Soil Invertebrate Populations Research Articles

Effect of land use on soil macrofauna in Southern Ghana

ABSTRACT The study explored the impact of land use changes on soil biodiversity, focussing on soil invertebrates in a converted natural forest. Using parallel transects 1 km in length positioned 200 m apart across cocoa, coffee, and cashew farms and natural forest areas, we sampled soil invertebrates with pitfall traps. The findings reveal a significant decline in soil invertebrate populations in cocoa, coffee, and cashew farmlands compared to natural forest. The number of soil invertebrates recorded in the wet season was generally less than the number found in the dry season. Mean soil invertebrate count in the natural forest was approximately double that of the count in cashew farms. Soil invertebrate density was highest in the dry season in the natural forest and lowest in the cashew farms. The study contributes a holistic understanding of the intricate relationships between land use changes and soil biodiversity, emphasizing the urgency of adopting conservation measures and policy interventions to safeguard the rich diversity of soil ecosystems for future generations.

Impacts of field margin orientation on populations of soil‐dwelling invertebrates in relation to the direction and intensity of field traffic

AbstractSown field margins are a central part of agri‐environmental schemes aiming to improve biodiversity and ecosystem services in agricultural landscapes. Despite the knowledge that key services are delivered by belowground biodiversity, the impacts of field margins on populations of soil invertebrates both within the margins and the neighbouring crops remain unclear. We investigated the effect of field margin orientation with respect to the direction of the tramlines upon populations of soil‐dwelling mesofauna with focus on Acari (mites) and Collembola (springtails). Two margins on adjacent sides of the same field and their neighbouring cropped areas were examined: one margin oriented perpendicular to the tramlines, and one parallel to the tramlines. This sampling design was repeated on two farms with distinct soil management (no till vs. minimum tillage) and crop rotation (diverse‐long‐rotation vs. cereal/oilseed‐short‐rotation) in two seasons (autumn vs. spring) over two years. The distribution of invertebrates in the cropped areas depended on the orientation of the margins and the taxa studied. Reduced abundance of Collembola and Acari were found at both farms in the cropped area where machinery turns (margin perpendicular to tramlines), in comparison with the cropped area where margins and tramlines were parallel. This study suggests the existence of interacting impacts between the margins and field operations (trafficking and resulting compaction) on populations of soil mesofauna.

Impact assessment of legacy wastes from ancient mining activities on current earthworm community

Mineral resource exploitation by human societies throughout history led to the deposit of mining and smelting wastes and the subsequent contamination of surrounding soils by trace metals. After several centuries, the impact of these legacy hazardous wastes may remain a cause of environmental concern, especially for indigenous soil invertebrate populations such as earthworms. Therefore, we conducted a passive biomonitoring campaign in a former metallurgical district (Vosges Mountains, eastern France). According to community descriptors, we evidenced a significant decrease of anecic and endogeic earthworm density in the former mining stations. To link these results to soil contamination and bioaccumulation levels in earthworm tissues, we propose an original modelling approach using nonlinear mixed-effects regression models. Beyond a dose-response relationship between metal internal concentrations and their levels in soils, we highlighted contrasted behaviors according to ecological groups (epianecics and endogeics most impacted). We interpreted these results in relation to some eco-physiological features without completely exclude the influence of textural characteristics of soil, especially for deep-burrowing species such as anecic strict. Nonetheless, the presence of earthworm populations currently living in highly contaminated sites and handling elevated internal concentrations raises the question of the acquisition of genetic adaptive traits and the trophic transfers of metals.

Uptake, toxicity, and maternal transfer of cadmium in the oribatid soil mite, Oppia nitens: Implication in the risk assessment of cadmium to soil invertebrates

Cadmium (Cd) is a heavy metal of concern in contaminated sites because of its high toxicity to soil biota and humans. Typically, Cd exposure is thought to be dominated by dissolved Cd in soil pore water and, thus, dermal uptake. In this study, we investigated the uptake, toxicity, and maternal transfer of Cd in a standard soil invertebrate, the oribatid mite (Oppia nitens), which is common to boreal and temperate ecozones. We found total soil Cd predicted Cd uptake in adult and juvenile O. nitens with no significant uptake from pore water by juvenile mites. Cadmium significantly inhibited juvenile production and recruitment as well as reduced adult fecundity. Adult O. nitens maternally transferred 39–52% of their Cd body burden to juveniles (tritonymphs) while the maternally-acquired Cd accounted for 41% of the juvenile internal Cd load. Our results suggest that dermal adsorption of metal ions is not important for O. nitens and that maternal transfer of Cd in soil invertebrates has ecological and toxicological implications for populations of soil invertebrates. Maternal transfer should be incorporated as a criterion in setting environmental soil quality guidelines (SQGE) for cadmium and other non-essential heavy metals.

