THE MINERALIZATION OF NITROGEN AND SULPHUR FROM PARTICLE-SIZE SEPARATES OF GLEYSOLIC SOILS

1983 ◽  
Vol 63 (4) ◽  
pp. 761-765 ◽  
Author(s):  
L. E. LOWE ◽  
A. A. HINDS
Keyword(s):  
Particle Size ◽  
Nitrogen Mineralization ◽  
Aerobic Incubation ◽  
Mineral N ◽  
Total N ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Sulphur Mineralization ◽  
Organic Fractions ◽  
Key Words Nitrogen

An aerobic incubation procedure was used to evaluate the susceptibility to mineralization of N and S in five Gleysolic soils and their particle-size fractions (2–50 μm, 1–2 μm, 0.2–1 μm and < 0.2μm). During an 8-wk incubation, the release of mineral N and S increased with decreasing particle size. The N:S ratio of the mineralization products was generally narrower than that of the starting materials. Total N mineralized from size fractions after 8 wk accounted for 4.5–25.4% of fraction N. For S the corresponding range was 2.7–43.3% of fraction S. The proportions of N and S released after 8 weeks showed no consistent relationship to particle size, although, in a number of cases, the proportions of N and S released were greater for the finer size fractions. It was concluded that complexing of organic fractions with clays did not, in itself, confer increased resistence to mineralization of N and S. Key words: Nitrogen mineralization, sulphur mineralization, particle-size separates, Gleysolic soils

Decoupled carbon and nitrogen mineralization in soil particle size fractions of a forest topsoil

2014 ◽  
Vol 78 ◽  
pp. 263-273 ◽  
Author(s):  
Carolin Bimüller ◽  
Carsten W. Mueller ◽  
Margit von Lützow ◽  
Olivia Kreyling ◽  
Angelika Kölbl ◽  
...  
Keyword(s):  
Particle Size ◽  
Nitrogen Mineralization ◽  
Soil Particle ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Carbon And Nitrogen ◽  
Soil Particle Size ◽  
Soil Particle Size Fractions

Carbon and nitrogen mineralisation in sand, silt, and clay fractions of soils under maize and pasture

Soil Research ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 361 ◽  
Author(s):  
R. L. Parfitt ◽  
G. J. Salt
Keyword(s):  
Particle Size ◽  
Clay Fraction ◽  
Good Evidence ◽  
N Mineralisation ◽  
Mineral N ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Carbon And Nitrogen ◽  
N Release ◽  
C Mineralisation

Although several studies have quantified either C mineralisation or net N mineralisation in particle-size fractions, no work has examined simultaneous C and net N mineralisation. Therefore, we conducted an 18-week laboratory incubation to compare simultaneous mineralisation in sand, silt, and clay fractions. The soils (silt loams) were collected from fields of long-term pasture and maize. Sand, silt, and clay were separated by mild dispersion in water followed by centrifugation. Samples were incubated at 25°C in the dark in a quartz matrix, and were leached every 2 weeks with 0.004 M CaCl 2 at a suction of 20 kPa to remove soluble products. C mineralisation was determined from CO 2 -C evolved each 2 weeks, and mineral N was measured in the leachate. C mineralisation, on a C basis, followed the order sand > clay > silt, and was related (r 2 = 0.88) to the proportion of O-alkyl C (carbohydrate C) estimated from 13 C NMR. The low mineralisation in the silt may also have been a result of the physical protection of substrates in small pores in this fraction. The rates of N release were initially rapid from the maize soil fractions, and were consistent with the high initial mineral-N contents; subsequently, the rates were slower, and probably related to C mineralisation. For the pasture soil, N mineralisation followed the order clay>silt>sand, and was inversely related to the C: N ratios. Immobilisation appeared to take place in the sand fraction, whereas a large part of the net N mineralisation occurred in the clay fraction. There is now good evidence that rates of C and net N mineralisation differ within discrete particle size fractions, and data on such fractions could be useful for constructing soil organic matter models.

