Higher Soil Moisture Levels Research Articles

The influence of channelisation on riparian plant assemblages

Summary1. A comparative study of species diversity and assemblage patterns of herbaceous ground‐flora communities in riparian areas was performed along natural mid‐sized lowland streams and their channelised counterparts. The areas had open vegetation and were positioned along 18 similar‐sized third to fourth order stream reaches.2. Alpha diversity was significantly higher along natural streams both at the sample plot and reach scale. Sample plot diversity peaked at intermediate distance from the natural stream reaches, whereas it increased with increasing distance from the channelised reaches. Both gamma diversity, measured and estimated from species‐area curves, and beta diversity, which is a measure of the change in diversity between areas, was similar along the two types of streams.3. Alpha diversity correlated with several of the measured and calibrated environmental variables. The positive correlation between bank slope and alpha diversity indicates that flooding plays a key role in maintaining high levels of diversity along natural streams.4. Species composition varied significantly between the two stream types. A cluster analysis identified four clusters of which two clusters (one and three) primarily included species associated with sample plots in areas along natural streams. Most cluster one and three species were also identified as indicator species for this stream type.5. Canonical correspondence analysis revealed that cluster one species were less productive species associated with high total soil carbon and nitrogen contents, whereas cluster three species were highly productive species associated with high soil moisture levels, probably partly resulting from flooding. Our results suggest that distance from the stream channel imposes a probabilistic gradient that sustains co‐occurrence of these two communities in riparian areas along natural mid‐sized lowland streams.

A Record of Late-Quaternary Moisture-Balance Change and Vegetation Response from the White Mountains, New Hampshire

Changes in regional moisture availability over time affect hydrologic systems, such as lakes, and ecological processes, such as plant growth and reproduction. Long-term changes in moisture balance may help to explain broadscale changes in forest composition during the Quaternary period. In this article, Holocene lake-level changes and fossil pollen from Echo Lake, New Hampshire, are documented and the relationship between moisture-balance fluctuations and vegetation change in northern New England over the past 12,000 years is examined. Ground-penetrating radar profiles and five sediment cores provide evidence for two periods of low water levels at ca. 11,000–8,000 cal yr BP and at ca. 5,000–2,000 cal yr BP, respectively. During the first interval of low water level, dry-tolerant white pine (Pinus strobus) became common in the surrounding watershed. By ca. 8,000 cal yr BP, when the water level rose, hemlock (Tsuga), beech (Fagus), and birch (Betula), which prefer high soil-moisture levels, had increased in abundance. The second period of low water levels coincided with a decline in hemlock populations that has been widely attributed to a pathogen outbreak. The correlation between lake-level and vegetation change suggests that moisture availability, in addition to temperature, helps to shape vegetation dynamics by directly affecting plant populations and by influencing plant-pathogen and other ecological interactions.

Effect of climatic fluctuations on body mass of a Mediterranean vole, Microtus cabrerae

The Cabrera vole ( Microtus cabrerae) is a microtine rodent endemic to the Mediterranean bioclimatic region of the Iberian peninsula. We investigated body mass variation in a population monitored during monthly trapping sessions from April 1997 to April 1999. No significant differences in body mass were found between adult males and females; also no seasonal pattern of body mass variation was detected. Likewise, no correlation was found between the monthly body mass average and rainfall, probably due to the peculiar characteristics of the habitats used by M. cabrerae. These consist of areas with high soil moisture and high phreatic level; thus, these features act as a buffer and maintain fresh vegetation when rainfall is scarce. Consequently, body mass of the population does not depend directly on rainfall. Body mass and body condition scarcely fluctuated before summer 1998, but decreased significantly from that season to winter 1998, in coincidence with the severe drought recorded in summer–autumn 1998, which affected the quality of food available to the Cabrera vole, and resulted also in a suppression of reproduction up to 3 months. Given the predicted climate change trend in the Iberian peninsula, the particular reproduction characteristics of the Cabrera vole, and the destruction of their habitats by human activities, we strongly recommend the protection of the habitats occupied by this rodent species.

