Re: Grapes and fertilizers, was Plant in yard possibly toxic to dog

Hello marleyrae,
I received your private message re. grapes and fertilizers. I think you could get more comprehensive information if you posted your question in the forum.
Being organic gardener I don't use any synthetic fertilizers. When planting shrubs or trees, or vines I amend the planting hole with organic ingredients before planting. Since my soil benefits from the addition of phosphorus I add some crushed Rock Phosphate when preparing the planting hole. I also add some Alfalfa meal at that time. After planting I apply organic mulch around the plant to create favourable living conditions and supply food for the soil organisms, that in turn produce fertilizer for my plants.
Again, don't be shy, post all your gardening questions in the forum. We have many experienced gardeners here to answer you.

 

When planting shrubs or trees, or vines I amend the planting hole with organic ingredients before planting. Since my soil benefits from the addition of phosphorus I add some crushed Rock Phosphate when preparing the planting hole. I also add some Alfalfa meal at that time. After planting I apply organic mulch around the plant to create favourable living conditions

Those are both mistakes. It was becoming clear by the 1960s that amending of planting hole backfill with textural modification materials (bark, peat, sand etc.) reduced success rates by interfering with how water was moving into and out of the amended planting holes.

Unless you really do happen to have a markedly phosphorus deficient site (not usual in this region, except heavily leached places on the outer coast) phosphorus does not need to be added - and can produce a toxic growing environment that cannot really be corrected without replacing the soil.

 

Thank you, Ron, for your opinion.

I fully agree with you that amending the soil can be detrimental if done either incorrectly or unnecessarily (comp. treating a healthy person with medications or a sick person with wrong medications).
My way of amending my naturally very shallow, compacted, lacking organic contents, acidic, sandy soil with organic ingredients is not a mistake and works perfectly for my plants. I don't amend my soil with bark or sand. I can believe you that amending soil with materials you propose could be a big mistake. As for peat moss or for example, lime, one should consider not only the kind of soil one is dealing with but also what one is going to plant there.

When talking about phosphorus I believe you had in mind frequent, repetitive, heavy applications of high potency synthetic fertilizers, widely practiced in conventional agri- and horticulture. One-time, informed and prudent addition of a small amount of low-potency, very slow-release natural phosphate fertilizer like crushed rock phosphate to the planting hole can't possibly, as you put it "produce a toxic growing environment that cannot really be corrected without replacing the soil". I am not making a mistake by doing so, either. As you may know acidic, sandy soils are often deficient in phosphorus.

Thanks again for expressing your opinion. I appreciate it.

 

Makes no difference what the amendments are or what the parent soil is, if a small area of soil - like a planting hole - is given a different texture by the amending then detrimental effects on water movement are a common outcome. This is a fact.

If phosphorus is already adequate, and you add more, an excess becomes possible. This is a fact.

There is no such thing as adding an amount or type of amendments or nutrients (fertilizer) too small or slow-acting to have a significant effect being a worthwhile undertaking. The purpose of adding such materials is to change the site conditions. Little effect, little point.

 

"If phosphorus is already adequate, and you add more, an excess becomes possible. This is a fact." Difficult not to agree. It is one of the reasons why I don't use any synthetic fertilizers, not just phosphates. On the flip side, if phosphorus is not adequate, prudent addition of rock phosphate to the planting hole is very beneficial.

"Makes no difference what the amendments are or what the parent soil is". It helps me to understand why amending the soil didn't work for you, since both factors are crucial. Incorrect amending of the soil leads only to deleterious results.

"There is no such thing as adding an amount or type of amendments or nutrients (fertilizer) too small or slow-acting to have a significant effect being a worthwhile undertaking." Agree, it should not be too small. Too small is, though, much safer than too much. We organic gardeners believe that small is beautiful. Amending the planting hole with not excessive amounts of organic ingredients is very much worth the effort, it will pay you not only during the whole life span of the plant but, like with trees and some long-lived shrubs, during your whole lifespan.

"if a small area of soil - like a planting hole - is given a different texture by the amending . . ." The planting hole should never be small. To the contrary, the bigger the better.

As for "detrimental effects on water movement are a common outcome" I am not sure I understand what you have in mind. Could you be more specific?

Thanks.