CHANGES IN NATURAL 15N ABUNDANCE OF SOILS ASSOCIATED WITH TILLAGE PRACTICES

1984 ◽  
Vol 64 (3) ◽  
pp. 345-354 ◽  
Author(s):  
F. SELLES ◽  
R. E. KARAMANOS ◽  
K. E. BOWREN
Keyword(s):  
Particle Size ◽  
Conventional Tillage ◽  
Soil N ◽  
Zero Tillage ◽  
Total N ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Tillage Practices ◽  
Total Soil ◽  
Total Soil N

The objective of this study was to determine changes in N dynamics in an Orthic Black Chernozem as a result of two tillage practices (conventional and zero tillage) using the variations in the natural 15N abundance of different soil-N fractions. After 14 yr, no significant differences in isotope composition of total soil-N between the two tillage practices could be found. However, changes were detected in the natural 15N abundance of the acid-hydrolyzable N and various organo-mineral size fractions which led to useful comparisons of the nature of N under the two systems. The N-content of the hydrolyzable-N fraction was similar at the 0- to 4- and 8- to 16-cm depth under both tillage practices, while it was significantly different at the 4- to 8-cm depth. The δa15N of this fraction was consistently higher than that of total soil N at all depths only under zero tillage. This was associated with the presence of more labile N compounds under zero tillage. No differences in the isotopic composition of the organomineral size fractions were found at the 0- to 4-cm depth. At the 4- to 8- and 8- to 16-cm depths, the δa15N values of the finer particle size fractions were higher under zero tillage than under conventional tillage. This indicates a more labile nature of the N associated with these size fractions under zero tillage. Key words: δa15N, conventional tillage, zero tillage, total N, acid-hydrolyzable fraction, particle size fractions

Digital soil mapping of compositional particle-size fractions using proximal and remotely sensed ancillary data

Geophysics ◽  
2012 ◽  
Vol 77 (4) ◽  
pp. WB201-WB211 ◽  
Author(s):  
S. Buchanan ◽  
J. Triantafilis ◽  
I. O. A. Odeh ◽  
R. Subansinghe
Keyword(s):  
Particle Size ◽  
High Resolution ◽  
Soil Mapping ◽  
Additive Models ◽  
Digital Soil Mapping ◽  
Unbiased Estimation ◽  
Ancillary Data ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Log Ratio

The soil particle-size fractions (PSFs) are one of the most important attributes to influence soil physical (e.g., soil hydraulic properties) and chemical (e.g., cation exchange) processes. There is an increasing need, therefore, for high-resolution digital prediction of PSFs to improve our ability to manage agricultural land. Consequently, use of ancillary data to make cheaper high-resolution predictions of soil properties is becoming popular. This approach is known as “digital soil mapping.” However, most commonly employed techniques (e.g., multiple linear regression or MLR) do not consider the special requirements of a regionalized composition, namely PSF; (1) should be nonnegative (2) should sum to a constant at each location, and (3) estimation should be constrained to produce an unbiased estimation, to avoid false interpretation. Previous studies have shown that the use of the additive log-ratio transformation (ALR) is an appropriate technique to meet the requirements of a composition. In this study, we investigated the use of ancillary data (i.e., electromagnetic (EM), gamma-ray spectrometry, Landsat TM, and a digital elevation model to predict soil PSF using MLR and generalized additive models (GAM) in a standard form and with an ALR transformation applied to the optimal method (GAM-ALR). The results show that the use of ancillary data improved prediction precision by around 30% for clay, 30% for sand, and 7% for silt for all techniques (MLR, GAM, and GAM-ALR) when compared to ordinary kriging. However, the ALR technique had the advantage of adhering to the special requirements of a composition, with all predicted values nonnegative and PSFs summing to unity at each prediction point and giving more accurate textural prediction.

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