Degradation of metolachlor in bare and vegetated soils and in simulated water‐sediment systems

A study was conducted to determine the half-life (t1/2), degradation rate, and metabolites of metolachlor in a water-sediment system and in soil with and without switchgrass. Metolachlor degradation in a laboratory was determined in sediment from Bojac sandy loam soil incubated at 24 degrees C. The study also was conducted in a greenhouse on tilted beds filled with Bojac soil and planted with switchgrass. In both experiments, samples were collected at days 0, 7, 14, 28, 42, 56, and 112 and analyzed for metolachlor and its major metabolites. The water-sediment oxidation-reduction potential took 28 d to reach -371 mV and the pH increased from 5.6 to 6.5 by the last sampling day (day 112). The average soil temperature of the tilted beds with or without switchgrass during the study was 21degrees C and the soil moisture content was 23% by volume. The t1/2 of metolachlor was 34 d in sediment and 8 d in the water phase. The t1/2 of metolachlor in soil from the switchgrass filter strip (6 d) was not different from that in soil without grass (9.6 d). The metolachlor metabolites ethanesulfonic acid (ESA) and oxanilic acid (OA) were detected in the water-sediment system and in soil from tilted beds. In both sediment and soil from tilted beds, the two metabolites peaked by day 56 of incubation and declined after that, indicating transformation to other products. In the water-sediment system, greater quantities of OA and ESA were detected in sediment than in the aqueous phase. The production of OA and ESA in the watersediment system occurred in the first 28 d, when the system was at an aerobic redox state. Metolachlor can degrade in sediment and the relatively high soil temperature and moisture level accelerated its breakdown in beds with and without switchgrass. Under warm and moist soil conditions, the presence of switchgrass has no effect on the degradation of metolachlor.

Photosynthetic Responses of a Temperate Liana to Xylella fastidiosa Infection and Water Stress

Abstract Xylella fastidiosa is a xylem‐limited bacterial plant pathogen that causes bacterial leaf scorch in its hosts. Our previous work showed that water stress enhances leaf scorch symptom severity and progression along the stem of a liana, Parthenocissus quinquefolia, infected by X. fastidiosa. This paper explores the photosynthetic gas exchange responses of P. quinquefolia, with the aim to elucidate mechanisms behind disease expression and its interaction with water stress. We used a 2 × 2‐complete factorial design, repeated over two growing seasons, with high and low soil moisture levels and infected and non‐infected plants. In both years, low soil moisture levels reduced leaf water potentials, net photosynthesis and stomatal conductance at all leaf positions, while X. fastidiosa‐infection reduced these parameters at basally located leaves only. Intercellular CO2 concentrations were reduced in apical leaves, but increased at the most basal leaf location, implicating a non‐stomatal reduction of photosynthesis in leaves showing the greatest disease development. This result was supported by measured reductions in photosynthetic rates of basal leaves at high CO2 concentrations, where stomatal limitation was eliminated. Repeated measurements over the summer of 2000 showed that the effects of water stress and infection were progressive over time, reaching their greatest extent in September. By reducing stomatal conductances at moderate levels of water stress, P. quinquefolia maintained relatively high leaf water potentials and delayed the onset of photosynthetic damage due to pathogen and drought‐induced water stress. In addition, chlorophyll fluorescence measurements showed that P. quinquefolia has an efficient means of dissipating excess light energy that protects the photosynthetic machinery of leaves from irreversible photoinhibitory damage that may occur during stress‐induced stomatal limitation of photosynthesis. However, severe stress induced by disease and drought eventually led to non‐stomatal decreases in photosynthesis associated with leaf senescence.

On quantifying soil water deficit of a partially wetted root zone by the response of canopy or leaf conductance

Abstract Quantifying the soil water deficit (SWD) and its relation to canopy or leaf conductance is essential for application of the Penman–Monteith equation to water-stressed plants. As the water uptake of a single root depends on the water content of the soil in its immediate vicinity, the non-uniform distribution of water and roots in the soil profile does not allow simple quantification of SWD from soil-based measurements. Using measurements of stem sap flux (with a heat pulse technique), soil evaporation (with micro-lysimeters) and meteorological parameters the canopy conductance was obtained through inversion of the Penman–Monteith equation. SWD was evaluated by averaging the soil water content profile of the root zone (monitored by layers with the TDR sensors) weighted by root distribution of the layers. The average canopy conductance at midday (11:00–15:00, Israel Summer Time), denoted as Gnoon, was computed for each day of the experimental period. Stable summer weather, typical of the Mediterranean region, and the fully developed crop canopy, made water stress the only plausible cause of a Gnoon decline. However, the daily decline of Gnoon did not occur at the same weighted average soil water content during the successive drying cycles. For the cycle with less irrigation, the decline in Gnoon occurred at higher soil moisture levels. Alternatively, when SWD was determined from the water balance, i.e., by defining water deficit as irrigation minus accumulated evapotranspiration, the Gnoon decline occurred at the same value of water deficit for all irrigation cycles. We conclude that a climate-based soil water balance model is a better means of quantifying SWD than a solely soil-based measurement.

