Turfgrass Lawns Research Articles

Guiding fall fertilization of cool‐season turfgrass lawns with NDVI sufficiency index

AbstractFall N fertilizers are applied to turfgrass at predetermined rates instead of being based on plant‐N status. Normalized difference vegetative index (NDVI) and the sufficiency index (SI) concept are used to assess plant‐N status in some agronomic crops but has not been evaluated for turfgrass. This study was conducted across 3 yr in Connecticut to determine fall and spring NDVI SI values in a mixed species, cool‐season lawn. Field experiments were set out with varying fall N rates with NDVI measured weekly in October and November, and in late April. Quadratic and Linear‐Response and Plateau (LRP) models were significant (P < .0001) for all fall and spring SI values in response to fall N rates. Fall SI was maximized between 140 and 155 kg N ha−1 for the quadratic model and plateaued between 79 and 102 kg N ha−1 for the LRP model. Spring SI was maximized at 189 and plateaued at ≥116 kg N ha−1 for quadratic and LRP models, respectively. In relation to commonly recommended fall N rates of 24.5, 49, and 98 kg N ha−1, the models suggest that no supplemental N is needed when SI is ≥92, ≥95, and ≥99% of the N‐rich reference in the fall, respectively. Late April SI >89% of spring N‐rich reference would indicate that excess fertilizer was applied the previous fall at rates >49 kg N h−1. The NDVI SI can provide site‐specific fall N fertilization guidance of cool‐season turfgrass lawns.

Investigating Monetary Incentives for Environmentally Friendly Residential Landscapes

State and local governments develop policies that promote environmentally friendly landscaping practices with the goal to mitigate adverse environmental impacts from heavily maintained residential lawns. One of the mechanisms to achieve low-input landscaping practices in the urban environment is to promote the conversion of monoculture turfgrass lawns into partial turfgrass, low-input landscapes. Rebate incentives are used as an instrument to encourage the adoption of such landscapes. This study investigates the effects of households’ monetary incentive requirement on households’ preferences and willingness to pay for low-input landscapes. The discrete choice experiment method was used to analyze responses from households categorized into low, medium, and high incentive requirement groups. The results show that rebate incentives may have significant positive effects on individuals’ intentions to adopt low-input landscapes. Participants with low incentive requirement were willing to pay more for environmentally friendly attributes, compared with their counterparts in the medium and high incentive requirement groups. Practical implications for relevant stakeholders are discussed.

Nitrous Oxide Emissions from Turfgrass Lawns as a Result of Fertilizer Application:A Meta-Analysis of Available Literature

Urban turfgrass lawns are known to contribute towards global anthropogenic nitrous oxide emissions. However, available literature on lawn N 2 O emissions is varied and inconclusive. To our knowledge, an effort to compile and understand urban lawn N 2 O emissions is, as yet, lacking. In th e present article, a meta-analysis was conducted to evaluate the effect of lawn fertilizer application on N 2 O emissions relative to no-fertilizer application, along with an examination of the variation of this effect with respect to the type and amount of fertilizer. The results show that lawn N 2 O emissions from fertilized plots are significant and are 41% (0.29 g N 2 O–N/m 2 /year) higher than that of control plots. However, studies with low N -input (<150 kg/ha) show higher percentage (40) of N 2 O emission than those with high N-input (22). Further , N 2 O emissions are higher for urea application plots (37%) compared to other -than-urea plots (30%), which consisted mostly of enhanced efficiency fertilizer plots. Overall, the results of this meta -analysis under-score current understand ings of the effect of fertilizer on soil N 2 O emissions, although it indicates that fertilizer amount is not the only driver of lawn N 2 O emissions. Also, the sub-group analysis of fertilizer type reinforces the importance of enhanced eff iciency fertilizers in reducing emissio ns which has clear policy implications. To improve our understan ding of lawn N 2 O emissions, more long-term studies that are well-documented, and geographically widespread, are re commended to build a database that can reduce uncertainties and facilitate lon g-term evaluations.

