An evaluation of western bean cutworm pheromone trapping techniques (Lepidoptera: Noctuidae) in a corn and soybean agroecosystem

Pheromone traps can be used to monitor for adult western bean cutworms, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), and for the timing of field scouting. Understanding the effect that different trapping techniques have on adult captures could help corn (Zea mays L.) producers make better pest management decisions. Several approaches to trapping adults were evaluated in 2005 and 2006 by using two different pheromone traps (sticky wing and jug traps) in two different environments (corn or corn/soybean [Glycine max (L.) Merr.] at three different heights (0.6, 1.2, and 1.8 m). There was no significant difference in the trap catches by trap type in either 2005 or 2006. There were significantly more adults captured in traps placed between two cornfields than traps placed between corn/soybean fields during both years. Trap height also was significant, with the traps at 1.2 and 1.8 m catching more moths than traps at 0.6 m during both years. These results show that trapping techniques do affect trap catches and that either trap type placed between two cornfields at either 1.2 or 1.8 m above the ground will maximize trap catches.     

Modeling N2O flux from an Illinois agroecosystem using Monte Carlo sampling of field observations

We modeled the expected range of seasonal and annual N₂O flux from temperate, grain agroecosystems using Monte Carlo sampling of N₂O flux field observations. This analysis is complimentary to mechanistic biogeochemical model outcomes and provides an alternative method of estimating N₂O flux. Our analysis produced a range of annual N₂O gas flux estimates with mean values overlapping with results from an intermodel comparison of mechanistic models. Mean seasonal N₂O flux was 1–4% of available N, while median seasonal N₂O flux was less than 2% of available N across corn, soybean, wheat, ryegrass, legume, and bare fallow systems. The 25th–75th percentile values for simulated average annualized N₂O flux rates ranged from 1 to 12.2 kg N ha^?1 in the conventional system, from 1.3 to 8.8 kg N ha^?1 in the cover crop rotation, and from 0.8 to 9.3 kg N ha^?1 in the legume rotation. Although these modeling techniques lack the seasonal resolution of mechanistic models, model outcomes are based on measured field observations. Given the large variation in seasonal N gas flux predictions resulting from the application of mechanistic simulation models, this data-derived approach is a complimentary benchmark for assessing the impact of agricultural policy on greenhouse gas emissions.     

Season long intraplant epizootics of entomopathogens,Beauveria bassiana andNosema pyrausta,in a corn agroecosystem

Intraplant epizootics of entomopathogens,Beauveria bassiana (Balsamo) Vuillemin, andNosema pyrausta (Paillot) were studied in a corn,Zea mays L., agroecosystem. Egg masses of the European corn borer,Ostrinia nubilalis (Hübner), infected withN. pyrausta were placed on midwhorl-stage corn plants. Conidia ofB. bassiana were applied in an aqueous suspension. Frass from the initial insects remaining within the plants was contaminated with sufficientN. pyrausta spores to infest 80% of the filial generation in each year of a 2-yr study. Viability ofN. pyrausta within the frass was monitored throughout the winter. Potential for impact of this inoculum on the filial generation is discussed. Conidia from cadavers of the European corn borer that were killed by the initial inoculum ofB. bassiana and/or conidia from the initial inoculum ofB. bassiana significantly reduced tunneling by the filial generation of the European corn borer. However, neither the concentration ofB. bassiana nor the age of the larvae exposed toB. bassiana, had any significant (P<.05) effect on tunneling by the 2nd-generation larvae. This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U.S. Department of Agriculture or cooperators, nor does it imply registration under FIFRA as amended.     

Comparative photorespiration in Amaranthus,soybean and corn

Summary A tracer technique was used to measure photorespiration in Amaranthus lividus, soybean and corn. Under a light intensity of 40 Wm^-2 (400–700 nm) efflux of tracer carbon dioxide from Amaranthus into air was comparable to that from soybean over a 30-min period and 10 times that from corn. Initial rates of efflux of tracer into air from Amaranthus were higher than from soybean and 9 times that from corn. Efflux of CO₂ from Amaranthus over 30 min in 120 Wm^-2 was only 5 times that of corn and the initial rate was only one third that of soybean. Though total efflux from soybean was similar at the two light intensities, the initial rate was slightly higher under 120 Wm^-2. For Amaranthus and soybean, pure oxygen doubled total efflux of CO₂ and substantially increased the initial rate compared with CO₂-free air whereas there was no effect on corn. A comparison of the light and dark curves suggests that light and dark respiration had different substrates. The results are interpreted in terms of the recycling of photorespiratory CO₂.     

