Soil Profile Nitrate Response to Nitrogen Fertilization of Winter Triticale

Abstract

Growing triticale (×Triticosecale Wittmack) as a winter crop has the potential to utilize residual NO3–N from previous crops, thus reducing its availability for leaching. Our objectives were to quantify N capture and changes in soil NO3–N levels in response to N fertilization of triticale grown following either silage corn (Zea mays L.) or soybean [Glycine max (L.) Merr.]. Field studies were conducted in 2003–2004 and 2004–2005 near Ames and Lewis, IA. Soil samples to a depth of 120 cm were collected after the corn and soybean were harvested and again after growing triticale with four rates of N fertilizer (0, 33, 66, and 99 kg N ha−1). Partial N budgets were computed using profile NO3–N before triticale planting, N fertilizer applications, plant uptake, and profile NO3–N after triticale harvest. Nitrogen capture by triticale at physiological maturity was 44 to 93 kg N ha−1 when no N was applied and was as high as 164 kg N ha−1 with addition of 99 kg N ha−1 Growing winter triticale reduced profile NO3–N by an average of 33 to 53 kg ha−1 at Ames and 46 to 53 kg ha−1 at Lewis. Winter triticale dry matter and grain yields were maximized while simultaneously capturing and efficiently utilizing soil N left from previous silage corn and soybean crops.