Help with leaf problem?

relatively more available to crops when it is precipitated by Ca. Therefore, loss of phosphate (fixation) through precipitation is actually of less concern in alkaline than in acid soils. PHOSPHORUS (P) is an immobile nutrient. So when a P fertilizer material is applied to the soil it remains in place.

Hopefully this helps clear it up some more, there for saying phosphorus is not flushable once in the soil it’s there, sorry to say where ever you read that phosphorus is a Mobile nutrient was wrong

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No that’s great info! I had been reading a study on nutrient mobility from MSU.

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PHOSPHORUS DOESN’T MOVE IN SOIL…VERY MUCH

The winter rains and even the floods didn’t wash phosphorus away. It is immobile and hardly moves at all in soil. So when a grower fertilizes with phosphorus it stays where it is placed. While nitrogen may be leached below the root zone of crops and could threaten groundwater in extreme cases, phosphorus resides in the rootzone. It is not of environmental concern unless it is moved on soil particles by erosion of the soil itself. Phosphorus is immobile because it is only slightly soluble in soil, precipitating rapidly with such elements as aluminum in acid soils and calcium in alkaline soils.
There is a down side to phosphorus immobility. When a grower topdresses a pasture or broadcasts across no-till ground, phosphorus remains at the soil surface. This isn’t necessarily a problem if the crop has sufficient feeder roots near the surface. But without those feeder roots or when the soil surface dries out, phosphorus becomes positionally unavailable. The phosphorus is available all right…at least chemically available…it’s just that the roots can’t get to it. That means fertilizer uptake efficiency by the crop will be less, which requires a higher application rate as compensation. It could also mean lost yield. Ideally, roots should be encouraged to grow deep into the soil so they have the opportunity to absorb both nutrients and water from as much soil volume as possible. This is an important consideration in high yield management. Topdressing doesn’t accomplish this.
But, let’s not over-generalize. More accurately, phosphorus does move in soil…but usually it is so slow and in such small amounts that for all practical purposes we simply say it is immobile. Here is an example of some, but not a lot of movement: Phosphorus was topdressed annually on a commercial apple orchard in the state of Washington at a rate of 80 pounds per acre P2O5. The soil was a fine sandy loam. After 17 years…and 17 applications… the zone of greatest enrichment by far was the top one inch of soil and accumulation below 12 inches was minor. Some movement of phosphorus was detectable to two feet. But this isn’t much mobility compared to nitrogen that would be mostly gone after just one growing season.
Management makes a difference. Applying phosphorus in irrigation water enhances its movement, especially when that application is to a localized soil area such as is done with drip or micro-sprinkler irrigation. Research in California has shown substantial movement of phosphorus applied through drip irrigation to 10 or 12 inches deep after just one season on a clay loam soil. This is enough movement to greatly enhance phosphorus availability to the growing crop, but not enough that it is in danger of leaching below the root zone. Other research has shown similar results. And even on sandy soil, movement was reported to only 36 inches deep. This is certainly good news both agronomically and environmentally.
So, phosphorus doesn’t move in soil…very much. That means we can build up the phosphorus fertility of our soils and not worry about losing our investment over the winter…even when it is very, very wet.

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I added more info explainining why phosphorus is immobile, I’m glad to see this helped, and my apologies I wasn’t trying to be rude

No problems. I’m here to learn from growers of Marijuana. Pretty sure most university study’s don’t use it in any botany projects. If something works for seasoned weed growers, that’s what I’m really interested in. I have an abundance of time available since becoming disabled, and read pretty much everything I can find on any relevant growing topics. But I’ve found that a large percentage of information from generalized plant studies doesn’t transfer so well to the wisdom of veteran pot growers, so I try to keep a sceptical note to whatever I read, until I’ve seen it verified by experienced growers. Sorry if I seemed confrontational in my post. Wasn’t my intention, I am a bit direct in how I speak. Probably from being a nurse for 25 yrs.

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Hey no problems buddy, I’m the same way I’m straightforward when I help people, and i didn’t see it as “confrontational” I can tell your still learning basis on nutrients, and thats why I’m here, is to help you and all others :thumbsup:

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Okay, thanks for the info. I have about 4 weeks left in flower. At this point how should I proceed as far as fertilizers are concerned? I have the Fox Farm trio nutrients now. Should I treat deficiencies as they come up? Because I have some leaves that look like they are calcium deficient?

Yes, you always wanna take care of deficiencies as they come uo, in soil once you see a deficiency physically, you are already 2 weeks behind, however don’t get discouraged, maybe feed for 2 more weeks. Any deficiencies can lead to a diminished harvest

I was concerned because of the nutrient burn I had originally posted about? I don’t want to make it worse. Should I use the Fox Farm Bloom going forward and should I use it at half strength? Sorry for all the questions, Id rather ask now then to have to try and correct it later! Thanks a million for your help!

Also, what should I use for the calcium deficiency? As I mentioned before I have all 3 bottles of the Fox Farm trio.

Cal mag for calcium deficiency, and yes use them at half strength but see if you can’t flush the toxicity out of the soil first, and my pleasure, or you can use all 3 of the trio at probably 1/4 tsp of each per gallon of water

When you get a minute could you view another leaf problem I am having? I created a new post for it called “Help with leaf damage”