HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Babbar, L. I. Articles by Zak, D. R. Search for Related Content PubMed Articles by Babbar, L. I. Articles by Zak, D. R. Agricola Articles by Babbar, L. I. Articles by Zak, D. R.

Nitrogen Loss from Coffee Agroecosystems in Costa Rica: Leaching and Denitrification in the Presence and Absence of Shade Trees

School of Natural Resources and Environment, Univ. of Michigan, Ann Arbor, MI 48109-1115.

^* Corresponding author (drzak{at}umich.edu).

ABSTRACT

Coffee (Coffea arabica L.) management in Costa Rica is changing from traditional agroecosystems, where coffee is grown beneath a tree overstory, to management systems where shade trees are removed and N fertilizer is applied at high rates (ca. 300 kg N ha^–1 yr^–1). Although fertilization increases coffee bean production, it also increases the potential for substantial loss of N to groundwater and the atmosphere. We investigated NO^–₃ leaching and the factors controlling denitrification in shaded and unshaded coffee plantations in the Central Valley of Costa Rica; both plantation types were fertilized with 300 kg N ha^–1 yr^–1. Nitrate leaching was quantified using porous ceramic cup lysimeters placed 60 cm below the soil surface. Losses were estimated by multiplying the soil water NO^–₃ concentration by the monthly soil water excess, determined as the difference between precipitation and actual evapotranspiration. In addition, a laboratory experiment was conducted to investigate the influence of NO^–₃, C, and O₂ availability on N₂O production and total denitrification (N₂O-N + N₂-N). Annual leaching losses of NO^–₃ were almost three times greater in unshaded plantations (24 kg NO^–₃-N ha^–1 yr^–1) than those in shaded plantations (9 kg ha^–1 yr^–1). In contrast, mean total denitrification rates in control soil samples from shaded plantations were 60% higher (732 µg N₂O-N kg^–1 d^–1) than in unshaded plantations (455 µg N₂O-N kg^–1 d^–1). Carbon additions elicited the largest increase in denitrification, generating nearly a threefold increase (+ C = 8396 µg N₂O-N kg^–1 d^–1; –C = 2985 µg N₂O-N kg^–1 d^–1) in both plantation types. Anaerobic conditions also significantly increased denitriflcation (+ O₂ = 4331 µg N₂O-N kg^–1 d^–1; µO₂ = 6656 µg N₂O-N kg^–1 d^–1). In both plantation types, the potential for N loss via NO^–₃ leaching was small compared with that for gaseous N loss.

This article has been cited by other articles:

				M. C. Ryan, G. R. Graham, and D. L. Rudolph Contrasting Nitrate Adsorption in Andisols of Two Coffee Plantations in Costa Rica J. Environ. Qual., September 1, 2001; 30(5): 1848 - 1852. [Abstract] [Full Text] [PDF]