Nitrogen recommendations
(based on spring broadcast
application)
Field Crops
Micronutrient test strip rates
Field Crops
Micronutrient test strip rates
This section contains tables of fertilizer recommendations for most Manitoba field
crops based on soil tests. These recommendations are based on field research conducted in
Manitoba and have been approved for use in Manitoba by the Manitoba Soil Fertility
Advisory Committee. Following are some brief points in using the attached recommendation
tables:
Recommendations are based on soil analysis performed according to the soil analysis section.
Soil analysis results may be reported by soil test laboratories as
lb./ac or ppm. Values in ppm can be converted to lb./ac by multiplying by a factor of 2
for each 6 inch increment of depth for the sample (e.g. multiply by 2 for 6 inch samples
and by 6 for 18 inch samples). Ratings for soil test levels are given as very low (VL),
low (L), medium (M), high (H), very high (VH, VH+).
Soil nitrate-nitrogen values used in these recommendations are based on
fall soil sampling. Manitoba research has shown that 8 lb./ac nitrate-N may mineralize
between late fall sampling and spring seeding. If samples are taken in the spring, deduct
8 lb./ac from the analytical values before using the tables.
Nitrogen rates are based on a spring broadcast application for all but
row crops, where rates are based on a spring band application. Relative efficiency of
nitrogen varies by method and time of application, so rates should be adjusted according
to table 4.
Table 4. Nitrogen Efficiency Based on Application Time and Placement.
Time and Method |
Relative Values |
Spring broadcast |
100% |
Spring banded |
120% |
Fall broadcast |
80% |
Fall banded |
100% |
Adjust nitrogen recommendations from tables according to method and time of application
according to this formula.
Rate of N to Apply = (Rate from chart) X (Relative Value of Spring Broadcast)
(Relative Value of Method Used)
Nitrogen recommendations for cereals, canola, flax, corn and sunflowers
are based on TARGET YIELDS. The TARGET YIELD is the yield that a crop might be expected to
produce based upon the amount of spring soil moisture and expected growing season
precipitation based on the grower's experience. The TARGET YIELD FERTILIZER
RECOMMENDATIONS indicate the fertilizer rate required to meet that yield expectation.
Target yield recommendations are not intended as yield predictions; nor do they imply
guaranteed yield attainment. Achieving such target yields depend upon good management and
cooperation of uncontrollable factors such as weather.
Nitrogen recommendations for cereals are further refined based upon soil
moisture supply. Moisture supply is dependent upon seasonal precipitation and soil
properties such as texture and drainage which affect moisture retention. Based on these
criteria, soils within the province have been assigned a moisture category of MOIST or
DRY. Soils of the MOIST category have a high water holding capacity or are in the cooler
areas which may experience periodic dry conditions. Examples are the clay soils of the Red
River Valley and the Grey Wooded soils.
Soils of the DRY category are intermediate in water holding capacity and experience dry
weather conditions.
The IDEAL moisture category would occur under irrigation or when yield is not resstricted
by lack of rainfall.
A full listing of Manitoba soils and their moisture category are available from your
Manitoba Agriculture, Food and Rural Initiatives office.
No nitrogen is recommended for production of perennial legumes and most
annual pulse crops (the exception is dry beans). All legumes should be properly inoculated
at seeding to ensure nitrogen fixation.
In dry years, deep-rooted crop such as sunflowers will extract nitrogen
below the 24 inch sampling depth. Consider sampling at the 2-4 foot depth for this crop.
High nitrogen rates are recommended for cereals and flax with high
target yields and low soil N. Severe lodging may occur, so growers should temper rates
based on their experiences.
Several of the phosphorus and potassium recommendations are based upon
specific placement techniques. Crops vary in their tolerance of seed placed fertilizer and
this influences recommendations (refer to Table 3 and Table 6).
- For more detailed fertilizer recommendations, a "Fertilizer Selection Expert
System" computer program has been developed by the University of Manitoba. This
program takes into account many production factors, including soil test results, before
making a customized recommendation that includes the optimum source of fertilizer, rate,
method and time of application. The recommendations are based upon Manitoba soil test
guidelines. The program is available from:
Solomon Sinclair Farm Management Institute
Room 403,
Agriculture Building,
University of Manitoba
Winnipeg, Manitoba R3T 2N2
Phone: (204) 474-9436
Fax: (204) 261-7251.
The cost is $50 and the program runs on DOS.
Example 1. A fall soil sample analysis is received with the following results:
Nutrient |
Nitrate-N (0-24 in) |
Phosphorus |
Potassium |
Sulphate-S (0-24 in) |
Result |
30 lb./ac |
15 ppm |
240 ppm |
20 lb./ac |
The crop to be grown is feed barley and the projected yield is 85 bu/ac.
The land is located on clay soils and is classified as a "moist" moisture
category.
Nitrogen fertilizer will be spring banded and phosphorus and potassium
will be seed placed.
From Appendix Table 3, 75
lb. N/ac are required "if spring broadcast". Use
Table
4 to determine rate of spring banded N = 75 X 100/120 = 63 lb. N/ac.
From
Appendix Table 12,
and 15 ppm soil P, one determines that 15 lb. /ac is required.
From
Appendix Table 13,
and 240 ppm soil K, one determines that no KO is required.
From Appendix Table 14,
and 20 lb./ac soil sulphate-S, one determines that 15 lb. S/ac is required.
Fertilizer Guidelines for Soil Tests
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Page |
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Introduction |
Nitrogen |
Phosphorus |
Potassium |
Sulphur |
Micronutrients |
The Fertilizer Act and Quality Standards |
Calculating Fertilizer Rates from Nutrient Recommendations |
Fall/Spring Fertilizer Price Differences |
Common Fertilizers and Their Characteristics |
Soil Testing and Proper Soil Analysis |
Manure |
Nitrogen Fixation |
Soil pH and Salinity | Manitoba Fertilizer Guidelines Based on
Soil Tests |
General Fertilizer Recommendations Without a Soil Test |
Manitoba Soil Fertility Guide
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