Correlation between Solvita Labile Amino-Nitrogen and CO2-Burst Soil Health Tests and Response to Organic Fertilizer in a Turfgrass Soil

ABSTRACTThe Solvita Soil Labile Amino-Nitrogen (SLAN) and Soil CO2-Burst (SSCB) tests are used in soil health assessments. Field experiments were conducted from 2014–2016 in Connecticut, USA to: (1) determine if SLAN and SSCB concentrations are correlated for a sandy loam soil under predominately Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] turfgrass lawns, and (2) compare the response of SSCB–C and SLAN–N concentrations in relation to varying rates of an organic fertilizer. Concentrations of SLAN–N were positively and significantly (P < .001) correlated with concentrations of SSCB–C for all years, both species, and combinations of years and species (r = 0.477 to 0.754). The response of SSCB–C and SLAN–N concentrations to organic fertilizer rates were positively linear and significant (P < .01) in all cases but one (2014 tall fescue SSCB–C concentrations). Rates of change across fertilizer rates were generally greater for SLAN–N concentrations. There was greater variation within the SSCB test than within the SLAN test. The results suggest that the SLAN and SSCB tests are well-correlated and both may be able to provide an estimate of a turfgrass soil’s N mineralization potential.

Alternative and Low-Use-Rate Herbicides Offer Similar Levels of Weed Control to Current Standards in Turfgrass Lawns in the Upper Midwest

Alternative and Low-Use-Rate Herbicides Offer Similar Levels of Weed Control to Current Standards in Turfgrass Lawns in the Upper Midwest

Exploring the Effect of Personal Norms and Perceived Cost of Water on Conservation

In recent studies, between 50% to 75% of residential water was used for outdoor irrigation (Milesi et al., 2012). Turfgrass lawns are widely used in outdoor landscapes and are the largest irrigated crop by total area in the United States (Milesi et al., 2005). Consequently, as more American homes utilize turfgrass lawns, outdoor irrigation is expected to increase (Devitt, Carstensen, &amp; Morris, 2008). Increases in outdoor water usage coupled with urbanization pressures water resources and intensifies the need for conservation. This study utilized hierarchical multiple regression to determine factors affecting urban residents’ intent to engage in water conservation. It also evaluated the effect of the Theory of Planned Behavior (TPB) variables on intent to conserve water, then included perceived cost of water and personal norms as additional factors affecting intent to conserve. A total of 1,809 urban residents in the U.S. were surveyed via a researcher-developed questionnaire using non-probability purposive sampling. Findings revealed both social and personal norms had strong effects on intent to conserve water. Recommendations follow that social and personal norms be made known to target audiences and used collectively in extension water conservation programs to promote behavior change.

Earthworm densities correlate with aboveground plant biomass and vegetation type across residential properties in Madison, Wisconsin, USA

Non-native earthworms have been increasing in density within cities in the USA and around the world, but how earthworms respond to variation in plant cover within these systems remains unclear. We collected earthworms and standing plant biomass from five residences in Madison, Wisconsin, USA, each possessing two plant cover types—a turfgrass lawn and a prairie garden containing flora native to the Midwestern USA—on two occasions (once each in 2007 and 2008). Soil moisture and temperature were also quantified. On average, volumetric soil moisture was 2.8% lower and standing plant biomass 384 g m−2 greater in the prairie gardens than in the turfgrass lawns. Earthworm densities increased by 0.1 and 2.7 individuals m−2 on average with each increase of 1 g m−2 in standing plant biomass and of 1% in soil moisture, respectively. Further, when the effects of plant biomass and soil moisture were factored out, earthworm densities were estimated to be 55 individuals m−2 lower in prairie gardens than in adjacent lawns. These findings suggest native-flora prairie gardens may provide less favorable habitat for non-native earthworms, all else being equal.

Normalized Difference Vegetative Index Response of Nonirrigated Kentucky Bluegrass and Tall Fescue Lawn Turf Receiving Seaweed Extracts

