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Comments on “No‐Tillage and Soil‐Profile Carbon Sequestration: An On‐Farm Assessment”
Author(s) -
Franzluebbers Alan J.
Publication year - 2009
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/sssaj2008.0275l
Subject(s) - tillage , carbon sequestration , environmental science , soil carbon , agroforestry , carbon fibers , agronomy , soil science , soil water , mathematics , carbon dioxide , ecology , biology , algorithm , composite number
Blanco-Canqui and Lal (2008) conducted a study to “…determine: (i) changes in SOC [soil organic carbon] within the topsoil due to conversion to NT [no tillage] farming, and (ii) the depth distribution (0–60 cm) of SOC in NT soils compared with PT [plow tillage] and forest soils.” The authors pointed out the diffi culties in interpreting the results of the farm-survey approach undertaken, especially regarding the difference in cropping history of each fi eld site, difference in current crop management system since enrolled in a particular tillage system, difference in type of tillage implements, difference in fertilizer use, and difference in crop residue returned. All of these concerns are real, but the greater concern was the sampling approach, which should have tempered the strength of conclusions. Only one fi eld was sampled within a major land resource area (MLRA), and therefore, conventional statistical analysis should not have been used to assess the effects of management within a MLRA. A more appropriate choice of analysis should have been to use the 11 MLRA sampling locations as replicates for the three management systems (plow tillage, no tillage, and woodlot). Because multiple fi elds of a management system within a MLRA were not sampled, then the only valid comparison was of management systems across MLRAs. How management affects SOC within a MLRA (>1 Mha) should not have been based on three cores (40 cm 2 ) within a single fi eld.