The essential role of calcium in soybean nutrition

Soybean growers aiming for higher yields know that success depends on balance. Today, that balance extends beyond nitrogen, phosphorus and potassium to include secondary nutrients like calcium. Once considered a background player, calcium has emerged as a key driver of plant strength by enhancing nutrient absorption and delivering more consistent returns across every acre.

While calcium often gets overlooked as a primary contributor to yield, it is necessary for developing a healthy and productive soybean crop.

The role of calcium in soybeans

Calcium positively affects several physiological processes within the soybean plant. It supports healthy nodule formation on roots that enable the plant to convert nitrogen into a usable form. Calcium also facilitates cell division and elongation, which allows for proper growth from the root system through the canopy.

Beyond growth, calcium contributes to cell wall strength. This is vital for maintaining structural integrity and resilience under environmental stress.

Adequate calcium levels help plants better manage biotic and abiotic stress, and resist disease pressure. Additionally, calcium improves soil structure, nutrient uptake, root development and microbial activity, all of which drive stronger plant performance.

Addressing the calcium needs of today’s soybeans

Modern high-yielding soybean varieties demand more calcium than ever before. However, even when soil tests indicate high calcium levels, the nutrient isn’t always readily available to plants. In many cases, less than 5% of the calcium measured in a standard soil test is plant available.

This knowledge is important because soluble (plant-available) calcium is often a very small percentage of the overall total calcium reported on a soil test. 

Field test results illustrated below (Figure 1) show soluble calcium only ranged between 1% and 2%.

To bridge this gap, supplemental calcium applications are often needed. The key is choosing a calcium source that is highly plant-available, so that nutrients are accessible during vital stages of growth and development. Doing so maximizes uptake efficiency, yield potential and return on investment.

Get more from every acre

SUL4R-PLUS^® granular calcium sulfate fertilizer delivers both calcium and sulfur in a controlled-release, water-soluble form for immediate availability and season-long nutrient uptake.

Yield data (Figure 2) demonstrate that SUL4R-PLUS can increase soybean yields by up to 12.2 bu/A, depending on application rate, compared to the untreated check.