The 2015 growing season at the Walcott research farm was wetter and cooler than normal. June and July were particularly wet, with about 14.5 inches of precipitation falling in these two months alone. The wet weather caused periodic ponding and nitrogen loss which was noticeable in the corn, particularly in the lowest laying parts of the farm and during the last several weeks of reproductive development. Despite the wetter than normal weather, corn yields were good, averaging 213 bu/ac. This is 26% higher than the average corn yield in eastern, IA (avg. eastern IA corn yield = 169 bu/ac).
Soybeans were however the champions, yielding 72 bu/ac on average, and is 37% higher than the average soybean yield in eastern, IA (avg. eastern IA soybean yield = 52 bu/ac).
- A full rate of Instinct II (37 oz/ac) applied with 130 lbs/ac of nitrogen as a pre-plant dribble band, UAN application increased corn yields a whopping 19.1 bu/ac.
- Using Instinct II at either a half or full rate (19 or 37 oz/ac) with 50 lbs of nitrogen as UAN at side-dressing (around V-6) also increased corn yields by about 6.5 bu/ac.
- When DKC 61-54 and M2A749 were allowed to naturally cross, they produced yields that were 10.6 bu/ac higher than the solid seeded M2A749 hybrid, and 8.9 bu/ac higher than the solid seeded DKC 61-54 hybrid.
- When a different Mycogen (M2V709) hybrid was allowed to cross with DKC 61-54, the plots with the hybrid mix yielded similarly to both the M2V709 and DKC 61-54 solid seeded hybrids.
- After analyzing all 7 years of Ken Washburn’s soybean micronutrient trials it was found that manganese sulfate applied at 1.3 lbs/ac with fall dribble banded P & K increased soybean yields 1.95 bu/ac over the untreated check (Pr .0188). At $9.00 soybeans, and after subtracting the $4.50 manganese sulfate cost, this resulted in a net profit increase of $13.05 per acre.
Instinct II – Corn
No surprise, in my mind, given the year, that 37 oz/ac of Instinct II applied with 130 lbs/ac of nitrogen as spring pre-plant dribble band, UAN application increased corn yields a whopping 19.1 bu/ac. Moreover, using Instinct II at either a half or full rate (19 or 37 oz/ac) with 50 lbs of nitrogen as UAN at side-dressing (around V-6) also increased corn yields by about 6.5 bu/ac.
So would we expect yield increases as large as these every year from Instinct II? The answer is no; in some years, particularly those that are dry, we might expect only small or even no yield increases from using Instinct II.
Because Instinct II is a nitrification inhibitor, it temporarily stops the conversion of ammonium (NH4+) to nitrate (NO3 –)—the nitrogen form that is highly susceptible to loss via leaching and denitrification. Therefore, in wet years (like 2015) or on wet farms—or on sandy farms in normal years—we would expect Instinct II to increase yields and profitability.
Using the 19.1 bu/ac yield increase observed in 2015 tells us that at $4.00 corn and $12.00/ac Instinct II cost we could go for 6 consecutive years with no yield increase from Instinct II and still break even. So like many agronomy inputs, Instinct II is not a silver bullet, but is a product that does what it’s advertised to do (slow nitrification) and can reduce production risk and increase long term profitability.
Hybrid Outcrossing – Corn
The idea here was to let two hybrids with a similar number of GDU’s to silking and pollen shed naturally cross by planting 50% of each in the same plot.
When DKC 61-54 and M2A749 were allowed to naturally cross, this produced yields that were 10.6 bu/ac higher than the solid seeded M2A749 hybrid, and 8.9 bu/ac higher than the solid seeded DKC 61-54 hybrid. When a different Mycogen (M2V709) hybrid was allowed to cross with DKC 61-54, the plots with the hybrid mix yielded similarly to both the M2V709 and DKC 61-54 solid seeded hybrids.
These results are similar to other experiments like this in that mixing hybrids did not always increase yields relative to the solid-seeded parents. Yield increases from mixing hybrids that require a similar amount of GDU’s to silking and pollen shed will be dependent on how genetically related the two hybrids are that are allowed to naturally cross.
Manganese – Soybeans
In my 4.5 months here at Liqui-Grow, one of the more common questions has been, “Does manganese increase soybean yields?” This is a good question given that in some universities’ studies manganese does increase soybean yields, but in others it does not. Thankfully, Ken Washburn—now retired Liqui-Grow Agronomist—has been diligent in his pursuit to answer this question.
Running the same randomized replicated trial—replicated 4 or 5 times—on micronutrients for soybeans since 2008 gives us the ability to take a good look at this question over years and different soybean varieties.
After finding the handwritten, raw data in the filing cabinets in my office, I submitted this information to a statistical analysis. Why? Statistics are a good way to understand if the treatment effects—in this case, the effects of manganese on soybean yields—are, in fact, real or just a reelect of natural variation present within fields.
My finding was that manganese sulfate applied at 1.3 lbs/ac with fall P&K increased soybean yields 1.9 bu/ac over the untreated check (P < 0.0188), and, statistically speaking, we are very confident that this did happen. At $9.00 soybeans, and after subtracting the $4.50/ac manganese sulfate cost, this resulted in a net profit increase of $13.05/ac.
I also might add that the Walcott Research Farm is not a place where we traditionally think manganese deficiencies would occur. Based on what we know today, manganese deficiencies are more likely in soils with pHs above 7, in organic soils, and soils that are sandy. However, the Walcott farm fits none of these categories. This data set supports the idea that perhaps manganese deficiencies are more wide spread than we think.