Silurian reef-dwelling pentamerid brachiopods, Wisconsin and Illinois, USA

Eight species of pentamerid brachiopods, assigned toApopentamerus, Capelliniella, Kirkidium, Lissocoelina, Rhipidium, Supertrilobus andStenopentamerus, occur in stromatoporoid-coral reefs of the Silurian (Wenlockian) Racine Formation, Wisconsin and Illinois, USA. One new taxon,Rhipidium kuglitschi n.sp., is described. In contrast to level-bottom communities, where single pentamerid species occur in great numbers over large areas, pentamerids were generally rare members of the Racine reef fauna, and most species have localized distributions. An increase in diversity from one pentamerid species in the north to six species in the south correlates with a southward increase in reef size. Four morphologic groups of pentamerid species differed in the shape of the mantle cavity, which suggests different dynamics of suspension-feeding. Where two or more species are present in single reefs, co-occurrence of these groups represents a partitioning of the pentamerid niche. The relatively high diversity, local distributions, and morphologic distinctions among the Racine pentamerid fauna represent an evolutionary radiation and functional specialization of pentamerids in Wenlock reefs.     

The influence of weather on western corn rootworm flight activity at the borders of a soybean field in east central Illinois

The evolution of a new strain of western corn rootworm (WCR) beetle (Diabrotica virgifera virgifera) that has adapted to crop rotation by flying from host cornfields to nearby soybean fields to lay eggs is presenting new challenges to farmers in the U.S.A. Corn Belt. Development of effective management tools for the WCR that display this new behavior require knowledge of atmospheric factors that influence their interfield movement. In this study, WCR movement into a soybean field is related to solar radiation, wind speed and direction, air temperature, and precipitation with consideration of biological factors that also influence flight. WCR flight activity and meteorological variables were measured above the canopy of a 1.64 ha soybean field in east-central Illinois between late July and early September, 1997. On 14 days, insect traps were sampled at 30-min intervals. Interfield movement of WCR occurred over a wide range of solar irradiances, air temperatures, and wind speeds. Darkness, air temperatures below 15 °C or above 31 °C, and wind speeds in excess of 2.0 m s^{- 1} prohibited aerial movement of WCR. Within these limits, atmospheric factors had only little influence on the biologically-driven temporal patterns of seasonal and daily WCR flight activity. Atmospheric conditions were conducive to WCR flight 62% of the time during the growing season when WCR were active. Weather conditions substantially reduced interfield WCR movement throughout about one-third of the days when female WCR beetles were abundant at the study site in 1997.     

Population dynamics of a Western corn rootworm (Coleoptera: Chrysomelidae) variant in east central Illinois commercial maize and soybean fields

Three on-farm sites in Iroquois County, IL, each containing an adjacent 16.2-ha commercial production maize, Zea mays L., and soybean, Glycine max (L.) Merr., field, were monitored for western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), adults from June through September 1999-2001. Mean captures of D. v. virgifera adults as measured with Pherocon AM yellow sticky traps were significantly greater in maize than in soybean. Overall mean numbers of D. v. virgifera adults captured with vial traps were significantly greater in soybean than in maize. Emergence cage data revealed that after 50% emergence of D. v. virgifera adults occurred, peak captures of D. v. virgifera adults occurred in maize as measured with vial and Pherocon AM traps. After maize reached the R2 (blister stage, 10-14 d after silking) stage of development and 90% emergence of D. v. virgifera adults had occurred, peak captures of D. v. virgifera adults were observed in soybean by using vial and Pherocon AM traps. Also, after maize reached the R2 stage of development, numbers of females significantly increased in soybean and decreased in maize. Captures of female D. v. virgifera adults frequently exceeded published economic thresholds in soybean, regardless of trap type used. Estimated survival of variant D. v. virgifera (egg to adult) in these commercial rotated maize fields was 10.7 and 9.4% from 1999 to 2000 and from 2000 to 2001, respectively. This compares with nonvariant D. v. virgifera survival estimates in continuous maize production systems in Iowa of 6.7 and 11% from 1983 to 1984 and from 1984 to 1985, respectively.     