Tolerance to fluctuating water regimes drives changes in mesofauna community structure and vertical stratification in peatlands

Peatlands are the largest natural carbon store as a result of environmental conditions that limit decomposition rates. However, climate change is predicted to threaten peatland C sink function through rising temperatures, lowered water tables and the expansion of vascular plants. Here, by selecting four peatland habitats differing in their dominant plant communities and abiotic conditions, we investigated the influence of the most relevant climatic factors (namely temperature and soil water content) in controlling the spatial and temporal responses of soil organisms and their potential links to above-ground plant functional diversity. We found that the soil mesofaunal communities under vascular plants were mainly dominated by microarthropods (oribatid mites and collembolans), and contrasted with those under mosses that consisted of enchytreids and dipterans (≈15% dissimilarity). We show that the balance of tolerance to drought and saturation determined the temporal dynamics and vertical stratification of the soil invertebrate populations. From this, we anticipate that the projected expansion of vascular plants not only will displace active peat forming vegetation species (mosses), but also those invertebrates that are poorly adapted to the new environment (enchytraeids and dipteral larvae). Our findings indicate future peatland responses to environmental changes should take into account the habitat complexity (above- and below-ground community structure) and the modulating effects of the abiotic environment.

Using data from schools to model variation in soil invertebrates across the UK: The importance of weather, climate, season and habitat

Soil invertebrates play important roles in nutrient cycling, the development of soil structure, food webs and even climate regulation. It is likely that climate change will have far-reaching impacts on soil invertebrates but a lack of information about how soil invertebrate populations vary with soil characteristics and climate make projections difficult. To address this gap, we present the results of a large-scale citizen science project that examined the abundance of soil macro-invertebrates across the UK.The abundance and biomass of twelve invertebrate groups were recorded by school children using standardised protocols on six occasions over two years. Using these data, we examined the relative impact of local habitat and soil characteristics, and weather and climate, upon these taxa.The abundance of many soil invertebrate groups varied with season and small-scale habitat factors. We found that the abundance and biomass of earthworms was strongly correlated with soil moisture. There was, however, little evidence that large-scale variation in soil invertebrate abundance could be explained by spatial variation in climate.Given the importance of earthworms for soil processes, periods of dry weather may reduce their ability to undertake nutrient cycling and the provision of other services such as food for invertivorous species. Future analyses of the impacts of climate change on soil invertebrates may usefully consider variables such as frequency of rain, rather than monthly or seasonal averages more widely used.Our results were generally in accord with patterns expected from previous literature, providing important quality assurance. This indicates that this could be an effective scheme for long-term monitoring of soil invertebrates and that it is possible to utilise educational establishments as a forum for large-scale environmental data collection. Not only can this deliver valuable environmental data, but also it can engage school children in the collection of scientifically valuable data.

A risk assessment example for soil invertebrates using spatially explicit agent-based models.

Current risk assessment methods for measuring the toxicity of plant protection products (PPPs) on soil invertebrates use standardized laboratory conditions to determine acute effects on mortality and sublethal effects on reproduction. If an unacceptable risk is identified at the lower tier, population-level effects are assessed using semifield and field trials at a higher tier because modeling methods for extrapolating available lower-tier information to population effects have not yet been implemented. Field trials are expensive, time consuming, and cannot be applied to variable landscape scenarios. Mechanistic modeling of the toxicological effects of PPPs on individuals and their responses combined with simulation of population-level response shows great potential in fulfilling such a need, aiding ecologically informed extrapolation. Here, we introduce and demonstrate the potential of 2 population models for ubiquitous soil invertebrates (collembolans and earthworms) as refinement options in current risk assessment. Both are spatially explicit agent-based models (ABMs), incorporating individual and landscape variability. The models were used to provide refined risk assessments for different application scenarios of a hypothetical pesticide applied to potato crops (full-field spray onto the soil surface [termed "overall"], in-furrow, and soil-incorporated pesticide applications). In the refined risk assessment, the population models suggest that soil invertebrate populations would likely recover within 1 year after pesticide application, regardless of application method. The population modeling for both soil organisms also illustrated that a lower predicted average environmental concentration in soil (PECsoil) could potentially lead to greater effects at the population level, depending on the spatial heterogeneity of the pesticide and the behavior of the soil organisms. Population-level effects of spatial-temporal variations in exposure were elucidated in the refined risk assessment, using ABMs and population-level endpoints while yielding outputs that directly address the protection goals. We recommend choosing model outputs that are closely related to specific protection goals, using available toxicity data and accepted fate models to the extent possible in parameterizing models to minimize additional data needs and testing, evaluating, and documenting models following recent guidance.

