Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Cotton as an entry point for soil fertility maintenance and food crop productivity in savannah agroecosystems - Evidence from a long-term experiment in southern Mali
Ripoche, A. ; Crétenet, M. ; Corbeels, M. ; Affholder, F. ; Naudin, K. ; Sissoko, F. ; Douzet, J.M. ; Tittonell, P.A. - \ 2015
Field Crops Research 177 (2015). - ISSN 0378-4290 - p. 37 - 48.
organic-matter - nitrogen-fertilization - chemical-properties - nutrient dynamics - semiarid tropics - use efficiency - pearl-millet - burkina-faso - dry-matter - management
Given the scarcity of manure and the limited land available for fallowing, cotton cultivation with its input credit schemes is often the main entry point for nutrients in cropping systems of West Africa. In an experiment carried out during 25 years in southern Mali, the crop and soil responses to organic fertilizer (=OF), inorganic fertilizer (=IF), and a combination of both (=OIF) were quantified and compared to a control treatment for a typical cotton-sorghum-groundnut rotation. From 1965 to 1979 (15 years, period 1), fertilizers were only applied on cotton and the control treatment was not fertilized. From 1980 to 1989 (10 years, period 2), the amount of manure applied was split between cotton and sorghum, and inorganic fertilizers were applied to the three crops. Inorganic fertilizers were also applied to plots with cotton and sorghum that were previously unfertilized control treatments. In favorable rainfall seasons maximum yields of fertilized treatments reached ca. 3.5 t ha-1 in the case of cotton and groundnuts, and ca. 2 t ha-1 in the case of sorghum. During period 1, cotton yields were steady (ca. 1 t ha-1) when no fertilizers were added. Cotton yields were 20% higher in the OF and OIF treatments than in the IF treatment. Sorghum and groundnut benefited from residual effects of fertilizer application on cotton leading to a 200% and 50% yield increase respectively compared to the control treatment. During period 2, yields of the three crops were similar across fertilized treatments. Groundnut yields in the OF treatment, and cotton yields in the OF and IF treatments were respectively 45%, 30% and 20% significantly higher than those in the respective control treatments. No added benefit on crop yields was observed from the combined use of inorganic and organic fertilizer. Soil nutrient contents (SOC, N, P, K) did not significantly change in any of the treatments after 25 years. Soil pH decreased in treatments receiving inorganic fertilizer. Despite low level of soil organic matter, crops responded to organic or inorganic fertilization and crop productivity over time was mostly influenced by the interaction between fertilization and rainfall variability. Our results highlight the role of cotton in West African landscapes as an entry point of nutrients via fertilization, which impacts positively on the productivity of the other crops in the rotation. Credit schemes by the cotton company for farmers to purchase fertilizer to which they would otherwise not have access are thus crucial for sustained crop productivity.
Soil carbon storage and stratification under different tillage/residue-management practices in double rice cropping system
Chen, Z. ; Zhang, H. ; dikgwatlhe, S.B. ; Xue, J. ; Qiu, K. ; Tang, H. ; Chen, F. - \ 2015
Journal of Integrative Agriculture 14 (2015)8. - ISSN 2095-3119 - p. 1551 - 1560.
