude annual price fluctuations. This study uses a continuous corn (Zea mays L.) (CC; 1970–1990) and corn–soybean [Glycine max (L.) Merr.] (CS; 1991–2014) Tillage × Fertilizer study in somewhat poorly drained soils in southern Illinois to reconstruct partial annual budgets with historical prices for crops, fertilizers, lime, herbicides, fuel, labor, and machinery. Combinations of tillage (moldboard plow [MP], chisel tillage [ChT], alternate tillage [AT], and no‐till [NT]) and fertilizer (Control, N‐only, N+NPK starter, NPK+NPK starter, and NPK broadcast) treatments were evaluated. The CC profits were highest in NPK‐applied treatments followed by N‐only and Control. The MP treatments were similar to ChT and more profitable than NT, while AT fell between. In CS, NPK‐applied treatments were similar regardless of tillage. Combined costs for herbicide, machinery, labor, and diesel were higher in MP and ChT systems than AT and lowest in NT, but were a small percentage of total costs (26.6, 26.0, 21.5, and 18.2%, respectively). Nitrogen fertilizer offered a return on investment of 396% in CC and 133% in CS while P & K returned 78% in CC and 109% in CS. Sensitivity analysis in CS showed that NT would be less profitable than MP if herbicide costs increased 850%. A 300% machinery cost increase would have made MP less profitable than NT. These findings suggest that since 1991 CS under NT carried the same potential for profit as other tillage systems under full fertility management.

Using cover crops in headlands of organic grain farms: Effects on soil properties, weeds and crop yields

Organic producers often rely heavily on tillage for weed management, which can create compaction, especially in headlands, and favor weed growth. To address Illinois organic grain farmers’ concerns, we explored the effect of cover crops in headland areas of their farms on soil properties, weeds, and yields in a participatory on-farm approach. A split-plot arrangement with two replications at each of four Illinois locations was used in two consecutive years within field areas [FA: headlands – or turn-rows – HL; non-headlands NHL] randomly selected as main plots where four cover crop treatments were randomly assigned (CC: fallow control C; forage radish FR; mix of forage radish and buckwheat FRbw; and mix of forage radish with hairy vetch and cereal rye FRhvr). Collaborating farmers planted soybean [Glycine max (L.) Merr.] in 2012 and corn (Zea mays L.) in 2013. Each fall and spring, we measured soil penetration resistance (PR), bulk density (BD), water aggregate stability (WAS), total carbon (TC), nitrate (N-NO3), ammonium (N-NH4), available phosphorus (P), and pH. Additionally, cover crop and weed growth, and cash crop yields were determined each year. Our results indicate HL areas had greater PR (+22%) and BD (+3%), as well as higher WAS (+4%), TC (+10%), P (+36%), and pH (+7%) in comparison to NHL areas on average through the fall and spring seasons. Though FRhvr significantly reduced spring weed biomass (−30%) compared to the controls, higher density of grass weeds (+44%) were present in HL areas through spring and summer regardless of CC treatments. Due to the resilient nature of these particular Illinois soils and extreme weather pattern observations, the cover crop treatments did not alleviate compaction nor influence soil properties for the duration of this project. However, there was a trend toward lower available P in the FRhvr treatments and reduced crop yields in those treatments within the NHL areas. Though the cover crop treatments chosen for this trial did not seem to provide clear benefits, our results point toward a beneficial feedback between the weed community and the soil properties within headland areas in these organic systems.

Corn residue, tillage, and nitrogen rate effects on soil carbon and nutrient stocks in Illinois

