|Follett, Ronald - Ron|
Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2004
Publication Date: 8/1/2005
Citation: Follett, R.F., Castellano, J., Buenger, E.D. Carbon dynamics and sequestration in an irrigated vertisol in central mexico. International Journal of Soil and Tillage Research. Vol. 83:148-158 (Aug. 2005 publication date) Interpretive Summary: Cropping system and N fertilization were important to high grain yield and crop residue production. Total yield of wheat grain and residue benefitted from and was higher when bean was the previous crop. However, corn grain yield and residue production always exceeded those from bean. Contribution of wheat (a C3 plant) to ÿ13C of soil relative to that of corn (a C4 plant) increased with increased N-fertilizer. Changes in C/N ratios indicated that CT systems mixed crop residue and less decomposed SOM with depth in the soil profile, a response consistent with incorporation of plant material by tillage. Much less crop residue was produced under WB-NT than under WC-NT so that less residue C was available to be sequestered as SOC. Highest rate of SOC sequestration was under WC-NT and was 1.0 and 1.9 Mg SOC yr-1 in the 0-15 and 15-30 cm depths, respectively. Corresponding SOC in 0-15 and 15-30 cm depths in the WC-CT treatment was 0.2 and 0.6 Mg yr-1 and amounts in all other treatments were equal or lower. Results from this study indicate no-till on N-fertilized WC systems can potentially increase SOC sequestration on large areas of irrigated Vertisols in Central Mexico while maintaining high crop yields.
Technical Abstract: A study conducted on a Vertisol in central Mexico evaluated use of traditional -deep and no-tillage systems on SOC dynamics for wheat (Triticum aestivum L.)-corn (Zea mays L.) and wheat-bean (Phaseolus vulgaris L.) cropping systems. Five tillage/crop-rotation (two crops per year) systems with four replications: (WC-CTb) wheat-corn, burning the residues of both crops, plowing and disking twice, (WC-CT) wheat-corn under conventional tillage (plowing and disking twice to incorporate crop residues following the harvest of each crop), (WC-NT) wheat-corn under no-till, (WB-CT) wheat-bean under conventional tillage, and (WB-NT) wheat-bean under no-till. Each crop received one of three fertilizer-N rates broadcast as urea: a) 0, 150, and 300 kg N ha-1 for corn; b) 0, 40, and 80 kg N ha-1 for bean; and c) 0, 125, and 250 kg N ha-1 for wheat. Baseline year was 1994 with relative changes measured from 1994 to 1999 for grain yield and residue production, crop residue C and d13C, SOC, soil C/N ratio, and change in soil d13C. High N rates increased SOC sequestration. In WC systems, more negative d13C was associated with higher N, indicating more contribution of wheat (a C3 plant) residue C than from corn (a C4 plant). In WB, N-rate and tillage had no effect on SOC. Highest rate of SOC sequestration was with WC-NT. Increase in SOC from 1994 to 1999 was 1.0 and 1.9 Mg SOC yr-1 in the 0-15 and 15-30 cm depths, respectively. In this study no-till on N-fertilized WC systems increased SOC sequestration on irrigated Vertisols while maintaining high crop yields.