The utilization by grass of sulphur and phosphorus from clover litter

Abstract

³⁵S and ³²P were used to produce double-labelled clover (Trifoliurn repens) which was subsequently used as litter on carpet grass (Axonopus affinis) swards. The re-utilization of ³⁵S and ³²P was studied under two temperatures (15/10 and 28/22°C) and three watering regimes (daily, every 3 days and every 6 days), in controlled environment chambers. No significant watering effects were observed, but temperature had a marked efftct on sulphur and phosphorus uptake by plants. After 56 days the total incorporations of sulphur and phosphorus, as percentages of that applied in litter, were: tops, S 3.9, P 3.6; roots, S 4.6, P 18.6 at 15/10°C; and tops, S 9.3, P 11.0; roots, S 5.6, P 17.3 at 28/22°C. The estimated half-times for disappearance of sulphur and phosphorus from litter ranged from 27 to 44 days.