Blastomycosis in indoor cats: Suburban Chicago, Illinois, USA

Blastomyces dermatitidis, the etiologic agent of blastomycosis, a potentially life-threatening systemic mycosis of humans and animals, is acquired from a yet incompletely defined environmental niche. There is controversy regarding the potential for contact with the fungus in or near one’s home, particularly in urban areas. We investigated an outbreak of blastomycosis among five urban, indoor cats diagnosed at three veterinary clinics March 3–July 13, 2005, in suburban Chicago, Illinois, by owner interviews, site visits, environmental cultures for B. dermatitidis, GIS analysis, and analysis of local weather data. There were no environmental exposures common to the five cats that lived a median of 300 m from nearest body of water, in homes on a loam soil. Closest and farthest case home sites were 3.4 and 26.1 km, respectively. All cats were confined indoors except one cat that averaged 15 min/week in his backyard and was exposed to excavation. B. dermatitidis was not isolated from any of 60 environmental samples. The annualized incidence rate March through July 2005 among 6,761 cats in these practices was 178/100,000, compared to none in the previous 4 years, and 0.14/100,000 cat visits from a nationwide animal hospital registry. Precipitation January through June 2005 was 9.30 versus period mean of 14.05 ± 1.69 inches the previous 4 years (P = 0.01). Circumstantial evidence suggests acquisition of B. dermatitidis from the home site environment in five cats. Relative drought may have contributed to an apparent outbreak of blastomycosis in this urban locale.     

Modeling denitrification in aquatic sediments

Sediment denitrification is a major pathway of fixed nitrogen loss from aquatic systems. Due to technical difficulties in measuring this process and its spatial and temporal variability, estimates of local, regional and global denitrification have to rely on a combination of measurements and models. Here we review approaches to describing denitrification in aquatic sediments, ranging from mechanistic diagenetic models to empirical parameterizations of nitrogen fluxes across the sediment-water interface. We also present a compilation of denitrification measurements and ancillary data for different aquatic systems, ranging from freshwater to marine. Based on this data compilation we reevaluate published parameterizations of denitrification. We recommend that future models of denitrification use (1) a combination of mechanistic diagenetic models and measurements where bottom-waters are temporally hypoxic or anoxic, and (2) the much simpler correlations between denitrification and sediment oxygen consumption for oxic bottom waters. For our data set, inclusion of bottom water oxygen and nitrate concentrations in a multivariate regression did not improve the statistical fit.     

Modeling nitrogen removal for a denitrification biofilter

Nitrous oxide (N₂O) is a major greenhouse gas, heavily contributing to global warming. N₂O is emitted from various sources such as wastewater treatment plants, during the nitrification and denitrification steps. ASM models, which are commonly used in wastewater treatment, usually consider denitrification as a one-step process (NO₃ ⁻ directly reduced to N₂) and are as such unable to provide values for intermediate products of the reaction like N₂O. In this study, a slightly modified ASM1 model was implemented in the GPS-X™ software to simulate the concentration of such intermediate products (NO₂ ⁻, NO and N₂O) and to estimate the amounts of gaseous N₂O emitted by the denitrification stage (12 biofilters) of the Seine-Centre WWTP (SIAAP, Paris). Simulations running on a 1-year period have shown good agreements with measured effluent data for nitrate and nitrite. The calculated mean value for emitted N₂O is 4.95 kgN–N₂O/day, which stands in the typical range of estimated experimental values of 4–31 kgN–N₂O/day. Nitrous oxide emissions are usually not measured on WWTPs and so, as obtained results show, there is a certain potential for using models that quantify those emissions using traditionally measured influent data.     

