In this case, the individual species is not the focus, but the function they play collectively in an environment. A summary of microbial indicators related to the cycle in which they act and the functions they play is shown Table 1. A soil with high microbial diversity has more chance to keep the ecological processes after a disturbance Kennedy, Such capacity is defined as resilience which means a biological buffering against disturbances in an ecosystem.
We may usually state that the functional redundancy is higher in less degraded soils Harris, , but the composition of the plant community may favor the prevalence or cause suppression of certain microbial functional groups in soil Matsumoto et al. Besides microbial activity and biomass, biochemical indicators such as soil enzymes can also be useful indicators of soil health Table 2.
They are involved in several metabolic processes and are also responsive to changes in soil use and management Nannipieri et al. Enzymes are catalysts in different reactions during carbon and nutrient cycling in soil Balota et al. They may be free in soil as exoenzymes excreted by plants, animals, and mainly microorganisms Weaver et al. Hence, when the soil microbial community is affected due to soil use and management, changes in soil enzyme activities are also expected Nayak et al.
The main limitation of using individual biochemical properties as indicators of soil quality is that they show a high degree of variability in response to climate, season, geographical location and pedogenetic factors. This might result in contradictory conclusions in different studies when describing the effects of a contaminant or a given management on the soil quality Gil-Sotres et al. Moreover, with the knowledge actually available, estimation of soil quality relying only on individual biochemical properties, simple indexes or ratios, cannot be considered reliable.
Thus, a minimum data set of biochemical properties capable of describing the complexity of the soil system is required for each situation, and it must be verified whether they are universally valid. Facing these challenges, the use of multivariate statistical techniques is a useful tool for selecting attributes for assessment of soil health. Lande-use changes affect the sooil carbon storage and cause changes quantitative and qualitativ. Land-use changes affect the soil carbon storage and cause quantitative and qualitative changes on soil organic matter, and consequently on physical and chemical characteristics that directly affect the soil microorganisms, like humidity, porosity, density, among others Bayer and Mielniczuk, Consequently, these alterations will also reflect on the nutrient cycling and availability of nutrients in soil.
Different land-use systems like annual and perennial crops, pastures and forests, generate different residues whose dynamics and cycling will also be different due to differences in composition e. In addition, more intense agricultural practices, with more soil stirring, can also affect the dynamics of organic matter, speeding up the oxidation process and reduce the stable organic matter, and consequently the biological activity. More conservative agricultural practices like no-tillage and organic farming has been used to attenuate the negative impact on soil health, thus keeping the system more balanced and sustainable.
Besides the classical techniques for assessing the soil biological quality, new approaches have been recently developed and are tools for helping us to understand the changes in soil biological quality. For example, profiling techniques consist of more specific tools that can be used for assessment of variations in the soil microbial community caused by land-use and management Kennedy and Smith, Considering that the metabolic diversity is consequence of the genetic diversity, environmental effects in gene expression, and ecological interaction among different populations Zak et al.
Phospholipids are found in membranes of all living cells and can be used as biomarkers. Phospholipid fatty acid PLFA profiling can be used to determine the phenotypic structure of microbial communities based on phylogenetic relations Zelles, The PLFA technique has also been used to elucidate different strategies employed by microorganisms to adapt to changes in environmental conditions due to land-use, climatic changes, and disturbances Kandeler, Different microbial groups are characterized by fatty acids linked to specific phospholipid esters, and a change in the structure of such communities is characterized by changes in the patterns and composition of the PLFA in soil.
Thus, the content of PLFA has been correlated with other measurements of microbial biomass in soil and therefore has been confirmed as a good indicator of changes in the microbial community Frostegard et al. In addition, this technique also allows for assessing the physiological status of the soil microbial communities. The development of methods based on recombinant DNA has represented great advances in the studies of soil biodiversity and microbial ecology Torsvik et al.
The profiling techniques are powerful tools, however cannot supply all the information alone, since each of them has intrinsic limitations. These limitations may cast doubts on the true relationship and contribution of the microbial diversity to the concept of soil quality. Thus, polyphasic approaches are indicated to bring complementary information. The arising of novel methods must be considered as a progress and complementary to the traditional methods, not a replacement. A minimal and distinct set of microbiological techniques is required for each situation and type of study to assess soil health.
