We analysed data from descriptive and experimental studies on the possible relationships between ... more We analysed data from descriptive and experimental studies on the possible relationships between plants, nematodes and mycorrhizal fungi in (successional) plant communities in The Netherlands. A key role for pathogenic nematodes in cyclic succession in grazed grassland confirmed similar results in foredune succession. Plants with clonal growth forms appear to be particularly susceptible to pathogenic fungi. A large role for ectomycorrhiza at the species level (functional composition) was observed in determining the effects of acid rain and increased atmospheric CO 2 on nutrient transfer to trees. Field studies showed a correlation between species richness of ectomycorrhizal fungi and hyphal-feeding nematodes in one case, but not in another. Population growth of hyphalfeeding nematodes on ectomycorrhizal hyphae was found to be strongly dependent on plant-mediated palatability of the fungus. We conclude that the limited available evidence suggests the importance of functional composition of species in determining interactions between plants, nematodes and mycorrhizal fungi, but the degree to which functional redundancy exists within the nematodes and within the mycorrhizal fungi warrants further investigation.
Managing Soil Quality: Challenges in Modern Agriculture, 2004
We think of the soil as a living system, where many, if not most, physical and chemical propertie... more We think of the soil as a living system, where many, if not most, physical and chemical properties and processes are mediated by the soil biota, affecting soil quality. Various aspects of the soil biota react sensitively to changes in the environment, including agricultural management. We conclude that changes in soil biodiversity, measured in terms of community structure of microbes and nematodes, give early warnings of long-term changes in organic matter, nutrient status and soil structure, which cannot be easily observed directly. These parameters are easy to measure and they are responsive to agricultural management. We also conclude that diversity confers stability/resilience on the ecosystem if (management) stress and disturbance reduce the number of species. However, at the level of the entire (soil) community, i.e. beyond the level of diversity within taxonomic groups (such as nematodes), a causal relationship between soil biodiversity and ecosystem functioning and stability does not seem to exist, and the existing knowledge at this level is not yet sufficiently complete and quantitative to be of practical value for management. Nevertheless, reductions of the soil biota result in loss of stability of the soil community with possible loss of ecosystem functioning. Finally, we provide scientific knowledge that can contribute to the process of establishment of reference values of indicators of soil quality and to agricultural management recommendations, but the assessment of values for management is something to be subjectively agreed upon in practical situations, rather than objectively assessed.
Biotic soil parameters have so far seldom played a role in practical soil assessment and manageme... more Biotic soil parameters have so far seldom played a role in practical soil assessment and management of grasslands. However, the ongoing reduction of external inputs in agriculture would imply an increasing reliance on ecosystem self-regulating processes. Since soil biota play an important role in these processes and in the provision of ecosystem services, biological soil parameters should be an integral part of soil assessment. The general objective of the current study is to investigate to what extent biotic soil parameters provide additional value in soil quality assessment of grassland on sandy soils. We measured abiotic and biotic soil parameters together with process parameters underlying ecosystem services in 20 permanent production grasslands. Cross-validated stepwise regression was used to identify abiotic and biotic soil parameters that explained the soil ecosystem services soil structure maintenance, water regulation, supply of nutrients, and grassland production, respectively. Process parameters underlying the ecosystem service soil structure maintenance such as bulk density and the percentage of sub-angular blocky elements were mainly influenced by SOM and its qualities. The correlations between penetration resistance at 0e10 cm and the percentage of soil crumbs with earthworms suggested a relationship to earthworm activity. Parameters underlying the service of water regulation showed no clear relationship to biotic soil parameters. Water infiltration rate in the field was explained by the penetration resistance at 10e20 cm. Process parameters underlying the service of nutrients' supply such as the potentially mineralizable C and N were mainly determined by soil total N. The potential C and N mineralization were more related to biotic soil parameters, whereby each parameter was the other's antithesis. The grassland production without N fertilization viz. the nitrogen supply capacity of the soil measured as N yield, was mainly explained by soil organic matter (SOM) and soil moisture, and to a lesser extent by soil total N. One gram of SOM per kg of dry soil corresponded to 3.21 kg N yield ha À1 , on top of a constant of 15.4 kg N ha À1. The currently applied calculations in the Dutch grassland fertilization recommendation, underestimated in 85% of the production grasslands, the measured nitrogen supply capacity of the soil by on average 42 kg N ha À1 (31%). This legitimizes additional research to improve the currently applied recommendations for sandy soils. The response of N yield to N fertilization ranged from 35 to 102%. This wide range emphasizes the importance of a better recommendation base to target N fertilizer. The response of N yield to N fertilization was predicted by the total number of enchytraeids, the underlying mechanism of which needs further investigation on different soil types. This knowledge can be important for the optimal use of fertilizer and its consequences for environmental quality.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is impo... more Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for ...
