Soybean nodules supply plant available nitrogen
Nodules on soybean roots are formed by a specific genus of soil-borne bacteria, Rhizobium, which form a symbiotic relationship with the plant. The nodules fix nitrogen from the atmosphere and transform it into plant available nitrogen, while the plant supplies necessary nutrients and energy for the bacteria to multiply and thrive.
Typically, nitrogen fixation via nodules supplies most of the nitrogen that a soybean crop needs during a given year and additional nitrogen applications are not advised as that can have a detrimental effect on nodules. If there is nitrogen available from applied fertilizer, the relationship between the nodules and the plants suffer, ultimately hindering the ability of the nodules to fix nitrogen. It’s a costly move for both growers and the plant-bacteria interaction.
Nodules hindered by low soil pH
Nodule formation and performance is hindered by soil pH below 5.7. Many fields in the Midwest have areas of the field, or wide expanses with values at or below this level. The acidification from nitrogen sources applied during corn rotations continue to drive pH values lower.
When ammonium sulfate (AMS) is used to supply sulfur for soybean crops, a two-headed monster is working against achieving maximum yield. First, nitrogen is being applied, which can hinder nodule formation and performance. Second, AMS is the most acidifying fertilizer used in agriculture today, and that acidity can further degrade nodules.
SO4 – a pH neutral sulfur source
SO4, which is pelletized gypsum, is a pH neutral sulfur source. Its natural solubility meets plant needs for sulfur throughout the growing season. An added benefit is the addition of calcium to replace that lost in the previous season’s harvest.
Increased soybean acres projected for 2017
Due to various agricultural economic metrics, 2017 appears to be on track for the largest soybean crop ever planted in the United States. The USDA predicts 85.5 million acres planted this year, 1.8 million more than last year.
Soybean and nodule health will be more important than ever with the predicted increase in acres planted. Ensure you are making the best decisions for crop health, including nodules, to maximize yields.