Removal of crop residues for use as ethanol production feedstock might deplete soil carbon and nutrient pools in site- and management-specific ways. We investigated the effect of residue removal (RR), tillage (T), and N fertilizer rate (Nr) after five years of continuous corn (Zea mays L.) on total soil carbon (TC) and nutrient stocks at four sites within Illinois. The experimental design was a split–split plot arrangement of treatments in a randomized complete block design with four replications, and all treatments remained in the same place each year. Main plots consist of one of three levels of corn residue removal (RR: full, partial, and none); split plots were two tillage systems (T: chisel tilled and no-till) and split–split plots were four N fertilizer rates (Nr: 67, 134, 201, and 268kgNha−1). The highest TC stocks were found under no-till without residue removal; removing any residue under no-till lowered TC to the levels found under chisel tillage. Removing residue in tilled soils produced higher TC values similar to the levels found with no residue removal and no-till. Residue removal tended to lower P and lowered K and EC in the surface 15cm soil. Tillage decreased the N and K stocks in the surface soil. Increasing the rate of N fertilizer lowered P, K, and pH, generally in an increasing, curvilinear manner, but the response of EC was concave, increasing at the highest N rate used. These responses were closely related to corn grain yields, indicating that the amount of nutrient removed by harvest of grain and residue and the amount of residue retained after harvest affect TC and nutrient stocks in Illinois soils. This information will help producers and policy makers to make better decisions regarding the feasibility of harvesting corn residue, and on agronomic practices that might accompany residue removal in order to prevent soil nutrient depletion.

Effects of Soil Type and Cover Condition on Cryptosporidium parvum Transport in Overland Flow

Overland transport kinetics of pathogens is controlled, in large part, by soil and vegetation. With an increasing number of concentrated animal operations, there is becoming a greater need to dispose of a vast amount of manure in a single, localized area. Animal manure contains a substantial amount of microbial pathogens, including Cryptosporidium parvum that may pose a threat of contamination of water resources. This study examines the kinetics of C. parvum in overland transport and critical factors involved in the design of best management practices, especially vegetative filter strips, to prevent the transport of harmful pathogens to water bodies. Three soil types were tested (Catlin silt-loam, Alvin fine sandy-loam, Darwin silty-clay), spanning the entire spectrum of typical Illinois soils. A 20-min rainfall event was produced using a small-scale (1.07 m × 0.66 m) laboratory rainfall simulator over a soil box measuring 0.67 m × 0.33 m. Each soil type was tested for pathogen transport kinetics with bare surface conditions as well as with smooth brome and fescue vegetative covers. Surface runoff, soil cores, and near-surface runoff were each analyzed for infective C. parvum oocysts using cell culture infectivity assays. Results showed that vegetation greatly reduced the recovery of infective oocysts, in addition to delaying the time to the peak recovery. However, there was no clear evidence of any one vegetation type being advantageous over another. The bare soil experiments resulted in a higher recovery of C. parvum oocysts from the Darwin soil compared to other two soils. Analyses of soil cores show a slightly higher recovery of oocysts in the Catlin soil compared to Alvin or Darwin soils.

Survival of Oospores of Phytophthora capsici in Soil.

This study assessed survival of Phytophthora capsici oospores in soil in Illinois. Soils differing in texture and other characteristics were collected from four Illinois Counties (Champaign, Gallatin, Madison, and Tazewell), equilibrated to -0.3 MPa, and infested with oospores of P. capsici at a density of 5 × 103 oospores/g of dry soil. Samples (25 g) of the infested soil were placed in 15-μm mesh polyester bags, which were sealed and placed at 2-, 10-, and 25-cm depths in 15.3-cm-diameter PVC tubes containing the same field soil as the infested bags. Tubes were buried vertically in the ground at the University of Illinois Vegetable Research Farm in Champaign in October 2004. Soil samples were assayed for recovery and germination of oospores 1 day and 3, 6, 12, 24, 30, 36, and 48 months after incorporation of oospores into the soil. Overall, the percentage of oospore recovery and the percentage of germination of oospores were not affected significantly by soil source and burial depth but both the oospore recovery and oospore germination were significantly (P = 0.001) affected by the duration of oospore burial. The rate of oospore recovery from soil samples was 61.06, 16.69, 10.28, 1.05, 0.30, 0.06, 0.05, and 0.004% after 1 day and 3, 6, 12, 24, 30, 36, and 48 months, respectively, following incorporation of oospores into the soil; and mean oospore germination was 47.17, 30.53, 21.33, 15.64, 7.42, 2.67, 2.61, and 0.00%, respectively. Survival of P. capsici oospores was compared in soil samples stored in a laboratory at 22°C versus on the soil surface or buried 2, 10, or 25 cm deep in a field. Oospores were recovered 1, 3, 6, 12, and 24 months after incorporation for both storage locations. The percentage of oospores recovered from samples stored in the laboratory was significantly (P = 0.004) greater than recovery from samples stored in the field, regardless of the depth of burial. Twenty-four months after incorporation of oospores, 26.52% of oospores were recovered from soil samples in the laboratory, whereas only 0.12% of oospores were recovered from soil samples in the field. Overall, the percentages of germination of oospores recovered from samples in the laboratory and field over 24 months were not significantly different. In both experiments, germinated oospores produced mycelia, sporangia, and zoospores, and were virulent on 'California Wonder' bell pepper. This study showed that oospores of P. capsici can survive and remain virulent in Illinois soils for more than 36 months but oospores were no longer viable after 48 months in soil in a field environment.