Understanding the impacts of agricultural intensification and extensification on soil biota commu... more Understanding the impacts of agricultural intensification and extensification on soil biota communities is useful in order to preserve and restore biological diversity in agricultural soils and enhance the role of soil biota in agroecosystem functioning. Over four consecutive years, we investigated the effects of agricultural intensification and extensification (including conversion of grassland to arable land and vice versa, increased and decreased levels of mineral fertilization, and monoculture compared to crop rotation) on major soil biota group abundances and functional diversity. We integrated and compared effects across taxonomic levels to identify sensitive species groups.Conversion of grassland to arable land negatively affected both abundances and functional diversity of soil biota. Further intensification of the cropping system by increased fertilization and reduced crop diversity exerted smaller and differential effects on different soil biota groups. Agricultural intens...
The introduction of N 2-fixing white clover (Trifolium repens) in grassland is a management measu... more The introduction of N 2-fixing white clover (Trifolium repens) in grassland is a management measure that may contribute to sustainable grassland systems by making them less dependent on inorganic fertilizers. However, little is known about the impact of this measure on soil biota and ecosystem services. We investigated earthworms, nematodes, bacteria and fungi in an experiment in which white clover-only and a mixture of grass and white clover without fertilization were compared with grass-only with and without fertilization. In comparison with grass-only, white clover-only had a lower total root biomass and a lower C/Nratio in the above-and below-ground plant biomass. These plant characteristics resulted in a lower bacterial biomass, a lower fungal biomass, a higher proportion of bacterivorous nematode dauerlarvae, a lesser proportion of herbivorous nematodes and a greater abundance of earthworms in clover-only. The quantity and quality (C/N-ratio) of the above-and below-ground plant biomass in the mixture of grass and white clover (20-30% clover in the DM) was comparable with grass fertilized with 150 kg N ha À1 of inorganic fertilizer. Differences between these treatments might show specific clover effects in the grass-clover mixture on soil biota other than quantity and C/N-ratio of the litter. However, the only differences were a higher proportion of bacterivorous nematode dauerlarvae and a different nematode community composition in grass-clover. The soil structure in white clover-only showed a higher proportion of angular blocky elements, a lower penetration resistance, a higher number of earthworm burrows, a higher potential Nmineralization and respiration than the soil in grass-only. This suggests that clover stimulates the ecosystem services of water infiltration and supply of nutrients, but is less conducive to soil structure maintenance. The grass-clover mixture differed from grass-only in a higher respiration and from cloveronly in a higher percentage of soil crumbs. We suggest that when clover is introduced in grassland to reduce the reliance on inorganic fertilizer, the mixture of grass and clover maintains the positive impact of grass roots on soil structure and increases the supply of nutrients via the soil food web. Thus, a grassclover mixture combines the agronomic benefits of the two plant types.
