The Role of Soil Organic Matter and Manures in Sustainable Nutrient Cycling - Sustainable Management of Soil Organic Matter - page 249

Table 4.4.1. Basic properties of the soils at the experimental site.

Depth
(cm)

pH
CaCl 2

CEC a
(mmol c kg − 1 )

CO 3 -C b
(g kg − 1 )

OC c
(g kg − 1 )

Clay d
(g kg − 1 )

Al Ox e
(g kg − 1 )

Fe Ox e
(g kg − 1 )

Fe DCB f
(g kg − 1 ) Horizon

A1 0-10 7.1 422 4 112 230 5.3 3.6 8.4

A2 10-25 7.3 284 24 69 210 4.7 3.3 7.7

C 25-95 7.6 63 70 11 70 1.4 1.6 5.0

a Cation exchange capacity, measured with 1 M NH 4 + acetate at pH 7.0 (Avery and Bascomb,
1974).
b Carbonate carbon, measured with a calcimeter according to Scheibler (Schlichting and Blume,
1966).
c Organic carbon, calculated by the difference between total carbon measured with a CHNS ana-
lyser (Vario EL, Elementar Analysensysteme GmbH, Hanau, Germany) and carbonate carbon.
d Estimated by using the sieve-pipette method (Avery and Bascomb, 1974).
e Oxalate-extractable Al and Fe (Schwertmann, 1964).
f Dithionite-citrate-bicarbonate-extractable Fe (Mehra and Jackson, 1960).

weathering along cracks in the bedrock. The organic forest floor layer was
mull-type.

Soil solution sampling

At the experimental sites three plots were each equipped with four bulk
precipitation and throughfall collectors, and with zero-tension (beneath the
forest floor and at 90 cm depth) tension lysimeters (at 15 and 30 cm
depth), suction cups (at 90 cm depth) and tensiometers (at 15, 30 and
90 cm depth). The tension at the tension lysimeters and the suction cups
was regulated according to the soil water tension. Rain and soil water were
collected at 7-day intervals during the growing season and at 14-day inter-
vals during the dormant season. The samples were filtered through 0.45 µ m

membrane filters and stored at C. The results presented here refer to

the sampling period from December 1997 to November 1998.

− 18 °

Chemical analyses

The water samples were fractionated into hydrophilic and hydrophobic
compounds using the XAD-8 resin method (Aiken and Leenheer, 1993).
The hydrophobic fraction is dominated by lignin-derived compounds
whereas the hydrophilic fraction represents mainly carbohydrates of
both plant and microbial origin (Guggenberger et al ., 1994). The original
samples and the hydrophilic fractions were analysed with a Shimadzu