Soil‐organic‐matter stability in sandy cropland soils is related to land‐use history

Abstract

Sandy cropland soils in NW Europe were found to contain unusually high organic-carbon (OC) levels, and a link with their land-use history has been suggested. This study's aim was to assess the discriminating power of physical and chemical fractionation procedures to yield information on soil-organic-matter (OM) stability for these soils. In relict-and cultivated-heathland soils, much higher proportions of 6% NaOCl treatment-resistant but 10% HF-soluble OC (MOC) and N (32.2% and 29.9%) were measured compared to a set of "permanent"-cropland soils without a history of heathland land use (11.9% and 8.5%). Also, the proportions of 6% NaOCl-and 10% HF treatment-resistant OC and N in the relict and cultivated heathlands (19.2% and 12.0%) were higher than in the permanent-cropland soils (17.7% and 5.7%). Stepwise multiple linearregression yielded a significant relationship between the annual mineralization (g C [100 g OC] -1 ), soil OC (g C kg -1 ) content, and %MOC: Annual mineralization = 4.347 -0.087 soil OC -0.032 %MOC (R 2 = 0.65). Combinations of incubation experiments for quantification of the labile soil OM pool with chemical fractionation may thus yield meaningful data for development of soilorganic-matter models with measurable pools, but their applicability will be limited to specific combinations of former land use with soil, climate, and current management.

Organic Matter in Clay Density Fractions from Sandy Cropland Soils with Differing Land‐Use History

“…These differences were also confirmed for a larger soil set studied by Sleutel et al (2010). Differences in N content ofthe physical fractions were smaller and insignificant.…”

“…Both were commonly practiced over centuries in Northwest Europe from Schleswig-Holstein to Belgium (Blume and Leinweber, 2004). Studies employing incubation experiments, physical and chemical fractionation methods (Springob and Kirchmann, 2002;Sleutel et al, 2010) and detailed spectroscopic characterizations (Sleutel et al, 2008) have confirmed both the similarity in soil OM stability of relict and cultivated heathlands on the one hand, and the lower stability of soil OM in sandy cropland soils without this historical land use on the other. Specifically, lipids, sterols and to a lesser extent N-containing compounds were selectively preserved from previous heathland land-use (Sleutel et al, 2008).…”

“…Specifically, lipids, sterols and to a lesser extent N-containing compounds were selectively preserved from previous heathland land-use (Sleutel et al, 2008). In addition, the high OM loadings of the claysized fraction (Sleutel et al, 2010) suggested more than 'mono-OM-layer-equivalent' covering of soil particles, that is, an OM loading equivalent to what would be expected for a single layer of moderately sized organic molecules. Because variation in organicmineral particle density may reflect variations in the thickness of organic accumulations (SoUins et al, 2006) we hypothesize that such thick OM layered particles are preferentially fractionated in lower density clay fractions.…”

Field-specific simulations of net N mineralization based on digitally available soil and weather data: II. Pedotransfer functions for the pool sizes

“…Within the here studied loess soils, humus class became as important as the clay contents. This did not apply to sandy soils, probably due to relatively high amounts of relatively stable SOM in podzolized sandy arable soils with very low clay contents (Sleutel et al 2010;Springob and Kirchmann 2002).…”

Contribution of Eucalyptus Harvest Residues and Nitrogen Fertilization to Carbon Stabilization in Ultisols of Southern Bahia

“…Corroborating our findings, in the Cerrado region, a 49 % difference in the clay content between two soils was responsible for a 46 % reduction in soil organic carbon (SOC) losses when the native vegetation was converted to conventional tillage systems (Dieckow et al, 2009). The lower aggregation capacity, specific surface, and charge density in sandy soils make soil C biochemistry properties of fundamental importance to SOC preservation over time (Sleutel et al, 2010). Remarkably, after three years of residue removal, δ 13 C-POM was less negative than initially recorded in the West region (Table 2), indicating a selective preservation of C derived from C 4 plants.…”