#6 Joana: Designing organic fertilisers by blending animal manures

How can mixing different animal manures together enhance their value and increase their ability to replace mineral fertilisers?

Joana Prado is a PhD student at the University of Lisbon and she is part of the EU project Nutri2Cycle.

Department and Section: Instituto Superior de Agronomia

University supervisor: David Fangueiro, Paula Alvarenga and Henrique Ribeiro 

Dissertation title:

Blending of raw and treated manure to produce bio-based fertiliser

Topic – in brief

The challenge:

  • manure is rather unpredictable in terms of its fertiliser value whereas farmers can be quite sure about effects and usefulness of mineral fertilisers
  • the nutrient ratio in manures is suboptimal for plant growth: if one applies according to nitrogen, too much phosphorous ends up in the fields – if one applies according to phosphorous, the crops lack nitrogen…

Joana’s approach:

  • Mix different types of manure to come closer to what crops needs and thus increase the manures’ ability to replace mineral fertiliser
  • Compare fertiliser value and emissions of manure-derived and mineral fertilisers


Aerobic-incubation (lab-scale):

  • application of manure blend on soil
  • measurements of mineralisation and nitrification rates to determine whether the nitrogen becomes available to the plant (mobilisation) or unavailable to the plant (immobilisation)
  • measurements of greenhouse gas emissions

Joana’s findings so far

  • Under Portuguese conditions, manure turned out to be safer than mineral fertiliser in terms of phosphorous leaching

Find her studies here and here.

Side notes:

Nitrogen mineralisation: conversion of organic nitrogen into inorganic nitrogen by microbes and enzymes. Plants can only take up nitrogen in the inorganic form. This process is also called mobilisation as opposed to immobilisation. In the organic form, the nitrogen is immobile because it cannot be taken up plants and thus ‘move’.

Learnings & advice

Trust yourself! & often problems seem bigger than they actually are.

Side note (informal :D)

Joana belongs to a Portuguese music group, called Tunassa-Tuna feminina do Instituto Superior de Agronomia. It is a group of friends that studys at ISA and plays music together. Joana plays the tambourine! They use the wardrobe that inspired JK Rowling to write and dress Harry Potter!

If you would like to connect with Joana check out LinkedIn and ResearchGate.

Joana’s funding: Her research is supported by EU Horizon 2020 project ‘Nutri2Cycle’ (grant number: 773682)

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