Recently, more importance has been given to members of soil fauna as indicators of soil health. This group comprises the invertebrate community that lives totally or during at least a phase of the life cycle in the soil Brown et al. They play roles in structuring processes of terrestrial ecosystems, fragmentation of plant residues, and establishing relationships at different levels with microorganisms. Therefore, they actively take part in processes that influence the soil properties and quality, and for this reason are good indicators of changes in the soil Lavelle and Spain, As stated above, the decomposition and transformations of organic materials in soil are predominantly carried out by microorganisms Adl, Nevertheless, the microbial processes are more effective when the organic material is more accessible, i.
Hence, the soil fauna is the main responsible for supplying pre-transformed organic material to the microorganisms after fragmentation, resulting from their feeding process. Besides increasing the contact surface, the fauna, especially earthworms, promotes a distribution of organic material vertically or horizontally along the soil layers Kostina et al.
The faunal activity also affects soil structure due to the aggregation of soil particles, in addition to the microbial effect Belnap, Moreover, the faunal action mixes soil particles and produces galleries, pores, tunnels, and other biological compartments that make the air and water flow easier, which also stimulates the microbial activity Lavelle et al.
Conversely, soils with low faunal activity show more compaction, which makes difficult the penetration of plant roots Drewry et al. This is a quite simple, easy, and economical procedure employed for assessment of the taxonomic diversity at order, class or key species level.
Soil fauna can be classified according to their food preference, mobility, functional diversity, and mainly by size Swift et al. The most representative organisms normally studied as indicators of soil health belong to the mesofauna, which lives in soil macropores and spaces in the soil-litter interface, feeding on fungal hyphae and organic matter, and thus taking part in nutrient cycling and soil aggregation Lavelle and Spain, Studies under different environmental conditions have shown that some springtail species are good indicators of soil health Ponge et al.
The macrofauna includes bigger soil organisms which sometimes are active in soil functioning Lavelle et al. Changes in the environment may reflect differently on a species, family or functional group composition of the soil faunae Wink et al. Using functional groups as bioindicators has been preferred instead of the total species diversity, due to the role they play in biological processes. The presence or absence of a particular species can be crucial for a given process in an ecosystem Brussaard et al.
For example, after some earthworm species had disappeared, the organic material accumulated on the soil surface, and thus the individual activity of the species was considered limiting. Despite the existence of other functional groups of organisms, they were not able to replace the role previously played by the earthworm species Hoogerkamp et al.
Nevertheless, the presence or absence of a certain species may be limiting for an ecosystem functioning Huston et al. Despite the quick response of soil fauna to changes in land-use and management, they are also very responsive to seasonality and climatic variations Sicardi et al.
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In addition, the inference of an interpretative value for biological attributes is not an easy task due to the huge amount of influences on soil organisms. For this reason, a compilation of studies in different environments would be interesting, in order to try to establish biological indices of soil quality, similarly to chemical and physical indices already established.
Indicators of soil health under varying soil tillage systems. Different soil uses in agricultural systems regarding management, crop rotation, frequency of application or amounts of applied chemicals lead to changes in physical, chemical, and mainly biological soil properties. In this context, the conventional tillage system is considered to be more aggressive because the intensive soil revolving disturbs some attributes associated to soil health, e.
Less aggressive techniques of soil use, like minimum tillage Sun et al. In general, the no-tillage system, in addition to adequate crop rotation, has shown to improve attributes associated to soil health. A more stable soil temperature and humidity due to the constant soil mulching, greater inputs and maintenance of organic matter, protection against rain drops, thus preventing soil erosion, do stimulate the soil microbial diversity and activity, and consequent enhancement of nutrient cycling Balota et al. One of the main effects of no-tillage is the maintenance of soil structure.
The adoption of no-tillage systems in subtropical southern Brazil for 30 years has increased the concentrations of soil organic C especially at the cm top layer, when compared to the conventional tillage Babujia et al. These findings have also been reported from several other geographic regions under temperate and tropical conditions Melero et al. Despite serving as indicator of alterations due to soil use, changes in soil organic C are usually of long-term effect.
Thus, more promptly responsive attributes must be used to monitor changes in soil attributes caused by anthropogenic effects. In this particular, the soil microbial biomass has been used as a promising indicator of soil health due to its rapid response to changes in soil use and management Nogueira et al.