Controls on chlorophyll-a in nutrient-rich agricultural streams in Illinois, USA

Nitrogen and phosphorus are the primary nutrients that affect water quality in streams in the midwestern USA and high concentrations of these nutrients tend to increase algal biomass. However, how nutrients interact with physical controls in regulating algal biomass is not well known in agricultural streams. Eighteen streams in east-central Illinois (USA) were sampled during June and September 2003 to analyze factors possibly regulating algal biomass. Additionally, two shaded and two non-shaded sites in the Embarras River in east-central Illinois were sampled intensively from June to December 2003. Both sestonic and periphytic chlorophyll-a (chl-a) were analyzed, and periphytic chl-a was assessed on natural substrata and unglazed ceramic tiles. Although high concentrations of nutrients were found in these streams (mean total P = 0.09–0.122 mg l⁻¹ and mean NO₃-N=4.4–8.4 mg l⁻¹), concentrations of sestonic chl-a were low among all sites and both sampling periods (<18 mg m⁻³, median values of 5 and 3 in June and September, respectively). Filamentous algae were an important component of the algal communities in streams with stable substrata. Periphytic chl-a was generally not related to the concentration of N or P in the water column, and in non-shaded streams periphyton appeared at times to be light-limited due to turbid water. Turbidity was found to be an important factor controlling chl-a on ceramic tiles across the 18 sites and for the Embarras River sites; chl-a decreased exponentially in concentration (132–0 mg m⁻²) as turbidity increased from 4 to 39 NTU (r ² = 0.80). In general, the interaction between hydrology and light (turbidity) likely controlled algal biomass in these nutrient-rich, agricultural streams.     

Wetland vegetation ecology on a reclaimed coal surface mine in southern Illinois,USA

An early successional wetland complex on a reclaimed surface coal mine in southern Illinois was studied 1985–1987. Seasonally, biomass was low, with above-ground values of 10–210g m^–2 and below-ground biomass of 1.5–2435 g m^–2. Biomass peaked in spring and did not vary much throughout the remainder of the growing season. Stem densities were high (179–1467 m^–2) because large numbers of seedlings became established as falling water levels exposed large areas of mudflats. Fluctuating water levels led to a lack of community zonation. Species diversity (H) was low to moderate over all sites with diversity values ranging between 1.86 and 3.27.     

Pollen interception by linyphiid spiders in a corn agroecosystem: implications for dietary diversification and risk-assessment

Dietary diversification, including consumption of plant tissues such as pollen, can enhance the fecundity of generalist predators, resulting in improved control of pest prey. Supplemental pollen feeding has been observed in many natural enemies, including sheet-web spiders (Araneae: Linyphiidae), which represent a major component of food webs in agroecosystems. Their horizontal, ground-based webs have the potential to intercept pollen grains during anthesis of crop plants, providing the opportunity for consumption of pollen to occur. In laboratory feeding trials, Frontinella communis and Tennesseellum formicum (Araneae: Linyphiidae) readily fed on pollen grains dusted on their webs, with 82 and 92% of spiders consuming pollen within the 210 min trial. These results revealed a strong potential for dietary supplementation with pollen in ground-based sheet-web spiders, indicating that pollen feeding may be an important component of the feeding biology of linyphiids. To measure pollen and prey interception in simulated linyphiid webs, a 20 m × 20 m grid of miniature sticky traps was established within and downwind of a corn agroecosystem. Traps were exposed for 24 h, all intercepted material was transferred to the laboratory for subsequent identification, and replaced with additional traps for 28 consecutive days in July and August 2008, to encompass periods before, during and after anthesis. Over 150,000 corn pollen grains and 5,000 prey items (dominated by Collembola and Hemiptera) were intercepted at simulated web-sites. Dates of peak anthesis resulted in pollen counts as high as 4,000 grains per web-site in the interior of the cornfield. Spatial Analysis by Distance Indices (SADIE) indicated significant temporal and spatial variability in pollen interception within and outside the corn field, but interestingly there was no significant spatial association between pollen and prey. Furthermore, transgenic Bacillus thuringiensis corn expresses insecticidal proteins in pollen, posing an exposure risk to non-target arthropods. Consumption of corn pollen may be a route to transgenic protein exposure in this important taxon of generalist predators.     

Effects of agroecosystem diversification on natural enemies of soybean herbivores

This study evaluated the effects of agroecosystem diversification through no-tillage and strip intercropping on the abundance of natural enemies of soybean (Glycine max Merrill) herbivores. Twenty-four plots (289 m² each) were arranged in a randomized complete block design for a 3 by 2 factorial experiment. Factors were cropping systems (corn monoculture, soybean monoculture, and strip intercropping of corn and soybean) and tillage systems (no-tillage and conventional tillage). Natural enemies were sampled during 1988, 1989 and 1990 by sweep net, suction net (D-Vac), pitfall traps and quadrat samples. Analyses of variance indicated that of 15 taxa analyzed, most foliage-inhabiting natural enemies were significantly more abundant in intercropping than in monoculture plots, whereas soil-inhabiting natural enemies had higher numbers in no-tillage plots than conventional tillage plots. Therefore, the results support the theory of greater abundance of natural enemies in more complex agroecosystems. Better environmental conditions in diversified treatments was the possible reason for these results. Corn in intercropping plots provided shade, reduced wind speed, alternate food, and possibly higher humidity and lower temperatures for soybean natural enemies. A similar effect was likely cuased by the stubble and weeds, in no-tillage plots.     