Agricultural intensification is known to impact the soil biota community. In a previous study, th... more Agricultural intensification is known to impact the soil biota community. In a previous study, the impact of agricultural intensification on total abundances and functional group structure of major soil biota groups were measured. In this study we address the effects of conversion of extensively managed grassland to arable land on taxonomic diversity at genus and species level of four major soil biota groups (predatory mites, earthworms, enchytraeids, nematodes and bacteria). Vice versa, the effect of agricultural de-intensification (re-establishment of grassland on former arable land) on soil biota taxonomic diversity was also studied. Conversion of an extensively managed grassland to arable land had detrimental effects on taxonomic richness and diversity across taxonomic groups in the short-term, with largest effects on soil biota with larger body size. Effects of arable management were detrimental shortly after conversion. Restoration of grassland resulted in establishment of a species-rich community of nematodes (with partly different species), and recovery of the earthworm community. Predatory mite species were less successful in re-establishing and negative effects on enchytraeid species persisted. When combining the results of Postma-Blaauw et al. (2010) with the present study, we conclude that agricultural intensification resulted in a reduction in abundance and taxonomic diversity of nematodes and bacteria, whereas functional group structure of these groups was little affected. In contrast, predatory mites and earthworms were affected both in functional group structure and in taxonomic diversity. We conclude that agricultural intensification affects total abundances and taxonomic diversity of soil biota in agricultural land, but not necessarily the functional group diversity. Reduced taxonomic diversity may result in reduced resilience to stress, whereas reduced total abundances of microbiota may affect ecosystem functions such as nutrient mineralization.
SummaryIn the Netherlands soil biological measurements are undertaken in a nationwide monitoring ... more SummaryIn the Netherlands soil biological measurements are undertaken in a nationwide monitoring programme. The measurements are combined in the Biological Indicator of Soil Quality (BISQ). About 300 locations were selected in a random stratified design comprising stringent combinations of land use and soil type. All locations were sampled in a six‐year cycle. In this contribution we describe the monitoring network and the BISQ and present average values for biomass, abundances and taxonomic diversity of various soil dwelling organisms derived from 10 years of measurements. We further highlight some results and discuss the possibilities in soil and land management policy frameworks for improving sustainable land management.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is impo... more Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for their ecological group classifications, and that earthworm species interactions would affect mineralization through competition and facilitation effects. A mesocosm experiment was conducted to investigate the effect of three earthworm species, representative of different ecological groups (epigeic: Lumbricus rubellus; endogeic: Aporrectodea caliginosa tuberculata; and anecic: Lumbricus terrestris), and their interactions on the bacterial community, and on nitrogen mineralization from 15 N-labelled crop residue and from soil organic matter.
66 Land Society, environment, and development: The Mt. Malindang Experience ASSESSMENT OF SOIL PR... more 66 Land Society, environment, and development: The Mt. Malindang Experience ASSESSMENT OF SOIL PROPERTIES AND ECOLOGICAL DIVERSITY IN MT. MALINDANG RANGE1 Renato D. Boniao2, Rosa Villa B. Estoista3, Carmelita G. Hansel3, Ron de Goede4, Olga M. ...
Society is faced with environmental issues that exceed the level of local governments, but which ... more Society is faced with environmental issues that exceed the level of local governments, but which need to be dealt with at international or even global scales. These issues include nature conservation and management, development of a more sustainable agriculture, effects of environmental pollution, biodiversity, and effects of global change. The development of political and technical protocols necessary to control the future state of such environmental issues requires a detailed knowledge of the structure and functioning of the world's ecosystems. Studies that integrate the interpretation of results from (detailed) community and ecosystem process and pattern studies and that, moreover, include social and economic aspects might be defined as 'integrated ecosystem studies'. Four examples of integrated ecosystem studies are presented, and it is concluded that a full understanding of the contribution of soil zoology to such studies requires detailed analyses of interactions of fauna with other system components. If not, analyses can result in superficial conclusions that possibly underestimate the vulnerability of ecosystems to disturbances or their sensitivity to management.
