No-Tillage Corn Hybrids Response to Starter Fertilizer

Starter fertilizer can help improve early-season corn (Zea mays L.) growth, especially under cool soil conditions, but corn hybrids may differ in their response to starter fertilizer. This study evaluated the response of corn hybrids to complete starter fertilizers applied under no-tillage, dryland conditions. Nine site-years of data were collected from 1993 through 1995 at four geographical locations: Doon (NW1) in extreme NW Iowa, Sutherland (NW2) in central NW Iowa, Lewis (SW), and Crawfordsville (SE). The soil types were as follows: NW1— Moody silty clay loam (fine-silty, mixed, superactive, mesic Udic Haplustolls); SW—Marshall silty clay loam (fine-silty, mixed, superactive, mesic Typic Hapludolls); SE—Nira silty clay loam (fine-silty, mixed, superactive, mesic Oxyaquic Hapludolls); and NW2—Primghar silty clay loam (fine-silty, mixed, superactive, mesic Aquic Hapludolls). Each hybrid was planted with and without starter fertilizer applied 2 in. to the side and 2 in. below the seed at planting. Hybrid-by-starter interactions were not significant for early-season dry matter production, nutrient concentration, or grain yield in any of the site-years, indicating that the hybrids, on average, responded similarly to starter fertilizer. Starter fertilizer increased early- season growth significantly in four of eight site-years and grain yield in seven of nine site-years. Average grain yield increases ranged from 4 bu/acre at the NW2 site in 1993 to 18 bu/acre at the SE site in 1995. Yield increases were not significant either year at the NW1 site. Increases in dry matter yield ranged from 18.7% at the SW site to 97.8% at the SE site in 1994. Starter fertilizer affected tissue K concentration to a much larger degree than it did N and P concentrations especially at the SE site. The results suggest that starter fertilizer will likely benefit no-tillage corn for most hybrids in the northern corn belt even on soils with adequate P and K. Research QuestionNo-tillage systems have become attractive options for many corn producers because of potential on-farm energy savings and the advantages of soil and water conservation. Residue cover on no-tillage systems can result in cooler and wetter soils especially at time of planting. Cool soil temperatures can reduce early-season growth, nutrient uptake, and yield of crops. However, starter fertilizers placed within the rooting zone of seedlings have been shown to improve early-season corn growth and development due to better availability of the nutrients. Responses to starter fertilizers can vary among corn hybrids since they may differ in rooting characteristics, uptake and utilization of nutrients. The objective of this experiment was to evaluate the response of different corn hybrids to starter fertilizer in no-tillage systems. Literature SummaryNitrogen and P are considered to be the essential ingredients in starter fertilizers. Some recent studies that have evaluated corn and grain sorghum response to N-P starter fertilizers in no-tillage environments, suggest hybrids respond differently to the starter fertilizer. Significant hybrid ×starter interactions were reported in warmer climates, indicating that the starter fertilizers improved the yields of some corn and grain sorghum hybrids but not others. Several studies have demonstrated the benefits of N-P starter fertilizer for no-tillage or conventional tillage corn in warmer climates, but little information is available on the differential response of no-tillage corn hybrids to complete starter fertilizer in cooler climates. The study evaluated the response of corn hybrids adapted to the midwestern US to starter fertilizer applied under no-tillage, dryland environment. Study DescriptionNine site-years of data were collected from sites at Iowa State University research farms near Doon (NW1), Lewis (SW), Crawfordsville (SE), and Sutherland (NW2) from 1993 through 1995. Soil test P levels were high at all sites except SW. Potassium levels all years at the SE site and in 1994 at the NW site were in the medium range so fertilizer K was broadcast before planting. Starter fertilizer amounts, plot size, and hybrids varied slightly among sites. Each of several hybrids was planted with and without complete starter fertilizer applied in a band 2 in. to the side and 2 in. below the seed at planting. All sites were planted using no-tillage practices, and each year the preceding crop was soybean. corn response to starter fertilizer in terms of early-season growth, nutrient concentrations, and grain yield was measured at most of the sites. Planting dates varied depending on weather but planting was completed before 20 May each year. Applied QuestionsDid the corn hybrids respond differently to complete starter fertilizers in no-tillage environment? Should producers manage hybrids differently with respect to starter fertilizer application? The hybrids used in this study did not respond differently to starter fertilizer at any location in any year as evidenced by the lack of significant hybrid-by- starter fertilizer interactions. We do not recommend that producers in the northern corn belt manage these hybrids differently with respect to complete starter fertilizers. How does complete starter fertilizer affect early-season plant growth, nutrient uptake, and grain yield of no-tillage corn in a cold climate? Starter fertilizer increased early-season growth significantly in four of eight site-years and grain yield in seven of nine site-years. Starter fertilizer also increased whole plant P concentrations in one site-year, N concentrations in two site-years, and K concentrations in four of eight site-years. When averaged across hybrids, grain yield increase from starter treatments for individual site- years ranged from 4 bu/acre at the NW2 site in 1993 to 18 bu/acre at the SE site in 1994. Increase in dry matter yield ranged from 18.7% at the SW site in 1995 to 97.8% at the SE site in 1994. Grain yield increases were consistent for all sites except the NW1 site. RecommendationsResults of this study suggest that complete starter fertilizer will likely be beneficial in no-tillage corn in the northern corn belt even on soils where P and K are considered to be adequate.