Under tropical conditions, increases in C and N microbial biomasses under no-tillage have been observed mainly at cm of soil depth Babujia et al. Soil microbial biomass is affected not only by the soil management system, but also by the composition of plant species in the crop rotation system Silva et al. Under temperate conditions, comparisons between conventional, minimum, and no-tillage soil management showed no differences among the total microbial biomass based on phospholipids profiling FAME techniques Sun et al.
Nevertheless, when fungal and bacterial biomasses were assessed separately, only the fungal biomass had been favored under the more conservationist soil management. The favoring of fungal biomass can be explained by the maintenance of the hyphal net in the system in which the soil is less revolved Frey et al.
On the other hand, under more aggressive, stressing conditions, as generally observed under conventional tillage, the bacterial community prevailed in relation to the fungal community Pankhurst et al. Thus, it is not rare to find general increase of microbial biomass in soil under no-tillage in relation to conventional tillage Helgason et al. Higher enzyme activities under conservationist systems as compared to conventional tillage were also reported Melero et al.
In general, higher activities of cellulase and amylase are associated with greater amounts of organic C at the topsoil layer. On the other hand, enzymes like phosphatase may be inhibited by phosphate fertilizers in a feedback effect Melero et al. Several other soil features have influence on enzyme activity; for example, dehydrogenase correlated negatively with soil pH, but correlated positively with total soil C Melero et al.
A stimulation of soil microbial activity is also expected to result in higher general enzyme activities Nayak et al. As a result, soil use systems that keep organic material on the soil surface maintain higher levels of soil microbial and biochemical activities, therefore pointing to greater environmental sustainability. Most of the forestry environments worldwide have undergone large losses in their floristic composition.
Approximately 13 million ha of native forests have been converted into other land use systems or lost by natural disasters according to FAO's biannual report FAO, All these changes in natural landscapes have caused loss of biodiversity, and increasing concerns associated to emissions of greenhouse gases and soil degradation. One of the main concerns regarding conversion of forest into agriculture is the decrease of C stocks in the soil with transference to the atmosphere as CO 2 Lemenih et al.
Therefore, it is very easy to lose the soil organic carbon due to soil use and management, but the recovery back to the original levels as found in the native forest is very difficult to be reached Nogueira et al. Another important indicator of soil health is the level of soil microbial biodiversity. Environmentally friendly strategies of soil use and management must maintain or increase the soil biodiversity and ultimately preserve the soil ecological functions in the environment.
Alternative tools independent of cultivation have been based on molecular biology and have brought new insights in studies on soil microbial diversity. Nevertheless, reforestation with Eucalyptus resulted in less bacterial diversity in soil Nogueira et al. Card and Quideau found similar results and also observed that microbial diversity in soil increased with the time elapsed after reforestation.
Vasconcellos et al. Reforestation with exotic species of economical interest or conversion to pastures causes deep interferences in the structure and functionality of the ecosystem Pankhurst et al. The soil fauna in native fields is more diverse than in reforestations with Pinus taeda , P. Similar results were found for microbial and biochemical processes related to N and C-cycling in southern Brazil Fagotti et al. The diversity of springtails decreased in reforestations in comparison with native fields, as the faunal diversity in general Deharveng, The intensity of changes in the land-use system may eliminate some species essential for biochemical processes Kouadio et al.
Studies on abundance, diversity, and structure of the invertebrate community in soil have been useful indicators of soil health in forest environments. Even under temperate conditions, the total abundance and species composition decreased with the intensification of land use Ponge et al. Similarly, Baretta et al. A spruce Picea abies forest in the Italian Alps Salmon et al. Great abundance of mites Acari was favored by the recalcitrant plant residue, but there was low density of springtails and absence of several other groups of soil macrofauna.
Conversely, during the different successional stages, there was a continuous up and down of several groups of invertebrates. The richness of the soil fauna was greater during the periods of revegetation, when the soil cover consisted of diverse growing trees and abundant herbaceous vegetation.
The effect of land use change on soil fertility parameters in densely populated areas of Kenya
Similar results were obtained by Lucas-Borja et al. One of the most important factors affecting biological indicators of soil health in forestry environments is the C to N ratio of the plant residues. Thus, changes in the structure of plant community, like conversion of native forest to monocultures, deeply alters the biological indicators of soil health due to changes in the quantity and quality of vegetal residues deposited on the soil surface and directly inside the soil as rhizodeposition Fagotti et al.
