The Role of Phosphorus In The Garden

2 comments by Halley -Author at MIGardener
                The Role Of Phosphorus In The Garden         

Phosphorus is a nutrient found in rocks. It is locked inside rocks, that slowly decay due [caption id="attachment_1112" align="alignright" width="167"] Bagged Rock Phosphate[/caption]to weathering. When the phosphorus is unlocked it is absorbed into water and can be used to feed plants and other living organisms. Phosphorus is interesting in the fact that not all places on earth have phosphorus rock, and there is not as much as we would think. One of the most important additions to our organic garden is the raw rock phosphate. Although slow acting, it weathers over time feeding the bacteria and the plants who both rely on this nutrient. The other way we get our phosphorus is through composting. Any organic gardener must compost to get sufficient amounts of phosphorus into the garden. Once living things used phosphorus and although we can use rock phosphate for most of what our plants need, it is much faster acting and already in its broken down and free to use state. Inorganic growers use synthetic fertilizers that contain high amounts of synthetic phosphorus, which is good in the time being, however the end result is leaching into the water system, and heavy salt buildup which kills soil organisms, and degrades the quality of soil over time. 

     The Role of Phosphorus In The Garden    
Phosphorus is used in many ways in the garden. Its two primary functions is to increase root development, and produce flowers. Phosphorus is also used to feed microorganisms that create a symbiotic relationship with the plant. The link between these microorganisms and plants is a vital one as well since many of them search out additional locked nutrients in the soil unavailable to plants and make them available to the plants. (see post: "The Role Of Nitrogen In the Garden" ) 

  Signs Of Phosphorus Deficiency  

           The first signs of a nitrogen deficiency is a purple tint on the undersides of leaves. The purple will then move into the stem in more extreme cases. Many times a phosphorus deficiency is also seen by a lack of flowers, and a weak plant, this is because the root system is not developed and the plant might appear to be top heavy or even by falling over. 


  4 great forms of phosphorus for the garden  

1. Grass clippings - When composted, grass contains about 2% phosphorus by weight
2. leaves - When composted, leaves contain about 3%
phosphorus by weight
3. Manure - Rabbit, cow, horse, goat, sheep, and chicken manure are VERY high in
phosphorus and can be anywhere from 3% up to 5% phosphorus by weight. 
4. Rock Phosphate - A slow release fertilizer, but an effective one at around 4% phosphorus by weight. 



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  • Juli

    How can I fix too much phosphorus in the soil? I had my soil tested and it’s “excessive” in phosphorus.

  • Robin

    Awesome. Thank you

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