A CONCEPTUAL ASSESSMENT OF THE IMPORTANCE OF DENITRIFICATION AS A SOURCE OF SOIL-NITROGEN LOSS IN TROPICAL AGROECOSYSTEMS

This paper attempts to answer the question: is denitrification a major route of N loss from tropical agro-ecosystems? This question turns ou t to be very difficult to answer due to a severe shortage of data on t his process for tropical agro-ecosystems other than rice. Given this l ack of data, I approach this question by analyzing data on denitrifica tion and nitrous oxide flux in tropical native forest and pasture soil s and attempt to make some conclusions and pose some hypotheses about the significance of denitrification in tropical agricultural soils. I also briefly review methods for measuring denitrification. The data an alysis suggests that denitrification in tropical forest soils is stron gly influenced by the nature and amount of soil C and N turnover. Stud ies to examine differences in denitrification in different tropical ag ricultural systems should focus on the effects of system management on C and N turnover. The data analysis also suggests that, just as in te mperate regions, denitrification may not be a significant route of N l oss from most tropical agricultural systems. However, field studies ar e necessary to determine if this is actually the case.