Phosphorus cycling in wheat pasture rotations .I. The source of phosphorus taken up by wheat

Abstract

Wheat plants (Triticum aestivum cv. Warigal) were grown in the field in a solonized brown soil (Calcixerollic xerochrept) to which 33P-labelled medic residues (Medicago truncatula cv. Paraggio) and 32P-labelled fertilizer had been added. Amounts of 31P, 32P and 33P in the wheat plants were determined at 7, 18, 32, 46, 61, 81 and 95 days after sowing. The 32P uptake by the wheat plants increased throughout the experiment and reached 11 -6% of the isotope applied by 95 days. Of the 33P applied in the medic residues, 5 -4% was recovered in the wheat plants. Most of the P taken up by the wheat plants was from soil P (i.e, from sources not added that season).