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Abstract
A greenhouse experiment was conducted using ornamental privet plants (Ligustrum japonicum Thunb.) to determine the effects of irrigation treatment (daily vs. every 2 days), container type (plastic vs. clay), and mix (redwood-sand; pine-sand; pine-soil; or sphagnum peat-perlite-sand) on the fate of applied N. The sinks for N that could be accounted for consisted of uptake by plants, N absorbed and/or adsorbed by the mix and container, and N leached. Growth rate and uptake of applied N was greatest for plants in plastic containers which were irrigated daily. The type of mix used did not appear to significantly affect plant growth. Compared with all other treatments, larger proportions of the applied N were absorbed and/or adsorbed by redwood-sand or pine-sand mixes in plastic containers irrigated on alternate days. Larger proportions of applied N were lost in leachate water from plastic containers that were irrigated daily than all of the other treatment variables. Unaccounted-for N (denitrified) was greater for plastic containers (16.2%) than clay containers (10.8%), and pine mixes had significantly greater proportions of applied N denitrified (17.7% for pine-sand and 18.9% for pine-soil) than redwood (9.3%) or peat (8.1%).