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Title: N response of no-till dryland winter triticale forage

Author
item Vigil, Merle
item Poss, David

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2016
Publication Date: 5/16/2016
Publication URL: https://handle.nal.usda.gov/10113/62778
Citation: Vigil, M.F., Poss, D.J. 2016. N response of no-till dryland winter triticale forage. Communications in Soil Science and Plant Analysis. 47(9):1117-1127.

Interpretive Summary: Triticale Forage is grown on 9.6 million acres worldwide. The forage-yield response to fertilizer nitrogen (N) of Triticale is impressive on soils that are deficient in plant available N. Our objective was to quantify the forage yield response of dryland winter triticale to applied fertilizer N and to N found in the soil at planting time (residual soil nitrate–N; (NO3-N)). A second objective was to develop the mathematical equations (regression equations) that describe and represent the yield data based on both applied N and residual soil nitrates-N. A final objective is to use the equations to calculate economic optimum N rates for this crop (EONR). Winter triticale was direct seeded no-till into wheat or millet stubble for four years at the USDA-ARS Central Great Plains Research Station. In each experiment (1994-95, 2006-07, 2008-09 and 2009-10) just prior to planting, the soil was sampled for NO3-N. Replicated field plots were top-dressed with 0, 22, 34, 67, 90, 101 or 135 kg of N fertilizer per ha as urea-N. Yield and total biomass N was then measured in each plot in late spring each year. Yields and yield response to applied and residual N was variable from year to year. Much of the variability could be attributed to precipitation received each year. A relative yield N response equation fitted to all four years of data was able to explain 93% of the variability in yield as a function of total available N. That equation provided reasonable EONR estimates that matched 87% of the EONRs calculated for individual years. More importantly the equation allowed the calculation of optimum N fertilizer rates that were flexible to hay yield, hay price and fertilizer N costs. This manuscript provides farmers with a practical useable and flexible tool for making fertilizer management decisions for triticale hay production.

Technical Abstract: Triticale’s forage-yield response to fertilizer nitrogen (N) is impressive on soils testing low in available N. Our objective is to quantify the forage yield response of dryland winter triticale to applied N and to residual NO3-N. A second objective is to fit the yield data to a regression equation based on both applied N and residual soil nitrates and use the fitted equation to calculate economic optimum N rates for this crop (EONR). Winter triticale was direct seeded no-till into wheat or millet stubble for four site years at the USDA-ARS Central Great Plains Research Station. In each experiment (1994-95, 2006-07, 2008-09 and 2009-10) just prior to planting, the soil was sampled for NO3-N. Replicated field plots were top-dressed with 0, 22, 34, 67, 90, 101 or 135 kg of N fertilizer per ha as urea-N. Yield and total biomass N was then measured in each plot in late spring each year. Yields and yield response to applied and residual N was variable from year to year. Much of the variability could be attributed to precipitation received each year. A relative yield N response equation fitted to all four years of data was able to explain 93% of the variability in yield as a function of total available N. That equation provided reasonable EONR estimates that matched 87% of the EONRs calculated for individual years.