Overdoing anything can cause issues but in general, organic fertilizer sources are very unlikely to contribute to pollution. Your alfalfa and soy meal (and any other dry or granular organic fertilizers) require processing and digestion by soil organisms before they become converted into plant usable forms. And this takes time, so by definition these types of ferts are slow release and slow release ferts are far less inclined to contribute to pollution due to lack of leaching. Typically, it is the fast acting synthetics that are the culprits in this regard. Organics tend to carry very reduced nutrient loads compared to the synthetics as well.

The exception would be fresh manures as there tends to be a lot of liquid leached by these and often with pretty high levels of P. Phosphorus is the biggest contributor to water pollution via eutrophication and subsequent algae blooms. To the point where many lawn fertilizers now omit any P component at all. And it is rarely lacking in most home landscapes anyway. Dried, aged or composted manures will have few issues with leaching or pollution.

"now someone tells me if i add too many nutients to the soil i could overfeed the eco- system and they'll turn to pollutants"

Would have to hear the full context of that statement and know the personal agenda of the person saying it. Otherwise it is little more than someone's personal opinion and easily mis-understood.

But as already said, excess of anything can create problems and should be avoided. Nor is adding too much of anything organic necessary or of any benefit and can cause problems.

To avoid doing that you first have to have an understanding of what you are using and what it provides the plants. For example, have you compared the nutrient values of alfalfa meal to soybean meal so understand why you wouldn't want to use both or why soybean meal could be plant-toxic in soil that is already high in potassium?

Do you know which of the prime nutrients (other than N that all soils can use) and micronutrients your soil lacks? If not then it is best to stick with alfalfa meal which is basically 3-1-2 + micros and use it at the standard light application rate:

Light Application: 12 lbs per 1,000 square feet, 1/4 cup per plant or 1 lb per 20 ft row

You can always side-dress with more if symptoms appear but if too heavily applied up front you can't eliminate it.

Some make the assumption that just because something is "organic" it can do no harm or that it has no application limits. Not true. All organic soil supplements and plant nutrients have their own rate and level of application label instructions. That is one of the big advantages to using water soluble organics IMO - you have better control over the rates and times of application.

So the real question is why and how and in what amounts do you plan to use the meals etc.? Don't know where you live but professional soil tests are available from numerous sources - even if you have to mail it off to a lab in the next state. Without one you are working blind and could easily waste money and yes, create problems for your soil.

Dave

Let me elaborate. ANYTHING you apply to the ecosystem that isn't native is, in some sense, a pollutant. You plant seeds that aren't native and, hey, you're polluting the ecosystem! Especially if they self-seed and become invasive. But even if they don't they are displacing the natural foliage. You dig in compost to fluff up the soil, and you've killed off all those native plants that don't like fluffy soil. Good heavens, you water, and kill off all those drought loving native plants. So the word "pollutant" is kind of relative. Just chill and do what you're doing. If you over-amend with alfalfa meal, gee, it'll take care of itself eventually.

Gardendgal is right about phosphorous. But it is a pollutant only in that it discourages native growth. It strongly enhances non-native growth!

But I agree with Dave that if you've never done a soil test, do at least one. Otherwise, you're just shooting in the dark.

yeah i chose soybean meal two years ago,because it had a nice balance of npk plus it could be applied to the soil as soon as two weeks before planting. but i will say something, had tomatoes coming out of my ears. some plants grew 8 ft tall i had to use two by twos. i live in nassau county, two of my beds are raised beds. funny thing here on long island i believe they outlawed phosphorus in lawn fertilizer. and your so right dave about not all organics being safe. some contain synonide, and at one time cocoa meal which can be dangerous for animals and pets if injested, then there was rotenone.

I don't want to start any arguments here, but it should be understood that you can find hugely toxic substances in situations that you'd have to call "organic". That word has some mythology attached to it that I have a hard time digesting. In practice, I guess I stay mostly "organic", but mainly in that I don't apply amendments, insecticides, and pesticides that are known to be harmful or toxic. But I don't judge harmfulness or toxicity on the basis of how "organic" anything is.

Just to make things perfectly clear: although you can overapply them, dry or granular organic fertilizers are very unlikely to contribute to water pollution just by their physical nature..........and that is the pollution we are most concerned about. On the other hand, fast acting synthetic fertilizers are huge contributors to water pollution, to the point where they are now restricting or limiting the ingredients, most notably P. We are only talking about fertilizers here....nothing else.

Organic pesticides can be some of the more toxic of any of the pesticides but we're not talking about pesticides.......only ferts. And that's an entirely different ballpark.

btw, the Nassau county extension service/Cornell University does soil testing. And as mentioned previously, you can send away to have soil testing done in just about any state in the union....it does not need to be local :-))

"you can find hugely toxic substances in situations that you'd have to call "organic""

That's my point. Excesses of anything, even organics, is possible. My soil is naturally alkaline with a ph of 8+. If I ever added lime I'd be in real trouble yet some folks throw it around routinely.

And soybean meal as I already mentioned is so high in potassium you could end up with K toxic soil if used inappropriately or if your native soil is already high in K. Stunted growth, blackened roots, minimal branching on plants, etc. (don't ask how I learned this the hard way). Now should you have K depleted soil - which is rare - soybean meal could be a life saver. But you have to know what your starting point is, what your soil has to begin with.

Dave

"And soybean meal as I already mentioned is so high in potassium you could end up with K toxic soil if used inappropriately or if your native soil is already high in K"

Really?? How do you come to this conclusion? Soybean meal is typically rated with an NPK of 7-2-1 or 7-2-0.

NPK of common organic fertilizers and amendments