Exclusion of soil macrofauna did not affect soil quality but increases crop yields in a sub-humid tropical maize-based system
Paul, B.K. ; Vanlauwe, B. ; Hoogmoed, M. ; Hurisso, T.T. ; Ndabamenye, T. ; Terano, Y. ; Ayuke, F.O. ; Pulleman, M.M. - \ 2015
Agriculture, Ecosystems and Environment 208 (2015). - ISSN 0167-8809 - p. 75 - 85.
conservation agriculture - organic-matter - microaggregate formation - agroecosystem function - aggregate stability - food security - termites - africa - tillage - biodiversity
Soil macrofauna such as earthworms and termites are involved in key ecosystem functions and thus considered important for sustainable intensification of crop production. However, their contribution to tropical soil and crop performance, as well as relations with agricultural management (e.g. Conservation Agriculture), are not well understood. This study aimed to quantify soil macrofauna and its impact on soil aggregation, soil carbon and crop yields in a maize-soybean system under tropical sub-humid conditions. A field trial was established in Western Kenya in 2003 with tillage and residue retention as independent factors. A macrofauna exclusion experiment was superimposed in 2005 through regular insecticide applications, and measurements were taken from 2005 to 2012. Termites were the most abundant macrofauna group comprising 61% of total macrofauna numbers followed by ants (20%), while few earthworms were present (5%). Insecticide application significantly reduced termites (by 86 and 62%) and earthworms (by 100 and 88%) at 0-15 and 15-30 cm soil depth respectively. Termite diversity was low, with all species belonging to the family of Macrotermitinae which feed on wood, leaf litter and dead/dry grass. Seven years of macrofauna exclusion did not affect soil aggregation or carbon contents, which might be explained by the low residue retention and the nesting and feeding behavior of the dominant termites present. Macrofauna exclusion resulted in 34% higher maize grain yield and 22% higher soybean grain yield, indicating that pest damage – probably including termites - overruled any potentially beneficial impact of soil macrofauna. Results contrast with previous studies on the effects of termites on plant growth, which were mostly conducted in (semi-) arid regions. Future research should contribute to sustainable management strategies that reduce detrimental impact due to dominance of potential pest species while conserving soil macrofauna diversity and their beneficial functions in agroecosystems.
Thermal shock and splash effects on burned gypseous soils from the Ebro Basin (NE Spain)
Leon, J. ; Seeger, M. ; Badia, D. ; Peters, P. ; Echeverria, M.T. - \ 2014
Solid Earth 5 (2014)1. - ISSN 1869-9510 - p. 131 - 140.
semiarid environment - erosion processes - organic-matter - aggregate stability - physical-properties - sediment yield - fire - gypsum - ash - wildfire
Fire is a natural factor of landscape evolution in Mediterranean ecosystems. The middle Ebro Valley has extreme aridity, which results in a low plant cover and high soil erodibility, especially on gypseous substrates. The aim of this research is to analyze the effects of moderate heating on physical and chemical soil properties, mineralogical composition and susceptibility to splash erosion. Topsoil samples (15 cm depth) were taken in the Remolinos mountain slopes (Ebro Valley, NE Spain) from two soil types: Leptic Gypsisol (LP) in a convex slope and Haplic Gypsisol (GY) in a concave slope. To assess the heating effects on the mineralogy we burned the soils at 105 and 205 degrees C in an oven and to assess the splash effects we used a rainfall simulator under laboratory conditions using undisturbed topsoil subsamples (0-5 cm depth of Ah horizon). LP soil has lower soil organic matter (SOM) and soil aggregate stability (SAS) and higher gypsum content than GY soil. Gypsum and dolomite are the main minerals (> 80 %) in the LP soil, while gypsum, dolomite, calcite and quartz have similar proportions in GY soil. Clay minerals (kaolinite and illite) are scarce in both soils. Heating at 105 degrees C has no effect on soil mineralogy. However, heating to 205 degrees C transforms gypsum to bassanite, increases significantly the soil salinity (EC) in both soil units (LP and GY) and decreases pH only in GY soil. Despite differences in the content of organic matter and structural stability, both soils show no significant differences (P <0.01) in the splash erosion rates. The size of pores is reduced by heating, as derived from variations in soil water retention capacity.
