Articles
INORGANIC NITROGEN LOADING AND DISTRIBUTION IN SOIL PROFILES BENEATH ROSE GREENHOUSES
Article number
547_27
Pages
227 – 233
Language
Abstract
Inorganic nitrogen (N) loading and distribution were surveyed in soil profiles beneath commercial rose greenhouses.
Nitrate-N concentrations, down to a maximum depth of 2 m and across all sampled sites, ranged from 2 to 343 mg kg-1 whereas NH4-N concentrations typically oscillated between 1 and 5 mg kg-1. Soils with clay to clay-loam textures showed a median NO3-N concentration of 70 mg kg-1 in the root zone (upper 30 cm soil layer). These values were lower for sandy soil profiles (median of 14 mg kg-1) but consistently uniform at all sampling depths.
Determinations of moisture content for each soil sample allowed the calculation of NO3-N concentrations in the soil solution, with median values of 225 and 188 mg L-1 in the root zone of heavy (clay, clay- loam) and light (sand, sandy loam) soils, respectively.
Maximum soil solution NO3-N concentrations exceeded 700 mg L-1 in some heavy textured soils.
The estimated total soil N loading on an area basis ranged from 171 to 1470 kg Ha-1 in shallow soil profiles (0-90 cm), and from 529 to 1736 kg Ha-1 in deeper soils (0-180 cm). Sixty percent of the all the surveyed greenhouses showed total N loadings  kg Ha-1 below the root zone.
These results highlight the pressing need to scrutinize N fertilization programs in commercial rose production and evaluate cultural practices and technologies that minimize environmental impact while sustaining productivity.
Nitrate-N concentrations, down to a maximum depth of 2 m and across all sampled sites, ranged from 2 to 343 mg kg-1 whereas NH4-N concentrations typically oscillated between 1 and 5 mg kg-1. Soils with clay to clay-loam textures showed a median NO3-N concentration of 70 mg kg-1 in the root zone (upper 30 cm soil layer). These values were lower for sandy soil profiles (median of 14 mg kg-1) but consistently uniform at all sampling depths.
Determinations of moisture content for each soil sample allowed the calculation of NO3-N concentrations in the soil solution, with median values of 225 and 188 mg L-1 in the root zone of heavy (clay, clay- loam) and light (sand, sandy loam) soils, respectively.
Maximum soil solution NO3-N concentrations exceeded 700 mg L-1 in some heavy textured soils.
The estimated total soil N loading on an area basis ranged from 171 to 1470 kg Ha-1 in shallow soil profiles (0-90 cm), and from 529 to 1736 kg Ha-1 in deeper soils (0-180 cm). Sixty percent of the all the surveyed greenhouses showed total N loadings  kg Ha-1 below the root zone.
These results highlight the pressing need to scrutinize N fertilization programs in commercial rose production and evaluate cultural practices and technologies that minimize environmental impact while sustaining productivity.
Authors
R.I. Cabrera, R.Y. Evans
Keywords
ammonium, fertilization, ground water pollution, nitrate, Rosa hybrida, root zone, soil solution
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