no-tillage - organic-matter - conservation tillage - climate-change - sequestration - impacts - agriculture - phosphorus - nitrogen
The importance of soil organic carbon (SOC) sequestration in agricultural soils as climate-change-mitigating strategy has become an area of focus by the scientific community in relation to soil management. This study was conducted to determine the temporal effect of different tillage systems and residue management on distribution, storage and stratification of SOC, and the yield of rice under double rice (Oryza sativa L.) cropping system in the southern China. A tillage experiment was conducted in the southern China during 2005-2011, including plow tillage with residue removed (PT0), plow tillage with residue retention (PT), rotary tillage with residue retention (RT), and no-till with residue retention on the surface (NT). The soil samples were obtained at the harvesting of late rice in October of 2005, 2007 and 2011. Multiple-year residue return application significantly increased rice yields for the two rice-cropping systems; yields of early and late rice were higher under RT than those under other tillage systems in both years in 2011. Compared with PT0, SOC stocks were increased in soil under NT at 0-5, 5-10, 10-20, and 20-30 cm depths by 33.8, 4.1, 6.6, and 53.3%, respectively, in 2011. SOC stocks under RT were higher than these under other tillage treatments at 0-30 cm depth. SOC stocks in soil under PT were higher than those under PT0 in the 0-5 and 20-30 cm soil layers. Therefore, crop residues played an important role in SOC management, and improvement of soil quality. In the 0-20 cm layer, the stratification ratio (SR) of SOC followed the order NT>RT>PT>PT0; when the 0-30 cm layer was considered, NT also had the highest SR of SOC, but the SR of SOC under PT was higher than that under RT with a multiple-year tillage practice. Therefore, the notion that conservation tillage lead to higher SOC stocks and soil quality than plowed systems requires cautious scrutiny. Nevertheless, some benefits associated with RT system present a greater potential for its adoption in view of the multiple-year environmental sustainability under double rice cropping system in the southern China.
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.
Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensivity distribution
Foekema, E.M. ; Kaag, N.H.B.M. ; Kramer, K.J.M. ; Long, K. - \ 2015
Science of the Total Environment 521-522 (2015). - ISSN 0048-9697 - p. 173 - 182.
principal response curves - organic-matter - toxicity - water - carbon - speciation - exposure - ph
The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6 m3 mesocosms. Five treatment levels, ranging from 2.9 to 31 µg dissolved Cu/L, were created in triplicate and maintained for 82 days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9 µg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7 µg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD.
Assessing the potential of biochar and charcoal to improve soil hydraulic properties in the humid Ethiopian Highlands: The Anjeni watershed
Bayabil, H.K. ; Stoof, C.R. ; Lehmann, J.C. ; Yitaferu, B. ; Steenhuis, T.S. - \ 2015
Geoderma 243-244 (2015). - ISSN 0016-7061 - p. 115 - 123.
central rift-valley - organic-matter - physical-properties - land management - nile basin - agronomic performance - chemical-properties - climate-change - maize yield - retention
Biochar has shown promise for restoring soil hydraulic properties. However, biochar production could be expensive in the developing world, while charcoal iswidely available and cheap. The objective of this study is therefore to investigate whether some of the charcoal made in developing countries can also be beneficial for improving soil hydraulic properties, and explore whether charcoal could potentially restore the degraded African soils. Laboratory and field experiments were conducted in the Anjeni watershed in the Ethiopian highlands, to measure soil physical properties including soil moisture retention and infiltration rates. Soils were dominantly clayey with pH in the acidic range, low organic carbon content, and steady infiltration rates ranging between 2 and 36 mm/h. Incorporation of woody feedstock (Acacia, Croton, and Eucalyptus) charcoals significantly decreased moisture retention at lower tensions (10 and 30 kPa), resulting in an increase in relative hydraulic conductivity coefficients at these tensions. While wood (oak) biochar decreased moisture retention at low tensions, corn biochar increased retention, but effects were only slight and not significant. Surprisingly, available water content was not significantly affected by any of the amendments. Overall findings suggest that wood charcoal amendments can improve soil hydraulic properties of degraded soils, thereby potentially reducing runoff and erosion.
Influence of source vegetation and redox conditions on lignin-based decomposition proxies in graminoid-dominated ombrotrophic peat (Penido Vello, NW Spain)
Schellekens, J. ; Buurman, P. ; Kuyper, T.W. ; Abbott, G.D. ; Pontevedra-Pombal, X. ; Martinez-Cortizas, A. - \ 2015
Geoderma 237-238 (2015). - ISSN 0016-7061 - p. 270 - 282.
