Subsurface Nutrient Placement
What it is:
Subsurface nutrient placement is the method of putting essential crop nutrients like nitrogen, phosphorus and potassium below the soil surface in the root zone available for plants to uptake. Subsurface placement of nitrogen and phosphorus is considered a best management practice (BMP) that protects surface water quality by dramatically decreasing nutrient runoff potential.
How it helps:
As more farming operations have moved towards no-till or minimal tillage, fertilizer has been broadcast applied to the soil surface and not incorporated. This can result in stratification of nutrients in the top few inches of the soil. This leaves highly soluble fertilizer exposed to rainfall which can wash fertilizer off into bodies of water or fertilizer can fall into cracks in the soil that lead to drainage tile. These nutrients can lead to algal bloom issues downstream. Research is showing that placing fertilizer below the soil surface greatly reduces the potential for nutrient loss. Also, by placing fertilizer closer to the root zone, fertilizer is used more efficiently, thereby reducing the amount of fertilizer needed to be applied. This can result in a significant cost savings to the producer.
Fertilizer placement will vary with every target crop but placing fertilizer below the soil surface can be done with multiple tools. Planting equipment can deliver some fertilizer needs to the crop by placing fertilizer either 2" x 2" from the seed or in the furrow. Also, more equipment manufacturers and dealers are building toolbars(See example 1) that place fertilizer 2 to 4 inches below the soil surface with low soil disturbance. Another option is a strip tillage toolbar (See example 2) which mixes fertilizer in a band while making a strip to plant the seed into.
The decision to place your nutrients below ground should be done in conjunction with your nutrient management plan. Changing how you place nutrients can be a major operational change and can come with increased costs for different pieces of equipment. But this change can also lead to more efficient use of fertilizer which can result in a cost savings.