Carbon Dioxide Efflux from Soil with Poultry Litter Applications in Conventional and Conservation Tillage Systems in Northern Alabama
2008
Roberson, T. | Reddy, K. C. | Reddy, S. S. | Nyakatawa, E. Z. | Raper, R. L. | Reeves, D. W. | Lemunyon, J.
Increased CO₂ release from soils resulting from agricultural practices such as tillage has generated concerns about contributions to global warming. Maintaining current levels of soil C and/or sequestering additional C in soils are important mechanisms to reduce CO₂ in the atmosphere through production agriculture. We conducted a study in northern Alabama from 2003 to 2006 to measure CO₂ efflux and C storage in long-term tilled and non-tilled cotton (Gossypium hirsutum L.) plots receiving poultry litter or ammonium nitrate (AN). Treatments were established in 1996 on a Decatur silt loam (clayey, kaolinitic thermic, Typic Paleudults) and consisted of conventional-tillage (CT), mulch-tillage (MT), and no-tillage (NT) systems with winter rye [Secale cereale (L.)] cover cropping and AN and poultry litter (PL) as nitrogen sources. Cotton was planted in 2003, 2004, and 2006. Corn was planted in 2005 as a rotation crop using a no-till planter in all plots, and no fertilizer was applied. Poultry litter application resulted in higher CO₂ emission from soil compared with AN application regardless of tillage system. In 2003 and 2006, CT (4.39 and 3.40 μmol m⁻² s⁻¹, respectively) and MT (4.17 and 3.39 μmol m⁻² s⁻¹, respectively) with PL at 100 kg N ha⁻¹ (100 PLN) recorded significantly higher CO₂ efflux compared with NT with 100 PLN (2.84 and 2.47 μmol m⁻² s⁻¹, respectively). Total soil C at 0- to 15-cm depth was not affected by tillage but significantly increased with PL application and winter rye cover cropping. In general, cotton produced with NT conservation tillage in conjunction with PL and winter rye cover cropping reduced CO₂ emissions and sequestered more soil C compared with control treatments.
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