Thursday, May 3, 2018

Fertilizing with urea

Looks like it is going to be wet in Eaton Rapids, Michigan and Ashland, Ohio.

Adding fertilizer to the soil is a subsidy.  Like all subsidies it is subject to all of the same problems as a government program throwing money at problems.

The resources seem to go everywhere except toward the intended target.

Consider urea:  Urea is 46% nitrogen and is the cheapest form of that nutrient that I can apply.  A 40 pound bag runs about $14-to-$17.

Nitrogen, as a nutrient, is highly mobile.  Think of it as being cash.

Apply too early
If I apply urea in the fall, the fall rains and melting winter snows will carry it down to the water table and it will be, mostly, unavailable to my plants.

If I apply it too early in the spring, the urea will not have time to decompose into forms that are usable by plants, that is, nitrates.

If I apply it mid-spring then the urea will get gobbled up by weeds that start growth earlier in the year than my preferred plants.

Even if the target species is growing it will not be able to "pull" much nitrogen from the soil.  Nutrients are "pulled" as plants transpire water.  Orchard trees don't transpire much moisture in spring because of the humidity, the cooler temperatures and because the leaves have not filled in the canopy.

There is risk in fertilizing too late
Plants that put on a sudden spurt of growth late in the growing season are vulnerable to winter-kill.  The growing points sequester the carbohydrates that are plant bud's natural antifreeze.

There is also a risk in the urea sublimating (going from vapor to solid, like dry ice) at temperatures above 80F.

The Goldilocks window
My best guess is that I get the most bang-for-the-buck when I spread urea in May.  It is best if I can spread it the day before it rains.

How much fertilizer?  Great question.  I have to give you a non-answer because it will vary by location.  I shoot for 3' of shoot extension on young trees and 8" of shoot extension on mature, producing trees.  I want to GROW that tree so it fills its allotted space and is capturing the maximum amount of sunshine.  Then I want to give the tree just enough N to keep it from tipping into alternate bearing.

I spread urea in the orchard yesterday.
I am pretty sure we got more than an inch last night.  I slept with the bedroom window open.
It is starting to look like a good year for gardening.

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