Evaluation and Selection of Indicators for Land Degradation and Desertification Monitoring: Methodological Approach
Kosmas, C. ; Karis, O. ; Karavitis, C. ; Ritsema, C.J. ; Salvati, L. ; Acikalin, S. ; Alcala, S. ; Alfama, P. ; Atlhopheng, J. ; Barrera, J. ; Belgacem, A. ; Sole-Benet, A. ; Brito, J. ; Chaker, M. ; Chanda, R. ; Coelho, C. ; Darkoh, M. ; Diamantis, I. ; Ermolaeva, O. ; Fassouli, V. ; Fei, W. ; Fernandez, F. ; Ferreira, A. ; Gokceoglu, C. ; Gonzalez, D. ; Gungor, H. ; Hessel, R. ; Juying, J. ; Khatteli, H. ; Kounalaki, A. ; Laouina, A. ; Lollino, P. ; Lopes, M. ; Magole, L. ; Medina, L. ; Mendoza, M. ; Morais, P. ; Mulale, K. ; Ocakoglu, F. ; Ouessar, M. ; Ovalle, C. ; Perez, C. ; Perkins, J. ; Pliakas, F. ; Polemio, M. ; Pozo, A. ; Prat, C. ; Qinke, Y. ; Ramos, A. ; Riquelme, J. ; Romanenkov, V. ; Rui, L. ; Santaloia, F. ; Sebego, R. ; Sghaier, M. ; Silva, N. ; Sizemskaya, M. ; Soares, J. ; Sonmez, H. ; Taamallah, H. ; Tezcan, L. ; Torri, D. ; Ungaro, F. ; Valente, S. ; Vente, J. de; Zagal, E. ; Zeiliguer, A. ; Zhonging, W. ; Ziogas, A. - \ 2014
Environmental Management 54 (2014)5. - ISSN 0364-152X - p. 951 - 970.
mediterranean conditions - aggregate stability - soil properties - rock fragments - organic-matter - vegetation - tillage - biomass - erosion - greece
An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.
Effects of wildfire on soil nutrients in Mediterranean ecosystem
Caon, L. ; Vallejo, V.R. ; Ritsema, C.J. ; Geissen, V. - \ 2014
Earth-Science Reviews 139 (2014). - ISSN 0012-8252 - p. 47 - 58.
geiger climate classification - central semiarid argentina - mixed-conifer forest - organic-matter - pine forest - water repellency - prescribed fire - aggregate stability - postfire regeneration - shrubland wildfires
High-intensity and fast-spreading wildfires are natural in the Mediterranean basin. However, since 1960, wildfire occurrence has increased because of changes in land use, which resulted in extensive land abandonment, increases in the fuel load and continuity in the landscape. The level of soil degradation related to wildfire occurrence depends on fire recurrence, topography of the site, intensity of the soil erosion processes and plant cover post-fire regeneration rate. Therefore assessing fire impacts on soil properties is critical to quantify land degradation processes and to assess post-fire restoration plans. This article reviews the changes in soil nutrient status of Mediterranean ecosystems affected by wildfires by focusing on the interactions between the different drivers and factors, and the underlying processes of these changes. Articles dealing with wildfires in areas belonging to the Mediterranean basin and characterized by an annual average rainfall of 300–900 mm and a mean annual temperature around 14–19 °C, have been reviewed. The data show that the soil nutrient content in Mediterranean drylands affected by wildfires depends on the vegetation type, fire recurrence and fire intensity. Immediately after a fire, the nutrient content in both the O and A horizons often increases because of ash deposition, nutrient release from the burnt vegetation and formation of stable nutrient forms. Ash deposition persistence on the soil surface is one of the most important factors in determining the soil nutrient content both immediately after a fire and for the long-term. For the restoration of burned habitats it is important to know the content and the spatial distribution of nutrients in the soil because this can act as a limiting factor to vegetation recovery. Carbon and nitrogen pools in the soil have been recognized as fundamental to vegetation recuperation after a fire. To promote the accumulation and retention of nutrients in soil after a fire, it is important to stabilize the burnt site by applying post-fire measures that limit soil erosion, surface runoff and wind loss of the ash. Depending on the plant species and the time elapsing between consecutive wildfires, fire is responsible for the transition from mature ecosystems (i.e. conifer forests) to shrublands, which are poorer in soil nutrient status. Wildfire occurrence can be reduced by planting fire-resilient plants in fire-prone areas. To define the best post-fire and restoration treatments, the impacts of fire on both the O and the A horizon as well as the impacts of different post-fire treatments on the soil nutrient content require further study.
Use of olive mill wastewater (OMW) to decrease hydrophobicity in sandy soil
Diamantis, V. ; Pagorogon, L. ; Gazani, E. ; Doerr, S.H. ; Pliakas, F. ; Ritsema, C.J. - \ 2013
Ecological Engineering 58 (2013). - ISSN 0925-8574 - p. 393 - 398.
biosurfactant production - microbial surfactants - aggregate stability - repellency - wastewaters - amelioration - degradation
This study explores the potential effectiveness of olive mill wastewater (OMW) as an alternative to industrial surfactants in decreasing hydrophobicity in sandy soil. The OMW was obtained from a storage lagoon and characterized by high concentrations of short-chain fatty acids, mainly butyric, propionic and acetic, which contributed approximately to 1/3 of the wastewater organic load. It was applied diluted with freshwater (1:1) in an agricultural field in Greece affected by water repellency at a rate of 4 L/m2. OMW was found to be effective in decreasing soil water repellency, which suggests the potential of OMW to be used as a natural surfactant. The decrease in hydrophobicity was attributed to the fatty-acid related surface-active properties, enabling rapid penetration of OMW into the soil matrix, and the consequent enhancement of soil microbial activity that enables degradation of soil hydrophobic compounds.
