Some have expressed concern about using chemicals to feed their plants, wanting to stay away from “synthetic” materials. Others don’t know how much to use. Let’s review some basics!
Suppose you have a garden 20′ X 30′ and you want to have a good yield of healthy tomatoes. A common practice is to work 3-4″ of composted horse or cow manure into the soil in the plot before planting. Is that a reasonable supposition? That’s 20′ X 30′ X 1/3′, – 20 cubic feet, or about 3/4 cubic yard of manure. A yard of soil weighs about 2,500#, may we assume composted manure weighs half as much? that would mean we have applied about 900# of manure to our garden.
If the manure is 1% nitrogen (a general assumption – plus roughly comparable amounts of P and K and smaller amounts of several other salts, often including table salt), then we have applied 9# of actual “chemical” nitrogen to the garden – all at once – at the beginning of the growing season. And total chemical salts you’ve applied amount to between 30# & 40#!
When you think you don’t use chemicals, you’re only fooling yourself. Everything in this world is a chemical! And your plants can’t use that nitrogen – or anything else, until it has decomposed from the organic state and become a water-soluble mineral.
Now, please remember also, there’s something called the nitrogen cycle. Nitrogen is volatile, and doesn’t stick around long – especially in warm weather, so how long do you suppose you have the benefit of those 9#’s of nitrogen?
When I garden I use a 13-8-13 mix. Is that scary – using such a highly concentrated material? Let’s compare the actual amount of nitrogen I’m applying to that 20′ X 30′ garden. Each week – 4 times for lettuce, 5 times for bush beans, 6 times for corn, and 12+ times for indeterminate tomatoes – I apply 8 OUNCES of nitrogen, 8 OUNCES potash, and 5 OUNCES phosphate, along with much smaller amounts of the other 10 elements. That’s for the entire 20′ X 30′ garden! So I am actually applying 1/18th as much mineral nutrients to my garden at any one time as the organic gardener – but doing it several times over the growing season. Which is better?
So, how much nitrogen do I use in total? It obviously depends on the crop, but let’s compare:
Lettuce – 2# – less than 1/4th the amount applied using manure.
Bush beans – 2 1/2# – less than 1/3rd the amount applied using manure.
Corn – 3# – 1/3rd the amount applied using manure.
Tomatoes – 6-7# – 2/3rds to 3/4ths as much as is applied using manure.
But I give my plants very small amounts on a regular basis, and apply it 4″ from the plant stems (far enough so as not to burn them) and water it in so that it’s immediately available. Doesn’t that make sense?
And what is the cost? Between $25 and $40 for the growing season. How much work is it to apply it all those times? Less than one hour over the growing season. What is the result, or yield? At least double that achieved using manure. And I’ll match size, looks, taste, and any other measure you’d care to make. after all. “THE PLANT CAN’T TELL THE DIFFERENCE BETWEEN NITROGEN FROM A LEAF AND THAT FROM A FERTILIZER BAG” (J. I. Rodale – Organic Gardening magazine).
Please also consider another factor in this equation. How many people have access to 900# of manure to use on their garden – (and remember I’m describing a very small garden!)? In rural areas it may be relatively
plentiful for the few who care enough to use it. But just suppose everyone had to depend on it!! There is not enough manure available to satisfy even 5% of the people if everyone had to grow a garden and live off it’s bounty.
Is a loving and all-knowing God going to arrange things so that 95%+ of the people can’t get “the only true” fertilizer?? I don’t think so! He has made concentrated deposits of all the necessary plant nutrients (which are also humans’ essential nutrients!!), and man has learned how to grind them up in the ratios they’re needed, and how to accurately apply them to the soil to grow healthy plants.
So, let’s do it!! :o)