Relating soil surface moisture to reflectance

The objective of this study was to explore the relationship between soil reflectance in the solar domain (400–2500 nm) and soil moisture. Ten soils covering a large range of composition have been sampled. To decrease the large dimensionality of the data set, we reduced the number of wavebands investigated thanks to a simple stepwise linear regression. Seven wavebands were selected, which represent the whole spectral domain for the 10 soils and all moisture conditions with a root mean square error (RMSE) better than 0.002, close to the experimental uncertainties. Each soil reflectance spectrum was normalized by the corresponding reflectance spectrum observed under the driest condition. This allows to minimize effects due to soil type, as well as those of other undesirable multiplicative factors such as roughness and measurement configuration. The relationship between the normalized soil reflectance and moisture was then investigated. For all the wavelengths and all the soils, results show that for low soil moisture levels, the reflectance decreased when the moisture increased. Conversely, after a critical point, soil reflectance increased with soil moisture. For some soils, the reflectance of the wettest conditions can overpass that of the driest conditions. The position of the critical point was related to soil hydrodynamic properties. For both low and high soil moisture levels, and the seven wavelengths selected, the relative reflectance was strongly correlated with moisture. Adjustment of the relationships over individual soil types provides better soil moisture retrieval performances. It also shows that the relationships are generally nonlinear. These results are discussed with regards to the underlying physical processes, as well as for application to soil moisture estimates from reflectance measurements.

The effect of soil moisture on mineral nitrogen, soil electrical conductivity,and pH

Inorganic nitrogen in the soil is the source of N for non-legume plants. Rapid methods for monitoring changes in inorganic N concentrations would be helpful for N nutrient management. The effect of varying soil moisture content on soil mineral nitrogen, electrical conductivity (EC), and pH were studied in a laboratory experiment. Soil NO3-N increased as soil water-filled pore space (WFPS) increased from 0 to 80 cm3 cm−3. At soil moisture levels greater than 80 cm3 cm−3, NO3-N concentration declined rapidly and NH4-N concentration increased, likely due to anaerobic conditions existing at higher WFPS levels. Soil pH did not change as soil moisture increased from 100 g kg−1 to 400 g kg−1 and increased from 6.2 to 6.6 at higher levels of soil moisture. Soil EC was correlated with soil mineral N concentration when measured in situ with a portable EC meter (R2=0.85) or in the laboratory as 1:1 soil water slurries (R2=0.92). Results suggest that EC can be used to rapidly detect changes in soil inorganic N status in soils where salts and free carbonates are not present in large amounts.

Climatic Controls of Saguaro (Carnegiea Gigantea) Regeneration: A Potential Link With El Niño

Saguaro cacti establish periodically in cohorts during years that are climatically favorable. Determining the establishment year is complicated by age-height relationships that vary considerably from site to site and require extensive data collection. Estimations of age-height relationships for only a few locales have thus limited the ability of researchers to estimate age in other populations, and consequently to relate periods of regeneration to climate. We collected data for 254 saguaros in the arid western portion of the species' range and employed a recently developed site-specific technique for estimating saguaro age to reconstruct the population structure at this locale. Second, we used discriminant analysis to determine which climate variables best predict regeneration years. We found that above-average temperatures in November coupled with concurrent high soil moisture levels, conditions typically associated with El Niño years, are associated with years characterized by high regeneration. Accordingly, these results suggest that El Niño events may be related to years of favorable regeneration for saguaros.

