The release of phosphorus from plant material added to soil

Abstract

An experiment was conducted to study the release of 32P from white clover plant residues in the presence and absence of growing oats plants in both low and high phosphorus status soils. Net reutilization of phosphorus from the added plant material after 48 days was highest in the high phosphorus system in the presence of plants (29.3 %) and least in the low phosphorus system in the absence of plants (0.6%). Watering to field capacity daily, every 3 days, or every 6 days, had no significant effect on reutilization rates. Evidence from the soil inorganic phosphorus data suggests that the addition of plant material resulted in a significant immobilization of soil phosphorus only in the low phosphorus soil in the absence of plants. The significance of these findings is discussed in relation to the large number of incubation studies conducted to study phosphorus turnover rates in soil.