A comparison of the wet and dry season DNA-based soil invertebrate community characteristics in large patches of the bromeliad Bromelia pinguin in a primary forest in Costa Rica

In Costa Rica, the Maquenque National Wildlife Refuge (MNWLR) contains a unique habitat gradient ranging from primary old growth forests, grasslands, pastures, to various ages of secondary forests. Within these primary old growth forests are extremely dense naturally occurring Bromelia pinguin (Bromeliaceae) patches that often grow with densities up to 2 plants per square meter. A previous study found that anti-fungal activity of this particular plant appears to be altering the fungal community in soils adjacent to these plants. No work has been previously conducted on the possible effects of this plant community on soil faunal communities and if seasonality contributes to changes in soil invertebrate populations along a moisture gradient. Thus, a study was conducted to assess the effects of this specialized plant community on soil invertebrates with respect to season, and if these changes in soil fauna guild structure could prove to be valid candidates as indicators of ecosystem condition with changes in precipitation. In addition, a meta-analysis was done to determine how the bromeliad-associated soil invertebrate communities differ from those in adjacent primary forest soils. Therefore, comparisons were determined from previous primary forest soil invertebrate environmental DNA (eDNA) to the current wet season bromeliad soil invertebrate eDNA. Roche 454 pyro-sequencing was conducted on the 650bp fragment of the cytochrome oxidase subunit I (COI) gene of invertebrates to obtain and characterize soil invertebrate sequence composition. To determine relationships among soil fauna guilds across seasons, relative abundance of the sequences were calculated, and used in conjunction with EcoSim niche overlap and co-occurrence values. From the bromeliad seasonal soil fauna eDNA study, it appears certain invertebrate guilds are driven by moisture as indicated by fluctuations in relative abundance of each invertebrate guild across seasons in bromeliad patch soils, as well as indicated by EcoSim niche overlap values. In particular, Guilds 1, 4, and 5, should warrant further investigation as indicators of habitat condition. The meta-analysis showed that a naturally occurring modified environment (the bromeliad patches), can result in differences in relative abundance and partitioning of a limited resource between invertebrate guild structure. Those guilds associated with microbivorous and complex decomposition activities (i.e. Guilds 3 and 4), are more abundant in primary forest soils than bromeliad patch soils and could potentially used for bioindicators of habitat perturbations.

Unifying elemental stoichiometry and metabolic theory in predicting species abundances.

While metabolic theory predicts variance in population density within communities depending on population average body masses, the ecological stoichiometry concept relates density variation across communities to varying resource stoichiometry. Using a data set including biomass densities of 4959 populations of soil invertebrates across 48 forest sites we combined these two frameworks. We analyzed how the scaling of biomass densities with population-averaged body masses systematically interacts with stoichiometric variables. Simplified analyses employing either only body masses or only resource stoichiometry are highly context sensitive and yield variable and often misleading results. Our findings provide strong evidence that analyses of ecological state variables should integrate allometric and stoichiometric variables to explain deviations from predicted allometric scaling and avoid erroneous conclusions. In consequence, our study provides an important step towards unifying two prominent ecological theories, metabolic theory and ecological stoichiometry.

Are population abundances and biomasses of soil invertebrates changed by Bt crops compared with conventional crops? A systematic review protocol

Background Bt crops modified by inserting and expressing the Cry toxin from Bacillus thuringiensis have raised environmental concerns over consequences for sustainability of soil biodiversity and ecosystems services in agricultural land. Part of this concern is related to the possible effects of the exposure to Cry toxins of non-target soil invertebrates as a result of Bt crops cultivation. Soil invertebrate members of microfauna, mesofauna and macrofauna play significant roles in nutrient cycling and energy flow and thus are crucial for soil ecological functions. In recent years, a number of studies have compared the population abundance and biomass of different members of soil biota in fields planted with genetically modified Bt crops and their conventional counterparts. In the present systematic review protocol, we describe the methodology and quality standards to perform a rigorous literature search and a quantitative synthesis of the evidence provided by these studies as required for conducting a Systematic Review.MethodsThe question that the systematic review will ask is whether populations of soil invertebrates differ under Bt crops and conventional crops. Relevant research literature will be collected systematically through a comprehensive search strategy. A scoping exercise was performed to identify search terms likely to capture appropriate studies and the results were verified using a list of relevant publications as references. The criteria against which studies will be included in the review are present, as well as the methodology for the quality assessment. To be included the study must contain relevant population abundances or biomass data on soil invertebrates exposed to characterised Bt proteins from field studies. The Review Protocol outlines the type of analyses that will be performed to assess bias of the selected studies and if covariables describing the heterogeneity of the studies introduce bias. Comparative effect sizes irrespective of statistical significance of effects will be calculated for individual studies and stored in publicly available databases ready for synthesis of all the studies. These treatment effects on population data will be compared across the studies in a meta-analysis using Hedges’ g.

