UMass Cranberry Station

Carolyn DeMoranville, UMass

Nitrogen in Cranberry Agriculture

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Why cranberry farmers use nitrogen Important in plant structure

and function• Protein, DNA• Chlorophyll

Each year the plant makes more leaves, stems, and roots and sheds leaves and roots

In the fruit, N is the element in the highest concentration

Nitrogen is arguably the most important fertilizer element applied to cranberries

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Nutrient Removed- leaves/

stems*

Removed –

100 bbl crop

Total

Nitrogen 13.6 5.0 18.6

N removed (pounds/acre per year) - Early Black

*Leaves and stems are removed as part of harvest operations

Since Early Black has small leaves and thin stems compared to hybrids, there is an assumption that N removal for those would be greater. This calculation does not include N in roots.

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How much N is required?

At least enough to replace what’s lost and to support new growth and fruiting

Cranberry varieties have differing needs for N – larger fruit, larger plants (leaves) and bigger crops mean more N is needed

Most growers developfertilizer programs basedon N.

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How cranberries get nitrogen

From soil• Cranberry soil very sandy - holds little• Organic matter - 1-2% only

From recycling in the plant• Some stored in stems and roots

From fertilizer

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Compare cranberry to other crops

Plant leaf tissue Avg. applied

Crop Nitrogen (%) Nitrogen (lb)

Cranberry 0.9-1.1 20-60

Blueberry 1.0-1.5 45-65

Apple 2.0-2.5 50-60

Peach 2.5-3.0 80

Corn 2.9-3.5 160-200

Wheat 2.6-4.0 75-110

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Nitrogen use in cranberry

If growers get N wrong – they pay a price in plant growth and crop

There is a body of research on N needs and rates

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Disadvantage to too much N

Davenport, Stevens in BC

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N rate decision tree – from the BMPs

Use less N if:• No or low crop• Native varieties• Deep peat• >3% organic• You sanded• You pruned• Tissue N >1.1%• Uprights long/runners• Frost damage• Insect/disease damage

Use more N if:• Bog renovated or new• Ben Lear or Stevens• Mineral soil• <1% organic• You mowed• Crop was heavy• Tissue N <0.75%• Uprights stunted/thin• Heavy bloom• General yellowing

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Nitrogen Form - Ammonium

Several studies show best growth and N uptake with ammonium (compared to nitrate)

Ammonium taken up 10x faster than nitrate

Little conversion of ammonium to nitrate at low pH; ammonium leaches less

Nitrogen – Nitrogen Cycle

Ammonium Soil T Low pH Removal in

crop (~23 lb in 150 bbl)

Fertilizer

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When do cranberries need nutritional support? Applications

coincide with growth and fruiting demands of the plants

Late May through early August

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Environmental considerations

Biggest concern is movement of N in surface water

Leaching limited • layered soil and barrier layers (why the

bog can hold a flood) • ammonium N forms

Groundwaterpathway – totalextent unknown

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Flooding practices

CES/SMAST Field Study Cranberry Bog NET Nitrogen Loss

Bog ID --> EH PV BEN WS M-K ASH

Irrigation 0.4 1.5 0.6 0.2 1.7 2.4Groundwater 0.0 0.0 1.0 0.3 0.0 0.0

Frost Protection 0.8 1.8 1.4 0.5 1.6 2.0Pest Management 0.0 0.2 0.1 0.1 0.1 0.1

Harvest 1.3 3.4 4.5 1.2 4.2 2.9Winter Protection 3.0 3.7 5.2 1.4 4.8 4.0

Total IN 5.5 10.5 12.8 3.6 12.4 11.3

Drainage/Infiltration 5.7 6.7 10.5 4.6 7.7 7.2Harvest 2.1 5.3 9.4 4.3 4.5 2.8Winter 4.0 4.6 6.4 1.7 4.0 5.2

Total OUT 11.9 16.5 26.3 10.5 16.2 15.2

Net Nitrogen Loss (lb/a/yr)= 6.4 6.0 13.5 7.0 3.7 3.8

Pine-Oak Forest 0.4Cranberry Bog Nitrogen Output 6.4 (Flow Through Bog = 8.6) Residential (density 1 per 2.5 acres) 5.7Direct Precipitation on Bay 9.8

Nitrogen Outflow from Bog

Nitrogen Output to Downgradient Systems (lb N/acre/yr)

Nitrogen Inflow to Bog

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How can we reduce N output?

Practice BMPs regarding rate, timing, split applications

Look at it more as a water problem• Amount of flow• Direction of flow• Pathway of flow

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Amount of flow

Follow recommendations on flooding, drainage, and irrigation

Research on looking at how to limit groundwater upwelling • Compare 2 upwelling sites (10 lb/a/yr) vs.• 4 not upwelling sites (5 lb/a/yr)

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Direction of flow

Diversion• Tail water recovery

Can also relate to attenuation

Research on how to limit flow-through situations – by-pass canals?• Compare flow-through (8.6 lb/a/yr)• To all other types (6.4 lb/a/yr)

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Pathway of flow

Attenuation function of ponds, steams, and wetlands

Mill Brook watershed (Howes and Millham, 1991)• TDN leaving the bog was 0.99 ppm• Downstream the load had decreased to 0.71 ppm

Vegetative channels or retention ponds between the bog and the final discharge point – how to best accomplish this?

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Literature review - attenuation

Denitrification in wetlands is effective at attenuating N• NO3 to N2

Denitrification in ponds and streams • Ponds – 50% attenuation

• 2 studies: 39-95% and 84-96%• Streams – 30% attenuation

• 30-40% observed in riverine systems

Uptake by vegetation less effective

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