Turf managers are continually seeking improved grasses, management practices, and products that enhance heat and drought tolerance and reduce supplemental irrigation needs. To this end, products like seaweed extract (SWE) have been extensively studied on short-cut (≤12 mm) golf turf and seedlings of various turfgrass species exposed to stress conditions. Few studies, however, have reported SWE effects on mature, higher cut (≥38 mm) cool-season turfgrass swards. A 3-year field study (2013–15) was conducted in Connecticut to determine the effect of various SWE treatments on the normalized difference vegetative index (NDVI) response of nonirrigated kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) turf managed as a lawn and cut at 76.2 mm. Separate experiments for each species were set out as randomized complete block designs with three replicates. Throughout the growing season in each year, various liquid SWEs were applied at a concentration of 9.55 L·ha−1 weekly or 19.1 L·ha−1 biweekly. A nontreated control was included. The study lacked extreme heat stress conditions during the yearly growing seasons, but periodic moisture deficits below normal were present. Within each year, there were no significant SWE effects on the NDVI of either species. The results suggest that there is no improvement in the NDVI by applying SWEs to mature, higher cut cool-season turfgrass lawns under less than extreme heat-stress conditions, water-stress conditions, or both. Because this study was conducted only at one site without extreme stress, further research of SWE applications to established, higher cut cool-season turfgrass lawns should be conducted across different locations and soils to determine the effects of applying SWE to these stands under extreme heat-stress conditions, water-stress conditions, or both.

Elevated soil nitrogen pools after conversion of turfgrass to water-efficient residential landscapes

As a result of uncertain resource availability and growing populations, city managers are implementing conservation plans that aim to provide services for people while reducing household resource use. For example, in the US, municipalities are incentivizing homeowners to replace their water-intensive turfgrass lawns with water-efficient landscapes consisting of interspersed drought-tolerant shrubs and trees with rock or mulch groundcover (e.g. xeriscapes, rain gardens, water-wise landscapes). While these strategies are likely to reduce water demand, the consequences for other ecosystem services are unclear. Previous studies in controlled, experimental landscapes have shown that conversion from turfgrass to shrubs may lead to high rates of nutrient leaching from soils. However, little is known about the long-term biogeochemical consequences of this increasingly common land cover change across diverse homeowner management practices. We explored the fate of soil nitrogen (N) across a chronosequence of land cover change from turfgrass to water-efficient landscapes in privately owned yards in metropolitan Phoenix, Arizona, in the arid US Southwest. Soil nitrate (–N) pools were four times larger in water-efficient landscapes (25 ± 4 kg –N/ha; 0–45 cm depth) compared to turfgrass lawns (6 ± 7 kg –N/ha). Soil –N also varied significantly with time since landscape conversion; the largest pools occurred at 9–13 years after turfgrass removal and declined to levels comparable to turfgrass thereafter. Variation in soil –N with landscape age was strongly influenced by management practices related to soil water availability, including shrub cover, sub-surface plastic sheeting, and irrigation frequency. Our findings show that transitioning from turfgrass to water-efficient residential landscaping can lead to an accumulation of –N that may be lost from the plant rooting zone over time following irrigation or rainfall. These results have implications for best management practices to optimize the benefits of water-conserving landscapes while protecting water quality.

Low-dose Application of Nonionic Alkyl Terminated Block Copolymer Surfactant Enhances Turfgrass Seed Germination and Plant Growth

Rapid seed germination and vigorous seedling growth are desired when establishing turfgrass lawns from seed. Low-dose concentrations of nonionic, block copolymer surfactants can have a direct effect on plant physiological functions and growth. The objectives were to determine if a low-dose application of a nonionic alkyl ended block copolymer surfactant applied directly to the seed, within a film coating, would 1) influence speed, synchrony, and final germination percentage (FGP), and 2) enhance seedling emergence and the speed of turfgrass establishment under deficit irrigation. Tests were performed with tall fescue (Schedonorus arundinaceus) and perennial ryegrass (Lolium perenne). Surfactant was applied directly to the seed using a rotary seedcoater at 0.1% by weight of seed. In the first experiment, germination was compared between seeds with a surfactant film coating (SFC) and untreated seeds in growth chambers at three different constant temperatures (10, 20, and 30 °C). For both species, the SFC decreased the time for seed germination, and improved germination synchrony, with the greatest treatment response at 10 and 30 °C compared with untreated seed. Application of a SFC did not influence FGP. In the second experiment, untreated and treated seed were compared in a grow-room study, with pots watered weekly to 70% of field capacity (FC). Perennial ryegrass density, cover, and aboveground biomass from the SFC were ≈47%, 48%, and 46% greater than untreated seed, respectively. Tall fescue density, cover, and aboveground biomass from the SFC seeds were ≈22%, 23%, and 28% greater than untreated seed, respectively. Overall these studies demonstrate that SFC can promote seed germination and also enhance turfgrass establishment under deficit irrigation.

