Closing the P-cycle across farm and regional scale

The phosphate use efficiency (PUE) is determined by losses in the food chain, including losses in the phosphate (P) supply to land (especially manure) and the removal of P in sludge, partly as a result of contaminants therein. Water boards are currently confronted with high costs to dispose the sludge and are interested in cheap processing routes for cleaning the sludge, together with companies that are currently composting (IMP) or burning (SNB) sludge.

In recent years the placement of manure in the Netherlands has reduced, due to decreased P utilization standards. From 2015 onwards, a so-called equilibrium P fertilization approach is practiced implying that the P application is equal to the expected P uptake. Phosphate flows can be reduced and the PUE can be increased by (i) reduction of P excretion by measures in the livestock (feed track whether or not combined with bio-refinery) and (ii) manure processing combined with reuse of manure on farmland either within or outside the country, but this implies the need for a high manure quality.

This study examines the potential of P recovery from manure and sludge and the related effect on economics and environment at farm level and on the environment at regional level. The goal of this project is to evaluate

  1. Methods for P recovery from animal manure and sludge and the technical and financial feasibility at regional scale
  2. The environmental and economic impact of changed application of manure and sludge products at farm level and regional level with a focus on C, N and P flows and thus on soil quality/fertility (organic matter balance, N and P avaialbility) and water quality (N and P runoff) on a regional scale