Allelopathic activity of Mexican sunflower [Tithonia diversifolia (Hemsl.) A. Gray] in soil under natural field conditions and different moisture conditions

The allelopathic activity of Mexican sunflower [Tithonia diversifolia (Hemsl.) A. Gray] in soil under natural field conditions and the effect of water stress on the growth and allelopathic activity of this plant were investigated. Seed germination, shoot growth and root growth of tested plant species in soil collected from a field where Mexican sunflower had been grown for 5 years were less than those in soil from an area without the plant. Growth of young leaves, mature leaves, senescent leaves, stem and roots of Mexican sunflower was reduced with decrease in soil moisture level. The allelopathic activity of water extracts (per dry weight of starting material) from each part of the plants grown at low soil moisture levels was greater than that of the water extracts from the same part of the plants grown at high soil moisture levels. The allelopathic activity was found in the soil from the pots previously planted with Mexican sunflower to a similar extent (per plant) at different soil moisture levels. These results suggested that, in the field, under water stress conditions, the growth of Mexican sunflower was reduced but the plants contained a greater amount of allelopathic substance(s) per dry weight than in the absence of water stress. It was considered that allelopathic activity of Mexican sunflower in soil was maintained to a similar extent under various soil moisture conditions in natural fields.

Effect of Soil Moisture on Ovipositional Behavior in the Southern Mole Cricket (Orthoptera: Gryllotalpidae)

The relationship between soil moisture and oviposition in an edaphic insect pest, the southern mole cricket, Scapteriscus borellii Giglio-Tos, was studied in a series of greenhouse experiments. Adults were captured in acoustic calling traps and associated pitfall traps during spring flights in southeastern North Carolina in 1996, 1997, and 1998. Female mole crickets were individually confined in chambers containing 2, 4, 7, 10, and 12% soil moisture. Oviposition and mortality were monitored daily. A significant linear relationship between oviposition and soil moisture was indicated by an increase in the number of crickets ovipositing in response to higher soil moisture levels. Additionally, a delay in oviposition was observed as a response to low soil moisture. There were no significant differences in the number of eggs per ovipositing female, indicating that when oviposition does take place, the individual response of the female is to lay a similar number of eggs regardless of moisture levels. The ovipositional response to a rapid increase in soil moisture was also examined. The rapid increase in moisture resulted in a significantly greater percentage of females ovipositing, as seen in the previous experiments.

Effect of soil moisture at different temperatures on Rhizoctonia root rot of wheat seedlings

The effect of soil moisture at different temperatures on root rot of wheat seedlings caused by Rhizoctonia solani AG-8 was studied in temperature controlled water tanks under glasshouse conditions. Four moisture levels (15, 30, 50 and 75% of soil water holding capacity at saturation which were equal to −10, −7, −5 and −3 kPa, respectively) were tested in tanks maintained 10, 15, 20 or 25 °C. The role of microbial activity in the effect of soil moisture and temperature on disease severity was also studied by including treatments of steam treated soil. Results showed that at soil moisture levels optimum for plant growth (50 and 75% WHC) disease was more severe at a lower temperature (10 °C), but under relatively dry conditions (15% WHC) disease levels were similar at all temperatures tested. In warm soils (20 and 25 °C) at high soil moisture levels (50 and 75% WHC), disease was more severe in steam treated soil than in non-steam treated soil, indicating that the suppression of disease in natural soil under these conditions was associated with high soil microbial activity.

Effects of Compost on Loblolly Pine Tree Growth In Northeast Texas

The objective of this study was to evaluate the effects of compost on loblolly pine tree growth. Approximately 750 seedlings were planted, 270 of which were measured monthly, in a northeast Texas forest ecosystem. Compost was applied at rates of 5, 25, and 50 tons per acre. Planting holes were filled with either native soil or compost. The 25-ton per acre application with soil backfill (25S) increased tree survival and growth relative to a control group and other compost amendments. After two years, trees in the 25S treatment survived twice as much and grew 41 percent higher than a control group. In general, compost applications yielded higher soil moisture levels, higher survival rates, and larger growth increases than the control group.

An Overview of a Nested Watershed Study in Arctic Alaska

The hydrology of a nest of three watersheds has been studied since 1992 on the North Slope of Alaska, with some additional data collected at individual sites previously. Hydrologic studies of nested watersheds are rare in the circumpolar arctic. Presented here is a comparison of the variability of important runoff-related processes from the headwater foothills to the low gradient, wetland dominated coastal area. Watersheds studied include Imnavait Creek, Upper Kuparuk River and finally the entire Kuparuk River. Also, runoff data from the low gradient Putuligayuk River, measured earlier (1970-1986), is included. Generally, rainfall constitutes 53 to 67 % of the annual precipitation. Most runoff is generated from the foothills; runoff is normally only generated from the coastal plain during snowmelt. Surface storage is an important process on the coastal plain where vertical processes (precipitation and evapotranspiration) are dominant during the summer. Continuous permafrost produces high soil moisture levels except where there are relatively steep slopes with gravity-induced drainage. Snowmelt results in a nearly saturated active layer with summer moisture levels closely allied with summer precipitation. High runoff ratios prevail during snowmelt and rainfall, except for the summer rainfall-generated runoff of the low gradient Putuligayuk River.