Evapotranspiration of urban lawns in a semi-arid environment: An in situ evaluation of microclimatic conditions and watering recommendations

As many regions worldwide are increasingly affected by water scarcity caused by unprecedented climate change and population growth, current practices of landscape irrigation need to be evaluated to develop scientifically based water-saving recommendations. We compared widely used evapotranspiration (ET) based guidelines of turfgrass watering requirements with ET from 8 irrigated turfgrass lawns (4 unshaded and 4 shaded by various degree) measured in situ by portable chambers in the Los Angeles Metropolitan area. ET from unshaded lawns was 40% higher than recommended irrigation inputs and ET from shaded lawns was mostly within recommended ranges. We evaluated the microclimate coefficient (kmc), a factor used to adjust ET from reference surfaces to local microclimatic conditions. While in situ kmc was mostly within the ranges recommended for California, (1) kmc ranges for particular landscape types deviated from observations, (2) minimum and maximum kmc were beyond recommended ranges, and (3) kmc had clear seasonal changes overlooked by current methodology. We propose a method to quantitatively estimate the effect of shade on kmc and improved categories and coefficients for applying the landscape coefficient method under realistic urban conditions.

Impact of Residential Prairie Gardens on the Physical Properties of Urban Soil in Madison, Wisconsin.

Prairie gardens have become a common addition to residential communities in the midwestern United States because prairie vegetation is native to the region, requires fewer resources to maintain than turfgrass, and has been promoted to help remediate urban soil. Although prairie systems typically have deeper and more diverse root systems than traditional turfgrass, no one has tested the effect of this vegetation type on the physical properties of urban soil. We hypothesized that residential prairie gardens would yield lower soil bulk density (BD), lower penetration resistance (PR), greater soil organic matter (SOM), and greater saturated hydraulic conductivity () compared with turfgrass lawns. To test this hypothesis, we examined 12 residential properties in Madison, WI, where homeowners had established a prairie garden within their turfgrass lawn. Despite a consistent trend in the difference between vegetation types, no significant main effects were found (i.e., a difference between vegetation types when averaged over depth) for any of the four soil properties measured in this study. Differences were found with depth and depended on a significant interaction with vegetation type. At the surface depth (0-0.15 m), soil beneath prairie gardens had 10% lower mean BD, 15% lower mean PR, 25% greater level of SOM, and 33% greater compared with soil beneath the adjacent lawns. These differences were not detected at deeper sampling intervals of 0.15 to 0.30 m and 0.30 to 0.45 m. Although not statistically significant, the consistent trend and direction among soil variables suggest that residential prairie gardens had changed the surface soil at a rate that marginally outpaced turfgrass and calls for controlled experiments to identify the mechanisms that might enhance these trends.

Defining Sufficiency Levels of Nitrogen in Cool‐Season Turfgrass Lawns Using Macy's Concept

Defining Sufficiency Levels of Nitrogen in Cool‐Season Turfgrass Lawns Using Macy's Concept

A Review of Organic Lawn Care Practices and Policies in North America and the Implications of Lawn Plant Diversity and Insect Pest Management

There are ≈40 million acres of turfgrass lawns throughout the United States, most of which are managed under chemical-intensive pest and fertilizer programs. “Organic lawn care” is being adopted more widely; however, unlike the formally defined policies and regulations that govern organic agriculture, the label organic lawn management has not been formally defined and is used to describe a variety of practices. Neighborhoods, cities, states, and provinces across North America are adopting policies regulating the use of pesticides and fertilizers in the landscape. In addition, a small but growing number of public institutions and individual consumers are successfully adopting alternative lawn care methods, including organic lawn care. Although perceived as environmentally friendly, the effects of organic management on insect diversity and pest management remain understudied. Organic lawn management may lead to increased lawn plant diversity, which in agroecosystems has enhanced ecological services provided by beneficial insect species. Effects of vegetative diversity on lawn pest management are less clear. Vegetative complexity and increased plant diversity in urban landscapes may enhance insect predator efficacy. The diversity of predatory insects varies between turfgrass varieties in response to prey populations. Mortality of insectivorous and granivorous ground beetles (Carabidae) while not directly impacted by pest management programs in turfgrass may be indirectly impacted by a reduction in the prevalence of plant species that provide alternative food resources. Previous studies have focused on herbivorous insects as well as predatory and parasitic insects that feed on them. Future studies should assess how lawn plant diversity resulting from organic management practices might impact insect communities in turfgrass.

