Nitrogen fertilization effects on irrigated no-till corn production and soil carbon and nitrogen

Authors: Halvorson, Ardell; JANTALIA, CLAUDIA - Embrapa

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2011
Publication Date: 7/28/2011
Citation: Halvorson, A.D., Jantalia, C. 2011. Nitrogen fertilization effects on irrigated no-till corn production and soil carbon and nitrogen. Agronomy Journal. 103: 1423-1431.

Interpretive Summary: Converting to no-till (NT) production can impact the amount of N needed to optimize corn yields and soil organic carbon (SOC) and N levels. Nitrogen fertilization impacts on irrigated, NT continuous-corn grain, stalk, cob, and stover yields, stover C and N uptake, and C:N ratios were evaluated for 11 yr on a clay loam soil. Changes in SOC and total soil N (TSN) were also monitored. Grain, stalk, cob, and stover yields increased with increasing N rate, as did N and C uptake. The C:N ratio of stalk residue declined with increasing N rate, but cob C:N ratio was not affected. Nitrogen fertilization increased SOC and TSN levels in the 0-7.6, 0-15.2, and 0-30.4 cm soil depths. Rate of change in SOC and TSN mass was lowest without N application. A decline in the soil C:N ratio with time was observed as TSN appeared to increase more rapidly than SOC. Under irrigated, NT continuous corn production, N fertilization optimized grain and residue yields, with the enhanced benefit of increased SOC and TSN levels in the semi-arid central Great Plains. Removal of cobs or partial stover residue as a cellulosic feedstock for ethanol production appears possible without negative effects on soil quality under irrigated, NT corn production.

Technical Abstract: Converting from conventional tillage (CT) to a no-till (NT) production system can affect N requirements for optimizing corn (Zea mays L.) yields while enhancing soil organic carbon (SOC) and N levels. Nitrogen fertilization impacts on irrigated, NT continuous-corn grain, stalk, cob, and stover yields, stover C and N uptake, and C:N ratios were evaluated for 11 yr on a clay loam soil. Changes in SOC and total soil N (TSN) were also monitored. Grain, stalk, cob, and stover yields increased with increasing N rate, as did N and C uptake. The C:N ratio of stalk residue declined with increasing N rate, but cob C:N ratio was not affected, with an average stover C:N ratio of 68 at the highest N rate. Nitrogen fertilization increased SOC and TSN levels with average SOC and TSN mass rate gains with N application of 0.388, 0.321, and 0.160 Mg SOC ha-1 yr-1 and 0.063, 0.091, and 0.140 Mg TSN ha-1 yr-1 in the 0-7.6, 0-15.2, and 0-30.4 cm soil depths, respectively. SOC and TSN mass rate changes were lower without N application. Increases in TSN appeared to be more rapid than SOC, resulting in a decline in the soil C:N ratio with time. Under irrigated, NT continuous corn production, N fertilization optimized grain and residue yields, with the enhanced benefit of increased SOC and TSN levels in the semi-arid central Great Plains. Removal of cobs or partial stover residue as a cellulosic feedstock for ethanol production appears possible without negative effects on soil quality under irrigated, NT corn production.