Fertilizer Recommendation Tables - 2007 Revision

Nitrate-nitrogen Soil Test and Spring Barley

The interpretation of the nitrate-nitrogen soil test for barley applies only to parts of the province outside of eastern Ontario that receive less that 2800 crop heat units.

Since soils can vary greatly in their ability to supply nitrogen, the general recommendation found in the Nitrogen Requirements - Annual Field Crops table on page five, may not be the most profitable for some fields. The amount of nitrate-nitrogen present in the soil near planting time can be a useful indicator of a soil's ability to supply nitrogen. A recommendation based on spring nitrate-nitrogen test should be considered as a guideline that is useful in formulating a nitrogen management program for spring barley.

Time and Depth Sampling

The nitrogen recommendations for spring barley based on soil test for nitrate-nitrogen were developed using samples that were taken near planting time. Samples were taken to a depth of 30cm within 5 days (before or after) of planting.

Samples should be collected as close to planting time as practical, allowing for sample shipping, analysis and receipt of results (contact the accredited lab to determine sample turn-around times). It is important that all cores in a field be taken to the same 30 cm depth. To ensure that the sample is representative of the field, take the same number of cores and use a sampling pattern similar to that recommended for the standard soil test under Soil Sampling in the Soils section, OMAFRA Publication 811, Agronomy Guide for Field Crops.

Where Caution is Required

There are situations where the fertilizer recommendations based on nitrate-nitrogen soil test should be adjusted. The nitrogen in manure or legumes applied or plowed down just before sampling will not have converted into nitrate and will not be detected by the soil test. Information will be provided with the soil test results on how to make appropriate adjustments.

Caution should also be exercised if the recommendation is for large quantities of nitrogen and there is a history of barley lodging at lower rates of nitrogen on that field.

The nitrate-nitrogen soil test has not been adequately assessed for:

1. Legumes or manure plowed down in the late summer or fall
2. Barley following legumes in a no-till system employing chemical burndown of the legumes.

1. *To convert the nitrate-nitrogen soil test (30cm depth) from kg/ha to ppm, divide by 4
2. *The price ratio is the cost of the nitrogen in the fertilizer ($/kg of N) divided by the selling price of the barley ($/kg of barley).