Influence of summer irrigation on soil invertebrate populations in a long-term sheep irrigation trial at Winchmore (Canterbury)

Soil invertebrates have limited defences against moisture stress but little is understood of how irrigation influences their community. This paper investigates the influence of five summer irrigation schedules on earthworms over a 15-month period in a long-term pasture irrigation study. The influence of the two extreme rates of irrigation on other soil invertebrates was also examined. The effects of frequent drought periods under dryland pasture favoured small and short-lived nematodes and oribatids. During wetter months, earthworm abundances were similar between dryland and irrigated treatments, while earthworms tended to migrate down the soil profile and aestivate in response to soil water deficits during summer. The higher abundance of earthworms in the summer months under irrigation may partly explain the lower soil carbon found under irrigation, due to enhanced rates of soil organic matter turnover, despite higher primary production and inputs of carbon. It is thus important to consider irrigation schedules not only to optimise plant growth, but also to optimise the invertebrate community and its activity.

Long-term experimental warming reduces soil nematode populations in the McMurdo Dry Valleys, Antarctica

Climate models predict significant future warming in polar regions. In the McMurdo Dry Valleys, Antarctica, projected summer climate warming is expected to increase snow and glacial melt, resulting in higher stream discharge, rising lake levels, and an increase in areas of moist soil, but the potential influence of warming and associated changes in hydrology on the soil ecosystem is poorly understood. To examine the effects of soil warming and changes in the availability of liquid water on populations of soil invertebrates and their habitat, we established a full-factorial warming and water addition experiment at one experimental site in each of the three hydrologic basins of Taylor Valley, Antarctica, and measured responses over 8 years. We hypothesized that an increase in temperature and moisture together would enhance habitat suitability for soil invertebrates thereby increasing abundance, biomass and diversity of the soil animal communities. Instead, warming treatments had an overall negative effect on density and body size of the microbial-feeding nematode Scottnema lindsayae, the dominant animal in the dry valleys, which decreased by 42% in warmed plots. While experimental moisture additions as a single annual pulse had no effect on nematodes, the surface flooding of one site from rapid melting of upslope subsurface ice (the result of an unusual natural warming event) drastically altered soil moisture, salinity, and animal communities; mortality of S. lindsayae increased and densities decreased. This extreme soil wetting event also resulted in an increase in chlorophyll a and populations of Eudorylaimus spp, a nematode species that prefers moist to wet habitats and feeds on soil micro-algae. Our results suggest that warming in the dry valleys could significantly affect soil nematode populations and species composition both directly and indirectly by altering species-specific habitat suitability for soil biota.

Assessing cypermethrin-contaminated soil with three different earthworm test methods

A series of tests (lethal, sublethal, and behavioral) on earthworms were conducted as an eco-assessment of pesticides. In this study, the toxicity of cypermethrin-contaminating soil on adult and juvenile earthworms was assessed. Beside the acute and chronic tests, an avoidance response test was carried out. It was shown that the all-round toxicity from cypermethrin was weak on adult earthworms. Compared with adult earthworms, the toxicity of juvenile earthworms from cypermethrin especially chronic toxicity increased significantly. Growth and reproduction of earthworms appeared to be more severely affected by cypermethrin at juvenile stage than at adult stage. Applied at 10 mg/kg, cypermethrin had obvious adverse impact on the growth of juvenile earthworms, while 20 mg/kg, cypermethrin caused significant toxic effects in reproduction. The results also indicated that ecotoxicological risk assessment using only adult specimens may underestimate the effects of cypermethrin on soil invertebrate populations.

