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Nitrogen Fertilization and Ground Cover in a Hybrid Poplar Plantation: Effects on Nitrate Leaching
Author(s) -
Mc Laughlin Richard A.,
Pope Phillip E.,
Hansen Edward A.
Publication year - 1985
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1985.00472425001400020017x
Subject(s) - agronomy , growing season , human fertilization , leaching (pedology) , lysimeter , mineralization (soil science) , environmental science , biology , soil water , ecology
A 3‐yr study in northern Wisconsin measured the effects of ground cover treatments and N fertilization on tree growth, NO 3 − ‐N leaching, and N mineralization in an irrigated hybrid poplar ( Populus deltoides Bartr. × P. trichocarpa Torr. and Gray, clone NC‐9922) plantation. Annually fertilized (112 kg N/ha per year) and unfertilized plots were either maintained weed‐free (bare soil), allowed to revegetate with native weeds, or seeded to birdsfoot trefoil ( Lotus corniculatus L.). Soil solution NO 3 − ‐N was monitored in samples from permanently installed cup lysimeters. During the first two growing seasons, fertilization in bare soil plots increased NO 3 − ‐N concentrations below the rooting zone to over 150 mg N/L. Tree growth response to fertilization in these plots occurred primarily in the third growing season, and NO 3 − ‐N concentrations were much lower in and below the rooting zone relative to previous years. Fertilization increased NO 3 − ‐N concentrations in the rooting zone during growing seasons two through four in trefoil plots and three and four in native weed plots. Nitrate‐N concentrations below the rooting zone in all trefoil and native weed plots averaged ≤ 11 mg/L until the end of the fourth growing season when it averaged 20 to 24 mg/L in fertilized plots. Fertilization significantly increased soil N mineralization in buried plastic bags only in plots with a ground cover and was 42 to 47% greater in these plots compared with fertilized bare soil plots. This study indicates that ground cover plays an important role in preventing leaching losses of fertilizer and native soil N in young biomass plantations.