Phosphorus

Farmer: Ian Lutey - Cambridgeshire

Ian's Question for the FarmPEP community - Please comment any responses or thoughts:

How is it best to manage phosphate availability in clay soils, with high calcium content? Organic, inorganic, foliar feeds or soil reserves?

Phosphate pollution is very topical at the moment but as phosphate doesn't move very far, surely this is a soil erosion issue rather than necessarily a result of over application of phosphate fertilisers (assuming soil indices around recommended levels). 

Land drainage and therefore water movement and holding capacity of the soil must also be a big influence on the soils ability to hold phosphate and its availability to the plant roots.

 

See attached article from ADAS crop physiologist Roger Sylvester-Bradley

Our Phosphorus Challenge by Roger Sylvester-Bradley209.61 KB

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Comments

Discussion

26/06/2024 - 01:28

Hi

Applying organically complexed P in the form of biosolids
or as a mixture of liquid P and humic substances can also enhance P nutrition and result in yield increases. 

As calcium intake increases without a corresponding increase in phosphorus intake, phosphorus absorption falls and the risk of phosphorus insufficiency rises. Intakes with high Ca:P. ratios can occur with use of supplements or food fortificants consisting of non-phosphate calcium salts. 

Bryan Hopkins and Jason.2005. PHOSPHORUS AVAILABILITY WITH ALKALINE/CALCAREOUS SOIL.Western Nutrient Management Conference. Vol. 6. Salt Lake City, UT. 

or more....

Maybe you should think about the wonderful dung beetles, experts in enhancing various soil types when taking care of your soil!!!

cheers

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26/06/2024 - 10:10

Phosphate nutrition is both interesting and important. I put forward my thesis and I hope I am not just stating the obvious:

  • Crop recommendations are still based too much on soil analysis and off-take and not on response. I suggest that the ability for crops to take up nutrient is more plant-specific than we recognise.
  • Seasonal variation in both soil moisture and evapotranspiration (i.e. the ability of the plant to move nutrient from the soil into the plant tissue at crucial times) could be considered more and managed.
  • We know that the root fungal complex is an important mechanism for taking up nutrients, particularly phosphate. Work by companies such as Myconourish makes it clear that not all mycorrhiza and other root endophytes are equal. It would improve this understanding
  • Is anyone aware of monitors allowing a real time measurement of soil water phosphate and plant phosphate content?
  • Similarly does anyone operate combined harvester sampling devices that allow GPS marked samples to be extracted during harvest for subsequent analysis and thus mapping? I envisage something similar to a cartridge belt moving through the grain intake with each canister labelled with a GPS marker during operation.

 

 

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