Thus, the removal of native plant community firstly changes microbial communities and soil fauna, and later also physical-chemical attributes like temperature, water availability, concentration of organic matter, nutrients, pH, etc. As reported by Bautista-Cruz et al. Biological indicators, however, are much more sensitive to detect alterations in soil health caused by land-use changes Wink et al.
In a forestry restoration chronosequence after mining, the increase of soil organic carbon was only 1. Substitution of native vegetation by exotic species also decreased the microbial biomass and activity in soil Rutigliano et al. However, certain soil enzymes may be activated by the presence of certain organic compounds, e. Assessment of indicators of soil health in different strategies of soil use has shown increase of total organic carbon and ammonification rate in forestry soils Nogueira et al.
In addition, the C and N microbial biomasses in the secondary and artificially reforested sites after 20 years tended to approximate values of the native forest, but in a site under Eucalyptus for 50 years, values were similar to an agricultural fallow site. Assessments of indicators of soil health are particularly important to evaluate the success of a given strategy for reclamation of degraded forestry environments Bastida et al. Greater emphasis has been given to biological and biochemical indicators due to their greater sensitivity Wink et al.
Soil enzyme activities have also been widely employed in forestry soils to assess effects of changes in land use Bastida et al. Despite their high sensitivity to environmental conditions, soil enzymes are also sensitive to seasonal variations. For example, dehydrogenase was the lowest in the autumn due to low temperatures that restricted the soil microbial activities, while the activity of urease was inversely correlated with the concentrations of ammonium in soil when both plants and microorganisms were less active.
On the other hand, phosphatase and arylsulphatase were not affected by temperature, but depended on the amount of litter on the soil surface Kang et al. Assessment of C and N microbial biomass, soil respiration and enzyme activities are correlated with the content of soil organic matter and the age of successional stages Jiang et al. Additionally, the enzyme activities also correlate with the soil microbial biomass Jiang et al. Forest cleaning, cropping and management affect the soil microbial diversity and activity Degens et al.
Decrease in microbial activity in intensively managed soil in comparison to well managed pastures has been observed Riffaldi et al. In general, the maintenance of soil organic C is the main factor that favors the microbial activity Lizarazo et al. In natural ecosystems, the rate between input and decomposition of organic material is under dynamic balance, with predominance of mineralization of nutrients.
Bastida et al. Similar results were observed in a secondary forest under regeneration for 20 years Nogueira et al. In general, the levels of soil organic carbon increase with the vegetation recovery Jiang et al. Besides the decreases in the soil organic carbon levels, changes in other physical-chemical attributes also affect the microbial activity in degraded soils. Erosion is one of the main factors affecting the physical soil conditions, in addition to soil compaction and decrease in aggregate stability Hartanto et al.
Background information about soil
The increase of the soil bulk density due to traffic of machines or animals and the loss of aggregate stability due to decrease in the soil organic carbon directly affect the plant root development and the water and air dynamics within the soil. As observed, the main causes of changes in diversity and activity of microbial community and fauna in forest soils is the quantity and quality of residues that return to the soil surface, and consequently, the soil organic matter levels.
Nevertheless, in order to better understand the effects of use and management on soil health, physical, chemical, and biological attributes should be assessed altogether because they are interconnected and run mutual interferences, although they have different levels of responsiveness to changes. Indicators of soil health in soils amended with residues. Residues like cattle, poultry, and pig dung have historically been used in agricultural soils.
Besides acting as source of nutrients, notably nitrogen and phosphorus, animal residues also contribute to improve soil physical and chemical properties Haynes and Naidu, Nowadays, several industrial and urban residues have also been applied as alternative sources of nutrients in agriculture, but many times without the appropriate studies on their potential environmental impacts. Due to its capacity for cycling a large sort of residues, soil has been seen as the receiving end of residues produced by several activities.
Nevertheless, depending on the nature and amount of residues, the soil's biological capacity for recycling may be exceeded, leading to soil contamination and interruption of several ecological functions. Landfarming aiming at microbial degradation of the organic fraction of petrochemical residues is an example of soil use as an efficient bioreactor Dua et al.
