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Soil Carbon and Nitrogen Organic Fractions in Degraded vs. Non‐Degraded Mollisols in Argentina
Author(s) -
Fabrizzi Karina P.,
Morón Alejandro,
García Fernando O.
Publication year - 2003
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2003.1831
Subject(s) - tillage , mollisol , conventional tillage , total organic carbon , organic matter , soil carbon , soil organic matter , soil water , agronomy , environmental science , nitrogen , environmental chemistry , chemistry , zoology , soil science , biology , organic chemistry
The use of no‐tillage has notably increased in the Pampas region of Argentina during the last 10 yr. Two tillage experiments with contrasting previous agricultural use, degraded and non‐degraded soils, were evaluated in the southeast of Buenos Aires province, Argentina. The objectives were to: (i) quantify the effects of tillage and N fertilization on quantity and vertical distribution of C and N in the soil organic matter (SOM) and particulate organic matter (POM) fractions as well as potentially mineralizable N (PMN), and (ii) evaluate these fractions as indicators of soil quality. Tillage systems were conventional tillage (CT), minimum tillage (MT), and no‐tillage (NT) (main plots), and N fertilization rates were 0, 120, and 150 kg ha −1 (subplots). Total organic C (TOC), total N (TN), POM‐C, POM‐N, and PMN were measured at 0‐ to 7.5‐ and 7.5‐ to 15‐cm soil depth. In Exp. I (degraded soil) TOC was greater under NT (27 g kg −1 ) than under CT (24 g kg −1 ) in the 0‐N treatments. No differences in TOC and TN were found in Exp. II at 0 to 7.5 cm (non‐degraded soil). Carbon in POM and POM‐N were greater under NT in the fractions of 212 to 2000 and 53 to 212 μm at 0 to 7.5 cm, but they were similar or greater under CT at 7.5‐ to 15‐cm depth in Exp. I. Stratification of TOC, TN, and POM were observed under NT in Exp. I. Potentially mineralizable N was greater under NT (62 mg kg −1 ) in Exp. I, however, no differences in PMN were observed in Exp. II. Carbon in POM 212 to 2000 μm and PMN were the more sensitive indicators of tillage effects, mainly in Exp. I.