Management alters C allocation in turfgrass lawns

Turfgrass is a large fraction of land cover in urbanized areas around the world, but little information exists about basic ecological processes in lawns or the controls on these processes. Here, we characterize biomass carbon stocks and fluxes in tall fescue (Festuca arundinacea) appropriate for use on home lawns, managed with differing levels of irrigation, mowing height, and fertilization to test for effects of common management practices. Total standing biomass C (to 10cm depth) averaged 6.04Mgha−1 over the course of the study, with slightly more C in roots than in stubble; management had little effect on the average standing biomass C pool, but there was substantial intraannual variation in biomass C stocks (>2MgCha−1), and the pattern of variation was affected by all three management practices. Net primary production (NPP) averaged 4.50MgCha−1yr−1; management did not affect NPP, but had significant effects on how C was allocated to each component of production (roots, stubble, or clippings). Despite low standing biomass, turfgrass lawns generate a large annual flux of C, and the allocation of that flux is strongly modified by management.

Pollinator assemblages on dandelions and white clover in urban and suburban lawns

Flowering weeds, though often deemed undesirable in turfgrass lawns, provide food resources for declining pollinator populations in urbanized landscapes. We sampled bees and other pollinators directly from flowering common dandelion (Taraxacum officinale) and white clover (Trifolium repens) in lawns of similar character in central Kentucky USA to identify species likely to be exposed if such weeds are inadvertently oversprayed during application of lawn insecticides. We also tested the hypothesis that pollinator assemblages visiting spring-blooming white clover in urban and suburban lawns are as species-rich and diverse as in more rural lawn settings. We collected about 50 different species of insect pollinators, including 37 species of bees, from the aforementioned lawn weeds. Two of the six species of bumble bees (Bombus spp.) collected are considered uncommon and possibly in decline. Hover flies (Syrphidae), honey bees (Apis mellifera), and non-Apid wild bees predominated on dandelions whereas proportionately fewer hover flies and more A. mellifera and Bombus spp. visited white clover, especially in summer. Species richness of bees visiting white clover was similar in urban, suburban or periurban-rural lawns, although A. mellifera were proportionately more abundant, and Bombus spp. were less abundant, with increasing percentage of hardscape in surrounding areas. Fostering public awareness of the diversity of bees and other pollinators that visit flowering lawn weeds might help nurture a sociocultural shift toward more pollinator-friendly lawn care practices.

Defining Sufficiency Levels of Nitrogen in Cool‐Season Turfgrass Lawns Using Macy's Concept

ABSTRACTFew correlation or calibration studies have been conducted to determine or validate sufficiency levels of N concentrations in the clippings of turfgrass for color and growth responses. In a series of field experiments conducted across six consecutive growing seasons (2007–2012) in Connecticut, clipping samples of Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) lawns were used to estimate yields and then analyzed for N concentrations. Chlorophyll and normalized difference vegetative index (NDVI) meters were used to quantify turf color before sampling. Macy's concept of three nutritional zones of plant tissue nutrient concentration was used to identify minimum and critical concentrations of N in the clippings that define sufficiency ranges for color and growth responses, in addition to luxury consumption. Averaged across all variables and seasons (spring, summer, and fall), the sufficiency ranges of N concentration in the clippings were estimated to be 32 to 46 g kg–1 for Kentucky bluegrass, and 28 to 42 g kg–1 for tall fescue. Differences in minimum and critical concentrations among seasons and between species were thought to be due to demand‐driven nutrient uptake. Luxury consumption of N was observed in both species. When used in context with local conditions, tissue analysis for N concentrations in cool‐season turfgrass clippings can provide an objective basis for guiding N fertilization.