Nevertheless, presence of heavy metals, salts and recalcitrant compounds sometimes leads to reduction of soil microbial activity. Paula et al. The use of urban residues in agriculture, like sludge from sewage treatment plants, liquid effluent from treated sludge, and composted domiciliary waste, has two main environmental objectives: nutrient cycling and alternative destination of residues, instead of disposition in sanitary landfills or discharge in surface waters.
Moreover, these residues can also be used for reclamation of degraded soils Tamanini et al.
melghandjodug.tk Due to the general predominance of organic matter, sewage sludge or composted domiciliary wastes increase the soil organic matter, and consequently its water holding capacity and nutrients, and stimulate the soil microbial activity Oliveira et al. Nevertheless, the main concerns on the risks of using residues on soil health are the presence of high levels of heavy metals and other organic or inorganic contaminants Lara et al.
Despite established criteria for application of residues in soil e. The use of urban or industrial residues as irrigation water and also as complementing source of nutrients may represent risks for soil health, depending on its characteristic Toze, For this reason, monitoring of biological, chemical and physical indicators of soil health is essential for safer strategies for the application of residues.
Fonseca et al. In addition to chemical attributes, monitoring microbial activity can also provide essential information on the soil health under a specific management, especially concerning to nutrient cycling Paula et al. Thus, the monitoring of soil functions in sites used for receiving residues is essential to prevent the soil degradation.
In addition, monitoring of chemical or even biological contaminants is also important to prevent any adverse effect on soil functions and plant growth and health. As a more comprehensive strategy, a pool of indicators can be useful for monitoring the impacts of application of residues on soil health. In the Agricultural sphere, an extensive knowledge on soil degradation is already present. All over the world, there are many thousands of km 2 of degraded soils, as a consequence of a kind of agriculture whose priority was only high crop productivity.
Thus, the excessive use of synthetic fertilizers, the systematic deforestation, soil erosion due to high tillage and the action of rains or winds, loss of organic matter and several other factors brought about increasing desertification, the loss of millions of tons of fertile top soil and, indirectly, silted up rivers and lakes, caused soil salinisation, climate changes and loss of biodiversity. Besides the need for constant monitoring and evaluations of physical-chemical and biological processes to achieve better soil health, it is imperious to keep in mind that soil microorganisms are the main agents of nutrient cycling and also have a complex interaction with plants.
Any land-use strategy that contributes to a better equilibrium of soil microorganisms is able to result in greater crop productivity, at low cost, and contributes to minimize the use of mineral fertilizers or pesticides, favoring high sustainability. To approach the environmental problems it is necessary to act on various fronts, as: i characterize the soils through their hydrodynamic activity, the dynamics of percolating solutions and their retention of different elements; ii to monitor available nutrients and augment their efficiency in plant nutrition; iii evaluate changes in soil physical and chemical properties; iv evaluate quantitative and qualitative changes of soil organic matter due to application of organic residues; v evaluate the effects on the soil microbial biomass and its metabolic activities; vi evaluate plant productivity and nutritional status; vii investigate the sustainability of the system and its relative dependence on sanitary, technical, and economic aspects.
New research lines must be implemented, and one of them is the need for a concentrated effort in organic composting. Another decisive point is the development of processes and methodologies to study ecotoxicological aspects of all kinds of residues, independently of origin, creating an interface with human health. Undoubtedly, we can claim that public health depends on healthy food, and this, in turn, is directly linked to the soil health. Finally, soil health is the first requirement for agricultural and environmental sustainability.
Enzyme activities as affected by soil properties and land use in a tropical watershed. Applied Soil Ecology Adl, S. The Ecology of Soil Decomposition. Cromwell Press, Trowbridge, UK. Anderson, T. The metabolic quotient from CO 2 q CO 2 as a specific activity parameter to assess the effects of environmental conditions, such as pH, on the microbial biomass of forest soils. Soil Biology and Biochemistry Andersson, M. Microbial enzyme activities in leaf litter, humus and mineral soil layers of European forests.
Babujia, L. Microbial biomass and activity at various soil depths in a Brazilian oxisol after two decades of no-tillage and conventional tillage. Badiane, N. Use of soil enzyme activities to monitor soil quality in natural and improved fallows in semi-arid tropical regions. Balota, E.
