Agronomy
Agronomic Articles
Nobody Likes to be Manipulated…
Unless You're Wheat - Cutting Edge, Spring 2021
I’d like to start a conversation about striking the optimal balance on fertility inputs and maximizing profitability in wheat. Historically, we’ve always tried to reduce our cost per acre in an attempt to increase profitability. An alternative approach is to think in terms of cost per bushel of grain produced. One way to reduce your overall cost per bushel is to grow more bushels. This doesn’t mean that you ignore input costs, it simply means you spend money on inputs until you achieve the highest marginal return and the lowest cost per bushel. With this being said, there is a relatively new kid on the block, that, in our first year of assessment, has significantly impacted the marginal return on wheat, the new kid’s name is: Manipulator.
Backstory
We’ve been playing with fertilizer placement in our direct seeded wheat trials for several years now. Each year we’ve pushed fertility and seeding rates higher. In doing so, we’ve identified three main challenges in wheat:
- How do we determine how much nitrogen is needed to maximize yield and protein?
- How do we reduce lodging even when applying high fertility rates? and
- How do we deliver a high-yield agronomic package in a one-pass configuration without causing harm to the seed?
The nutrient that typically provides the highest return on investment and the largest increase in yield is nitrogen. The graph at right1 shows a typical yield and protein curve for wheat, although there are differences between varieties. The graph shows that as available nitrogen increases, yield and protein increases. At a certain point, however, additional nitrogen diminishes yield and protein. Our goal is to hit the top end on both curves.
For 2020, we designed a trial that looked at the effects of increasing nitrogen fertility on wheat yield and protein. All other nutrients were held constant. Our nitrogen source for the trial was 46-0-0. We seeded the plots with a 30' PHD on 10" spacing equipped with PLS™ Openers and MRB® Fertilizer Applicators. The plots were 400' by 30' and were replicated three times.
The variety we grew was Landmark. Our target plant stand was 30 plants/sq foot. To achieve this stand, the wheat was seeded at 152 lb/ac. Phosphate, potash and copper were applied in the seed row at 77 lb/ac, 50 lb/ac and 8 lb/ac respectively. Treatments included 0*, 140, 170, and 200 lb of actual N (0-419 lb of product) applied exclusively through the Mid Row Bander® Fertilizer Applicators. (*only one repetition)
We also wanted to add another variable to the trial due to the potential for lodging under high nitrogen fertility. To address the lodging concern, we treated one replicated block of the trial with a plant growth regulator (PGR). PGRs are chemicals that can be applied to plants that affect flowering, maturity, root growth or stem elongation. PGRs can be grouped into five classes: Auxins, Gibberellins, Abscisic Acids, Cytokinins and Ethylenes. The product we used in our trial is named Manipulator which is an Anti-Gibberellin. Manipulator is a plant growth regulator intended to help reduce lodging by shortening the straw and is registered for use in wheat, barley and oats. We applied Manipulator at the recommended rates by itself at the 5 leaf, 2 tiller stage.
Results:
The results closely followed the yield and protein response curve in Figure 1. Compared to the check (0 nitrogen), there was a definitive yield response to the addition of any amount of nitrogen. The yield was statistically the same between 140, 170 and 200 lb of nitrogen. However, as more nitrogen was added, the protein increased.
The Manipulator treatments showed a decrease in lodging and a significant yield increase. The block treated with the PGR was on average six inches shorter and had no lodging. The Manipulator treatments significantly increased wheat yield, although there was a slight decrease in protein. Available moisture and nutrients that would have gone into stalk development was reallocated by the plant into seed production. In addition, the treatments with Manipulator were very even in development, making it much easier to time the crop for fusarium fungicide application and desiccation.
Looking at these results, it’s a safe prediction to make that in the future, producers will try to increase yield and protein in wheat so they can lower their overall cost per bushel. This will most likely require more fertilizer and seed to be applied pushing the requirements of the seeding equipment.
In our testing this year in other plots, we used a TriMax™ Triple-Shoot System. Having three airways with three separate fans allowed us to put very high volumes of product down, without having to worry about seed burn. In the future, we plan to expand our trials by using the TriMax™ System for increasing our starter fertilizer amounts, as well as pushing the nitrogen rates. However, even though the wheat genetics have some excellent standability compared to older varieties, we will need some help from a PGR to keep the wheat standing.
To wrap up the conversation, there is a line that Producers should attempt to walk between input costs and productivity to maximize profitability. A PGR is one more tool in the toolbox that may help you achieve this in your operation, provided you can get enough product down safely at the time of seeding.