Fertility Levels Key to Raising Top Soybeans, Part II

A common practice for farmers in a corn-soybean rotation is to apply enough P&K prior to planting corn to supply their crops for two years.  This works well until corn yields are higher than expected, and no extra nutrients are added for the subsequent soybean crop.  Soybeans are big users of Phosphorus (P) and Potassium (K), and soybean yields will suffer unless more nutrients are applied to compensate for the higher corn yields.

Nitrogen is essential to photosynthesis.  Nitrogen is usually supplied to soybean plants by a process called nitrogen fixation, which is associated with Rhizobia bacteria in the soil.  It’s important to note, however, that these bacteria are not always present – especially if soybeans haven’t been grown in that field for a few years.  Recent studies show that adding an inoculant to seed may have beneficial effects if planted in soils with low organic matter content or in fields that have undergone significant flooding in recent years.  Try inoculants in your own fields and study whether they benefit your production levels.

In addition, be sure to monitor the calcium levels in your fields.  There are soils in the Upper Midwest that contain too much calcium.  Known as alkali soils, they can cause other problems for soybean development including stunting, poor root development and iron deficiency chlorosis.

Soybean yields will also suffer if micronutrient levels are deficient, even if there is adequate P & K present.  If soil tests show low levels of Sulfur, Zinc and Boron, add them to your fertilizer blends.

Managing nutrient levels will help produce maximum yields – and returns – from your soybean crop given the high market values.