Combining organic and mineral P fertilisers (online)

Does combined use of organic and mineral phosphorus fertilisers support mycorrhizal colonisation

Phosphorus (P) fertilisers come from phosphate rock, a finite resource . Therefore, alternative sources need to be used to ensure the sustainability of food production systems. Organic amendments (OA), such as manures and composts, can be used, but vary in the amount and forms of P they contain.  Arbuscular mycorrhizas (AM) — symbioses between plant roots and fungi — can enhance plant P uptake. They also provide other benefits to soil and plant health. In this project, four OA were investigated for their potential to be used as P fertilisers. The relationship between the chemical properties of the OA and plant (wheat) P uptake from the OA was determined. A second experiment was conducted to determine whether chicken litter with straw bedding can be effectively used in combination with mineral P fertilisers, supplying crops with P while having minimal effect on AM colonisation.

Take home messages

  • Incorporation of organic amendments (OA) into phosphorus (P) management plans can have beneficial effects on arbuscular mycorrhizas (AM). 
  • OA alone may not be able to meet crop P demands.
  • Combined use of OA and mineral P fertilisers successfully met crop P demands.
  • Bicarbonate-extractable P gives a good indication of the P fertiliser potential of OA.