Start / Soil and fertilization / Liming and fertilization
See how much nitrogen corn needs as topdressing, after deducting what is already in the soil and at planting, and what that equals in urea.
Pre-sizing and estimating tool: the results do not replace a design, calculation, or report signed by a qualified professional, nor verification against the applicable standards.
Technical responsibility. This calculator is under verification. The reference values and examples are hypothetical, to illustrate the calculation, and are not technical references. The user is responsible for the data entered, the choice of parameters, and the use of the results, and must validate them with a qualified professional before any decision, purchase, application, or construction work.
Kilos of topdressing N for different yields; the highlighted bar is yours.
How much comes from the soil, from sowing and from topdressing, in kg/ha.
Drag the controls to simulate data different from what you entered (from 30% less to 30% more) and watch the result change instantly.
Kilos of topdressing N per hectare for yields of 100 to 200 bags/ha and efficiencies of 50%, 70% and 90%.
The calculation done in steps, with the values you entered.
The calculation memo gathers this page's inputs, results, equations, assumptions, and references, with fields for project, responsible person, and review. The full report also includes the charts and interpretations, in color. In the print window, choose Save as PDF.
Enter the expected yield in bags per hectare, the N required per tonne of grain, the N credit from soil and rotation, the N already applied at planting, the topdressing N efficiency, and the N content of the urea.
150 bags/ha, 20 kg N per tonne, 30 kg credit, sowing with 20 kg, 70% efficiency and urea with 45% N.
Yield = 150 × 0.06 = 9 t/ha. N required = 9 × 20 = 180 kg. Shortfall = 180 − 30 − 20 = 130 kg. Topdressing = 130 ÷ 0.70 = 186 kg N/ha. Urea = 186 ÷ 0.45 = 413 kg/ha.
Because it defines how much the crop takes up per tonne of grain. It is the basis for the total, and the reference varies with the hybrid and the yield level.
Because this N is already available to the plant. Without the deduction, the topdressing recommendation becomes larger than the crop needs.
It depends on the soil, the rain after application, and the form of the fertilizer. The default value is a reference; adjust it using your experience and the regional recommendation.
No. Timing and split application depend on the crop stage and the weather. Check the technical recommendation for your region.
Important notice: the Agrocalcs tools make estimates and preliminary sizing based on the data entered and on published engineering methods. They do not replace a design, a calculation report or a report signed by a qualified professional (CREA/ART), nor verification against the applicable technical standards and legislation, such as the Regulatory Standards of the Ministry of Labor. Material and fuel properties vary: check with the manufacturer or with analyses of your process before deciding. By using the site, you agree to the Terms of Use.
© 2026 Agrocalcs. Found an error? Write to contato@agrocalcs.com.br.