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Title: Nutrient source and tillage influences on nitrogen availability in a Southern Piedmont corn cropping system

Author
item Schomberg, Harry
item Endale, Dinku
item Jenkins, Michael
item Fisher, Dwight

Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2011
Publication Date: 6/7/2011
Citation: Schomberg, H.H., Endale, D.M., Jenkins, M., Fisher, D.S. 2011. Nutrient source and tillage influences on nitrogen availability in a corn cropping system on a southern Piedmont soil. Biology and Fertility of Soils. 44(7):823-831. DOI: 10.1007/s00374-011-0582-0.

Interpretive Summary: Combinations of conservation tillage and poultry litter (PL) can increase crop production in southeastern USA soils compared to conventional tillage (CT) and chemical fertilizer (CF). The reason for the beneficial response is usually attributed to improved water and nutrient availability. We evaluated the effects of tillage (NT and CT) and N source (CF and PL) on soil mineral N content and crop N uptake over three years for a corn (Zea maze) cropping system at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA. Equivalent applications of available N were made to CF and PL treatments assuming 50% mineralization of the PL during the cropping season. Mineral N in the top 10 cm was measured during the corn growing season with in situ undisturbed soil cores. Soil mineral N contents varied each year and were influenced by time (period), tillage and N source. In 2003, soil mineral N content was greater in CT-CF (100 kg ha-1) than in NT-PL (95 kg ha-1). In 2004 average soil mineral was lower in CT-CF (93 kg ha-1) compared to NT-PL (140 kg ha-1). Again in 2005, average soil mineral N was lower in CT-CF (60 kg ha-1) compared to NT-CF (71 kg ha-1). Estimates of N mineralization based on differences between successive incubation period indicated that rates were generally greater for PL than for CF treatments. In 2003 the differences was almost 1 kg N ha-1 day-1. Differences between NT-PL and CT-CF were significant in 2004 and 2005. Across the three growing seasons, corn aboveground biomass was consistently greater in the NT-PL treatment than in the NT-CF and CT-CF treatments. Correlation between aboveground biomass and N mineralization was much greater for the PL than for CF (0.75 vs. 0.48). Patterns of N mineralization and total soil mineral N indicated that the distribution of N through the growing season may have more closely matched that of N corn demand. Results indicate that NT management may enhance N availability in systems using PL as a nutrient source compared to CT and CF.

Technical Abstract: Combinations of conservation tillage and poultry litter (PL) can increase crop production in southeastern USA soils compared to conventional tillage (CT) and chemical fertilizer (CF). The reason for the beneficial response is usually attributed to improved water and nutrient availability. We evaluated the effects of tillage (NT and CT) and N source (CF and PL) on soil mineral N content and crop N uptake over three years for a corn (Zea maze) cropping system at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA. Equivalent applications of available N were made to CF and PL treatments assuming 50% mineralization of the PL during the cropping season. Mineral N in the top 10 cm was measured during the corn growing season with in situ undisturbed soil cores. Soil mineral N contents varied each year and were influenced by time (period), tillage and N source. In 2003, soil mineral N content was greater in CT-CF (100 kg ha-1) than in NT-PL (95 kg ha-1). In 2004 average soil mineral was lower in CT-CF (93 kg ha-1) compared to NT-PL (140 kg ha-1). Again in 2005, average soil mineral N was lower in CT-CF (60 kg ha-1) compared to NT-CF (71 kg ha-1). Estimates of N mineralization based on differences between successive incubation period indicated that rates were generally greater for PL than for CF treatments. In 2003 the differences was almost 1 kg N ha-1 day-1. Differences between NT-PL and CT-CF were significant in 2004 and 2005. Across the three growing seasons, corn aboveground biomass was consistently greater in the NT-PL treatment than in the NT-CF and CT-CF treatments. Correlation between aboveground biomass and N mineralization was much greater for the PL than for CF (0.75 vs. 0.48). Patterns of N mineralization and total soil mineral N indicated that the distribution of N through the growing season may have more closely matched that of N corn demand. Results indicate that NT management may enhance N availability in systems using PL as a nutrient source compared to CT and CF.