http://cat.inist.fr/?aModele=afficheN&cpsidt=1181537
Résumé / Abstract
Continuous cropping or decreasing the frequency of summer fallow (F) in cereal-based dryland rotations may have benefits
other than greater water utilization and erosion control. We hypothesized that rotations with no fallow or minimum
fallow frequency can produce more biomass and cover than the traditional winter wheat (Triticum aestivum L.)-summer
fallow systems (W-F), and ultimately, greater amounts of soil organic matter (SOM). To this end, we evaluated changes in
various pools of SOM at the 0- to 5- and 0- to 15-cm depths on a Weld loam (fine, smectitic, mesic aridic Paleustolls)
that were caused by (i) decreasing fallow or increasing cropping intensities, (ii) specific rotations of the same length
but with different crop sequencing, and (iii) accumulated residue and roots from reduced- or no-tillage from 1993 to
1997. Total soil organic carbon (SOC) and N for the 0- to 5-cm depth increased by 20% with continuous cropping rotations
compared with W-F rotations. Particulate organic matter-carbon (POM-C) doubled, while POM-N, and soluble organic C (OC)
increased by one third for the same comparison. At the 0- to 15-cm depth, SOC, POM-C, and POM-N did not differ among
systems with fallow, nor among systems with cropping intensities greater than W-F. Thus, significant differences always
existed between W-F and continuous cropping. Generally, fallow had a negative influence on SOC accumulation, and
continuous cropping a positive influence on surface SOM. Changes in SOC did not correlate with yields in the five-year
comparison of this ongoing study.
Revue / Journal Title
Soil Science Society of America journal (Soil Sci. Soc. Am. j.) ISSN
0361-5995 CODEN SSSJD4
Source / Source
1999, vol. 63, no1, pp. 186-191 (33 ref.)