Agricultural intensification is known to impact the soil biota community. In a previous study, th... more Agricultural intensification is known to impact the soil biota community. In a previous study, the impact of agricultural intensification on total abundances and functional group structure of major soil biota groups were measured. In this study we address the effects of conversion of extensively managed grassland to arable land on taxonomic diversity at genus and species level of four major
We analysed data from descriptive and experimental studies on the possible relationships between ... more We analysed data from descriptive and experimental studies on the possible relationships between plants, nematodes and mycorrhizal fungi in (successional) plant communities in The Netherlands. A key role for pathogenic nematodes in cyclic succession in grazed grassland confirmed similar results in foredune succession. Plants with clonal growth forms appear to be particularly susceptible to pathogenic fungi. A large role for ectomycorrhiza at the species level (functional composition) was observed in determining the effects of acid rain and increased atmospheric CO 2 on nutrient transfer to trees. Field studies showed a correlation between species richness of ectomycorrhizal fungi and hyphal-feeding nematodes in one case, but not in another. Population growth of hyphalfeeding nematodes on ectomycorrhizal hyphae was found to be strongly dependent on plant-mediated palatability of the fungus. We conclude that the limited available evidence suggests the importance of functional composition of species in determining interactions between plants, nematodes and mycorrhizal fungi, but the degree to which functional redundancy exists within the nematodes and within the mycorrhizal fungi warrants further investigation.
Managing Soil Quality: Challenges in Modern Agriculture, 2004
We think of the soil as a living system, where many, if not most, physical and chemical propertie... more We think of the soil as a living system, where many, if not most, physical and chemical properties and processes are mediated by the soil biota, affecting soil quality. Various aspects of the soil biota react sensitively to changes in the environment, including agricultural management. We conclude that changes in soil biodiversity, measured in terms of community structure of microbes and nematodes, give early warnings of long-term changes in organic matter, nutrient status and soil structure, which cannot be easily observed directly. These parameters are easy to measure and they are responsive to agricultural management. We also conclude that diversity confers stability/resilience on the ecosystem if (management) stress and disturbance reduce the number of species. However, at the level of the entire (soil) community, i.e. beyond the level of diversity within taxonomic groups (such as nematodes), a causal relationship between soil biodiversity and ecosystem functioning and stability does not seem to exist, and the existing knowledge at this level is not yet sufficiently complete and quantitative to be of practical value for management. Nevertheless, reductions of the soil biota result in loss of stability of the soil community with possible loss of ecosystem functioning. Finally, we provide scientific knowledge that can contribute to the process of establishment of reference values of indicators of soil quality and to agricultural management recommendations, but the assessment of values for management is something to be subjectively agreed upon in practical situations, rather than objectively assessed.
Biotic soil parameters have so far seldom played a role in practical soil assessment and manageme... more Biotic soil parameters have so far seldom played a role in practical soil assessment and management of grasslands. However, the ongoing reduction of external inputs in agriculture would imply an increasing reliance on ecosystem self-regulating processes. Since soil biota play an important role in these processes and in the provision of ecosystem services, biological soil parameters should be an integral part of soil assessment. The general objective of the current study is to investigate to what extent biotic soil parameters provide additional value in soil quality assessment of grassland on sandy soils. We measured abiotic and biotic soil parameters together with process parameters underlying ecosystem services in 20 permanent production grasslands. Cross-validated stepwise regression was used to identify abiotic and biotic soil parameters that explained the soil ecosystem services soil structure maintenance, water regulation, supply of nutrients, and grassland production, respectively. Process parameters underlying the ecosystem service soil structure maintenance such as bulk density and the percentage of sub-angular blocky elements were mainly influenced by SOM and its qualities. The correlations between penetration resistance at 0e10 cm and the percentage of soil crumbs with earthworms suggested a relationship to earthworm activity. Parameters underlying the service of water regulation showed no clear relationship to biotic soil parameters. Water infiltration rate in the field was explained by the penetration resistance at 10e20 cm. Process parameters underlying the service of nutrients' supply such as the potentially mineralizable C and N were mainly determined by soil total N. The potential C and N mineralization were more related to biotic soil parameters, whereby each parameter was the other's antithesis. The grassland production without N fertilization viz. the nitrogen supply capacity of the soil measured as N yield, was mainly explained by soil organic matter (SOM) and soil moisture, and to a lesser extent by soil total N. One gram of SOM per kg of dry soil corresponded to 3.21 kg N yield ha À1 , on top of a constant of 15.4 kg N ha À1. The currently applied calculations in the Dutch grassland fertilization recommendation, underestimated in 85% of the production grasslands, the measured nitrogen supply capacity of the soil by on average 42 kg N ha À1 (31%). This legitimizes additional research to improve the currently applied recommendations for sandy soils. The response of N yield to N fertilization ranged from 35 to 102%. This wide range emphasizes the importance of a better recommendation base to target N fertilizer. The response of N yield to N fertilization was predicted by the total number of enchytraeids, the underlying mechanism of which needs further investigation on different soil types. This knowledge can be important for the optimal use of fertilizer and its consequences for environmental quality.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is impo... more Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for ...