Land-Use and Land-Management Change: Relationships with Earthworm and Fungi Communities and Soil Structural Properties
Spurgeon, D.J. ; Keith, A.M. ; Schmidt, O. ; Lammertsma, D.R. ; Faber, J.H. - \ 2013
BMC Ecology 13 (2013). - ISSN 1472-6785 - 13 p.
arbuscular mycorrhizal fungi - ectomycorrhizal fungi - aggregate stability - ecosystem services - organic-matter - common garden - no-till - biodiversity - europe - invertebrates
Background Change in land use and management can impact massively on soil ecosystems. Ecosystem engineers and other functional biodiversity in soils can be influenced directly by such change and this in turn can affect key soil functions. Here, we employ meta-analysis to provide a quantitative assessment of the effects of changes in land use and land management across a range of successional/extensification transitions (conventional arable¿¿¿no or reduced tillage¿¿¿grassland¿¿¿wooded land) on community metrics for two functionally important soil taxa, earthworms and fungi. An analysis of the relationships between community change and soil structural properties was also included. Results Meta-analysis highlighted a consistent trend of increased earthworm and fungal community abundances and complexity following transitions to lower intensity and later successional land uses. The greatest changes were seen for early stage transitions, such as introduction of reduced tillage regimes and conversion to grassland from arable land. Not all changes, however, result in positive effects on the assessed community metrics. For example, whether woodland conversion positively or negatively affects community size and complexity depends on woodland type and, potentially, the changes in soil properties, such as pH, that may occur during conversion. Alterations in soil communities tended to facilitate subsequent changes in soil structure and hydrology. For example, increasing earthworm abundances and functional group composition were shown to be positively correlated with water infiltration rate (dependent on tillage regime and habitat characteristics); while positive changes in fungal biomass measures were positively associated with soil microaggregate stability. Conclusions These findings raise the potential to manage landscapes to increase ecosystem service provision from soil biota in relation to regulation of soil structure and water flow. Keywords: Meta analysis; Earthworm; Fungi; Functional biodiversity; Soil porosity; Microaggregate stability
Hierarchical saturation of soil carbon pools near a natural CO2 spring
Kool, D.M. ; Chung, H. ; Tate, K.R. ; Ross, D.J. ; Newton, P.C.D. ; Six, J. - \ 2007
Global Change Biology 13 (2007)6. - ISSN 1354-1013 - p. 1282 - 1293.
elevated atmospheric co2 - long-term exposure - organic-matter - nitrogen limitation - no-tillage - aggregate stability - agricultural soils - grassland - dioxide - sequestration
Soil has been identified as a possible carbon (C) sink to mitigate increasing atmospheric CO2 concentration. However, several recent studies have suggested that the potential of soil to sequester C is limited and that soil may become saturated with C under increasing CO2 levels. To test this concept of soil C saturation, we studied a gley and organic soil at a grassland site near a natural CO2 spring. Total and aggregate-associated soil organic C (SOC) concentration showed a significant increase with atmospheric CO2 concentration. An asymptotic function showed a better fit of SOC and aggregation with CO2 level than a linear model. There was a shift in allocation of total C from smaller size fractions to the largest aggregate fraction with increasing CO2 concentration. Litter inputs appeared to be positively related to CO2 concentration. Based on modeled function parameters and the observed shift in the allocation of the soil C from small to large aggregate-size classes, we postulate that there is a hierarchy in C saturation across different SOC pools. We conclude that the asymptotic response of SOC concentration at higher CO2 levels indicates saturation of soil C pools, likely because of a limit to physical protection of SOC.
