No‐Till Row Crop Response to Starter Fertilizer in Eastern Nebraska II. Rainfed Grain Sorghum

Abstract

Early grain sorghum [Sorghum bicolor (L.) Moench] plant growth is often slowed by cool soil temperatures in no‐till production systems. This inhibitory effect may be reduced through use of starter fertilizer with a grain yield response. Twelve trials were conducted in southeastern Nebraska to determine sorghum response to different starter fertilizer nutrient combinations and placement methods at different topographic positions within locations. Soil orders at trial sites included Mollisols, Alfisols, and an Entisol. Placements of N + P and N + P + S in furrow, over the row, and 50 mm deep and 50 mm to the side of the seed (50 by 50 mm) were compared for effects on early growth, grain yield, and grain water content. Treatment by topographic position interaction effects occurred at one location for early growth and grain water content and at three locations for yield. The mean effect of starter fertilizer treatments was a 48% increase in early growth in five of seven trials with low soil test P (STP; Bray‐P1 ≤ 15 mg kg−1); however, yield and grain water content responses to starter were not related to STP. Including S in the starter fertilizer did not increase yield. Placement effects were not consistently significant. The frequency and magnitude of no‐till grain sorghum response to starter fertilizer were not sufficient for starter fertilizer use to be profitable, irrespective of STP and topographic position.