chromatography-mass-spectrometry - cuo-oxidation-products - brown-rot fungi - pyrolysis-gc/ms - wall degradability - calluna-vulgaris - organic-matter - phenolic-acids - plant-tissues - cell-walls
Most knowledge about the degradation of lignocellulose in natural environments is based on woody tissue and aerobic systems; however, in peatlands the contribution of graminoids to organic matter (OM) is often significant and anaerobic conditions prevail. In order to reconstruct past environmental conditions from peatlands and predict possible feedback mechanism between peatlands and climate change, a better understanding of the decomposition of graminoid tissue and the effects of anaerobic conditions on decomposition are needed. Samples (51) from the upper 1 m of the graminoid-dominated Penido Vello peatland (Xistral Mountains, Galicia, NW Spain) were analysed with pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and 13C cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy (13C CPMAS NMR). Carbon and nitrogen contents were also determined. Depth profiles of molecular groups identified using 13C CPMAS NMR were consistent with those of depth-related distributions of quantified pyrolysis products (aliphatics, polysaccharides and aromatics). Molecular proxies were selected from peat pyrolysates to reflect the state of decay of 1) lignocellulose (the summed lignin and polysaccharide pyrolysis products, Lg and Ps, respectively), 2) lignified cellulose (levoglucosan/Ps) and hemicellulose (4-hydroxy-5,6-dihydro-(2H)-pyran-2-one/Ps), 3) macromolecular lignin including syringyl (S), guaiacyl (G) and p-hydroxyphenyl (H) ratios (S/G; H/(S + G), and side chain oxidation and shortening (vanillic acid/G, syringic acid/S, 4-acetylguaiacol/G, 4-acetylsyringol/S, C3-guaicols/G and C3-syringols/S) and 4) non-lignin phenolic acids (4-vinylphenol/H, 4-vinylguaiacol/G). Factor analysis was applied to these proxies and 120 quantified pyrolysis products to examine the influence of possible underlying factors that could explain the observed variation. Botanical changes and several degradation stages including surface decay (both aerobic and anaerobic), aerobic sub-surface decay and depth related decay (long-term anaerobic) were identified with factor analysis and all affected the variance of lignin-based decomposition proxies. The net effect of these environmental factors on the lignin proxies was examined using their depth records. This revealed that some lignin decomposition proxies were not in agreement with the literature: 1) G and S moieties with a C3 alkyl side chain showed no correlation with bog hydrology at the time of peat formation; 2) G and S moieties with acetyl side chains were related to both relatively dry (secondary aerobic decay) and wet (first stage of decay) conditions; 3) vanillic acid and syringic acid were related partly to ericoids (indicating dry conditions) and partly to free phenolic acids (less depleted under wet conditions); and 4) preferential decay of G over S moieties was found during the first stage of decay (both aerobic and anaerobic) and long-term anaerobic decay. These contradictions can be explained by the dominance of non-woody lignin sources (graminoids) and the prominence of anaerobic decay in peatlands. Our findings indicate that the effect of anaerobic decay and source vegetation should be considered when using lignin proxies to deduce aerobic decay in peat records.
Use of the nitrification inhibitor dicyandiamide (DCD) does not mitigate N2O emission from bovine urine patches under Oxisol in Northwest Brasil
Mazzetto, A.M. ; Barneze, A.S. ; Feigl, B.J. ; Groenigen, J.W. van; Oenema, O. ; Klein, C.A.M. de; Cerri, C.C. - \ 2015
Nutrient Cycling in Agroecosystems 101 (2015)1. - ISSN 1385-1314 - p. 83 - 92.
nitrous-oxide emissions - greenhouse-gas emissions - grazed pasture system - pastoral soils - tropical conditions - microbial biomass - methane emission - grazing animals - organic-matter - temperature
Animal production systems are important sources of greenhouse gases (GHGs), especially methane (CH4) and nitrous oxide (N2O). GHG emissions from urine patches have been extensively studied in temperate climates, with few studies under tropical conditions. Here we examined the driving factors of N2O and CH4 emission from urine patches in the tropics, as well as the role of the nitrification inhibitor DCD (dicyandiamide) in mitigating emissions. We hypothesized that the high temperature and periodical rainfall can increase GHG emissions from urine patches through accelerating mineralization of urine-N. We measured CH4 and N2O emissions from beef cattle urine (360 kg N ha-1) in Rondônia state (Brazil, tropical climate), during two different seasons (winter and summer), with and without the application of DCD (10 kg ha-1). No effects of DCD on cumulative N2O emissions were detected in summer, but DCD retarded the main emission peak. During winter DCD increased N2O emissions from 10.8 to 39.2 mg N–N2O m-2 (p = 0.05). Emission factors averaged 0.4 % for summer and 0.1 % for winter, which is significantly lower than the IPCC default value of 1 %. The climate, associated with soil (acidic pH, WFPS and low N content) and plant properties (biological nitrification inhibition) resulted in a low emission factor. We concluded that the IPCC default emission factor for tropical systems may be reduced, and that the application of DCD is not recommended in such systems.
