weterman
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Question about the n,p,k in soil.

Just wondering how much is good. how much is bad. Do certain plants like certain elements more than others? Can someone just explain why I need each element?

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rainbowgardener
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Re: Question about the n,p,k in soil.

Here's a nice article about plant nutrients:

https://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm

Plants need NPK and a lot of other nutrients. Nitrogen is basic plant food and helps grow big leafy plants. Phosporus is needed for good root growth and blooming. Potassium helps with water regulation and other processes and is needed for fruiting.

So lawn fertilizers are almost all N, because all you are growing is leaves (the blades of grass are its leaves). For growing roses, etc fertilizers tend to be high in P for the blooming. For growing tomatoes, you need a lot of P and K. Too much N and you get big leafy plants at the expense of flowering and fruiting.

But synthetic fertilizers only provide the NPK and none of the other nutrients and not in the best form for plants to use. Too much of one nutrient, can lock up the others in the soil, making them unavailable. So yes you can easily overdo the NPK and either burn or starve your plants.

Plants need all the nutrients and they need a whole range of soil life and micro-organisms to break the nutrients down in to a form they can use it.

What you want is compost and/or a good organic fertilizer with all the trace nutrients and micro-organisms.
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PunkRotten
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Re: Question about the n,p,k in soil.

Organic fertilizers need bacteria to break them down for your plants to use. From what I was told, in a usual bed in the garden there is sufficient amount of P and K. It is usually the N that is low. And from what I found out, plants use about 6x more N than the other two. Addition of compost and/or worm castings usually helps things out. As RBG pointed out, some plants like some nutrients more than others. I am adding some Nitrogen to a bed of garlic and onions because they like N ( some people don't realize they fall under leafy crops). Usually the pre-bagged organic fertilizers are mixed in a good balance for you. I don't recommend experimenting/fooling around with nutrients unless you know what you are doing. Some of my beds are low in nutrients because they have had plants grown on them almost non stop and they took more nutrients than I could replace. So now I need to supplement. If you wanna give your plants a good boost and have them grow well, just add some compost and/or worm castings like I say, and you could use some liquid fish/kelp fertilizer and/or organic stakes or granules. Follow the instructions so you don't overdo it. Applying azomite to your beds once a year wouldn't hurt either.

weterman
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Joined: Fri Oct 11, 2013 2:55 am

Re: Question about the n,p,k in soil.

Okay, cool. Thanks.

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