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Title: Addition of cover crops enhances no-till potential for improving soil physical properties

Author
item BLANCO, HUMBERTO - Kansas State University
item Mikha, Maysoon
item PRESLEY, DEANN - Kansas State University
item CLAASSEN, MARK - Ministry Of Science And Innovation, Csic

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2010
Publication Date: 6/1/2011
Citation: Blanco, H., Mikha, M.M., Presley, D.R., Claassen, M.M. 2011. Addition of cover crops enhances no-till potential for improving soil physical properties. Soil Science Society of America Journal. 75(4):1471-1482.

Interpretive Summary: Inclusion of cover crops may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a wheat-grain sorghum rotation, four N rates, and hairy vetch as cover crops after wheat during the first rotation cycles and replaced in subsequent cycles with sunn hemp cover crop and late-maturing soybean as cover crop in no-till on a Geary silt loam soil. At the end of a 15-yr period, we studied the cover crop impacts on soil physical properties and assessed relationships between soil properties and cover crops for increasing soil organic C (SOC) concentration. Sunn hemp reduced bulk density by about 5% in the 0- to 3-inch soil depth. Both sunn hemp and late-maturing soybean reduced maximum bulk density by 5% and increased critical water content by 10%, indicating that soils under cover crop may be less susceptible to compaction and be trafficked at greater soil water content without causing compaction than soils without cover crop. Cover crops also increased mean weight diameter of aggregates by 80% in the 0- to 3-inch depth. Sunn hemp increased cumulative infiltration by about 300%, and it improved soil properties more than late-maturing soybean. Bulk density and maximum bulk density decreased while weight diameter of aggregates and cumulative infiltration increased with the cover crop with increase in SOC concentration. Adding cover crop to no-till systems improved soil physical properties mainly by accumulating SOC.

Technical Abstract: Interest in the use of cover crops (CC) is growing. Inclusion of CC may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a wheat [Triticum aestivum (L.)]-grain sorghum [Sorghum bicolor (L.) Moench] rotation, four N rates, and hairy vetch (Vicia villosa Roth) CC after wheat during the first rotation cycles and replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean (LMS) (Glycine max L.) CC in no-till on a Geary silt loam (fine-silty, mixed, superactive, mesic Udic Argiustoll). At the end of a 15-yr period, we studied the cumulative impacts of CC on soil physical properties and assessed relationships between soil properties and CC-induced increase in soil organic C (SOC) concentration. Sunn hemp reduced bulk density by about 5% in the 0- to 7.5-cm soil depth. Both SH and LMS reduced Proctor maximum bulk density by 5% and increased critical water content by 10%, indicating that soils under CC may be less susceptible to compaction and be trafficked at greater soil water content without causing compaction than soils without CC. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. Sunn hemp increased cumulative infiltration by about 300%, and it improved soil properties more than LMS. Bulk density and maximum bulk density decreased while MWDA and cumulative infiltration increased with the CC-induced increase in SOC concentration. Adding CC to no-till systems improved soil physical properties mainly by accumulating SOC.