Intercropping enhances soil carbon and nitrogen
Cong, W. ; Hoffland, E. ; Li, L. ; Six, J. ; Sun, J.H. ; Bao, X.G. ; Zhang, F.S. ; Werf, W. van der - \ 2015
Global Change Biology 21 (2015)4. - ISSN 1354-1013 - p. 1715 - 1726.
organic-matter - crop-rotation - ecosystem processes - root distribution - northwest china - food security - nutrient-use - diversity - biodiversity - sequestration
Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4% +- 1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 184 +- 86 kg C ha-1 yr-1. Soil organic N content in the top 20 cm was 11% +- 1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 45 +- 10 kg N ha-1 yr-1. Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil d15N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration.
Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots
Peuke, A.D. ; Gessler, A. ; Trumbore, S. ; Windt, C.W. ; Homan, N. ; Gerkema, E. ; As, H. van - \ 2015
Plant, Cell & Environment 38 (2015)3. - ISSN 0140-7791 - p. 433 - 447.
carbon-isotope composition - mushrooms agaricus-bisporus - distance water transport - organic-matter - membrane-permeability - assimilate transport - plants - leaves - starch - stress
Anoxic conditions should hamper the transport of sugar in the phloem, as this is an active process. The canopy is a carbohydrate source and the roots are carbohydrate sinks.By fumigating the shoot with N2 or flooding the rhizosphere, anoxic conditions in the source or sink, respectively, were induced. Volume flow, velocity, conducting area and stationary water of the phloem were assessed by non-invasive magnetic resonance imaging (MRI) flowmetry. Carbohydrates and d13C in leaves, roots and phloem saps were determined. Following flooding, volume flow and conducting area of the phloem declined and sugar concentrations in leaves and in phloem saps slightly increased. Oligosaccharides appeared in phloem saps and after 3 d, carbon transport was reduced to 77%. Additionally, the xylem flow declined and showed finally no daily rhythm. Anoxia of the shoot resulted within minutes in a reduction of volume flow, conductive area and sucrose in the phloem sap decreased. Sugar transport dropped to below 40% by the end of the N2 treatment. However, volume flow and phloem sap sugar tended to recover during the N2 treatment. Both anoxia treatments hampered sugar transport. The flow velocity remained about constant, although phloem sap sugar concentration changed during treatments. Apparently, stored starch was remobilized under anoxia.
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.
Pro-glacial soil variability and geomorphic activity - the case of three Swiss valleys
Temme, A.J.A.M. ; Lange, K. de - \ 2014
Earth Surface Processes and Landforms 39 (2014)11. - ISSN 0197-9337 - p. 1492 - 1499.
proglacial area morteratsch - melting glaciers - organic-matter - damma glacier - front range - switzerland - forefield - evolution - alps - landscape
Soils in pro-glacial areas are often approached from a chronosequence viewpoint. In the chronosequence approach, the objective is to derive rates of soil formation from differences in properties between soils of different age. For this reason, in chronosequence studies, soils are sampled in locations that are assumed geomorphically stable and that have different age. As a result, these studies do not necessarily yield a complete view of soil variability in pro-glacial areas, and may miss important relations between geomorphology and soil development. In this contribution, we present new soil observations from three closely related pro-glacial areas in Switzerland. These observations were intended to get closer to a complete view of soil variability, and to assess impacts from factors other than time on soil development. About 40 soils were visited in each pro-glacial valley in a combined design-convenience sampling scheme and described in the field. Linear modelling was used to assess effects of time and topographic factors on soil properties. The time since glacial retreat turned out to rarely explain more than half of the variation in soil properties, and a linear model combining effects of time and topographic variables explained typically about half of the variation in each pro-glacial valley. Models differed and were not transferable between valleys. Apparently, time and the present-day shape of the landscape combined are insufficient information to accurately predict soil properties. Field evidence points to the importance of the geomorphic history and regime of the valleys as a reason for this. Copyright (C) 2014 John Wiley & Sons, Ltd.