Mycorrhizas and tropical soil fertility
Cardoso, I.M. ; Kuyper, T.W. - \ 2006
Agriculture, Ecosystems and Environment 116 (2006)1-2. - ISSN 0167-8809 - p. 72 - 84.
vesicular-arbuscular mycorrhiza - guinea savanna zone - low p soil - farmers fields - glomus-intraradices - aggregate stability - west-africa - calliandra-calothyrsus - agricultural practices - phosphatase-activity
Major factors that constrain tropical soil fertility and sustainable agriculture are low nutrient capital, moisture stress, erosion, high P fixation, high acidity with aluminium toxicity, and low soil biodiversity. The fragility of many tropical soils limits food production in annual cropping systems. Because some tropical soils under natural conditions have high biological activity, an increased use of the biological potential of these soils to counter the challenges of food production problems is proposed. Most plant species (including the major crops in the tropics) form beneficial associations with arbuscular mycorrhizal (AM) fungi. These fungi could be the most important and poorly understood resource for nutrient acquisition and plant growth in agriculture. This review treats the role of AM fungi in enhancing physical, chemical, and biological soil quality. It focuses on the roles of AM in maintenance and improvement of soil structure, the uptake of relatively immobile elements, both macronutrients (phosphorus) and micronutrients (zinc), the alleviation of aluminium and manganese toxicity, the interactions with other beneficial soil organisms (nitrogen-fixing rhizobia), and improved protection against pathogens. Mycorrhizal associations enable a better use of sparingly soluble phosphorus pools, thereby increasing the efficiency of added phosphorus fertilizer and of the large relatively immobile phosphorus pools. Mycorrhizal management through agroforestry, reduced soil disturbance or crop rotation, is often a better option than mycorrhizal inoculation, considering the problems and costs of large-scale inoculum production. Research directions that are needed to increase understanding of mycorrhizal associations in tropical cropping systems and to increase mycorrhizal benefit are indicated.
Effect of soil crusting on the emission and transport of wind-eroded sediment: field measurements on loamy sandy soil
Goossens, D. - \ 2004
Geomorphology 58 (2004)4. - ISSN 0169-555X - p. 145 - 160.
mineral aerosol production - crushing-energy meter - saltating particles - desert soils - aggregate stability - dust accumulation - erosion - surfaces - abrasion - tunnel
Abstract Field data are reported for the horizontal and vertical flux of wind-eroded sediment on an agricultural field in northern Germany. Measurements were made during a windstorm that hit the region on 18 May 1999. The magnitude of both fluxes was significantly affected by the presence of a surface crust covering the test field. Measuring the physical crust strength at 45 locations with a torvane, the relationships between crust strength () and the horizontal (Fh) and vertical (Fv) sediment fluxes were investigated. Both fluxes decreased as the surface crust became stronger. The decay behaved as an exponential function for both types of flux. The horizontal sediment flux over a crusted surface can be accurately predicted by completing Marticorena and Bergametti's [Journal of Geophysical Research 100 (1995) 16415] erosion model with a crust function. The vertical particle flux over crusted soil can be calculated by adding a similar function to Alfaro and Gomes's [Journal of Geophysical Research 106D (2001) 18075] dust production model. The study also suggests that the gradual bombardment of a surface crust by impacting particles does not immediately result in a decay of the crust's protective effect, provided that the crust has a minimum thickness. However, once the crust becomes perforated, its protective effect disappears very quickly, leading to much higher horizontal and vertical sediment fluxes than predicted for undamaged crusted soil.
Soil structure and characteristics of organic matter in two orchards differing in eartworm activity
Jongmans, A.G. ; Pulleman, M.M. ; Balabane, M. ; Oort, F. van; Marinissen, J.C.Y. - \ 2003
Applied Soil Ecology 24 (2003)6. - ISSN 0929-1393 - p. 219 - 232.
grain-size determination - aggregate stability - dynamics - megascolecidae - oligochaeta - management - carbon - metals - casts - loam
By consuming plant remains and soil, earthworms incorporate organic matter (OM) into the soil and form biogenic soil structures, which can affect OM dynamics. We carried out a (micro)morphological study of soil structure development and OM distribution in two orchards (45 year) in a Dutch calcareous marine loam: RI- without, and KR+ with high earthworm activity, the result of different levels of heavy metal contamination from fungicides. In both soils, sedimentary–stratification was absent to 60 cm depth and equal amounts of biogenic calcite spheroids were counted, suggesting similar earthworm activity in the past. In RI- the current vol.% of worm-worked groundmass in thin sections was 6% in the Ah and 7% in the Bw horizon compared with 51% in the Ah and 16% in the Bw horizon of KR+. Disappearance of earthworms with time in RI- gave rise to a compacted physicogenic soil structure with angular and prismatic aggregates and the absence of earthworm biopores. Due to restricted fragmentation and incorporation of OM fragments in casts, a litter layer formed at the soil surface. OM coatings were present in fissures and root pores of the Ah horizon, indicating the absence of mixing of organic and mineral soil materials. OM fragments were relatively coarse (>50 µm) and heterogeneously distributed through the Ah groundmass. Stronger decalcification in RI- than in KR+ could be ascribed to higher production of organic acids in the litter layer of RI- and the absence of soil homogenisation by earthworms. In KR+ earthworm activity was high, which has resulted in a biogenic structure with granular and subangular blocky aggregates and many worm casts and biopores. Particulate OM was relatively fine (