Nitrate accumulation in forage brassicas

Fletcher, Andrew; Chakwizira, E.

doi:10.1080/00288233.2012.672428

Cited by 9 publications

(21 citation statements)

References 14 publications

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“…2A) is potentially returned to the soil and lost through leaching (Di & Cameron 2002) late in winter or early spring when paddocks are bare after the grazing, causing environmental pollution (Wang et al 2003). High crop N uptake may also contribute to animal health problems during grazing, such as nitrate poisoning (Nichol 2007;Fletcher & Chakwizira 2012).…”

Section: Discussionmentioning

confidence: 99%

“…Conversely, Chakwizira et al (2013) commented that the low CP (or nitrogen concentration = CP/6.25) could result in reduced total nitrogen excreted by animals to the environment, compared with the high N (CP) concentration crops such as winter-fed brassicas e.g. kale (Fletcher & Chakwizira 2012). The overall low CP may not necessarily be problematic considering the animals are fed maintenance diets at this time of the year.…”

Section: Discussionmentioning

confidence: 99%

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Growth, nitrogen partitioning and nutritive value of fodder beet crops grown under different application rates of nitrogen fertiliser

Chakwizira

Ruiter

Maley

2014

New Zealand Journal of Agricultural Research

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Nitrogen (N) supply needs to be closely matched to crop demand to achieve optimum N use efficiency (NUE). Sub-optimal N supply can lead to poor yields, whereas excess N application may cause nitrate leaching and environmental pollution. An experiment with five rates of N: 0, 25, 50, 100 and 200 kg ha −1 , was carried out at Lincoln, Canterbury, in New Zealand to define the effects of N supply on growth, N uptake and define how derived NUE may influence nutritive value of fodder beet production. Both dry matter (DM) yield and N uptake increased with N supply, by 39% and 129%, respectively, when 200 kg N ha −1 was applied, compared with the control plots. Leaf area index (LAI) also increased with N supply. However, the control crop did not attain critical LAI (LAI crit ) and those receiving 25 and 50 kg N ha −1 attained LAI crit for only a short period of time compared with crops supplied with ≥100 kg N ha −1 . This meant that they intercepted less radiation and subsequently had lower DM yield than the high N treatments. The specific leaf nitrogen increased 13% to 2.34 g N m −2 leaf when ≥50 kg N ha −1 was applied, compared with the control plots. The NUE decreased by 64% from 93 kg DM kg −1 N for the 25 kg N ha −1 plots compared with the 200 kg N ha −1 plots. Nitrogen rate had no effect on the nutritive value of fodder beet. The results suggest 100 kg N ha −1 was adequate for optimum DM production and N was important for canopy development and subsequent DM accumulation.Keywords: Beta vulgaris L.; critical leaf area index (LAI crit ); nitrogen use efficiency (NUE); uptake efficiency (NupE); utilisation efficiency (NutE); nutritive values and specific leaf nitrogen (SLN)

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Growth, nitrogen partitioning and nutritive value of fodder beet crops grown under different application rates of nitrogen fertiliser

Chakwizira

Ruiter

Maley

2014

New Zealand Journal of Agricultural Research

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“…Nitrate‐N concentration varies with plant parts (Crawford et al ., ; Griffith and Johnston, ; Guillard et al ., ; Fletcher and Chakwizira, ), being higher in the stems, petioles and midrib than the leaf lamina. Forage intake of kale and rape crops has been shown to vary with plant part (Barry et al ., ; Armstrong et al ., ).…”

Section: Introductionmentioning

confidence: 98%

“…() found that N uptake for kale crops was ~250 kg N ha −1 when no N was applied and ~500 kg N ha −1 when 500 kg N ha −1 was applied; with both crops producing about 25 t DM ha −1 . This may lead to the accumulation of antinutritional compounds, such as nitrate–nitrogen (NO 3 –N) (Griffith and Johnston, ; Pelletier et al ., ; Fletcher and Chakwizira, ,b) with the potential risk of NO 3 –N poisoning of grazing ruminant animals (Nichol, ). The implication is that any excess N applied and taken up by the crops is stored as NO 3 –N.…”

Section: Introductionmentioning

confidence: 99%

“…Nitrate‐N concentrations have also been shown to vary with N supply (Pelletier et al ., ; McDonald et al ., ; Fletcher and Chakwizira, ), stage of growth (Griffith and Johnston, ) and drought stress (Brakenridge, ). The general agronomic recommendation for N application in forage brassica crops in New Zealand is to split into two applications at 6 and 12 weeks after sowing (WAS) for forage kale crops and 4 and 8 WAS for forage rape crops (Fletcher and Chakwizira, ). This limits the concentration of NO 3 –N in the soil and the risk of leaching losses during the season.…”

Section: Introductionmentioning

confidence: 99%

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Effects of nitrogen rate on nitrate–nitrogen accumulation in forage kale and rape crops

Chakwizira

Johnstone

Fletcher

et al. 2014

Grass and Forage Science

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Nitrogen fertilizer is applied to supplement soil nitrogen supply to maximize forage brassica crop dry‐matter production. However, nitrogen fertilizer applications in excess of that required to maximize growth result in potentially toxic nitrate–nitrogen (NO3–N) concentrations in grazeable plant tissues. Three experiments, two for forage kale at Lincoln (Canterbury) and one for forage rape at Hastings (Hawke's Bay) in New Zealand were grown under different rates of nitrogen (0–500 kg N ha−1) to determine the effect of different rates of nitrogen on NO3–N content of different plant parts of the crops. One of the kale experiments was grown with either full irrigation or no rain and no irrigation over summer, hereafter referred to as summer drought. The NO3–N concentration on a whole plant (weighted average) basis increased from 0·1 mg g−1 dry matter for the control plots to 2·30 mg g−1 for the 500 kg N ha−1 plots for forage kale. It increased from 0·99 for the control plots to 3·37 mg g−1 for the 200 kg N ha−1 plots for forage rape crops. However, NO3–N concentration increased with N supply under the summer‐drought plots from an average of 0·33 mg g−1 when ≤120 kg N ha−1 was applied to 2·30 mg g−1 for the 240 kg N ha−1 treatments but was unaffected by N supply under irrigation. The NO3–N concentrations were higher in the stems and the petiole (which included the midrib of the leaf) than leaves in all three experiments. The NO3–N concentration was highest at the bottom of the kale stem and decreased towards the top. We recommend N application rates based on soil tests results, and for conditions similar to the current studies up to 300 kg N ha−1 under irrigation and adjusted lower N rates for regions prone to dry summers.

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A forage brassica simulation model using APSIM: Model calibration and validation across multiple environments

Watt

Bell

Pembleton

2022

European Journal of Agronomy

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Nitrate accumulation in forage brassicas

Cited by 9 publications

References 14 publications

Growth, nitrogen partitioning and nutritive value of fodder beet crops grown under different application rates of nitrogen fertiliser

Growth, nitrogen partitioning and nutritive value of fodder beet crops grown under different application rates of nitrogen fertiliser

Effects of nitrogen rate on nitrate–nitrogen accumulation in forage kale and rape crops

A forage brassica simulation model using APSIM: Model calibration and validation across multiple environments

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