Soil Carbon Dynamics in Residential Lawns Converted from Appalachian Mixed Oak Stands

The conversion of unmanaged forest land to homesites dominated by managed turfgrass lawns continues to increase and has large potential impacts on biogeochemical cycling. The conversion process from forest into mowed turfgrass involves a major disturbance to soil properties and shift in ecological conditions, which could affect soil physical, chemical and biological properties, including carbon sequestration. We conducted a study on 64 residential properties, ranging from 5 to 52 years since development, to compare soil carbon content, bulk density, temperature, and moisture, between lawns and the surrounding forests from which they were converted. Homeowners were surveyed on lawn management practices and environmental attitudes, and the relationships between these and soil properties were investigated. Soil bulk density was significantly higher in the upper 10 cm of lawns compared to adjacent forest (35% higher at 0–5 cm and 15.6% higher at 5–10 cm). Total soil C content to 30 cm of lawn (6.5 kg C m−2) and forest (7.1 kg C m−2) marginally differed (p = 0.08), and lawns contained significantly greater C (0.010 g C cm−3) than forests (0.007 g C cm−3) at the 20–30 cm soil depth (p = 0.0137). In the lawns, there was a positive relationship between time since development and surface (0–5 cm) C concentration (p = 0.04), but a negative relationship at 20–30 cm (p = 0.03). Surface soils also exhibited a positive correlation between fertilization frequency and C (p = 0.0005) content. Lawn management intensity (fertilizer and pesticide use) increased with environmental commitment. Homeowners with a higher environmental commitment had lawns with greater soil carbon levels. Our results indicate that converting unmanaged Appalachian hardwood forest into managed, turfgrass-dominated residential landscapes may affect C depth distribution, but results in little change in total soil carbon sequestration in the upper 30 cm.

Adding trees to irrigated turfgrass lawns may be a water‐saving measure in semi‐arid environments

ABSTRACTEvapotranspiration (ET) of irrigated urban plants is a large yet uncertain component of urban water budgets in semi‐arid regions. A detailed understanding of plot‐scale ET and its sensitivity to plant species composition is necessary to improve estimates of urban water vapour fluxes and water balance. We used portable enclosed chambers and empirical equations to quantify ET from (1) unshaded urban lawns covered exclusively by turfgrass and (2) urban lawns comprised of open‐grown trees and turfgrass groundcover in the Los Angeles Metropolitan area. Turfgrass at all locations had a non‐limiting supply of soil water because of regular sprinkler irrigation. ET of irrigated turfgrass reached a maximum of 10. 4 ± 1·3 mm d−1and was always higher than plot‐scale tree transpiration, which did not exceed 1 mm d−1. In summer, total plot ET of the lawns with trees was lower than lawns without trees by 0·9–3·9 mm d−1. Turfgrass ET was highly sensitive to solar radiation, and the ratio of ET of lawns with trees to ET of lawns without trees decreased with tree canopy cover. Hence, reductions in turfgrass ET caused by shading effects of open‐grown trees were more important in influencing total landscape ET than the addition of tree transpiration. This suggests that low‐density planting of trees that partially shade irrigated urban lawns may be a water‐saving measure in semi‐arid irrigated environments. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Spatial organization of soil nematode communities in urban landscapes: Taylor's Power Law reveals life strategy characteristics

It is well known that Taylor's power law describes spatial aggregation, but its ecological interpretation remains elusive. Here we used data on spatial organization of soil nematode communities in urban landscapes to test relationships between nematode life history characteristics and the power law aggregation indicator, b. Forty seven genera of soil inhabiting nematodes were identified from 360 samples taken from turfgrass lawns at three public schools located in each of three northeast Ohio cities in July and October 2007. The nematodes were classified according to their life-styles in three life history classifications: trophic group, colonizer-persistor (cp) class, and functional guild, a combination of trophic group and cp-class. Estimates of Taylor's b for 28 more common genera ranged from 1.21 to 2.34. Estimates of b for trophic group, cp-class and functional guild ranged from 1.41 to 2.10, 1.34 to 1.97 and 1.41 to 2.39, respectively. Segregating genera by their trophic group, cp-class and functional guild each accounted for as much inter-genus variation in Taylor's power law as fitting 28 separate regressions. The improvements of fit in parallel line analyses for the three life-style categories over 28 lines for individual genera were highly significant. Bacterial- and plant-feeding groups were more highly aggregated than omnivorous and predatory nematodes. Nematodes in cp-classes 1 and 2 tended to be more aggregated than those in higher cp-classes. The functional guilds were generally more highly aggregated than individual genera, suggesting a higher degree of aggregation at the functional guild level. We conclude that nematode genera vary in their spatial organizations, but membership in a cp-class and functional guild accounts for much of this variability. Thus, Taylor's power law aggregation indicator, b, is sensitive to nematode feeding habits and life strategy traits as they influence a population's pattern of spatial organization.