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Nitrogen and Phosphorus Interactions in an Intensively Managed Nursery Soil‐Plant System
Author(s) -
Teng Y.,
Timmer V. R.
Publication year - 1994
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1994.03615995005800010035x
Subject(s) - chemistry , nutrient , phosphorus , zoology , dry matter , leaching (pedology) , agronomy , phosphate , nitrogen , loam , antagonism , ammonium , soil water , biology , ecology , biochemistry , receptor , organic chemistry
Nitrogen in forest tree nurseries is usually applied as topdressing during the growing season, while P is incorporated in the soil before seeding. Combined N and P topdressing as monoammonium phosphate (MAP) may improve nursery stock production. To test this practice, white spruce [ Picea glauca (Moench) Voss] seedlings top‐dressed with MAP, or factorial combinations of ammonium nitrate (AN) and phosphoric acid (PA) were grown for two seasons in a loamy sand nursery soil. Seedlings receiving AN alone increased in biomass (34%) but took up less P despite relatively high available P (310 mg kg −1 ) in the bulk soil. Phosphorus additions stimulated growth (107%) and also N and P uptake. Equivalent N dosages, as MAP or AN + PA, increased dry matter production by 362%, demonstrating a significant positive N × P interaction. Two nutritional responses seem to be involved in this interaction: (i) a countering of N antagonism on P uptake when N only was applied, and (ii) a synergistic effect of N and P uptake when these nutrients were applied together. Lower specific absorption rates of roots and suspected depletion of rhizospheric P probably accounted for the antagonistic effect in N‐only treatments, while increased root absorption efficiency and higher P availability in addition to the N supplied in N + P treatments contributed to the synergistic interaction. The N + P treatments resulted in lower seasonal NH 4 ‐N and NO 3 ‐N levels in subsoil than those from N‐only treatments, suggesting less leaching of N from combined N and P topdressings.