ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Soil phosphorus status of organic farming in Flanders: an overview and comparison with the conventional management (2005)

Bossche, A. ; Neve, S. ; Hofman, G.

Oxford, UK : Blackwell Publishing Ltd

Soil use and management 21 (2005), S. 0

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ISSN: 1475-2743

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract. A number of organic farms in Flanders were sampled to investigate the general phosphorus (P) status and degree of P saturation (Psat) of the soils. Where possible, the soil P status was compared to that in conventional agriculture and related to farm characteristics: agricultural land use, soil texture, fertilization intensity and time since conversion. Generally, the P status of the organic farms was high, and similar to that of conventional farms in Flanders, which is due to the restricted time since conversion to organic farming on most farms. The average soil Psat was slightly lower (37%) than the average value for East Flanders (39%) taken over the soil profile to 90 cm. However, a large proportion of the field areas on organic farms still had a Psat greater than 30% (critical Psat value), which may be an indication that P saturation will continue to be a problem for these farms.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1079/SUM2005355

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2

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Estimates of carbon stock changes in Belgian cropland (2003)

Sleutel, S. ; Neve, S. ; Hofman, G.

Oxford, UK : Blackwell Publishing Ltd

Soil use and management 19 (2003), S. 0

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ISSN: 1475-2743

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract. Article 3.4 of the Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere by improved management of agricultural soils. To make use of this possibility, a good estimate of soil organic carbon (SOC) stocks and baseline emissions (in 1990) are crucial factors. Over 210 000 topsoil (0–24 cm) measurements have been made in Belgian cropland in the period 1989–1999, which are available for seven different agro-pedological regions and for three periods (1989–91, 1992–95, 1996–99). We used this extensive SOC data set to estimate SOC stocks and fluxes in Belgian cropland. The measurements of SOC were extrapolated to 1 m depth using an exponential SOC depth distribution model, based on another large data set of over 5184 fully described soil profiles on Belgian cropland made during the National Soil Survey. The SOC data were combined with cropland area figures to calculate SOC stocks to 1 m depth. The 1990 baseline SOC flux of Belgian cropland was then obtained using two different calculation methods, which each yielded similar results and showed that SOC stocks were decreasing in the 1990s at a mean rate of 608 kton OC yr−1. Consequently, a large part of the Belgian cropland acted as a net source of CO2 emissions during the period 1989–1999.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1475-2743.2003.tb00299.x

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3

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Using time domain reflectometry for monitoring mineralization of nitrogen from soil organic matter (2000)

De Neve, S. ; Van de Steene, J. ; Hartmann, R. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 51 (2000), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The mineralization of nitrogen from soil organic matter is important when one tries to optimize nitrogen fertilization and assess risks of N losses to the environment, but its measurement is laborious and expensive. We have explored the possibilities for monitoring N mineralization directly using time domain reflectometry (TDR). Net N and S mineralization were monitored over a 101-day period in two layers (0–30 and 30–60 cm) of a loamy sand soil during aerobic incubation in a laboratory experiment. At the same time electrical conductivity of the bulk soil, σa, was measured by TDR. A series of calibration measurements with different amounts of KNO3 at different soil moisture contents was made with the topsoil to calculate the electrical conductivity, σw, of the soil solution from σa and θ. The actual σw was determined from the conductivity of 1:2 soil:water extracts (σ1:2) with a mass balance approach using measured NO3– concentrations, after correction for ions present prior to the addition of KNO3. The average N mineralization rate in the topsoil was small (0.12 mg N kg−1 day−1), and, as expected, very small in the subsoil (0.023 mg N kg−1 day−1). In the top layer NO3– concentrations calculated from σa determined by TDR slightly underestimated measured concentrations in the first 4 weeks, and in the second half of the incubation there was a significant overestimation of measured NO3–. Using the sum of both measured NO3– and SO42– reduced the overestimation. In the subsoil calculated NO3– concentrations strongly and consistently overestimated measured concentrations, although both followed the same trend. As S mineralization in the subsoil was very small, and initial SO42– concentrations were largely taken into account in the calibration relations, SO42– concentrations could not explain the overestimation. The very small NO3– and SO42– concentrations in the B layer, at the lower limit of the concentrations used in the calibrations, are a possible explanation for the discrepancies. A separate calibration for the subsoil could also be required to improve estimates of NO3– concentrations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2000.00306.x

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4

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The influence of model type and incubation time on the estimation of stable organic carbon in organic materials (2005)

Sleutel, S. ; De Neve, S. ; Prat Roibás, M. R. ; [et al.]

Oxford, UK; Malden, USA : Blackwell Science Ltd

European journal of soil science 56 (2005), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: There is a renewed interest in the stability and turnover of organic carbon (C) in organic materials added to soil, partly driven by concerns about global changes. We used mineralization data from laboratory incubations to determine the amount of stable organic C present. Four organic wastes were incubated with soil under controlled conditions and C mineralization was monitored, and four additional C mineralization experiments were selected from the literature. All data were rescaled to a common temperature, and we fitted five different models with biological significance to the C mineralization data, namely a first-order model (M1), a parallel first-order model (M11), a parallel first-zero-order model (M10), a second-order model (M2) and a Monod kinetic model (Monod). All models could describe the mineralization data satisfactorily. However, this does not automatically imply that the individual parameter values are realistic estimates of the underlying biological processes. All models were then fitted for progressively shorter incubation times and were used to extrapolate C mineralization to predict the amount of (measured) stable organic C. The M11 and Monod models performed best in estimating stable organic C, but they did not fit the short-term incubation data (〈 100 days) for some materials. The M2 model allowed stable organic C to be estimated within less than 3% of the true value for all materials based on an incubation time of less than 60 days. The M1 and M10 models systematically and strongly under- or overestimated stable organic C as the incubation time was shortened, and should not be used for extrapolation from short-term data.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2389.2004.00685.x

