Our understanding of the contribution of crop root residues to phosphorus (P) cycling is mainly derived from studies using excavated roots re-introduced to soil. This study aims to quantify total below-ground P (BGP) of mature canola in situ and to estimate directly the proportion accessed by subsequent wheat. ³³P-Labelled phosphoric acid was fed by stem wick to canola (Brassica napus) grown in sand or loam in pots. Shoots were removed from all plants at maturity. Half of the pots were destructively sampled. After a 3-week fallow, wheat was grown for 5 weeks in the remaining undisturbed pots. At canola maturity, 23–36% of the ³³P was partitioned in recovered roots and 34–40% in the soil. More ³³P was recovered in the loam than the sand. Within the soil, 6–10% of the fed ³³P was present in resin P and 3–5% was in hexanol-released P pools. Ratios of shoot P : BGP (8 : 1 in sand and 15 : 1 in loam) were much narrower than those of shoot P : recovered root P (17 : 1 in sand and 39 : 1 in loam). A greater proportion and amount of the mature canola BG³³P was recovered by wheat grown in the loam (26%, 2.6 mg/plant) than in the sand (21%, 1.5 mg/plant). The majority of canola BG³³P remained in the bulk soil. Input of P below-ground by mature canola and subsequent P benefit to wheat was greater in loam than sand. The P from canola below-ground residues contributed up to 20% of P uptake in wheat during the first 5 weeks of growth. Longer term benefits of P from below-ground residues require investigation.