Sugar Applications in Corn and Soybeans
The application of sugar to a spray mixture has been evaluated to determine it's effect on plant growth. One of the more notable instances of sugar application was the use by Kip Cullers in his record yielding soybean record of 160 bushels per acre. In a question and answer session, Kip Cullers stated that he added sugar to the tank when spraying Roundup to help with yellow flash. He believes that adding sugar also helps protect soybeans or "softens the blow" when applying Roundup. He believes that adding sugar feeds the microbes. He applies anywhere from 2 to 3 pounds of sugar per acre.
Adding a little sugar to the soil stimulates microbes that need active carbon to thrive. Active carbons are always in short supply because microbes readily consume it and sugars are active carbon. In the soil, sugar supplies energy to microbes feeding on cellulose and humic materials and stimulate mineralization. Sugar as a foliar application is less clear. Sugar can't replace or substitute for the sugar produced by photosynthesis, so it doesn't influence yield. Nothing is absolute for example, molasses products do contain vitamins, minerals and biostimulants or biochelators that when added to a foliar cocktail can improve performance and stimulate photosynthesis.
There are several sources of sugar that are considered for use. Granulated sugar is easy to use, soluble and readily available. Molasses and blackstrap molasses are viscous liquids, inexpensive and readily available at feed mills or beet processing plants, but handling can be messy when poured by hand or transferred with a gear pump.
There have been some trials in Nebraska and South Dakota. In the Nebraska trials one producer found a non-significant two bushel yield advantage of the non-treated plot compared to the sugar treated plot. Other producers found a significant two bushel advantage of the plots treated with sugar, compared to the non-treated plots. What they did find, consistently, was a noticeable difference in standability at harvest. In 2012, a small plot study was conducted at the University of Nebraska-Lincoln South Central Ag Lab near clay center to determine any differences between sugar application, fungicide application and untreated checks in corn. All treatments were applied at R2. The untreated check did show the most stalk rot. The sugar application reduced the lodging rating by half.
In a study conducted in South Dakota, it was shown that applying sugar to crops increases the numbers of beneficial insects. South Dakota research entomologists showed that lady beetles benefited from a combination of prey and non-prey foods. They found more lady beetles in the sugar treated plots compared to the untreated plots.
The application of sugar to corn and soybeans has not always shown increased yield. However, in nearly all of the corn studies, sugar treated plots have shown increased stalk strength at harvest. Research has also shown an increase in the number of beneficial insects in fields where sugar was applied.