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5

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Temperature effects on N mineralization: changes in soil solution composition and determination of temperature coefficients by TDR (2003)

De Neve, S. ; Hartmann, R. ; Hofman, G.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 54 (2003), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: We studied the changes in composition of the soil solution following mineralization of N at different temperatures, with a view to using TDR to calculate temperature coefficients for the mineralization of N. Mineralization from soil organic nitrogen was measured during aerobic incubation under controlled conditions at six temperatures ranging from 5.5 to 30°C, and at constant water content in a loamy sand soil. We also monitored during the incubation the concentrations of SO42–, Cl–, HCO3–, Ca2+, K+, Mg2+ and Na+, and the pH and the electrical conductivity in 1:2 soil:water extracts. Zero-order N mineralization rates ranged between 0.164 at 5.5°C and 0.865 mg N kg−1 soil day−1 at 30°C. There was a significant decrease in soil pH during incubation, of up to 0.6 pH units at the end of the incubation at 30°C. The electrical conductivity of the soil extracts increased significantly at all temperatures (the increase between the start and the end of the incubation was 4-fold at 30°C) and was strongly correlated with N mineralization. The ratio of bivalent to monovalent cations increased markedly during mineralization (from 2.2 to 5.9 at 30°C), and this increase influenced the evolution of the electrical conductivity of the soil solution through the differences in molar-limiting ion conductivity between mainly Ca2+ and K+. Zero-order mineralization rate constants, k, for NO3– concentrations calculated from TDR varied between 0.070 (at 5.5°C) and 0.734 mg N kg−1 soil day−1 (at 30°C), which were slightly smaller, but in the same range, as the measured rates. Underestimation of the measured N mineralization rates was due, at least in part, to differences in cation composition of the soil solution between calibration and mineralization experiments. A temperature-dependence model for N mineralization from soil organic matter was fitted to both the measured and the TDR-calculated mineralization rates, k and kTDR, respectively. There were no significant differences between the model parameters from the two. Our results are promising for further use of TDR to monitor soil organic N mineralization. However, the influence of changing cation ratios will also have to be taken into account when trying to predict N mineralization from measured electrical conductivities.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2003.00521.x

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6

Electronic Resource

Influence of soil compaction on carbon and nitrogen mineralization of soil organic matter and crop residues (2000)

De Neve, S. ; Hofman, G.

Springer

Biology and fertility of soils 30 (2000), S. 544-549

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ISSN: 1432-0789

Keywords: Key words Soil compaction ; Carbon mineralization ; Nitrogen mineralization ; Crop residues ; Soil organic matter

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract We studied the influence of soil compaction in a loamy sand soil on C and N mineralization and nitrification of soil organic matter and added crop residues. Samples of unamended soil, and soil amended with leek residues, at six bulk densities ranging from 1.2 to 1.6 Mg m–3 and 75% field capacity, were incubated. In the unamended soil, bulk density within the range studied did not influence any measure of microbial activity significantly. A small (but insignificant) decrease in nitrification rate at the highest bulk density was the only evidence for possible effects of compaction on microbial activity. In the amended soil the amounts of mineralized N at the end of the incubation were equal at all bulk densities, but first-order N mineralization rates tended to increase with increasing compaction, although the increase was not significant. Nitrification in the amended soils was more affected by compaction, and NO3 –-N contents after 3 weeks of incubation at bulk densities of 1.5 and 1.6 Mg m–3 were significantly lower (by about 8% and 16% of total added N, respectively), than those of the less compacted treatments. The C mineralization rate was strongly depressed at a bulk density of 1.6 Mg m–3, compared with the other treatments. The depression of C mineralization in compacted soils can lead to higher organic matter accumulation. Since N mineralization was not affected by compaction (within the range used here) the accumulated organic matter would have had higher C : N ratios than in the uncompacted soils, and hence would have been of a lower quality. In general, increasing soil compaction in this soil, starting at a bulk density of 1.5 Mg m–3, will affect some microbially driven processes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003740050034

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7

Electronic Resource

Temperature effects on C- and N-mineralization from vegetable crop residues (1996)

Neve, S. ; Pannier, J. ; Hofman, G.

Springer

Plant and soil 181 (1996), S. 25-30

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ISSN: 1573-5036

Keywords: C-mineralization ; crop residues ; incubation ; N-mineralization ; temperature

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Net N-mineralization and nitrification from soil organic matter and from vegetable crop residues (leaf-blades of cauliflower and stems of red cabbage) were measured at 4 temperatures during aerobic incubation in the laboratory. C-mineralization from leaf-blades of cauliflower was monitored at 3 different temperatures. N-mineralization from soil organic matter was best described by zero order kinetics N(t)=kt whereas N- and C-mineralization from the crop residues were described by single first order kinetics. Stems of red cabbage mineralized much more slowly than leaf-blades of cauliflower. S-shaped functions were fitted to the relationship between the rate constants of both C and N-mineralization and temperature. The rate parameter κ of the S-shaped function reflects the temperature dependence of the mineralization rate k. The parameter κ for N-mineralization of the stem material (κ=5.36) was significantly higher than for the leaf-blades (κ=3.38), indicating that there is a strong interaction between temperature and resistance to degradation in the soil. N-mineralization from soil organic matter was least sensitive to temperature (κ=2.63). Temperature dependence of nitrification was not significantly different from mineralization over the temperature range considered. Rate constants for C-mineralization of cauliflower leaf-blades were higher than for N-mineralization, but the temperature dependence of the rate constants was not significantly different for both processes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00011288

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