Soil Fertility Status of Soils in Illinois

Our objective was to survey the phosphorus (P), potassium (K), pH, calcium (Ca), magnesium (Mg), and organic-matter (OM) levels of soils in Illinois, including the degree of nutrient vertical stratification. Soil samples were collected from depths of 0–8 and 8–18 cm in 547 randomly chosen fields throughout Illinois and analyzed for nutrients, pH, and OM. Forty-six percent of samples were below the critical range for K (130 to 150 mg K kg−1), and 59% of samples were above the soil P levels, requiring no additional fertilization. Soil pH ranged from 4.7 to 8.1. Mean Ca and Mg levels were nonlimiting for crop production, and OM was correlated (R2 = 0.690) with corn grain yield. Vertical stratification (surface/subsurface ratio) was 2.4:1 for P and 1.5:1 for K. Many fields with greater than needed P levels and less than suggested levels for K present opportunities for improvement in fertilizer management.

Performance of drainage water management systems in Illinois, United States

Drainage water management (DWM) is the practice of varying the drainage intensity of a subsurface drainage system to ensure that no more water is transported from a field than is necessary for optimizing crop growth and for facilitating seedbed preparation and other agrotechnical practices. This variation is achieved by using stop logs in a control structure to adjust the outlet elevation of the drainage system. An experiment was set up to test the hypothesis that the implementation of this practice will reduce nitrate (NO₃) loads from subsurface drainage systems in Illinois, United States, without adversely affecting yields. This experiment consisted of instrumenting and collecting precipitation, flow, and water quality data from four pairs of fields on different soils in Illinois. Each pair consisted of one field with a conventional (free) drainage system and one field with a drainage system whose outlet was managed in accordance with the Illinois Practice Standard for DWM. Annual NO₃ load reductions from the managed fields ranged from 37% to 79%, with an average load reduction of 61%. However, because of difficulties in measuring flow under submerged outlet conditions and because water left the managed fields by pathways other than through the outlets of the drainage systems, the efficacy of the practice is likely less than these numbers would indicate. There were no consistent patterns to the relationship between DWM and yields. In some instances, yields increased on the managed fields, and in others, yields decreased. Because of confounding factors, such as weather and topography, studies of longer duration are required to determine the effect of DWM on yield.

A Taxonomically Based Ordinal Estimate of Soil Productivity for Landscape-Scale Analyses

In this article, we introduce, evaluate, and apply a new ordinally based soil Productivity Index (PI). The PI uses family-level Soil Taxonomy information, that is, interpretations of features or properties, recognized in Soil Taxonomy, that tend to be associated with low or high soil productivity, to rank soils from 0 (least productive) to 19 (most productive). The index has a wide application generally at landscape scales. Unlike competing indexes, it does not require copious amounts of soil data, for example, pH, organic matter, or cation exchange capacity, in its derivation. Geographic information system applications of the PI, in particular, have great potential. Results confirmed that for 1,000 sites in southern Michigan, the mean PI of cultivated sites is significantly higher (10.94) than that of forested sites (7.77). We also compared the PI with published productivity values for Illinois soils. The positive statistical correlations that resulted confirmed that the PI is an effective measure of productivity for areas that do not have robust productivity data or a wealth of local soil knowledge, as does Illinois. Last, 2009 crop yield data for 11 Midwestern states were used to further evaluate the PI. In a geographic information system, we determined the soils and crops in particular fields and thus were able to ascertain the mean PI value per soil, per crop, per county. Statewide summaries of these data produced statistical correlations among yields of specific crops and PI values that were all positive; many exceeded 0.60. For regionally extensive applications, the PI may be as useful and robust as other indexes that have much more exacting data requirements.

