Nitrate Accumulation in Vegetables. I. Spinach Grown in Upland Soils¹

Abstract

The nitrate concentrations in spinach (Spinacia oleracea L.) blades and petioles were determined for different sources and times of application of N fertilizers to a Honeoye fine sandy loam and a Lima silt loam to determine the effect of N fertilization on the concentration of nitrates in the plant parts used for consumption for food. Nitrate concentrations were determined potentiometrically, using a nitrate‐selective ion electrode, on plant samples taken at time intervals after N fertilization and at harvest stage for processing. Nitrogen fertilization substantially increased the NO3 concentrations of spinach grown in upland soils. The following observations were significant: (a) More NO3 accumulated in leaves of plants broadcast with N fertilizers before planting than if an equivalent amount of N fertilizer was supplied by sidedressing one week before harvest. (b) The N carrier was a significant factor in governing NO3 accumulation when it was applied as sidedressing.

Effects of urease and nitrification inhibitors application on urea fate in soil and nitrate accumulation in lettuce

“…Some authors reported that it can also reduce NO 3 accumulation in comparison with NO 3 fertilizers when side-dressed to growing crop (Barker et al, 1971). However, in most soils NH 4 applied is rapidly nitrified.…”

Effects of Chemical Treatments and Controlled Atmospheres on Postharvest Nitrate‐nitrite Conversion in Spinach

“…The high levels of nitrite observed in spinach treated with DHA-S was probably related to its injurious effect on spinach leaf tissue. Sodium dehydroacetate, by impairing the integrity of leaf tissue, might facilitate the penetration of bacteria into nitrate-rich locations such as the veins (Peck et al, 1974) and the petioles (Barker et al, 1971;Peck et al, 1974).…”

Effect of different concentrations of urea with or without nickel addition on spinach (Spinacia oleraceaE.) growth under hydroponic culture

“…Firstly, urea can be easily hydrolyzed to NH4 +, whose uptake by plants may result in a dramatic pH decrease in the nutrient solution (Luo et al 1993). Secondly, the presence of NH4-N instead of N0 3 -N in the nutrient solution may interfere with the uptake of nutrients, particularly cations (Barber 1984). Another problem is that plants grown with urea without Ni supplementation accumulate urea and show chlorosis or develop necrosis of the leaf edges (Gerendas and Settelmacher 1997b).…”