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Messages posted to thread:

Bob25-Nov-02 01:41 AM EST
Susan25-Nov-02 04:57 PM EST 6a   
DAVE26-Nov-02 06:41 AM EST   
Odette19-Apr-10 02:18 PM EST 4a   
Daniel06-May-10 07:16 PM EST 5a   

Subject: fertilizers
From: Bob
Date: 25-Nov-02 01:41 AM EST

Can someone tell me about the use of fertilizers such as 20-20-20 and 15-30-15? My specific question is: Do these products contain chemicals that can harm the environment or are they "natural chenmicals" found in nature and we add them to help the growth process? Someone told me that they were dangerous to the environment. Can it be harmful to use them either indoors during the winter or outdoors during the summer? Thank you

Subject: RE: fertilizers
From: Susan
Zone: 6a
Date: 25-Nov-02 04:57 PM EST

The assumption that things that are 'natural chemicals' are somehow better or harnless has always bothered me! NPK in fertilizer does not tell you whether the source is 'natural' or not; it just tells you the ratios of available nutrients. Most chemicals, if used incorrectly - i.e. mixed in wrong concentrations; applied at the wrong rates; applied at the wrong times; etc., can have harnful effects.

A neighbour of ours still has dead swatches on his lawn two years after hand broadcasting fertilizer on his lawn! Nitrogen can burn the plants you apply it to if you apply it heavily - everyone is familiar with dead spots on lawns from female dog urine - an overdose of urea, a component in many nitrogen fertilizers as well as in dog urine! Phosphorus promotes root growth and shoot and fruit formation. It is also usually very (rock phosphate is an exception) soluable in water. Phosphate is the chemical most at issue in run-off as excess phosphate in water systems can promote growth in things like algae too. But insoluable rock phosphate does not provide the phosphorus in a form the plants can use.

NPK from 'inorganic 'sources (e.g. granular fertilizers) are available to plants immediately while NPK from the breakdown of organic material (e.g. compost) is released slowly as the microbes in the soil break down the organic matter. Using organic material such as compost does have the added benefit of improving soil tilth but the plants use the nutrients in the same way as NPK from 'inorganic' sources.

If you are responsible (use only what you need and apply it correctly) in how you use the fertilizer, indoors or out, I can't see any cause to be alarmed about their use.

Subject: RE: fertilizers
From: DAVE
Date: 26-Nov-02 06:41 AM EST

BRAVO SUSAN. It's frustrating to hear people equate the words natural, organic and safe. Anthrax is natural but far from safe. Bob- Each plant has an optimum mix of NPK. The nutrients can come from the existing soil or can be applied. Too much of any one nutrient can cause damage while too little may cause plants to develop at less than their potential. It's always best to follow the instructions that come with the fertilizer.

Subject: RE: fertilizers
From: Odette
Zone: 4a
Date: 19-Apr-10 02:18 PM EST

Regarding fertilizers: is it safe to use Miracle-Gro in a flower garden near a lake? The soil at my cottage is very poor. I amend it as best I can with compost, but it's not enough. The flower garden is at the top of a hill about 30 feet from the lake. I'm grateful for any advice since I don't want to harm the lake. thanks.

Subject: RE: fertilizers
From: Daniel
Zone: 5a
Date: 06-May-10 07:16 PM EST

Fertilizer is best applied based on a soil test report. The choice of form is up to you; chemical or organic. The report will identify deficiencies and with some ability to determine imbalances. A major influence is your soil pH and organic matter content. Identifying what you are growing when you submit the soil sample(s) allows the lab to give proper recommendations.

The typical 5-5-5 rating for fertilizer only identifies the proportion of NPK. Select the proportion to meet your soil test needs.

Chemical fertilizer is largely in a salt form which actually dehydrates your soil and the soil organisms. It is little wonder that conventional farming relies so heavily on irrigation.

Compost and composted manures are a safe alternative. There are plenty of organic options with good information available on-line. Few labs give organic recommendations so look around. Stick with the same lab for the knowledge that the reports over years are based on the same test methods.

Check out the ATTRA and Cornell sites for good organic information.

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