Plant accurately, plant in narrower rows, apply fewer (correct) nutrients accurately, and a dryland yield approaching 19 tons per hectare is not just a theoretical figure.
Dr Eric Winans, a specialist in grain production and chief researcher at Brandt’s research farm in Springfield, Illinois, US, shared the secrets of their record yields with South African maize and soybean producers at Elim Fertiliser, Brandt and Landbouweekblad’s maize and soybean congress at Sun City last year.
Winans, standing in for Randy Dowdy who required urgent heart surgery before the congress, said he and his team examine aspects such as the latest germplasm, cultivation practices and soil fertility in their high-yield systems. They supplement this with a network of trials across the US in collaboration with universities and third-party research personnel, and on-site trials with farmers such as those mentored by world record holders for maize yields like David Hula and Dowdy.
In the US, Hula is known as “King David” and he is the world record holder for maize yields with a harvest of 41 t/ha achieved with irrigation in 2023.
In a virtual presentation, Hula confirmed what Winans had told congress delegates. Both are strong proponents of Dr Fred Below’s seven management factors for record maize production.
Dr Below, an agricultural scientist, gained fame in 2008 for what he called “the seven wonders of the maize yield world”.
When correctly applied, farmers could achieve yields of 16,3 t/ha in dryland systems, he said.
“Today, several of our best farmers regularly achieve 16,3 t/ha. So, over the past three, four years, I’ve had the privilege to assist Dr Below in fine-tuning the seven wonders, and now we have the seven wonders of 18,9 t/ha,” Winans told farmers at the congress at Sun City.
“As far as high-yield management is concerned, we are close to the point where we are going to close the so-called base yield gap. This is the difference between whatever your theoretical yield potential is in a given area, and what is possible if you rely on the seven wonders formula.”
With the correct management, the yield potential of modern germplasm is high.
“Just look at David Hula’s record maize yield. The dryland world record is 26,5 t/ha. Yet research shows that many of the dryland areas in America and around the world do not even realise 60% to 70% of the actual theoretical potential yield.”
The same applies to irrigated production. The difference between Hula’s record and the American average under irrigation is 11,1 t/ha.
Get your soil right
Before entering the high-yield world, according to Winans, a few prerequisites must be in place, and the most important are soil structure and drainage.
“Drainage is really important. Illinois would be a swamp if it weren’t for good drainage. You need to get water off your land in areas where it doesn’t drain properly.”
Regarding soil structure, he said farmers should building soil carbon through the use of cover crops.
“This can improve your soil health and structure and combat weeds and diseases.”
Then you need to make sure you start with a clean slate. This includes proper soil pH and the standard soil tests for nitrogen (N), phosphorus (P) and potassium (K). “With those basics or prerequisites, we can start applying the principles of 18,9 tons.”
Healthy management principles
The first and most important factor that affects yield, according to Winans, is the weather, closely followed by fertility. “These two components by far have the biggest impact on your yield in any given year.”
One of the biggest takeaways from the Brandt research farm is that the planting date must be as early as possible. “It’s about maximising the entire growing season.”
But ultimately, the weather determines the planting date.
“If you talk to David Hula or Randy Dowdy, they will tell you regardless of the crop, you must ensure you have fast, uniform emergence and rapid vegetative growth. So, if you plant one to three weeks late, you’ve already limited yourself and may have lost 80% of the ultimate yield potential.”
Next is the choice of a maize cultivar. “There are many different cultivars. So, choose what works in your management set-up. Think about planting density, crop rotation and cover crops, cultivation practices, pest and disease control, as well as the biological products you prefer.”
Narrower row spacing
Another management factor farmers have a lot of control over is plant density.
The average planting density in America is 79 000 plants per hectare, with 76 cm row widths. “Yield is about plants per hectare, seeds per plant, and then the weight of each maize kernel,” Winans said. Of these, the number of plants per hectare is the only one the farmer has control over. “By making a wrong decision, you can limit the yield potential on planting day itself.”
With 76 cm row widths, Winans observed in his research that when he increased plant density from 74 000 plants/ha to 75 000, he lost 1-2% of individual plants’ root mass. In a planting of 104 000 plants/ha, there was a 20% reduction in root mass.
“The flip side of that is everything was planted in 76 cm rows, but we also did a lot of research on 51 cm rows.”
The obvious advantage of narrower row spacing was increased light interception early in the season but also plants that closed the row quickly with a leaf canopy.
With 51 cm row spacing, Winans had almost the same number of plants per hectare as in the 76 cm high-density planting, but he planted more rows per hectare, reducing plant competition. Additionally, the root mass for this planting and the 76 cm rows at 94 000 plants/ha were also about the same.
“So, we can tolerate a higher plant density if we narrow the row spacing because we get back 20% to 25% of that root mass at any given plant density.”
With the 76 cm rows, there was no significant yield advantage at a higher plant density of 109 000 plants/ha. However, there was a big jump in yield from 18 t/ha to 18,5 t/ha in the narrow row system.
“I foresee a movement towards narrower plant rows in the future, precisely because it means more maize heads per hectare.”
Correct application of fertiliser
More plants per hectare and the higher yield potential may necessitate a change in how farmers apply fertiliser.
According to Winans, Illinois soils have high organic content and it’s not necessary to replenish NPK every year. In high-yield production systems, farmers determine how much of these elements the harvest has taken from the soil then replenish them.
Producers pursuing high production, however, become more specialised in meeting their plants’ needs. The best sources of fertiliser, correct quantities at the right times and proper placement become crucial for success.
This is also where the use of biological agents becomes important. Agents such as living bacteria or enzymes that enhance the effectiveness of fertiliser or expedite nutrient uptake in the plant, or make minerals and organic nutrients already present in the soil available to plants, come into play.
Winans believes biological agents will play an even more important role in long-term soil building. “With record yields, it’s not necessarily about using more inputs and more products, but about the more efficient use of these products. The right application practices can make a huge difference.
Application
“We place some fertiliser directly in the seed furrow, especially something like phosphorus and zinc that contribute to rapid and uniform emergence. Then we place fertiliser with a higher salt index, like urea-ammonium nitrate or ammonium thiosulphate, nitrogen, and other sulphur-based fertiliser substances, a safe distance away from the seed with the planter. About two inches (5 cm) away and two inches deep in the soil surface is a good measure.”
Once you reach the grain-filling stage, there is nothing you can do to change the yield potential, Winans said. All you can do at that point is protect it. At this stage, it’s essential to help plants photosynthesise optimally for a longer time. Then, key elements such as nitrogen, phosphorus, potassium, sulphur, zinc and boron become crucial. (See table below.)
Please note: Farming conditions in the US and South Africa differ significantly, especially concerning organic content and rainfall. Therefore, it’s advisable to conduct small-scale experiments on your farm before making significant changes.
