1. Soil carbon and nitrogen organic fractions in degraded vs. non-degraded mollisols in Argentina
- Author
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Fabrizzi, Karina P., Moron, Alenjandro, and Garcia, Fernando
- Subjects
Soils -- Research ,Earth sciences - Abstract
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.sup.-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.sup.-1]) than under CT (24 g [kg.sup.-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 [micro]m 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.sup.-1]) in Exp. I, however, no differences in PMN were observed in Exp. II. Carbon in POM 212 to 2000 [micro]m and PMN were the more sensitive indicators of tillage effects, mainly in Exp. I.
- Published
- 2003