How Well Do Critical Nitrogen Concentrations Work for Cabbage, Carrot, and Onion Crops?

Abstract

<jats:p>With the introduction of nutrient management legislation in Ontario, there is a need to improve the efficiency of nitrogen (N) utilization. One possibility is to use critical nutrient concentrations in plant tissue as an indicator of the N nutritional status of the crop. Plant tissue analysis was used to determine the total N and nitrate-N (NO<jats:sub>3</jats:sub>-N) concentrations of cabbage (<jats:italic>Brassica oleracea</jats:italic> var. <jats:italic>capitata</jats:italic> L.<jats:italic>)</jats:italic>, carrots (<jats:italic>Daucus carota</jats:italic> L.), and onions (<jats:italic>Allium cepa</jats:italic> L.) grown in Ontario. The tissue samples were collected from plants as part of N fertilization studies from 1999 to 2001 on the organic soils in the Holland/Bradford Marsh area and the mineral soils near Simcoe, Ontario. Yield was assessed at harvest as an indicator of the N requirement of the crop. Testing the usefulness of critical NO<jats:sub>3</jats:sub>-N concentrations to indicate the N requirement of the crop was problematic because: 1) few published references were available to indicate a critical level of NO<jats:sub>3</jats:sub>-N in these crops; 2) tissue NO<jats:sub>3</jats:sub>-N concentrations were highly variable; and 3) field data rarely matched published references. Tissue total N concentrations from the trials corresponded to published critical N concentrations in some cases, however, the use of published critical N concentrations would have resulted in either over or under-application of fertilizer to the crops. Cultivar, soil type, and climate were shown to affect tissue N concentrations. Based on these results it was concluded that local research and field verification is required before tissue N critical nutrient concentrations become useful for determining fertilizer needs of cabbage, carrots, and onions grown in Ontario.</jats:p>

Timing Nitrogen Applications for Quality Tops and Healthy Root Production in Carrot

“…This lack of significant correlation is consistent with the results of Westerveld et al (2003b). Further, consistent with the findings of Westerveld et al McKeown 2006, 2007a;Westerveld, McKeown, and McDonald 2006a) and White and Strandberg (1978), plants took up more N than was estimated to be available in the top 30 cm of soil when applied at the rates of 45 and 90 kg ha −1 .…”

“…Consistent with earlier studies of Hemphill and Jackson (1982), Sanderson and Ivany (1997), Warncke (1996), Westerveld et al (2003aWesterveld et al ( , 2003b, McKeown (2006, 2007a), andMcDonald (2006a, 2006b), carrot yield did not significantly respond to increasing N rate (Table 5). Available N between 153 to 189 kg ha −1 (treatment 3 in most of the studies) produced the greatest numerical yield although it did not statistically differ, regardless of site conditions or protocol.…”

Excessive Fertilization is Detrimental to Yield and Quality for Onion Grown on High Organic Matter Content Paddy Soils

“…Some have indicated that N fertilizer has little effect on bulb yield (Hensel and Shumaker, 1992;Shock, 2005;Westerveld et al, 2003). The small responses to N were due to annual overapplication (Westerveld et al, 2003), nitrogen fertilization practices based on crop nutrient uptake (Shock, 2005), inaccuracy of soil test recommendations (Russo, 2008), initial residual soil nitrate and ammonium, nitrate in the irrigation water, and mineralized N during the onion growing season (Shock et al, 2004). Marketable yield at 0 kg·ha −1 of N-P-K was 40.8 Mt·ha −1 , which was 70% of the yield achieved at the recommended 241 rate (Table 1).…”

Establishment of Critical Sap and Soil Nitrate Concentrations using a Cardy Nitrate Meter for Two Carrot Cultivars Grown on Organic and Mineral Soil

“…It is also possible that wilting of leaves caused increased NO 3 -N concentrations because of a concentrating effect. Another possibility is that critical NO 3 -N concentrations are highly dependent on the growth stage of the carrot (Westerveld et al 2003b). Sap NO 3 -N concentrations clearly decline over the growing season, especially during the early and midseason sampling stages.…”

“…However, this estimate was based on a 1-year study, and potential variations among years, soil types, or cultivars were not examined. In addition, critical tissue NO 3 -N concentrations determined in other regions are not useful for N management of carrots, onions, and cabbage in Ontario because of variations in climate, soil, and cultivar (Westerveld et al 2003b). The usefulness of sap NO 3 -N tests is reduced in certain instances because of variability in sap NO 3 -N concentrations caused by aging of sample material (sweet corn), differences among sites (sugarbeets), differences among cultivars (tomato), and large decreases in concentrations over the season (potato) (Coltman 1988;Hartz et al 1993;Geypens and Vandendriessche 1996;Last and Tinker 1968).…”