A unique long-term trial
Microbial biomass in soils under different tillage and crop rotation systems. Biology and Fertility of Soils Soil enzyme activities under long-term tillage and crop rotation systems in subtropical agro-ecosystems. Brazilian Journal of Microbiology Baretta, D. Earthworm populations sampled using collection methods in Atlantic Forests with Araucaria angustifolia. Scientia Agricola Multivariate analysis of soil microbiological and chemical attributes in forests with Araucaria angustifolia. Bastida, F. Microbiological activity in a soil 15 years after its revegetation.
Past, present and future of soil quality indices: a biological perspective. The result of soil degradation is not only that farm land has to go out of production, but also that there is an increasing need for more inputs and investments to maintain high levels of productivity. In Zimbabwe, soil nutrient losses by erosion are three times higher than the total quantity of fertilisers applied Stocking, Occurrence of erosion can be considered the most important factor causing soil degradation. Under the concept of sustainability, the first negative factor in relation to productivity and profitability, and the major aggressor of the environment is soil erosion.
Consequently, sustainability can only be achieved if soil erosion is stopped completely. When agriculture is practised on slopes in undulating topography, and rains of a certain intensity occur, soil preparation especially with disc implements results in bare soil, and this results in water erosion, or in regions of heavy winds in wind erosion.
For the same experiment after extreme precipitations of mm on June 9 and 18, , soil losses of This resulted in times higher soil losses when soil was prepared. Venialgo When soil losses are higher than natural soil regeneration rates, sustainable agriculture is not possible. Recent studies show that soil erosion is a selective process, with the most fertile soil particles taken away. Eroded soil sediments usually contain several times more nutrients than the soils they originated from Stocking, Applied fertilisers are also transported by erosion to streams, rivers, lakes and to the sea, and therefore lost forever.
Considering that world phosphate reserves are going to be exhausted in 40 to 50 years Hoffman et al. Even under the assumption that phosphate reserves are going to last much longer, it has to be kept in mind that reserves are finite. Research has shown, that soil cover is the most important factor that influences water infiltration into the soil, thus reducing runoff and erosion Mannering and Meyer, In the tropics and subtropics organic matter content of the soil has an overriding importance in relation to soil fertility.
According to Cannel and Hawes , organic matter content of the soil is probably one of the most important characteristics in relation to soil quality, due to its influence on soil physical, chemical and biological properties. Therefore the efficiency of mineral fertilisers is greatly reduced if at the same time organic matter is not added. On the other hand it is necessary to consider that organic matter is mineralised about five times more rapidly in the tropics than in temperate regions.
Soil tillage results in rapid mineralisation of organic matter stored in the soil, liberating nitrogen that will be available for plants. This can lead during a few years to an increase in yield. However, when soil tillage is performed under favourable conditions for mineralisation of organic matter heat, humidity, good aeration leaving the soil under fallow bare , valuable nitrate reserves are lost by lixiviation washed into deeper soil layers , without crops being able to utilise them. Once organic matter has been consumed, more nitrogen cannot be liberated and yields of crops remain low.
The result is a depleted soil, where the indispensable organic matter is missing. Many depleted soils of Paraguay and other countries of Latin America are an example of bad land management, with excessive soil tillage resulting in organic matter exhaustion. The long term influence years of soil preparation on the organic matter content in northeastern United States temperate climate is described by Rasmussen and Smiley In that period a reduction in the organic matter content of the soil from 2.
This shows how difficult it is to raise organic matter content of the soil once it has fallen. The influence of 20 years of different soil preparation on the organic matter content of the soil in Kentucky, USA, is reported by Thomas Table 1. These organic matter contents were also reflected on maize yields after 20 years in the same experiment Thomas, Yields of maize without nitrogen were initially much lower in no- tillage than in conventional tillage.
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The situation changed after 13 years due to organic matter depletion in conventional tillage, and since then yields under no- tillage without nitrogen have been always higher G. Thomas, , pers. There is enough scientific evidence from warmer areas that shows, that no- tillage has positive effects on chemical, physical and biological soil properties compared to conventional soil preparation Kochhann, These changes can be beneficial or detrimental to the functions and regenerative capacity of the soil biota.
Thus, the activity of soil organisms and land management practices requires effective management for maximum productivity and sustainable use of resources. Box 1: The Kifissia workshop on soil health as an indicator of sustainable management. Emphasized the links of soil quality to society and health, environmental degradation, novel ecological production systems and the land manager. Noted that soil health and quality indicators, and the changes in those indicators, can be a major link between the strategies of conservation management practices and achievement of major goals of sustainable agriculture.
