Lecture 9: Nutrient cycling in plant-soil-microbe continuum Flashcards
What is the P crisis?
Will run out as mining finite resources
What are the 3 major pools of P
organic, labile, complexed inorganic
What is labile P?
orthophosphate
What is organic P?
sugars, phospholipids, DNA, phytate
What is inorganic P?
trapped in ions
Biological conversion of P
immobilisation and mineralisation
Biological and chemical conversion of P
fixation and solubilisation
Chemical traits of P
free form is highly reactive so forms complexes which require conversion back to labile to be used by crops
Does P vary by soil location?
Yes
Crop requirements for P
microbes require P to fix nitrogen
How do plants access P and what effects does this have?
orthophosphate taken up through transporters
growth of plant releases organic C from roots
this attracts soil microbes
these deplete orthophosphate and immobilise it
need other microbes to remineralise it
What are the problems with P mining?
finite
energetically expensive
few locations left
decreasing purity
Impacts of P fertilisers
improve yields
imbalance nutrients
runoff
eutrophication
Direct biology/biotech approaches for P crisis
improve P use efficiency of plants
reduce reliance on rock P
improve recycling of immobililsed P
