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Tillage and residue management effects on soil carbon and nitrogen under irrigated continuous corn
- Schmer, M. R, Jin, V. L., Wienhold, B. J., Varvel, G. E., Follett, R. F.
- Soil Science Society of America journal 2014 no.6 v.78 pp. 1987-1996
- Zea mays, biofuels, biomass production, carbon, carbon cycle, continuous cropping, conventional tillage, corn, corn stover, discing, forage, grain yield, irrigation, isotopes, nitrogen, no-tillage, nutrient content, soil amendments, soil nutrients, soil organic carbon, soil profiles
- Demand for corn (Zea mays L.) stover as forage or as a cellulosic biofuel has increased the importance of determining the effects of stover removal on biomass production and the soil resource. Our objectives were to evaluate grain yield, soil organic C (SOC), and total soil N (0 to 150 cm) in a 10-year, irrigated, continuous corn study under conventional disk tillage (CT) and no-till (NT) with variable corn stover removal rates (none, medium, high). Natural abundance C isotope compositions were used to determine C additions by corn (C4-C) to the soil profile and to evaluate the retention of residual C3-C. After ten years of management treatments, mean grain yields were 7.5% to 8.6% higher for NT when residue was removed compared with no stover removal, while grain yields were similar for CT in all stover removal treatments. Turnover of SOC occurred as C3-C stocks were replaced by C4-C in the 0- to 120-cm soil profile. Total SOC and N stocks changed mainly in surface soils (0 to 30 cm), with no detectable cumulative changes at 0 to 150 cm. Specifically, SOC declined after 10 yr under CT at 0 to 15 cm and was affected by residue management at 15 to 30 cm. Total soil N was greater when no stover was removed (P = 0.0073) at 0 to 15 cm and from residue management at 15 to 30 cm. Total soil N was greatest when no residue was removed (P=0.0073) compared to high stover removal at 0 to 15 cm. Long-term NT ameliorated medium stover removal effects by maintaining near-surface SOC levels. Results support the need to evaluate SOC cycling processes below near-surface soil layers.