Jc. Cole et Jm. Dole, TEMPERATURE AND PHOSPHORUS SOURCE AFFECT PHOSPHORUS RETENTION BY A PINE BARK-BASED CONTAINER MEDIUM, HortScience, 32(2), 1997, pp. 236-240
These studies were conducted to determine the effect of 1) temperature
on P leaching from a soilless medium amended with various P fertilize
rs, 2) water application volume on P leaching, and 3) various fertiliz
ers on P leaching during production and growth of marigolds (Tagetes e
recta L. 'Hero Flame'). Increasing temperature linearly decreased leac
hing fraction; however, total P leached from the single (SSP) or tripl
e (TSP) superphosphate-amended medium did not differ regardless of tem
perature. Despite a smaller leaching fraction at higher temperatures a
nd no change in the total P leached, P was probably leached more readi
ly at higher temperatures. More P was leached from the medium amended
with uncoated monoammonium phosphate (UCP) than from the medium contai
ning polymer-coated monoammonium phosphate (CTP at all temperatures, a
nd more P was leached from UCP-amended medium at lower temperatures th
an at higher temperatures. More P was leached from TSP- than from SSP-
amended medium and from UCP- than from CTP-amended medium regardless o
f the water volume applied, but leachate P content increased Linearly
as water application volume increased for all fertilizers tested. Plan
t dry weights did not differ regardless of P source. Leachate electric
al conductivity (EC) was lower with TSP than with SSP. Leachate EC was
also lower with CTP than with UCP. A higher percentage of P from cont
rolled release fertilizer was taken up by plants rather than being lea
ched from the medium compared to P from uncoated fertilizers.