Quality and Quantity of Organic Fractions as Affected by Soil Depth in an Argiudoll under Till and No-till Systems

GALANTINI, JA.; DUVAL, M.; MARTINEZ, JM.; MORA, V.; BAIGORRI, R.; GARCÍA-MINA, JM.

International Journal of Plant & Soil Science

SCIENCEDOMAIN international

Año: 2016 vol. 10 p. 1 - 12

Aims: The aim of this study was to evaluate the long-term effect of tillage systems on the quantity and quality of organic carbon fractions at different soil layers. Study Design: The experimental design was a split plot with three blocks. The long-term effects (25 years) of conventional- (CT) and no-tillage (NT) systems on a Tipic Argiudoll was sampled at 0- 5, 5-10, 10-15 and 15-20 cm soil depth.Place and Duration of Study: The field experiment was carried out at Tornquist (38° 07? 06? S - 62°02? 17? O) and soil sampling was performed during wheat seeding (June 2011).Methodology: Total soil organic carbon (SOC) content and the following fractions were determined: Coarse particulate (POCc , 105-2000 µm), fine particulate (POCf, 53-105 µm) and mineral-associated (MOC, 0-53 µm) carbon fractions; humic (HA) and fulvic (FA) acids; and total (CHt) and soluble (CHs) carbohydrates. The main physico-chemical properties of HA and FA were analyzed using both FT-IR and fluorescence spectroscopies.Results: After 25 years, total SOC at the 0-20 cm depth was 9% higher in no-tilled than in tilled soils. The POCf was the SOM fraction that turned out to be the most sensitive to tillage effects. The POCc:POCf:MOC ratio at 0-20 cm was similar for NT (3:14:82) and CT (5:10:84); however, differences were found across soil depths. Tilled soils showed higher aromaticity, starting by CHdegradation,in more superficial soil layers.Conclusion: The no-tillage system presented a different pattern which can be related to distribution of crop residues and conditions for humification along the soil depth.