Invertebrates increase the sensitivity of non-labile soil carbon to climate change

The fate of global soil carbon stores in response to predicted climate change is a ‘hotly’ debated topic. Considerable uncertainties remain as to the temperature sensitivity of non-labile soil organic matter (SOM) to decomposition. Currently, models assume that organic matter decomposition is solely controlled by the interaction between climatic conditions and soil mineral characteristics. Consequently, little attention has been paid to adaptive responses of soil decomposer organisms to climate change and their impacts on the turnover of long-standing terrestrial carbon reservoirs. Using a radiocarbon approach we found that warming increased soil invertebrate populations (Enchytraeid worms) leading to a greater turnover of older soil carbon pools. The implication of this finding is that until soil physiology and biology are meaningfully represented in ecosystem carbon models, predictions will underestimate soil carbon turnover.

Chronic toxicity of polycyclic aromatic compounds to the springtail Folsomia candida and the enchytraeid Enchytraeus crypticus

An urgent need exists for incorporating heterocyclic compounds and (bio)transformation products in ecotoxicological test schemes and risk assessment of polycyclic aromatic compounds (PACs). The aim of the present study therefore was to determine the chronic effects of (heterocyclic) PACs on two terrestrial invertebrates, the springtail Folsomia candida and the enchytraeid Enchytraeus crypticus. The effects of 11 PACs were determined in chronic experiments using reproduction and survival as endpoints. The results demonstrated that as far as narcosis-induced mortality is concerned, effects of both homocyclic and heterocyclic PACs are well described by the relationship between estimated pore-water 50% lethal concentrations and log Kow. In contrast, specific effects on reproduction varied between species and between compounds as closely related as isomers, showing up as deviations from the relationship between pore-water 50% effect concentrations and log Kow. These unpredictable specific effects on reproduction force one to test the toxicity of these PACs to populations of soil invertebrates to obtain reliable effect concentrations for use in risk assessment of PACs.

Snow-Patch Influence on Soil Biogeochemical Processes and Invertebrate Distribution in the McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys is the largest of the ice-free areas in Antarctica. Precipitation events in excess of 1 cm of snow accumulation are rare. During the winter, snow is transported by strong katabatic winds blowing from the polar plateau, and deposited into the lee of topographic features (e.g., stream channels and other topographic depressions). At the start of the austral summer (early October), as much as 10% of the valley soils may be covered by distributed snow patches. Because liquid water is the primary driver of biological, physical, and chemical processes in this polar desert, quantifying fluxes of water from snow patches is important to understanding the influence of hydrology on soil biology and nutrient cycling. During the austral summer of 1999–2000, four snow patches that had developed during the previous winter in Taylor Valley were studied. We measured snow-patch area, depth, and snow water equivalent, as well as subnivian (under snow) and nearby exposed (control) soil temperature, light intensity, soil moisture, invertebrate abundance, soil organic matter content, and 95-d labile pools of C and N. Subnivian soils differed from exposed soils being as much as 26.8°C colder than exposed soils; average soil moisture ranging from 6.9 to 13.6% compared to 0.4% in exposed soils; soil invertebrate populations exceeding 7900 individuals kg−1 dry soil versus less than 1200 individuals kg−1 dry soil in exposed soils; and soil invertebrate species richness values greater than 2 taxa, compared to 1.3 taxa in exposed soils. The results of this study show that these seasonal, sparse snow patches may be an important source of moisture and control habitat of soil ecosystems in this extreme environment.

Mapping of soil insect infestations sampled by excavation and acoustic methods.

Geostatistical analysis was used to map traditionally and acoustically sampled populations of soil invertebrates at two different times in a hayfield at Grove Hill, AL, and once in an Auburn, AL, hayfield. The distributions of nearly all the soil invertebrates and their sounds were nonrandom in all three mapping studies. The maps constructed by excavation and acoustic sampling methods were compared by correlating the estimated (kriged) soil invertebrate counts with the estimated (kriged) counts of sounds per minute (pulse rate). Acoustic and traditional estimates were positively correlated in the Auburn study. Kriged estimates for green June beetle grub counts overlapped significantly with kriged estimates of sound pulse rate (R2 = 0.47). Overlap with sound pulse rates increased slightly when other soil organisms were counted along with green June beetle grubs: estimates of sound pulse rates were significantly correlated with counts of all white grubs (R2 = 0.50), all white grubs with earthworms (R2 = 0.52), all white grubs with earthworms and earwigs (R2 = 0.59), and total invertebrates (R2 = 0.59). The correlation between acoustic and traditional estimates was not significant at Grove Hill in either year, possibly because of a lack of experience in signal analysis or because the soil invertebrates may not have generated enough sounds to be detected above the background noise levels. These results suggest that acoustic technology is a promising tool for detecting insect pests in soil, but that further study and additional analysis are needed to improve interpretation of acoustic data obtained in the field.