The impact of garlic mustard on sandy forest soils

Garlic mustard (Alliaria petiolata), an exotic biennial herb invasive to North American forests, has potential to affect resource availability in invaded soils. Garlic mustard produces a suite of toxic chemicals that impact diversity both above and belowground and thus likely alter ecosystem processes. To examine the effects of garlic mustard on soil biota and ecosystem processes, we sampled soil from invaded and uninvaded stands at a pine plantation on sandy soils in central Illinois. Several of the pine stands were also planted with the N2-fixing tree black locust (Robinia pseudoacacia). Results indicate that pine soils underlying garlic mustard have higher pH, and exhibit higher rates of N mineralization, relative nitrification and soil respiration compared to soils without garlic mustard. Nitrogen turnover on pine invaded stands is more similar to pine soils with the black locust trees present than to uninvaded pine stands without black locust. Garlic mustard cover was much greater in stands with black locust trees planted, suggesting that garlic mustard may be attracted to high N sites. Catabolic response profiles, which provide a measure of soil microbial function, indicated a shift in substrate use for one of the substrates tested in the presence of garlic mustard. While many of the soil characteristics measured did not differ between invaded and uninvaded stands, the differences with regard to N turnover were striking and will likely have long term effects on soil nutrient status, with potential to feedback to forest health.

Diaspore morphometrics and self-burial in Hesperostipa spartea from loam and sandy soils1

Studies associated with diaspore self-burial have emphasized the role of awns and substrate surfaces to explain burial differences between species. However, limited research has been conducted to determine the effect of diaspore morphometrics on intraspecific self-burial differences. The aim of this study was to evaluate morphometric and self-burial differences between diaspores of Hesperostipa spartea growing in loam versus sandy soils. Hesperostipa spartea diaspores were collected in three black soil prairies (loam soils) and three sand prairies (sandy soils) in Illinois. Eight morphometric measurements were made from 50 diaspores per site to determine differences between diaspores from these two soil types. Two studies were conducted to determine if self-burial rate and depth of burial differed between diaspores from loam versus sandy soils. Morphometric results showed that sandy soil diaspores were smaller than loam soil diaspores. In addition, regardless of the soil of origin, diaspores were more successful at self-burial in loam soil than in sandy soil due to microtopography. Lastly, diaspores from sandy soil self-buried deeper than diaspores from loam soil regardless of soil substrate. This study demonstrates that there are intraspecific morphometric differences between Hesperostipa spartea diaspores from loam versus sandy soil prairies and that these morphometric differences affect self-burial.

An Economic Based Nitrogen Recommendation System for Grain Sorghum Production in Southern Illinois

Grain sorghum [Sorghum bicolor (L.) Moench] production in Illinois is predominately limited to lower productivity soils in southern Illinois. Nevertheless, the need for optimizing profits dictates N recommendations based on price of fertilizer N as well as predicted grain sorghum prices after harvest. The objectives of this study were to: (i) determine the optimum N rate for grain sorghum production in southern Illinois and determine the effects of changing N prices and grain sorghum prices on recommended N rates; and (ii) evaluate interactions between N rates, planting rates, and row widths. A factorial arrangement of four N rates (0, 40, 80, and 120 lb N/acre), three planting rates (60,000, 90,000, and 120,000 seeds/acre), and two row widths (15 and 30 inches) were studied at three locations in southern Illinois from 2003 through 2005. Planting rate had no effect on yields. The 30-inch rows out-yielded 15-inch rows at two locations in 2004, but for other site-years, there were no differences, nor were there any interactions with planting rates and N rates. Increasing N rates increased yields and, on average, had a curvilinear effect which allowed for the calculation of optimum economic N rates based on the price of N and the value of the grain sorghum. Nitrogen recommendations could then be determined for any number of combinations of these two variables.