Factors affecting denitrification in agricultural headwater streams in Northeast Ohio,USA

As a result of increased anthropogenic nitrogen (N) loading in surface waters of agricultural watersheds, there is enhanced interest to understand and quantify N removal mechanisms. Denitrification, an important N removal mechanism in aquatic systems, may contribute to reducing N pollution in agricultural headwater streams. However, the key factors controlling this process in lotic systems remain unclear. The objective of our study was to examine the factors regulating rates of denitrification in the sediments of agricultural headwater streams in the mid-western USA. Denitrification rates were variable among streams and treatments (<0.1–28.0 μg N g AFDM⁻¹ h⁻¹) and on average, were higher than those reported for similar headwater streams. Carbon quantity and quality, and pH had no effect on denitrification, while temperature and nitrate ( ) concentrations had a positive effect on rates of denitrification. Specifically, controlled denitrification following Michaelis-Menten kinetics. We calculated a value of k_m (1.0 mg -N L^-1) that was comparable to other studies in aquatic sediments but was well below the median in-stream concentrations (5.2–17.4 mg -N L⁻¹) observed at the study sites. Despite high rates of denitrification, this removal mechanism is most likely saturated in the agricultural headwater streams we examined, suggesting that these systems are not effective at removing in-stream N. Handling editor: D. Ryder     

Effects of elevated CO2 and O3 on leaf damage and insect abundance in a soybean agroecosystem

By altering myriad aspects of leaf chemistry, increasing concentrations of CO₂ and O₃ in the atmosphere derived from human activities may fundamentally alter the relationships between insect herbivores and plants. Because exposure to elevated CO₂ can alter the nutritional value of leaves, some herbivores may increase consumption rates to compensate. The effects of O₃ on leaf nutritional quality are less clear; however, increased senescence may also reduce leaf quality for insect herbivores. Additionally, changes in secondary chemistry and the microclimate of leaves may render plants more susceptible to herbivory in elevated CO₂ and O₃. Damage to soybean (Glycine max L.) leaves and the size and composition of the insect community in the plant canopy were examined in large intact plots exposed to elevated CO₂ (~550 μmol mol⁻¹) and elevated O₃ (1.2*ambient) in a fully factorial design with a Soybean Free Air Concentration Enrichment system (SoyFACE). Leaf area removed by folivorous insects was estimated by digital photography and insect surveys were conducted during two consecutive growing seasons, 2003 and 2004. Elevated CO₂ alone and in combination with O₃ increased the number of insects and the amount of leaf area removed by insect herbivores across feeding guilds. Exposure to elevated CO₂ significantly increased the number of western corn rootworm (Diabrotica virgifera) adults (foliage chewer) and soybean aphids (Aphis glycines; phloem feeder). No consistent effect of elevated O₃ on herbivory or insect population size was detected. Increased loss of leaf area to herbivores was associated with increased carbon-to-nitrogen ratio and leaf surface temperature. Soybean aphids are invasive pests in North America and new to this ecosystem. Higher concentrations of CO₂ in the atmosphere may increase herbivory in the soybean agroecosystem, particularly by recently introduced insect herbivores. Handling editor: Gary Felton.     

Effects of grassland succession on communities of small mammals in Illinois, USA

Native grasslands are among the most imperiled of the North American ecosystems, with only ∼4% of their pre-settlement area remaining, but some grassland habitats are being restored and maintained through such methods as prescribed burning and mowing, which may provide habitat for animal species endemic to this ecosystem. I determined how succession of the plant community, due to a four-year rotational burn in 16 grassland fragments, influenced species richness and local abundances of small mammals in Illinois, USA. Species richness was relatively low in grasslands that were recently burned and highest in older successional grasslands. The most abundant species, Microtus ochrogaster, M. pennslyvanicus, Peromyscus maniculatus, P. leucopus, and Reithrodontomys megalotis showed very different responses to succession; Microtus spp. were most abundant in older successional grasslands, preferring areas with more cover of bunchgrasses, whereas the other three species were relatively abundant in grasslands of all successional ages. P. maniculatus was most abundant in any habitat that had ample open ground. The grasslands at my study site are a mixture of restored and non-restored grasslands. Overall, adding additional time between burns and restoring more of the grasslands by planting bunchgrasses that are native to this area may increase abundances of most mammal species at my study site.     