Noted that confirmation of the effectiveness of systems for residue management, organic matter formation, N and C cycling, soil structure maintenance and biological control of pests and diseases will assist in discovering and developing system approaches that are both profitable and environmentally friendly.
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Recognized that the challenge is to make better use of diversity and resilience of the biological community in soil to maintain a quality ecosystem, thus fostering sustainability. Strategies could be fine-tuned using practices, such as crop rotation for greater crop diversity and tighter cycling of nutrients; reduction of soil disturbance to maintain soil organic matter and reduce erosion; and development of systems that make better use of renewable biological resources such as legume companion crops and animal manuring. Communicating to a broad and diverse audience the critical importance of soil as related to the environment, society and economics.
Prescriptive and descriptive assessment of the sustainability of agricultural systems for the land manager and for scientists. The Kifissia workshop concluded that an increased understanding must be sought of the linkages between soil properties, soil processes and ecosystem functions in order to improve the methodology for sustainable productivity, biodiversity and environmental protection. Moreover, efficient implementation of sustainable policies requires educational outreach to various segments of society and the translation of science into practices that land users can use.
The workshop proposed that soil health indicators and sustainable management strategies must be linked through agricultural systems that:. It is a process of testing alternative hypotheses through management action, learning from experience, and making appropriate change to policy and management practice. The process is useful because:.
It may not be completely clear how to achieve one or more of the objectives. Experiments or trials using different methods may be needed. Something beneficial may happen unexpectedly. If so, a decision will be required on whether to capitalize on such events. The web of life in the soil is a very complex and rich component of agricultural biodiversity and has important interrelationships with other components of the ecosystem. Human management practices influence its functions and activity both directly and indirectly.
Thus, it needs to be addressed through an ecosystem approach. Land managers need unbiased information that will enable them to develop biologically based management strategies to control or manipulate soil stabilization, nutrient cycling, crop diseases, pest infestations, and detoxification of natural and human-made contaminants. Such improved management strategies depend on a good understanding of soil organisms and their ecological interactions and of the effects on soil biota of habitats, food sources, host interactions, and the soil physical and chemical environment.
The ecology regulating both beneficial and detrimental organisms is essential to harnessing and controlling their activity in agro-ecosystems. Such knowledge will yield great benefits in terms of the production of abundant, high-quality agricultural products with less dependence upon external inputs. A vast range of innovative soil management practices involving biota and biotic products is available. Moreover, many of these practices are sustainable, environmentally friendly, affordable and applicable to developing nations. Many of the tools are based on traditional agricultural practices, while others are novel and take advantage of recent major advances in biotechnology.
Biotic solutions should be encouraged in order to address the wide range of soil-related physical, chemical and biological problems. The goal is to understand the soil biota and to utilize this living component of the soil for the benefit of agricultural systems in order to increase crop productivity and quality, reduce input costs, and reduce negative environmental impacts.
The review of cases and discussions during the workshop led to the following general guidelines for soil management and sustainable agriculture:. An integrated agro-ecosystem management approach is required for the review and development of better soil biological and other farming practices in view of the interactions among plant diversity and other resources, management practices, knowledge and organizational capacity resource use in space and time.
Attention needs to focus on biophysical, socio-economic and policy aspects, as well as on cultural and knowledge considerations that influence decision-making processes. The process must be interdisciplinary in order to address the interactions among plants, the soil, organic matter inputs, moisture, pests and diseases, soil biological activity and productivity. This can facilitate a process to build an integrated soil biological management approach. Such a process should combine biological, physical and chemical management issues.
It should address productivity and environmental sustainability. Adaptive management and integrated ecosystem approaches require scientific rigour and a joint learning process among different actors. Sustainable biological management is not simply a question of managing nutrients. Primarily, it entails restoring the productive potential as many lands are already degraded and enhancing the efficiency of soil management soil-crop-water interactions.
There is a need to value the ecosystem services provided and to quantify the on- and off-farm benefits provided by sustainable biological management in agriculture reduced costs of water purification and infrastructure maintenance; C sequestration; biodiversity conservation; etc. There is a need to expand the education process to: i build capacities at field and planning scales for integrated agro-ecological approaches at all levels, from schools to universities; ii to educate and sensitize policy-makers on the importance of soil biological functions and sustainable agriculture; and iii to empower communities and civil society organizations for lobbying, decision-making, etc.