Effect of deferred grazing during summer on white clover content of Waikato dairy pastures, New Zealand

New Zealand dairy pastures rotationally grazed at intervals of 25 to 30 days to low residual herbage masses (<1400 kg DM ha−1) over summer often suffer white clover death. An experiment was conducted over 1994–1997 in mixed perennial ryegrass/white clover dairy pastures to examine the effects of deferred grazing, the practice of holding over pasture in situ for 50, 75, or 100 days over summer, on white clover growth compared with a more common 25‐day grazing interval. Additional pasture cover built up in 100‐day deferred (100D) plots resulted in significantly (P < 0.05) lower soil temperatures and higher soil moisture levels than in the 25D treatment. Clover stolon survival was up to 63% higher in deferred pastures than the 25D treatment. This, combined with higher clover seedling density, resulted in significantly (P< 0.05) higher clover contents in pastures following deferral compared with the 25D grazed pasture. These differences did not persist through to the following spring. Deferred grazing also resulted in small increases in total herbage accumulation but had little effect on ryegrass tiller density.

Use of climatic data and satellite imagery to model the abundance of Culicoides imicola, the vector of African horse sickness virus, in Morocco.

African horse sickness (AHS) is a vector-borne, infectious disease of equids caused by African horse sickness virus (AHSV). The only proven field vector of the virus is the biting midge Culicoides imicola. Following a recent epizootic (1989-91) of AHS in Morocco, light traps and automatic weather stations were operated for 2 years at twenty-two sites distributed over much of the country. The annually-averaged mean daily trap catch of C. imicola at these sites was negatively correlated with wind speed, and positively correlated with the average and mean annual minimum NDVI (Normalized Difference Vegetation Index, a remotely sensed measure of vegetation activity). There were no significant correlations between the mean daily trap catch and air temperature, soil temperature, relative humidity, saturation deficit, rainfall, altitude or the mean annual maximum or range of NDVI. The best two-variable model, which combined WindspeedMnAvMn (the average daily minimum wind speed of the least windy month) and NDVImin (the average annual minimum NDVI) as predictors, explained over 50% of the variance in the annually-averaged mean daily trap catch of C. imicola. There was a significant, positive correlation between minimum wind speed at night and the daily mortality rate of adult female C. imicola and it is suggested that the relationship between wind speed and the abundance of C. imicola arises from effects on adult mortality or dispersal. Considering several climatic variables, in North Africa NDVImin was most significantly correlated with total annual rainfall. It is suggested that the relationship between NDVImin and the abundance of C. imicola arises from the impact of soil moisture on both. It is proposed that areas of Morocco with higher levels of soil moisture in late summer or autumn provide more, larger and/or more enduring breeding sites for C. imicola, as well as supporting more photosynthetically active vegetation and hence having higher NDVI.

A SYNOPTIC CLIMATOLOGY OF EXTREME UNSEASONABLE FLOODS IN THE SOUTHEASTERN UNITED STATES, 1950–1990

Unseasonable floods are floods that occur in the season of lowest flood frequency, or dry season. Such floods pose a unique problem to flood planners and forecasters, yet little research has investigated the physical processes associated with unseasonable floods. The purpose of this study is to construct a synoptic climatology of extreme unseasonable floods for the southeastern United States. Results indicate that the types of storms creating unseasonable floods are location specific, with four unique regions across the study area: Carolina (tropical storms/hurricanes), Georgia Coastal Plain (Gulf depressions), Gulf-Atlantic (frontal), and Tennessee (frontal with upper-air enhancement). The precipitation created by these storms is low to moderate, rarely exceeding the 10-year 24-hour storm total. The precipitation levels suggest that a combination of meteorological conditions and land-surface conditions create the extreme events. A statistical analysis indicates that high soil-moisture levels combine with the moderate rains to produce extreme unseasonable floods. [Key words: unseasonable floods, synoptic climatology, land-surface conditions, southeastern United States.]