Understanding the impacts of agricultural intensification and extensification on soil biota commu... more Understanding the impacts of agricultural intensification and extensification on soil biota communities is useful in order to preserve and restore biological diversity in agricultural soils and enhance the role of soil biota in agroecosystem functioning. Over four consecutive years, we investigated the effects of agricultural intensification and extensification (including conversion of grassland to arable land and vice versa, increased and decreased levels of mineral fertilization, and monoculture compared to crop rotation) on major soil biota group abundances and functional diversity. We integrated and compared effects across taxonomic levels to identify sensitive species groups.Conversion of grassland to arable land negatively affected both abundances and functional diversity of soil biota. Further intensification of the cropping system by increased fertilization and reduced crop diversity exerted smaller and differential effects on different soil biota groups. Agricultural intens...
The introduction of N 2-fixing white clover (Trifolium repens) in grassland is a management measu... more The introduction of N 2-fixing white clover (Trifolium repens) in grassland is a management measure that may contribute to sustainable grassland systems by making them less dependent on inorganic fertilizers. However, little is known about the impact of this measure on soil biota and ecosystem services. We investigated earthworms, nematodes, bacteria and fungi in an experiment in which white clover-only and a mixture of grass and white clover without fertilization were compared with grass-only with and without fertilization. In comparison with grass-only, white clover-only had a lower total root biomass and a lower C/Nratio in the above-and below-ground plant biomass. These plant characteristics resulted in a lower bacterial biomass, a lower fungal biomass, a higher proportion of bacterivorous nematode dauerlarvae, a lesser proportion of herbivorous nematodes and a greater abundance of earthworms in clover-only. The quantity and quality (C/N-ratio) of the above-and below-ground plant biomass in the mixture of grass and white clover (20-30% clover in the DM) was comparable with grass fertilized with 150 kg N ha À1 of inorganic fertilizer. Differences between these treatments might show specific clover effects in the grass-clover mixture on soil biota other than quantity and C/N-ratio of the litter. However, the only differences were a higher proportion of bacterivorous nematode dauerlarvae and a different nematode community composition in grass-clover. The soil structure in white clover-only showed a higher proportion of angular blocky elements, a lower penetration resistance, a higher number of earthworm burrows, a higher potential Nmineralization and respiration than the soil in grass-only. This suggests that clover stimulates the ecosystem services of water infiltration and supply of nutrients, but is less conducive to soil structure maintenance. The grass-clover mixture differed from grass-only in a higher respiration and from cloveronly in a higher percentage of soil crumbs. We suggest that when clover is introduced in grassland to reduce the reliance on inorganic fertilizer, the mixture of grass and clover maintains the positive impact of grass roots on soil structure and increases the supply of nutrients via the soil food web. Thus, a grassclover mixture combines the agronomic benefits of the two plant types.