Soil invertebrate and plant responses to mowing and carbofuran application in a North American tallgrass prairie

Relationships between soil invertebrate populations and primary production of a tallgrass prairie were investigated using the insecticide-nematicide carbofuran and a range of mowing intensities to manipulate invertebrate densities and resource quantity and quality. The trophic composition of nematode populations was monitored through each of two growing seasons. Earthworm and macroarthropod densities and primary production were assessed at the end of the second season. Invertebrate densities were generally reduced in carbofuran-treated plots, although individual weights of surviving macroarth-ropod herbivores increased significantly (p<0.05). Carbofuran failed to affect estimates of above- or belowground plant biomass after two years of treatment. Changes in resource quantity and quality resulted in rapid responses by dominant invertebrate consumer populations. A 28% reduction in live root mass and a 24% increase in root detritus following two years of mowing was associated with a 54% decrease in herbivorous nematode densities, a 47% increase in microbivorous nematode densities, and a 41% increase in native earthworm biomass.

Composition of the soil fauna in forested and grassy plots at Delhi, Ontario

There were several differences between invertebrate fauna collected from 15 cm deep cores taken from previously cultivated soil (now in grass) and fauna of a similar Fox loamy sand series in a nearby woodlot at Delhi, Ontario (42°51′ N, 80°30′W). Soil invertebrate populations in the grassy field were less dense (931 × 103 vs. 1853 × 103 animals/m2) and less diverse, had less than half of the biomass (1.2 vs. 2.9 g dry wt./m2), and exhibited little significant decrease in invertebrate densities with increasing soil depth compared with woodlot soil cores; woodlot soils exhibited significant decreases in invertebrate densities with increasing soil depth. The litter layer (LFH) of the woodlot provided the highest invertebrate densities and biomasses of any soil horizon tested over the 5-month sampling period. Percent abundances at both sites for most taxa were relatively similar; nematodes, protozoans, and mites were most abundant and earthworms, least abundant. The category "other arthropods" (including hexapods, myriapods, and araneids) was the largest contributor at both sites when taxa were ranked according to biomass. Earthworms were virtually nonexistent in the grassy field and were represented by only two species, Dendrobaena octaedra (Savigny) (which was dominant in both abundance and biomass) and Aporrectodea tuberculata (Eisen), in woodlot soil. Woodlot faunal densities and biomasses for most taxa were similar to comparable Eurasian sites of similar climate and vegetation.

Effects of pesticides and fertilizer on invertebrate populations of grass and wheat plots in Kent in relation to productivity and yield

AbstractAt a site in Kent, perennial ryegrass (Lolium perenne) variety S24 and Italian ryegrass (L. multiflorum) variety RVP, wheat varieties Armada and Norman, and the original mixed grass ley were grown in small plots during 1982–84. Two toxic pesticides (phorate and aldicarb) were applied to half the total number of plots three times each year to eliminate soil invertebrate populations. Fertilizer was also applied to most plots. The yields of the crops, grown with and without pesticide, and the effects of the fertilizer were compared. Grass herbage yield was measured on three occasions during the summers of 1983 and 1984. Wheat grain yields were also determined in 1983.During the first year significant differences were not apparent in grass dry matter yield between pesticide‐treated and non‐treated plots, but significant differences were found in the second year. The perennial ryegrass was more susceptible to pest damage than the Italian ryegrass or the grass ley. Grass yields varied between cuts and in relation to variety and pesticide treatment, yields tending to be greater in untreated plots. Fertilizer treatment greatly increased grass dry matter yields, particularly with the Italian ryegrass. The effects of pesticide treatment on both wheat varieties varied although some yield enhancement was evident.Invertebrate animal populations in pesticide and fertilizer‐treated plots were also assessed in autumn 1982, spring and autumn 1983 and spring 1984. In contrast to pesticide treatment, fertilizer treatment had little effect on soil invertebrate populations. Nematode populations were reduced at each sampling occasion by the pesticide treatment. Slug populations were initially unaffected but were subsequently reduced. Leatherjackets, by far the most abundant pest in both grass and wheat plots, were markedly affected by pesticides on all sampling occasions. Generally, fewer soil‐dwelling dipterous larvae were recovered in spring than in autumn. Stem‐boring dipterous larvae were virtually absent.