Wheat residue management options for no-till corn

Corn (Zea mays L.) yield reduction following winter wheat (Triticum aestivum L.) in no-till systems prompted a study on the effects of tillage and residue management systems on corn growth and seedbed conditions. Four methods for managing wheat residue (all residue removed, straw baled after harvest, straw left on the soil surface, straw left on the soil surface plus application of 50 kg ha−1N in the fall) were evaluated at two tillage levels: fall moldboard plow (MP) and no-till (NT). No-till treatments required at least 2 more days to achieve 50% corn emergence and 50% silking, and had the lowest corn biomass at 5 and 7 wk after planting. Grain yield was similar among MP treatments and averaged 1.1 t ha−1 higher than NT treatments (P &lt; 0.05). Completely removing all wheat residue from NT plots reduced the number of days required to achieve 50% corn emergence and increased grain yields by 0.43 and 0.61 t ha–1 over baling and not baling straw, respectively, but still resulted in 8% lower grain yields than MP treatments. Grain yield differences among MP treatments were insignificant regardless of the amount of wheat residue left on the surface or N application in the fall. Early in the growing season, the NT treatments where residue was not removed had lower soil growing degree days (soil GDD) compared with MP (baled) treatment, and higher soil moisture levels in the top 15 cm compared with all other treatments. The application of 50 kg N ha−1 in the fall to NT (not baled) plots influenced neither the amount of wheat residue on the soil surface, nor the soil NO3-N levels at planting. Our results suggest that corn response in NT systems after wheat mostly depends on residue level. Key words: Winter wheat, straw management, no-till, corn, soil temperature, soil moisture

Thiamine (vitamin B1) seed treatment enhances germination and seedling growth of bean (Phaseolus vulgaris L.) exposed to soaking injury

AbstractSeed treatment with thiamine mononitrate significantly increased germination rate of bean (Phasenius vulgaris L.) seedlings germinated at high soil moisture levels and low night‐temperature (5° C). Beneficial effects of thiamine applications on germination were also observed in soil‐free germination tests when the seeds were submerged in water for 1–4 d at 18°C. Optimum response was achieved at thiamine concentrations of 3 mM, applied during the first 24 h of imbibition. As an early response to the thiamine treatment, vital staining with triphenyltetrazolium chloride revealed a lower proportion of damaged tissue of the embryonic axes. In later stages of seedling development, thiamine seed treatment resulted in a lower proportion of abnormal seedlings with malformations of the shoot apex and of the primary leaves. The beneficial effect of thiamine was more pronounced when the temperature during submergence was kept at 25° C compared to 5° C. There was no response to thiamine applications when the germinating seeds were exposed to low temperature treatments only. The thiamine effect could be mimicked by raising the osmotic potential of the incubation medium, indicating a relationship to soaking injuries. The results suggest that normal seedling development may be impaired by thiamine deficiency in the embryonic tissue induced by soaking injury, whereas low temperatures are not involved as a stress‐factor.

A Comparison of Four Processing Tomato Production Systems Differing in Cover Crop and Chemical Inputs

Four tomato production systems were compared at Columbus and Fremont, Ohio: 1) a conventional system; 2) an integrated system [a fall-planted cover-crop mixture of hairy vetch (Vicia villosa Roth.), rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), and barley (Hordeum vulgare L.) killed before tomato planting and left as mulch, and reduced chemical inputs]; 3) an organic system (with cover-crop mixture and no synthetic chemical inputs); and (4) a no-input system (with cover-crop mixture and no additional management or inputs). Nitrogen in the cover-crop mixture above-ground biomass was 220 kg·ha-1 in Columbus and 360 kg·ha-1 in Fremont. Mulch systems (with cover-crop mixture on the bed surface) had higher soil moisture levels and reduced soil maximum temperatures relative to the conventional system. Overall, the cover-crop mulch suppressed weeds as well as herbicide plots, and no additional weed control was needed during the season. There were no differences in the frequency of scouted insect pests or diseases among the treatments. The number of tomato fruit and flower clusters for the conventional system was higher early in the season. In Fremont, the plants in the conventional system had accumulated more dry matter 5 weeks after transplanting. Yield of red fruit was similar for all systems at Columbus, but the conventional system yielded higher than the other three systems in Fremont. In Columbus, there were no differences in economic return above variable costs among systems. In Fremont, the conventional systems had the highest return above variable costs.