Agricultural intensification is known to impact the soil biota community. In a previous study, th... more Agricultural intensification is known to impact the soil biota community. In a previous study, the impact of agricultural intensification on total abundances and functional group structure of major soil biota groups were measured. In this study we address the effects of conversion of extensively managed grassland to arable land on taxonomic diversity at genus and species level of four major soil biota groups (predatory mites, earthworms, enchytraeids, nematodes and bacteria). Vice versa, the effect of agricultural de-intensification (re-establishment of grassland on former arable land) on soil biota taxonomic diversity was also studied. Conversion of an extensively managed grassland to arable land had detrimental effects on taxonomic richness and diversity across taxonomic groups in the short-term, with largest effects on soil biota with larger body size. Effects of arable management were detrimental shortly after conversion. Restoration of grassland resulted in establishment of a species-rich community of nematodes (with partly different species), and recovery of the earthworm community. Predatory mite species were less successful in re-establishing and negative effects on enchytraeid species persisted. When combining the results of Postma-Blaauw et al. (2010) with the present study, we conclude that agricultural intensification resulted in a reduction in abundance and taxonomic diversity of nematodes and bacteria, whereas functional group structure of these groups was little affected. In contrast, predatory mites and earthworms were affected both in functional group structure and in taxonomic diversity. We conclude that agricultural intensification affects total abundances and taxonomic diversity of soil biota in agricultural land, but not necessarily the functional group diversity. Reduced taxonomic diversity may result in reduced resilience to stress, whereas reduced total abundances of microbiota may affect ecosystem functions such as nutrient mineralization.
SummaryIn the Netherlands soil biological measurements are undertaken in a nationwide monitoring ... more SummaryIn the Netherlands soil biological measurements are undertaken in a nationwide monitoring programme. The measurements are combined in the Biological Indicator of Soil Quality (BISQ). About 300 locations were selected in a random stratified design comprising stringent combinations of land use and soil type. All locations were sampled in a six‐year cycle. In this contribution we describe the monitoring network and the BISQ and present average values for biomass, abundances and taxonomic diversity of various soil dwelling organisms derived from 10 years of measurements. We further highlight some results and discuss the possibilities in soil and land management policy frameworks for improving sustainable land management.
Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is impo... more Knowledge of the effects of species diversity within taxonomic groups on nutrient cycling is important for understanding the role of soil biota in sustainable agriculture. We hypothesized that earthworm species specifically affect nitrogen mineralization, characteristically for their ecological group classifications, and that earthworm species interactions would affect mineralization through competition and facilitation effects. A mesocosm experiment was conducted to investigate the effect of three earthworm species, representative of different ecological groups (epigeic: Lumbricus rubellus; endogeic: Aporrectodea caliginosa tuberculata; and anecic: Lumbricus terrestris), and their interactions on the bacterial community, and on nitrogen mineralization from 15 N-labelled crop residue and from soil organic matter.
66 Land Society, environment, and development: The Mt. Malindang Experience ASSESSMENT OF SOIL PR... more 66 Land Society, environment, and development: The Mt. Malindang Experience ASSESSMENT OF SOIL PROPERTIES AND ECOLOGICAL DIVERSITY IN MT. MALINDANG RANGE1 Renato D. Boniao2, Rosa Villa B. Estoista3, Carmelita G. Hansel3, Ron de Goede4, Olga M. ...
Society is faced with environmental issues that exceed the level of local governments, but which ... more Society is faced with environmental issues that exceed the level of local governments, but which need to be dealt with at international or even global scales. These issues include nature conservation and management, development of a more sustainable agriculture, effects of environmental pollution, biodiversity, and effects of global change. The development of political and technical protocols necessary to control the future state of such environmental issues requires a detailed knowledge of the structure and functioning of the world's ecosystems. Studies that integrate the interpretation of results from (detailed) community and ecosystem process and pattern studies and that, moreover, include social and economic aspects might be defined as 'integrated ecosystem studies'. Four examples of integrated ecosystem studies are presented, and it is concluded that a full understanding of the contribution of soil zoology to such studies requires detailed analyses of interactions of fauna with other system components. If not, analyses can result in superficial conclusions that possibly underestimate the vulnerability of ecosystems to disturbances or their sensitivity to management.
Agricultural intensification is known to impact the soil biota community. In a previous study, th... more Agricultural intensification is known to impact the soil biota community. In a previous study, the impact of agricultural intensification on total abundances and functional group structure of major soil biota groups were measured. In this study we address the effects of conversion of extensively managed grassland to arable land on taxonomic diversity at genus and species level of four major
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