Management of crop residues affects the transfer of phosphorus to plant and soil pools: Results from a dual-labelling experiment

Release of nutrients, including phosphorus (P), from crop residues remaining post-harvest is an important potential source of nutrients for subsequent crops. A glasshouse experiment examined the effect of size (ground 60% of the added residue P was detected in plant, microbial and resin P pools when incorporated in soil compared to ∼25% for the two surface-placed residue treatments. When considering residue management strategies based on the potential for influencing P supply to crops, incorporating residues will increase the rate of release and decomposition and therefore the potential for plant roots (if present) to access this P. The results also show that even though residue P takes longer to break down when retained on the soil surface (e.g. under no-till management), this system was still able to provide small but agronomically significant amounts (0.6–0.7 kg P ha−1) of P to subsequent crops. •The effect of crop residue size and placement on residue P release was measured.•Residues contributed 9–44% of the total P taken up by plants.•Residue treatments provided similar amounts of P as fertiliser P to wheat plants.•More than 60% of incorporated residue P was released into plant and microbial pools.•Only 25% of residue P was released in to the same pools when surface-placed.