Salt stress in a membrane bioreactor: Dynamics of sludge properties, membrane fouling and remediation through powdered activated carbon dosing
Temmerman, L. De; Maere, T. ; Temmink, H. ; Zwijnenburg, A. ; Nopens, I. - \ 2014
Water Research 63 (2014). - ISSN 0043-1354 - p. 112 - 124.
waste-water treatment - organic-matter - energy-consumption - high salinity - mbr - filterability - ultrafiltration - flocculation - temperature - mechanisms
Membrane bioreactors are a well-established technology for wastewater treatment. However, their efficiency is adversely impacted by membrane fouling, primarily inciting very conservative operations of installations that makes them less appealing from an economic perspective. This fouling propensity of the activated sludge is closely related to system disturbances. Therefore, improved insight into the impact of fouling is crucial towards increased membrane performance. In this work, the disturbance of a salt shock was investigated with respect to sludge composition and filterability in two parallel lab-scale membrane bioreactors. Several key sludge parameters (soluble microbial products, sludge-bound extracellular polymeric substances, supramicron particle size distributions (PSD), submicron particle concentrations) were intensively monitored prior to, during, and after a disturbance to investigate its impact as well as the potential governing mechanism. Upon salt addition, the supramicron PSD immediately shifted to smaller floc sizes, and the total fouling rate increased. Following a certain delay, an increase in submicron particles, supernatant proteins, and polysaccharides was observed as well as an increase in the irreversible membrane fouling rate. Recovery from the disturbance was evidenced with a simultaneous decrease in the above mentioned quantities. A similar experiment introducing powdered activated carbon (PAC) addition used for remediation resulted in either no or less significant changes in the above mentioned quantities, signifying its potential as a mitigation strategy. (C) 2014 Elsevier Ltd. All rights reserved.
Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon
Broadbent, E.N. ; Zambrano, A.M.A. ; Asner, G.P. ; Soriano, M. ; Field, C.B. ; Souza, H.R. de; Pena Claros, M. ; Adams, R.I. ; Dirzo, R. ; Giles, L. - \ 2014
PLoS One 9 (2014)2. - ISSN 1932-6203 - 23 p.
carbon-isotope discrimination - tropical rain-forests - n-15 natural-abundance - northeastern costa-rica - below-ground carbon - land-use change - n-p ratios - secondary forest - organic-matter - brazilian amazon
Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar d13C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil d13C dynamics were largely constrained by plant species composition. Foliar d15N had a significant negative correlation with both stand age and species successional status, – most likely resulting from a large initial biomass-burning enrichment in soil 15N and 13C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession.
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.
Performance assessment of nitrate leaching models for highly vulnerable soils used in low-input farming based on lysimeter data
Groenendijk, P. ; Heinen, M. ; Klammler, G. ; Fank, J. ; Kupfersberger, H. ; Pisinaras, V. - \ 2014
Science of the Total Environment 499 (2014). - ISSN 0048-9697 - p. 463 - 480.
