Digital Corner

by Dale Cowan

The Secret of Soybean High Yield Secrets

Ever year it seems we attend agricultural conferences and evitability there is a session on “Secrets to High Yield Soybean.” Perhaps the biggest secret is the soybean plant is intrinsically a high yield potential plant. Often references can be found to theoretical yields in a stress-free environment of 120 to 160 bushels per acre. Indeed, the top soybean yield in 2023 was 203 bushels per acre by Alex Harrell from southwest Georgia. A different sort of growing environment with group 4 variety under irrigation and a weekly evaluation of nutrient status by plant tissue and combination of fertigation and foliar feeding with a host of products. The most interesting part was the harvest population of 77,000 plants per acre.

The point of these yield competitions is to show maximum potential not necessarily economics. Although practices do get evaluated and those that are practical do get applied to commercial fields over time.

The biggest take home point and why soybean yields are not optimized is due to combination of abiotic and biotic stresses that occur in a random pattern throughout the growing season often at critical growth stage that reduce potential yields. Participants in these yield competitions make it a point to alleviate any stress they see developing in the crop at any time during the growing season. This is a prerequisite to winning a yield competition, nothing is left to chance. What can we learn from these competitions? What do we need watch for? What are the critical growth stages that form yield?

One of the first inputs you learn from the yield competition is participants are in their fields every week observing crop development. You never know what you might learn but if you never look you never learn anything. 

High yields are often associated with soils that support high yields or have the ability to respond positively to crop inputs. The term soil health is an overarching concept to describe resilience and yield stability. Obtaining healthy soil can be a long journey. One of the approaches I have been fond of for over 40 years is the use of complex rotations (more than 2 crops), reduced tillage, wise and judicious use of crop residue, organic amendment such as manure and biosolids, including cover crops. Follow a 4 R Nutrient Stewardship plan for all nutrient sources and regular soil testing every 4 years to keep track of trends and nutrient balances. In addition, a good weed control program to track and manage for resistance development, a plant health strategy and an IPM program for insect pests. Nothing rare or outrageous here, all well-known and documented to be best management practices over the years.   

Looking at yield components that drive yield; number of pods, beans per pod and weight of the beans is where we need to focus to understand how to influence yields. Very little research has been done on these yield components in terms of factors that influence their development and what are the critical crop growth stages.  

Published research and practical experience shows that yield environments (YE) determine plant populations. Low Yield Environments (LYE) requiring higher plant densities to assure there is enough plants and leaf area to intercept as much sunlight to optimize photosynthesis and dry matter yields considering other limiting factors that come into play in LYE. Medium yield (MYE) and high yield environments (HYE) produce higher yields with lower populations. Often LYE have populations planted at 200-275K, MYE 160K – 200K and HYE planted as low as 140K to 160K. The determination of yield ranges in LYE, MYE and HYE is somewhat arbitrary. Most company seed guides usually follow a ranking of LYE <40 bushels per acre, MYE 40 to 55 and HYE 55 + bushels per acre. Individual farmers may rank their own fields differently especially if 80-bushel yields are obtained on some fields, they might say anything less than 50 bus is a LYE.  

Total seed produced correlates to yield more so than seed weight. The plant must produce pods before seeds so the correlation between pods and seeds is similar. In LYE there is less branching, less leaf area so having sufficient plants to produce enough pods and seeds is required. As we move into MYE and HYE the lower populations have more branching, more flower nodes on the main stem and more pods per plant. Regardless of yield environment the number of beans per pod changes very little and the seed weight is not highly correlated to yield as one would expect. The thousand seed weight (TSW) in some of our soybean plots ranges from 130 grams to 180 grams which equates to 3400 seeds per pound down to 2500.  

We have just begun our soybean plot harvest where we are not only tracking yields but harvest populations, pods per plant, seeds per pod and TSW. Only have a few plots off so far so really earlier in our analysis. Nonetheless here are a few numbers from the first plot. We have DK 3212XF yielding 59.8 bushels at 15.2 % moisture TSW of 180 grams, 2522 seeds per pound, final harvest population of 185k. Final seeds at harvest 9.0 million. Another variety PS3022XFN yielding 59.2 at 15.9% moisture, TSW 162 grams, 2802 seeds per pound final harvest population of 180K. Harvested seeds at 9.9 million.

