Determine Nitrogen Levels In Sweet Corn With Presidedress Nitrate Test

Crop Focus chartEditor’s Note: This article was excerpted from The Sweet Corn Nutrient Management Guide, Oregon State University. For more inforomation, go to http://extension.oregonstate.edu/catalog and type “Sweet Corn Nutrient Management Guide� in the search box.

Two approaches have been evaluated inOregonfor postharvest nitrogen (N) testing in sweet corn: stalk nitrate-N and soil nitrate-N testing. Both tests are designed to assess whether the overall plant-available N supply for the crop (from organic inputs, fertilizer, irrigation water, and N mineralized from soil organic matter) was excessive. Of the two end-of-season tests, the postharvest soil nitrate test, which will be discussed in this article, is the most useful and reliable.

Postharvest tests will not indicate whether N supply was deficient or adequate. When building an N monitoring program, start with the presidedress nitrate test (PSNT). In westernOregon, using the PSNT when sweet corn has five or six leaves is an excellent indicator of the need for additional N.

Postharvest testing has the most value where organic inputs supply N because accurate predictions of the timing and amount of plant-available N supply are difficult with these materials.

Determine Excess Nitrogen
The postharvest nitrate test is used to diagnose accumulation of excess N at the end of the season. Excess N accumulates when plant-available N supplied from all sources exceeds crop capacity for N uptake.

Begin by collecting soil (0- to 12-inch depth) immediately following harvest. When rainfall follows harvest and substantial crop residue decomposition occurs, soluble N may move from decomposing leaves into soil. This soluble N may add nitrate-N not present at harvest time, confounding test interpretation.

The effect of N fertilizer application rate on postharvest nitrate-N has been measured in a number of on-farm and experiment station field trials. Based on these trials, when a NO3-N (nitrate-N) test for the top foot of soil is above 50 pounds per acre, N supply from all sources was probably greater than needed for maximum ear yield.

An example of the relationship between N fertilizer rate, crop N uptake, and postharvest soil nitrate is shown in the chart below. Maximum ear yields occurred with 100 to 200 pounds of N per acre in these trials. At N fertilizer rates of 0 to 150 pounds of N per acre, sweet corn was efficient in N uptake, and postharvest nitrate-N was less than 50 pounds N per acre.

At the highest N fertilizer rate (200 pounds per acre), postharvest nitrate-N averaged 75 pounds per acre and had the most variability (range of 43 to 123 pounds per acre). Although a relationship has been shown between N fertilizer rate or N supply and postharvest soil NO3-N, keep in mind that soil NO3-N is linked with irrigation practices. Low NO3-N values at harvest may be a result of excess irrigation.

Topics:

Leave a Reply

Crop Protection Stories
Close-up of mature diamondback moth
Insect Control
January 13, 2017
3 Ways to Save Your Vegetable Crops From Diamondback Moths
An integrated approach is key to managing this destructive pest. Read More
Crop Protection
January 10, 2017
New Research May Help in the Fight Against Insect-Transmitted Viruses in Vegetables
The findings depict the first time that a viral effector protein has been seen as attracting insect vectors to feed on plants through odor.  Read More
2-spotted spider mites
Crop Protection
January 9, 2017
Vegalab US Offers a New Formulation of Spider Mite Control   
The biological product attacks spider mites in two ways. Read More
Crop Protection
January 5, 2017
Labor, Efficiency, and the Future of Weed Control
Increases in labor costs will affect the costs of production of vegetable crops in California, so growers will have to take advantage of production practices that help reduce weed pressure. Read More
Crop Protection
January 5, 2017
Scientists Aim to Improve Nitrogen, Water Use Efficiency in Lettuce
Genetic research intends to develop varieties with enhanced nutrient uptake. Read More
potato field
Crop Protection
January 4, 2017
New Potato Insecticide/Fungicide Seed Treatment Available
Syngenta’s CruiserMaxx Vibrance receives EPA registration. Read More
Crop Protection
January 4, 2017
Common Purslane Needs Diligence to Conquer in Vegetable Crops
A pest in the West, purslane has potential to impact all vegetables grown throughout North America. Read More
The Latest
Crop Protection
January 16, 2017
Monsanto, NRGene Enter Agreement for Big…
Technology platform is designed to help Monsanto analyze, store, and mine its genomic data sets to enhance breeding and R&D opportunities. Read More
Crop Protection
January 10, 2017
New Research May Help in the Fight Again…
The findings depict the first time that a viral effector protein has been seen as attracting insect vectors to feed on plants through odor.  Read More
Crop Protection
January 9, 2017
Vegalab US Offers a New Formulation of S…
The biological product attacks spider mites in two ways. Read More
Crop Protection
January 5, 2017
Labor, Efficiency, and the Future of Wee…
Increases in labor costs will affect the costs of production of vegetable crops in California, so growers will have to take advantage of production practices that help reduce weed pressure. Read More
Crop Protection
January 5, 2017
Scientists Aim to Improve Nitrogen, Wat…
Genetic research intends to develop varieties with enhanced nutrient uptake. Read More
Crop Protection
January 4, 2017
New Potato Insecticide/Fungicide Seed Tr…
Syngenta’s CruiserMaxx Vibrance receives EPA registration. Read More
Crop Protection
January 4, 2017
Common Purslane Needs Diligence to Conqu…
A pest in the West, purslane has potential to impact all vegetables grown throughout North America. Read More
Citrus
December 17, 2016
Pesticide Safety Manual Released
EPA, Pesticide Educational Resources Collaborative updates manual for worker standards. Read More
Citrus
December 13, 2016
Monsanto Shareholders OK Deal With Bayer
Companies one step closer to "advancing together." Read More
Citrus
December 13, 2016
USDA Frees Up $4 Million For GMO Researc…
National Institute of Food and Agriculture allocates funding to help evaluate genetically modified organisms. Read More
Citrus
December 13, 2016
Pesticide Residues Practically Nil
Pesticide data program summary released after testing 10,000 samples from fresh produce, vegetables, and processed foods. Read More
Crop Protection
December 6, 2016
New Fact Sheet Analyzes Weed Seeds And T…
Topics covered include how weed seeds travel, when they germinate, and ways they can be eliminated. Read More
Crop Protection
December 6, 2016
Scientists Aim To Improve Nitrogen, Wate…
Genetic research intends to develop varieties with enhanced nutrient uptake. Read More
Crop Protection
December 6, 2016
Orondis Opti Fungicide Receives Registra…
The product provides control of Oomycete diseases in vegetables and other specialty crops. Read More
Crop Protection
December 4, 2016
Bio Huma Netics Opens New Lab Facility
Facility to improve quality control and help expand product line. Read More
Crop Protection
November 30, 2016
The Effect Of Soil Fertility On Fusarium…
Ongoing research sheds light on the role soil health plays in the severity of the deadly pathogen. Read More
Citrus
November 29, 2016
Review Shows Low Risk To Aquatic Inverte…
Peer-reviewed evaluation of more than 100 studies finds uses of imidacloprid are unlikely to harm aquatic invertebrate communities, or the birds and fish that rely on them. Read More
Crop Protection
November 29, 2016
Tackle Whiteflies Head On
Reported in outdoor landscapes this year, vegetable growers must be prepared to mitigate the spread of the Q-Biotype. Read More