long-term experiments - hydraulic-properties - hydrological models - standardized assessment - nitrogen dynamics - simulation-models - organic-matter - porous-media - drain flow - water
The agricultural sector faces the challenge of ensuring food security without an excessive burden on the environment. Simulation models provide excellent instruments for researchers to gain more insight into relevant processes and best agricultural practices and provide tools for planners for decision making support. The extent to which models are capable of reliable extrapolation and prediction is important for exploring new farming systems or assessing the impacts of future land and climate changes. A performance assessment was conducted by testing six detailed state-of-the-art models for simulation of nitrate leaching (ARMOSA, COUPMODEL, DAISY, EPIC, SIMWASER/STOTRASIM, SWAP/ANIMO) for lysimeter data of the Wagna experimental field station in Eastern Austria, where the soil is highly vulnerable to nitrate leaching. Three consecutive phases were distinguished to gain insight in the predictive power of the models: 1) a blind test for 2005–2008 in which only soil hydraulic characteristics, meteorological data and information about the agricultural management were accessible; 2) a calibration for the same period in which essential information on field observations was additionally available to the modellers; and 3) a validation for 2009–2011 with the corresponding type of data available as for the blind test. A set of statistical metrics (mean absolute error, root mean squared error, index of agreement, model efficiency, root relative squared error, Pearson's linear correlation coefficient) was applied for testing the results and comparing the models. None of the models performed good for all of the statistical metrics. Models designed for nitrate leaching in high-input farming systems had difficulties in accurately predicting leaching in low-input farming systems that are strongly influenced by the retention of nitrogen in catch crops and nitrogen fixation by legumes. An accurate calibration does not guarantee a good predictive power of the model. Nevertheless all models were able to identify years and crops with high- and low-leaching rates.
Labilities of aqueous nanoparticulate metal complexes in environmental speciation analysis
Town, R.M. ; Leeuwen, H.P. van - \ 2014
Environmental Chemistry 11 (2014)2. - ISSN 1448-2517 - p. 196 - 205.
ombrotrophic peat bog - humic-acid - fulvic-acid - stripping chronopotentiometry - ionic-strength - dissociation kinetics - diffusive gradients - dynamic speciation - solvent exchange - organic-matter
An inherent property of a dispersion of charged nanoparticles is that their charges and reactive sites are spatially confined to the particle body which is at a different potential from that in the bulk medium. This feature has important consequences for the reactivity of nanoparticulate complexants: the diffusive rate of reactant supply is lower as compared to molecular complexants, whereas the local concentration of reactant ions may be enhanced if the particle’s electric field has the opposite charge sign. These effects are most dramatic for soft nanoparticles for which the electrostatic accumulation mechanisms operate on a 3-D level. We show how the interplay of these effects governs the reactivity of charged nanoparticulate metal complexes (M-NPs) at the surface of an analytical speciation sensor. A theoretical framework is presented that describes the lability of M-NP species over a range of effective timescales for different electrochemical and other dynamic speciation analysis techniques. The concepts are illustrated by electrochemical stripping data on metal complexes with natural soft nanoparticles of humic acid.
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.
Do earthworms affect phosphorus availability to grass? A pot experiment.
Vos, M.J. ; Ros, M.B.H. ; Koopmans, G.F. ; Groenigen, J.W. van - \ 2014
Soil Biology and Biochemistry 79 (2014). - ISSN 0038-0717 - p. 34 - 42.
pontoscolex-corethrurus glossoscolecidae - organic-matter - phosphate adsorption - colloidal phosphorus - lumbricus-terrestris - geophagous earthworm - soil-phosphorus - tropical soil - plant-growth - casts
The largest part of phosphorus (P) in soil is bound by the soil solid phase; its release to the soil solution therefore often does not meet the demand of plants. Since global P fertilizer reserves are declining, it becomes increasingly important to better utilize soil P. We tested whether earthworm activity can increase P availability to grass (Lolium perenne L.) in a 75-day greenhouse pot experiment in a soil with low P availability. The full factorial design included two factors: P fertilization (control without P; phytate; and inorganic P) and earthworm population (control without earthworms; Lumbricus rubellus Hoffmeister, Lr; Aporrectodea caliginosa Savigny, Ac; and Lumbricus terrestris L., Lt). At four times during the experiment, aboveground plant growth and P uptake were determined. In a separate incubation experiment, earthworm casts and bulk soil were analyzed for inorganic and organic P in water extracts. We observed higher levels of dissolved P pools (p <0.001) in the water extracts of earthworm casts compared to those of the bulk soil. The magnitude of the difference differed between earthworm species, with the largest levels for Lr: from
Production-ecological modelling explains the difference between potential soil N mineralisation and actual herbage N uptake
Rashid, M.I. ; Goede, R.G.M. de; Brussaard, L. ; Bloem, J. ; Lantinga, E.A. - \ 2014
Applied Soil Ecology 84 (2014). - ISSN 0929-1393 - p. 83 - 92.
