Decomposition from legume and non-legume crop residues:
effects on soil organic carbon fractions under controlled conditions
Cover crop (CC) residues protect the soil from erosion
and their permanence on the surface is largely influenced by their biochemical
constituents. We performed a study under controlled conditions to investigate
the dynamics of legume and non-legume CC residues decomposition and the
transformations of the soil labile organic carbon fractions in the surface
layer (0-15 cm). The experiment was carried out on a Typic Argiudoll (clay
loam, 27.4 g kg⁻¹ soil organic matter, 14 mg kg⁻¹
extractable phosphorus and 6.5 pH) placed in undisturbed pots (1570 cm³) in a
greenhouse under controlled conditions of temperature (25 ± 1 °C). We evaluated
three CC species (oat, Avena sativa
L.; vetch, Vicia sativa L.; Persian
clover, Trifolium resupinatum L.) and
a no-CC control (fallow). Shoot residues were applied on the soil surface at
5.4, 5.4 and 2.7 g dry matter (equivalent to 6, 6 and 3 Mg ha⁻¹ for
oat, vetch and clover, respectively) and incubated for 362-days (eight sampling
times). The water content in the pots was maintained periodically by weight at
60% of soil water-holding capacity. The soil samples were analyzed for
particulate organic carbon (POC), and total and soluble carbohydrates (CHt and
CHs, respectively). Oat and vetch residues decomposed faster than clover, with
the decomposition rate constant (k) values of 1.3, 1.4 and 1.9 year⁻¹,
respectively. At the end of the experiment, POC concentration was lower in
vetch (1.83 g kg⁻¹) and clover (1.96 g kg⁻¹) than
in oat (2.21 g kg⁻¹) and fallow (3.00 g kg⁻¹),
indicating a loss of 45-64% from their initial values. Soil CHt was influenced
by residue quality, where the periods of greatest residue decay (vetch 21-59 days
and oat 93-130 days) corresponded to higher soil CHt. Hence, this organic
carbon fraction is sensitive to residue decomposition and can be indicators of
changes in soil organic matter over short periods of time.
Organic quality changes during residue decomposition
Sa Pereira E, M. Duval, J.A.
Galantini. 2017. Decomposition from legume and non-legume crop residues: effects on
soil organic carbon fractions under controlled conditions. Spanish Journal of Soil Science 7(2) 86-96 https://doi.org/10.3232/SJSS.2017.V7.N2.06
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