This recognizes that on certain sensitive issues, e. There is a need to promote participatory, grassroots-driven processes to facilitate the adoption of better soil biological management and sustainable agriculture. This requires attention on how to build on and promote community organization and networking; concepts of land care and stewardship; gender issues; and appropriate technology options for end users. FFS approaches and other learning-by-doing experiential approaches are very useful for improving technology adaptation and exchange, taking into account local constraints and opportunities.
Economic considerations are the primary driving force for the adoption of unsustainable agricultural practices e. The low benefit-cost ratio of agriculture is a key issue. Is compensation for the ecosystem services provided by farmers the only option, or are there other ways e. The search for good practice also requires incentives to encourage adaptive management approaches, e.
There is also a need to mobilize a sense of responsibility and accountability: i for the adoption and promotion of good farming practice by farmers; ii for government compliance to fulfil commitments to implement conventions and agreements at all levels; and iii for responsible practice by agro-industry.
In the case of no-tillage, for example, the private sector is interested in sales of herbicides and seeds rather than in cover crops and crop rotations, which are essential for sustainability and help minimize the use of chemicals. There is a need to document the processes and methodologies for intervention, technology development and adaptation, as well as activities and impacts.
In this regard, case studies should document both successes and failures. Besides the agriculture sector, there is a need to consider wider development issues of rural exodus, the desire for modern amenities education, television, etc. Figure 4. Diagram of an adaptive management framework for soil ecosystems: entry points and opportunities for intervention. The Londrina workshop participants suggested the preparation of a schematic diagram of an adaptive management framework for soil ecosystems Figure 4.
The basis of all efforts to conserve biodiversity and natural ecosystems effectively while supporting economic development lies in the ability of scientists, resource managers, policy- and decision-makers, and the concerned public to have the widest possible access to the existing body of knowledge on biodiversity and ecosystem resources and processes. Much information exists on biodiversity and ecosystems from a legacy of past research and inventories , and much more is being collected.
However, it is still not possible for all potential beneficiaries to locate, retrieve, integrate and apply this information in a consistent fashion. In many cases, public and private funds are spent unknowingly on re-collecting information that may already exist in some undocumented or unavailable fashion. Much existing biodiversity and ecosystem information cannot be used widely and may be in danger of being lost because, for example, it is not yet converted into an electronic format or other readily usable form.
There was a suggestion to make a user-friendly inventory of projects and activities upon which to build for the development of guidance, tools, approaches and materials for different scales, systems, etc. The products and expertise of these projects and processes could provide guidance for specific systems and situations for, inter alia :.
There was also a suggestion to develop a checklist and format for case studies in order to enhance their usefulness in terms of clarity and eventual replicability. There was also a proposal to prepare a conceptual diagram linking the different dimensions, to facilitate review and analysis, as initiated by the adaptive management group. The case-study format should specify, inter alia , the following information:. Who identified the problem? Who identified the solution?
A particular strategic issue that the workshop identified was the need to enhance understanding of the benefits and value of soil biological activity and soil ecosystem functioning, illustrating, inter alia :. The other main strategic issue identified was the need to develop an approach that focuses on organic matter within a systems approach including technical, socio-economic, cultural and policy and institutional considerations, specifically:.
It was suggested that case studies be compiled for each category of soil biological solutions in order to demonstrate the valuable role and functions of soil biodiversity and related ecosystem functions in different farming contexts. Three key areas of intervention include the production system as a whole, organic matter management, and the cropping system or plant-soil interface. Soil quality, landscape quality, soil biota, nutrient cycling and biodiversity are integral aspects of sustainable development. A holistic, ecological approach is required for future research on soil-plant-animal systems.
This will enable redesign of farming systems from an overemphasis on production towards more quality and internal regulation. This will result in lower mineral fertilizer losses, lower pest and disease pressure, and reduced susceptibility to climate extremes, thereby contributing to sustainable land management on-farm and at regional scale. PLATE 6. A mixed arable-livestock system from the Eastern Plains of Colombia - [ J. Primarily at a functional group level, soil biota regulate vital ecosystem processes such as decomposition the breakdown of complex organic compounds into nutrients available for plant growth , C sequestration, and nutrient cycling.