Six Keys to High Yield Soybeans
As we look to drive soybean yields higher, we realize that many of the fertility recommendations used in recent history, are based off research done in the middle of the past century. Do today’s genetics require different fertility recommendations? I’ll answer that in this article. There are fundamentals in agronomy that do not change, as well as factors that change over time, and we’ll discuss both below.
When I think of keys to success in high yield soybeans, I think of 6 areas of focus.
We all know the biggest variable is often the weather, and we think there is nothing we can do about it but is there? Well, I’ll touch on that in a bit when we get to planting dates. We do know that one of the most critical times for a weather effect on yield is during the pod fill stage of growth. The final 2-3 weeks of pod fill determines around 50% of the yield for the season. Moisture stress, heat stress, or lots of cloudy days during pod fill will impact yields.
Planting dates are something more growers are paying attention to. We know that soybeans are a light-sensitive crop, and if we can get the crop to flower during the longest days of the year, late June to early July, we will have an opportunity to increase pod set. Planting in late April or early May sets you up to flower during the longest days of the year. This timeline also helps us to avoid flowering during the hot days of August, reducing the chance of pod abortion. In this way, we can impact the weather’s effect on the crop.
Adequate nutrient availability is key to high yields. N-P-K and S are all very important as well as key micronutrients.
To provide adequate N, we must first get great nodulation. High levels of N availability in the soil can decrease nodulation, which can negatively impact grain fill during the reproductive stages. Some studies are suggesting that foliar applied N can be helpful at R2-R3, specifically when yields exceed 75-80 bu/acre. Soybeans utilize the equivalent of 4-5 lbs. of N for every bushel produced, and at very high yield levels, we may be restricted by how much nutrient flow we can actually move from the root and through the plant to support yield.
Are you focused on Phosphorus availability? Did you know that the need and uptake of Phosphorus increases each day from germination out through the next 70-80 days? Have you considered that with earlier planted soybeans and cooler ground conditions there could be a benefit to having more readily available Phosphorus?
We all know that Potash is vital to high yield soybeans, and that maximum uptake of Potassium begins to occur about 40 days after planting (or just before R1) and continues to increase for the next 40-50 days, (through R5). The soybean plant takes in 3 lb. of Potash per acre, per day, during these stages of growth. This is often a time when growers apply small amounts of foliar K to maximize nutrient availability to the plant.
Zinc is vital to early plant growth and is key to chlorophyll production within the plant. Boron helps the plant produce protein and is especially needed during the vegetative and flowering stages of growth, pulling nutrients through the plant to the point where cell division and growth occurs. Manganese plays an important role in photosynthesis, and since soybeans are a light-sensitive crop, soybeans are more sensitive to Manganese deficiency than many other crops. Manganese also supports the production of chlorophyll within the plant.
As you consider nutrient availability, it is important to remember that different soil health, soil types, soil pH, tillage practices, and soil moisture content all contribute to actual plant accessible nutrients. Finding ways to bridge the availability gaps will set you up for increased yield potential. Test your soils frequently and utilize tissue samples as needed to identify key fertility issues that you can address to build yield. PowerAG has several products to use in soybeansthat you may want to consider such as MegaPower MP, HarvestPower MP, BorPower, PK Power, just to name a few.
Plant breeding and technology have greatly increased the opportunity for higher yields. Several researchers together with folks at the University of IL recently did a study called, “Modern Soybean Varieties Nutrient Uptake Patterns.” In their research they point out that today’s genetics require higher nutrient accumulation of N, P, Mg, and Ca by up to 18% to support higher yields.
I’ve seen growers produce 100 bushel per acre soybean yields on both 7″ and 30″ row spacing, so who’s right? Either row spacing has merit, depending on your growing conditions, disease pressure, fertility, and date of planting. There are good reasons to choose either. I suggest that more important than the spacing discussion is the precision with which you plant your crop. Are you getting great seed-soil contact? Are you getting uniform planting depth and coverage? I suggest stand counts between 140-165,000 plants per acre if you desire to achieve 100 bushel beans or higher. I summarized the average plant populations of yield contest winners here in PA, and the average stand counts usually are in the 155-165,000 ppa range.
The use of seed treatments has increased and become a great tool to fight off seedling disease issues and increase seedling populations. Targeting pests where needed and diseases with a foliar program is recommended where disease thresholds justify the crop protection investment.
Although you’ve probably heard all these tips mentioned before, the growers who pay attention to details in all these areas, are most likely to achieve higher yields.
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