Field investigation of innate immunity in passerine birds in suburban Chicago, Illinois, USA

The innate immune system is the first line of defense against pathogens, and it plays a fundamental role in coordinating a protective immune response in birds. Although many studies have evaluated avian immune responses in the laboratory, many fewer studies to date have done so in a field setting. To gain insight into interspecific differences in immune function in wild birds, we used a field-deployed in vitro microbicidal assay to measure constitutive innate immunity of whole blood collected from three common passerines in suburban Chicago, Illinois, in 2009. Data from one microbe, Escherichia coli 8739, revealed that American Robins (Turdus migratorius) had significantly lower bactericidal capacity than House Sparrows (Passer domesticus) or Gray Catbirds (Dumetella carolinensis). Bactericidal capacity for E. coli 8739 tended to be lower for birds infested with chewing lice than those without chewing lice, and male birds had lower microbicidal capacity than females in the case of Staphylococcus aureus. This study demonstrates the potential for field-deployable eco-immunologic tools to inform infectious disease ecology research.     

Pohlsepia Mazonensis, An Early 'Octopus' From The Carboniferous Of Illinois, USA

Pohlsepia mazonensis gen. et sp. nov. from the Mazon Creek Konservat Lagersta¨tte (Carboniferous) of Illinois is an exceptionally preserved soft-bodied fossil coleoid, with well-defined body and arms. Lacking an internal shell and possessing eight subequal and two modified arms, Pohlsepia can be compared with both the living cirrate octopods and the decabrachian sepiardarids, both of which lack a well-developed internal skeleton. Given its sac-like body, lack of a well-defined head and presence of fins, Pohlsepia can be safely compared with modern cirrate octopods. It is the oldest known completely soft-bodied coleoid and as such has great significance with respect to the phylogeny of the group, given that both the octobrachian and decabrachian clades have previously been thought to have evolved in the Jurassic. K ey words : Coleoidea, Octobrachia, Konservat Lagersta¨tte , Mazon Creek, Carboniferous.     

Hydrolysis of organic phosphates by corn and soybean roots

Because of the importance of organic phosphates as sources of P for plants, this work was performed to study the hydrolysis of nine organic phosphates by sterile, intact corn (Zea mays L.) and soybean (Glycine max L.) roots. Results showed that the rates of hydrolysis ofp-nitrophenyl phosphate (PNP) in buffered solutions by roots of three varieties of corn and three varieties of soybean ranged from 13 to 22 μmol PO₄−P g⁻¹ root h⁻¹ and from 2.1 to 2.2 μmol PO₄−P 0.1 g⁻¹ root h⁻¹, respectively. The average rate of hydrolysis of PNP in nonbuffered solutions was 2- to 3-fold lower for corn roots and 6- to 10-fold lower for soybean roots as compared with those obtained with buffered solutions. The orthophosphate released from hydrolysis of organic P compounds in buffered solutions during a 48-h incubation of corn roots showed that the maximum rate of hydrolysis of PNP was 4 to 6 times greater than the commonly used substrates: α- and β-glycerophosphates, phenolphthalein diphosphate, and glucose-6-phosphate. The rates of hydrolysis of glucose-6-phosphate and glucose-1-phosphate were similar and about 6- to 12-fold lower than that of PNP. Phosphoethanolamine and phosphocholine were hydrolyzed slightly, ando-carboxyphenyl phosphate was not hydrolyzed. The rates of hydrolysis of organic P compounds in nonbuffered solutions by corn and soybean roots were 1 to 3 and 1 to 10 times lower than those in buffered solutions, respectively. The trends in rates of hydrolysis by soybean roots of buffered organic P substrates were similar to those observed with corn roots, with the exception of glucose-1-phosphate and phosphoethanolamine.