The plot overall has 15 varieties with an average yield of 61.2 at 13.7% moisture and average TSW 159 grams, average seeds per pound at 2856. I can appreciate that yield components can vary quite a bit and still have similar final yields. The plot is a clay soil texture, planted May 18 fertilized according to soil test, 82 pounds of P2O5 and 47 pounds of K2O per acre, targeted population of 200K, in 7.5-inch row spacing. Once we have all of our data collected, I can share that at a later date. 

We are approaching soybean harvest in the 50% to 70% completed with some farmers finished. Yields have generally exceeded expectations. Research has shown up to 39% of yield variance is attributed to the yield environment. Yield environments influence the optimum seeding rates. Over seeding in a high yield environment may not optimize yields as lodging and increases incidence and severity of crop diseases and lowers yield potential. Conversely in a low yield environment not planting sufficient population carries a greater yield penalty. Within any given field a range of yield environments exist. Utilizing yield maps is one way to assess those environments and offer a means to do site specific seeding rates to optimize yields. 

The multi-year, normalized yield map offers insight into areas of the field that are higher and lower yielding. Forming the foundation to adjust seeding rates.

At AGRIS Cooperative, we have the system to analyze and create seeding options for soybeans. All we need is for the customer to share yield and soil test data to start us on the seeding strategy.

Choosing high performing soybean varieties is a critical step in the process. We have just started on collecting our plot data. Once completed it will be available on our website. Working with our Crop Sales Specialists who have seen our variety offerings all season long can bring a different perspective on variety performances.     

We look forward to reviewing your seed requirements and having those critical production conversations that optimize crop performance. 

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It All Starts With Seed

by Andre Coutinho

As fall arrives, we start to plan our next crop season.

Fall fertilizer has been the main subject since the wheat harvest. But as we move into fall, we need to discuss how to choose the appropriate hybrid. But how do we do this? We will discuss briefly some strategies for choosing your corn hybrids for next year.

Maturity groups

Corn growth is driven by temperature. Having that in mind, the first thing to decide is which Crop Heat Unit (CHU) range your field is located in. That means you can have different ranges for different fields depending on their location. Also, this will help you set some strategies like planting different relative Maturity hybrids to reduce risk of all hybrids flowering at the same time during a potentially stressful time and to spread out harvest risks for ear molds and standability.

Figure 4-4 Optimum Date to Seed Winter Wheat across Ontario

Yield

Yield will always be one of the factors that growers most talk about and with good reason, it drives profitability. The more you grow the more you have sell at any price. You will find many trial results of market hybrids and new hybrids to support your decision. But since yield will vary from farm to farm, you should think of trying some new hybrids in their introductory year. This way you can compare new hybrids coming and how they compare in performance to your current selections. Often, a review of agronomic practices such as fertility, especially nitrogen management, weed control and plant health programs supported by appropriate fungicide programs is also equally important. 

Disease Ratings

Most corn companies started to rank their hybrids based on susceptibility to ear molds after 2018. If you are a hog producer or any livestock producer for that matter. Reducing Gibberella ear molds and associated mycotoxins will improve animal performance. 

Positioning

Hybrids will always be classified in different ways, but two groups should be highlighted: racehorses and workhorses. A racehorse is a hybrid that will produce above-average yield if it finds good field conditions, while a workhorse is the opposite and is consistent in yield in both good and poor conditions. Use this information to evaluate the ability of a hybrid to fit your fertility management strategy and specific field conditions.

Standability

Standability and dry down should also impact your hybrid decision. Standability is key in facilitating a timely harvest and fast dry down so harvest can be begin earlier under favorable weather conditions and reduce drying costs. Allowing for timely soil sampling, fall fertility and other field management practices to occur in a timely manner.

The AGRIS Cooperative places numerous hybrid trials across our territory each year. Often, performance data needs to be supported by a trusted advisor. One that has actually seen the hybrids in numerous fields all season long and can provide that added comfort of a personal touch to support your most important buying decision, your hybrid choices.

Source: Publication 811 (Figure 1)

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