Enhancing Crop Yields

After a somewhat late start, crops are starting to thrive. While the temperatures have been hot, most farmers having been getting some rain. Generally, rain (in moderation) makes grain! Overall crops are looking good but may be about 1-2 weeks behind in maturity. The first part of August may turn slightly cooler which helps crops grow and improve yields.

To get the highest yields, crops require certain nutrients. Most plant nutrient nutrients are processed by soil microbes. Soil microbes thrive on fluctuating wet and dry periods. Right after a nice rain, you may notice crops have a more intense green color. That’s soil microbes supplying nutrients to your crops. In late July and August, these rains may be million-dollar events for the farmer. As far as temperature, crops grow best when day-time temps stay below 85-87°F with night-time temps around 70°F.

Many farmers are now spraying their crops with fungicides to maintain or enhance yields. Some are adding micronutrients. Micronutrients make up less than 2% of crop fertilizer needs but they greatly increase biological activity associated with growth and yield. Here are a few micronutrients that can pay off greatly.

While most nutrients are most cheaply applied in the row or even broadcast, foliar sprays can be applied directly to plant tissues. Even Y drops, giving nitrogen fertilizer directly to the base of corn plants, is now becoming a common practice as corn tassels. On soybeans, Manganese is commonly sprayed as a foliar fertilizer on soybeans. Avoid applying Mn with glyphosate (Roundup) because it gets tied up. Also avoid applying glyphosate when soybeans are blooming, because it can cause blossoms and pods to abort. This can be severe during dry or droughty periods, but also hurts the plant (maybe not as severely) during wetter periods.

For soybeans, R3 is the reproductive stage when soybeans are setting pods. Farmers have the opportunity to greatly increase soybean seed size by applying 3-5 pounds of actual zinc as a foliar spray at this time. Farmers striving for high soybean yields have found that seed size can go from around 2250 seeds per pound (smaller seeds) to much larger soybean seeds (1375 seeds per pound). The uptake of zinc by soybeans resembles a roller coaster. It makes it first peak during the vegetative stage as the plant is rapidly growing, takes a roll and decreases and then makes another new peak around R3. Soybeans can greatly respond to added zinc applied at this time. Most zinc formulations put on the seed are only around .25% zinc which is way too expensive to apply. A dry fertilizer (zinc sulphate monohydrate) or similar products can be added to a spray, keeping it in suspension. Five pounds can dissolve in 15 gallons of water along with some fulvic acid to increase plant absorption.

Another benefit for soybeans is the application of ammonia sulfate at 20 pounds per acre. Dr. Tony Vyn, Agronomist at Purdue University has found 10-30 bushel increases by applying when soybeans are blooming. The ammonia is a form of nitrogen that promotes a yield enhancing plant hormone called cytokinin that enhances flowering and blooming. The sulphate is needed by soybeans to make proteins in the soybean seed (soybean oil). For 60-bushel soybeans, at least 17# of actual sulfur are needed per acre while 90-bushel soybeans need 25-26# sulfur. Farmers may get 6-10# S from the atmosphere and about 2.5# S for each 1% soil organic matter. Often S is a limiting factor on high yielding soybeans, so added sulfur may greatly enhance yields.

On corn, weather conditions seem to be setting up for concerns about corn tar spot. Corn tar spot starts early in the growing season, going through several cycles. Corn tar spot thrives under cooler humid conditions. Corn tar spots start on the lower leaves and then moves upward and under the right conditions can explode quite quickly resulting in yield losses of 50 bushel per acre. Reduced ear weight, poor kernel fill, and even stalk rot and lodging increase yield losses.

For corn tar spot, fungicides need to be applied early before the disease gets too far along. Some micronutrients that appear to help decrease the incidence of tar spot damage include zinc, manganese, copper, and iron. Zinc activates enzymes that impact carbon dioxide, immune functions from diseases, and protein synthesis. Manganese is used to split the water molecule to form carbohydrates and proteins. Iron is needed for nitrogen metabolism and to activate the enzyme that makes chlorophyll. Copper activates the enzymes for lignin and stalk strength. Adequate micronutrients nutrition speeds up biological processes that enhance plant growth and crop yield.