NDSU Extension - Griggs County


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April 13

The Extension Connection

By Megan Vig

                We are all itching to say goodbye to winter.  It’s hard for producers to look back to previous growing seasons and not cringe knowing they’ve been in the fields this time of the year applying fertilizer.  Though it may be tempting to get a start soon, this is a friendly reminder to not apply commercial fertilizers to snow-covered, frozen fields.  This week I share information from Dan Kaiser, University of Minnesota Extension Nutrient Management Specialist.

 Application of any fertilizer source should not occur when the ground is still frozen, especially on top of snow.  All commercial fertilizer products are water soluble and will dissolve readily in liquids.  There is an extreme risk for fertilizer to run off the field with snow melt, regardless of the fertilizer source.  In order for the soil to retain the applied nutrients, they need to come in contact with soil particles.  This reaction will not happen in frozen soils and any fertilizer applied will move with water off the field or to low areas of the field.  Environmental issues aside, applying fertilizer on frozen or snow covered soils presents a significant economic risk, as that purchased material will not be available to the crop.

                If the soil is frozen but there is no snow can I safely apply fertilizer?  It depends on how much precipitation might occur in the future.  Solid surfaces pose a significant risk for loss if any precipitation event, rain or snow, happens while the ground is still frozen.  To avoid economic risk, wait to apply fertilizer until the soil thaws to incorporate the fertilizer, or at a point where the nutrients can react with the soil.

                If I need to make multiple fertilizer passes this spring, what are my options?  With phosphorus and potassium, use your soil tests.  For high and very high soil tests, it is not likely that P and K will be short.  Any P or K that is needed can be applied in-furrow as a starter if that option is available.  Mobile nutrients like nitrogen or sulfur are more critical for corn production because of the crop’s level of response to these nutrients.  Without P and K application soil tests may decline but the impact of not applying will not likely impact crop production in the short term.  In most cases, nitrogen and sulfur application can be delayed until after planting to allow for spring application of phosphorus.  The nitrogen contained with the phosphorus in fertilizer sources used should be sufficient until an early side-dress application of N is made. 

                When making fertilizer decisions, always err on the side of caution.  Time is always a limiting factor with spring application, but applying too early increases your risk for nutrient loss and affects your bottom line.  Do not end up paying for inputs that won’t be available for the crop when it needs it most.

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