Sodium-Affected Soils in South-Central Illinois, USA: A Summary of Settings, Distribution, and Genesis Pathways

Sodium-Affected Soils in South-Central Illinois, USA: A Summary of Settings, Distribution, and Genesis Pathways

Impacts of 2008 flooding on agricultural lands in Illinois, Missouri, and Indiana

The 2008 spring rains in Illinois, Missouri, and Indiana delayed planting, drowned corn and soybean plants, and resulted in significant replanting. From May 30, 2008, to June 12, 2008, the previously saturated soils could not retain any more rainfall, and the wetlands, potholes, and depressions in the upland landscape filled with water (figure 1) and then began to runoff through waterways and into small streams (figure 2). As much as 30% of the upland soils in south central Illinois, northern Missouri, and southern Indiana were affected by ponding. Approximately one-third of that ponded acreage was not replanted in 2008. As overland flow started to occur, so did sheet, rill, and gully erosion. Where significant topsoil loss occurs, it can eventually result in the erosion phase change of the soil. Any soil erosion phase change from slightly to moderately or severely eroded can reduce the crop yield potential from 0.3 to 1 Mg ha−1 (5 to 15 bu ac−1), depending on whether the soils have favorable or unfavorable sub-soils for rooting. One year's erosion events do not change the erosion phase of the soil unless gullying occurs. However, the 2008 soil loss, when added to the soil loss from erosion in…

Soil Magnetic Susceptibility: A Quantitative Proxy of Soil Drainage for Use in Ecological Restoration

Abstract Flooded, saturated, or poorly drained soils are commonly anaerobic, leading to microbially induced magnetite/maghemite dissolution and decreased soil magnetic susceptibility (MS). Thus, MS is considerably higher in well‐drained soils (MS typically 40–80 × 10−5 standard international [SI]) compared to poorly drained soils (MS typically 10–25 × 10−5 SI) in Illinois, other soil‐forming factors being equal. Following calibration to standard soil probings, MS values can be used to rapidly and precisely delineate hydric from nonhydric soils in areas with relatively uniform parent material. Furthermore, soil MS has a moderate to strong association with individual tree species’ distribution across soil moisture regimes, correlating inversely with independently reported rankings of a tree species’ flood tolerance. Soil MS mapping can thus provide a simple, rapid, and quantitative means for precisely guiding reforestation with respect to plant species’ adaptations to soil drainage classes. For instance, in native woodlands of east‐central Illinois, Quercus alba, Prunus serotina, and Liriodendron tulipifera predominantly occur in moderately well‐drained soils (MS 40–60 × 10−5 SI), whereas Acer saccharinum, Carya laciniosa, and Fraxinus pennsylvanica predominantly occur in poorly drained soils (MS <20 × 10−5 SI). Using a similar method, an MS contour map was used to guide restoration of mesic, wet mesic, and wet prairie species to pre‐settlement distributions at Meadowbrook Park (Urbana, IL, U.S.A.). Through use of soil MS maps calibrated to soil drainage class and native vegetation occurrence, restoration efforts can be conducted more successfully and species distributions more accurately reconstructed at the microecosystem level.

SOIL ORGANIC CARBON STORAGE IN SOUTHERN ILLINOIS WOODLAND AND CROPLAND

Many factors including land use, management history, soil type, climate, and soil landscape processes affect the dynamics of soil organic C (SOC). The primary objective of this research was to compare the storage of SOC on sloping woodland and cropland landscapes of southern Illinois. The cropland area was previously cultivated between the 1880s and the 1930s, used for crop production with forages in crop rotation between the 1930s and the 1960s, and remained in hayland from the 1960s to 1989. Since 1989, row crops were grown on a yearly rotation system using conservation tillage practices. The woodland area was never cleared and farmed but part of the landscape was subjected to periodic grazing before the 1960s. The SOC concentration of various soil layers, to a depth of 1 m, was measured and expressed on both a gravimetric and volumetric basis. The woodland landscape had significantly higher SOC in the surface layer (0-0.05 m) on all 6 landscape segments; however, the 0.05- to 0.15-m layer in the cropland landscape contained significantly more SOC. The subsurface rooting zone SOC values varied by landscape segment for both land uses. Results suggested that the cropland landscape retained 95% of the total SOC on a volumetric basis during the last 130 years of agricultural use. The years with forages may have increased the SOC of the cropland site and help offset losses due to soil erosion and aeration as a result of tillage. The woodland and agricultural landscapes appear to have similar amounts of SOC when the crop rotations included forages, cover crops, conservation tillage, and contour farming. Results suggest that southern Illinois soils can be used for cropland with conservation practices and forages while still maintaining the SOC levels of woodland.