winter-wheat fields - nitrogen mineralization - organic-matter - food webs - grassland soils - forest soils - community - manure - earthworms - management
We studied two different grassland fertiliser management regimes on sand and peat soils: above-ground application of a combination of organic N-rich slurry manure and solid cattle manure (SCM) vs. slit-injected, mineral N-rich slurry manure, whether or not supplemented with chemical fertiliser (non-SCM). Measurements of field N mineralisation as estimated from herbage N uptake in unfertilised plots were compared with (i) potential N mineralisation as determined from a standard laboratory soil incubation, (ii) the contribution of groups of soil organisms to N mineralisation based on production-ecological model calculations, and (iii) N mineralisation calculated according to the Dutch fertilisation recommendation for grasslands. Density and biomass of soil biota (bacteria, fungi, enchytraeids, microarthropods and earthworms) as well as net plant N-uptake were higher in the SCM input grasslands compared to the non-SCM input grasslands. The currently used method in Dutch fertilisation recommendations underestimated actual soil N supply capacity by, on average, 102 kg N ha-1 (202 vs. 304 kg ha-1 = 34%). The summed production-ecological model estimate for N mineralisation by bacteria, fungi, protozoa, and enchytraeids was 87–120% of the measured potential soil N mineralisation. Adding the modelled N mineralisation by earthworms to potential soil N mineralisation explained 98–107% of the measured herbage N uptake from soil. For all grasslands and soil biota groups together, the model estimated 105% of the measured net herbage N uptake from soil. Soil biota production-ecological modelling is a powerful tool to understand and predict N uptake in grassland, reflecting the effects of previous manure management and soil type. The results show that combining production ecological modelling to predict N supply with existing soil N tests using aerobic incubation methods, can add to a scientifically based improvement of the N fertilisation recommendations for production grasslands.
Soil N mineralization in a dairy production system with grass and forage crops
Verloop, J. ; Hilhorst, G.J. ; Oenema, J. ; Keulen, H. van; Sebek, L.B.J. ; Ittersum, M.K. van - \ 2014
Nutrient Cycling in Agroecosystems 98 (2014)3. - ISSN 1385-1314 - p. 267 - 280.
net nitrogen mineralization - in-situ methods - organic-matter - field measurement - incubation method - pasture soils - cover crops - rates - denitrification - netherlands
This paper describes the dynamics of soil N mineralization in the experimental intensive dairy farming system ‘De Marke’ on a dry sandy soil in the Netherlands. We hypothesized that knowledge of the effects of crop rotation on soil N mineralization and of the spatial and temporal variability of soil N mineralization in a farming system can be used to better synchronize N application with crop N requirements, and hence to increase the recovery of applied N and to reduce N losses. Soil N mineralization was recorded continuously in the soil layer 0–0.30 m, from 1992 to 2005, using a sequential in situ coring technique on six observation plots, of which two were located in permanent grassland and four in crop rotations with a 3 year grassland phase and an arable phase of 3 or 5 years, dominated by maize. Average annual soil N mineralization was highest under permanent grassland: 381 kg ha-1 and lowest under =3rd years arable crops: 184 kg ha-1. In temporary grassland, soil N mineralization increased in the order: 1st year, 2nd year, 3rd year grassland and in arable crops after grassland mineralization decreased in the order: 1st year, 2nd year, =3rd years. Total mineral N input, i.e. the sum of N mineralization and mineral N supply to soil, exceeded crop N requirements in 1st year maize and was lower than the requirements in 1st year temporary grassland. N mineralization in winter, outside the growing season, was 77 kg ha-1 in maize and 60 kg ha-1 in grassland. This points at the importance of a suitable catch crop to reduce the susceptibility to N leaching. Temporal and spatial variability of soil N mineralization was high and could not be related to known field conditions. This limits the extent to which N fertilization can be adjusted to soil N mineralization. Variability increased with the magnitude of soil N mineralization. Hence, situations with high soil N mineralization may be associated with high risks for N losses and to reduce these risks a strong build-up of soil organic N should be avoided. This might be achieved, for instance, by fermenting slurry before application on farmland to enhance the fraction mineral N in slurry at the expense of organic N.
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