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Soil Carbon Accumulation under Switchgrass Barriers
- Blanco-Canqui, Humberto, Gilley, John E., Eisenhauer, Dean E., Jasa, Paul J., Boldt, Alan
- Agronomy journal 2014 v.106 no.6 pp. 2185-2192
- Argiudolls, Glycine max, Panicum virgatum, Sorghum bicolor, Zea mays, aggregate stability, agricultural soils, agroecosystems, carbon, conventional tillage, corn, crop rotation, cropland, filter strips, grain sorghum, grasses, nitrogen, no-tillage, organic matter, porosity, silty clay soils, soil aggregates, soil aggregation, soil depth, soil organic carbon, soybeans, topographic slope, Nebraska
- The benefits of grass barriers or hedges for reducing offsite transport of non-point-source water pollutants from croplands are well recognized, but their ancillary benefits on soil properties have received less attention. We studied the 15-yr cumulative effects of narrow and perennial switchgrass (L.) barriers on soil organic C (SOC), total N, particulate organic matter (POM), and associated soil structural properties as compared with the cropped area on an Aksarben silty clay loam (fine, smectitic, mesic Typic Argiudoll) with 5.4% slope in eastern Nebraska. Five switchgrass barriers were established in 1998 at ∼38-m intervals parallel to the crop rows in a field under a conventional tillage and no-till grain sorghum [ (L.) Moench]–soybean [ (L.) Merr.]–corn (L.) rotation. Compared with the cropped area, switchgrass barriers accumulated about 0.85 Mg ha yr of SOC and 80 kg ha yr of total soil N at the 0 to 15 cm soil depth. Switchgrass barriers also increased coarse POM by 60%. Mean weight diameter of water-stable aggregates increased by 70% at 0 to 15 cm and by 40% at 15 to 60 cm, indicating that switchgrass barriers improved soil aggregation at deeper depths. Large (4.75–8 mm) macroaggregates under switchgrass barriers contained 30% more SOC than those under the cropped area. Switchgrass-induced changes in SOC concentration were positively associated with aggregate stability (= 0.89***) and porosity (= 0.47*). Overall, switchgrass barriers integrated with intensively managed agroecosystems can increase the SOC pool and improve soil structural properties.