KEY TAKEAWAYS
- Banding nutrients closer to rows can minimize risk of loss and increase nutrient availability.
- Hybrids respond differently to precision fertilizer placement.
- NK is committed to providing information on best placement and management of hybrids based on field research.
Hybrids respond differently to management practices such as seeding rate, fertility, sidedress nitrogen, and foliar-applied fungicide. Understanding how hybrids respond to these management practices can help farmers not only select the right hybrids for their farm, but also aid in management decisions throughout the growing season.
Table 1. Visual image and table showing the amount of nutrients applied with the planter and the placement of the fertilizer in relation to the seed.Hybrid Response to Fertility Trial
The NK Agronomy Research Team conducted trials to characterize hybrids for their response to enhanced fertility practices utilizing precision fertilizer placement.
A total of 36 NK® corn hybrids ranging in relative maturity (RM) between 80 and 118 day were evaluated across 10 locations throughout the Midwest. At a given location there was 14 to 18 hybrids planted depending on the RM range for the location.
Figure 1. Planter used to apply fertilizer in-furrow, 2×2×2, and surface dribble.
Each hybrid was tested under two fertility programs: base versus incremental zone-placed fertilizer programs. The base program was the grower’s normal fertility program at each location. In most cases it was broadcast phosphorus (P) and potassium (K) in the fall followed by a single or split application of nitrogen (N) in the spring. Some locations received manure as the bulk fertility needs. The incremental zone-placed fertilizer program included additional precision placed fertility added to the base program.
Precision fertilizer placement was completed using a research planter that can apply 1) seed-safe fertilizer in-furrow on the seed, 2) higher rates of fertilizer in a 2×2×2 placement, 3) dribble sulfur and nitrogen next to the row on the soil surface behind the planter (Figure 1). AVAIL® T5 was added to the 2x2x2 fertilizer and iNvigorate® was added in-furrow to maximize nutrient use efficiency. Nutrients, rates, and placement of fertilizer for zone-placement components were consistent across all locations and are outlined in Table 1.
Locations varied in soil fertility levels (Table 2). All locations had adequate P and K soil test levels except Slater, IA which was low in K fertility. Sulfur (S) soil test values were very low to low and zinc (Zn) was adequate to high for all locations. The base rate of N applied was the local grower management choice which ranged between 150-200 lbs/acre of N.
Table 2. Soil test values for 10 locations across the Midwest.
Response to Precision Fertilizer Placement
On average across all hybrids and locations, incremental zone-placed fertilizer increased yield by 10 bu/acre over the base fertility program. The yield response was between 4 and 18 bu/acre depending on the location (Graph 1). Corn grown at 7 out of the 10 locations had a statistically significant yield response to incremental zone-placed fertilizer. Hybrids at Slater, IA experienced the greatest response to the precision placed fertilizer yielding 18 bu/acre more than the base program. The large response was likely driven by low soil test values for multiple nutrients including K and S. The other locations had sufficient P and K soil test values, so it is suspected that many of the responses were driven from additional N and S. Clinton, IL was planted early on April 26 into cool soils where S mineralization was likely reduced. In the base fertility plots, plants were visually yellowing near the new growth, a common symptom of early-season S deficiency (Figure 2). Whereas, in the plots with incremental zoned-placed fertility, plants were greener and taller likely from the 17 lbs/acre of S applied with the planter along with additional N.
Graph 1. Effect of incremental zone-placed fertility on yield averaged across hybrid at 10 Midwest locations in 2023.
 compared to base fertility program (left) at Clinton, IL in 2023.JPG)
Figure 2. Corn growth response to incremental zone-placed fertilizer (right) compared to base fertility program (left) at Clinton, IL in 2023.
Not All Hybrids Respond the Same
There was a large range in hybrid response to incremental zone-placed fertilizer between the different locations. Hybrid response ranged from 0 to 17 bu/acre at Janesville, WI and 2 to 37 bu/acre at Slater, IA.
Every hybrid was not at an equal number of locations. In addition, some locations were overall more responsive to fertility than others meaning solely comparing the average response between hybrids is not a fair comparison in determining the responsiveness of hybrids. It is important to compare hybrids against each other within a location. The NK Agronomy Research Team evaluates hybrid response to incremental zone-placed fertility using two main criteria. First, the hybrid response at each location is compared to the average response of all the other hybrids that were at that location. Second, the consistency of that hybrid response across all the locations is noted. Hybrids that consistently show a response above the location average are typically characterized as more responsive hybrids. Hybrids that show an average or below average response, or the response is inconsistent across locations is typically considered a less responsive hybrid. A hybrid characterized as less responsive does not mean it will not respond to incremental zone-placed fertilizer, it simply means on average it responds less than other hybrids in the portfolio.
For example, Graph 2 illustrates how two short-season hybrids respond differently. NK0295 and NK0367 brands were both planted at the same 5 locations. NK0367 brand consistently showed a greater response across all 5 locations compared to the other hybrids at each location. On average, it was 8 bu/acre more responsive compared to all hybrids at those locations. In comparison, NK0295 brand was more responsive than the average hybrid at 3 of the 5 locations. On average, it was 1 bu/acre more responsive than all other hybrids. Graph 3 illustrates the same concept with full-season hybrids NK1040 and NK1188 brands. NK0367 and NK1040 brands are characterized as more responsive hybrids to precision fertilizer placement compared to NK0295 and NK1188 brands which are moderately responsive.
Summary
Crop nutrition is the foundation to achieving maximum genetic yield potential. Many fields have untapped yield potential that can be uncovered utilizing precision fertilizer placement. Placing nutrients near the root zone increases nutrient availability to the plant and sets the yield trajectory for the rest of the growing season.
There can be a large range in hybrid response to incremental zone-placed fertilizer. NK works hard to have a deep understanding of our hybrids. It is critical to know what environments a given hybrid thrives in, but also how to manage each individual hybrid. Results from these hybrid characterization research studies provide growers with knowledge to get the most out of their seed investment.
Graph 2. Yield response of hybrids NK0295 and NK0367 brands to incremental zoned-placed fertilizer compared to the average response of all other hybrids combined at each location.
Graph 3. Yield response of hybrids NK1040 and NK1188 brands to incremental zoned-placed fertilizer compared to the average response of all other hybrids combined at each location.