Tuesday, March 19, 2013

Timing spring fertilization of pecan groves

    Today we fertilized our pecan grove (photo at right). Renting a fertilizer spreader from the local Coop, we applied 150 lbs urea/acre along with 100 lbs potash/acre.  That figures out to 69 lbs/ acre of nitrogen and 60 lbs/ acre of potassium.  The cost of this application (including spread rent) was $61.35/acre. This application follows the spreading of 100 lbs urea/acre we made last October. 
    Timing fertilizer application is important to ensure that money spent on fertilizer actually gets into the tree. I use two key pieces of information to time the spring fertilizer application: bud development and the weather forecast.
    Starting in March, I scout the grove to see when pecan buds start swelling. The initiation of bud enlargement is marked by a condition called outer scale split.  As buds start to swell in size, the protective scale that covers the bud cracks open and the bud cap falls from the tree. In the photo at left, you can see both outer scale split and a bud whose outer scale has already fallen from the tree.
    Outer scale split also marks the time when pecan tree roots enter their springtime flush of new growth.  Fertilizer is most readily absorbed by actively growing roots, so waiting until outer scale split ensures that the nutrients applied today will be taken up immediately.  
    The second factor in decided to fertilizer today was the weather. The Neosho River is still at very low levels and the chances of a springtime flood seems remote (at least for the next several weeks). Later this week, we are expecting a wintery mix of light rain, sleet, and light snow. This kind of light precipitation will be prefect for moving fertilizer nutrients down into the rooting zone of our pecan trees.