Geisseler Lab
Nutrient Management
Crop Nitrogen Calculator for California
This calculator was developed based on results from several studies in commercial
fields in California. Information on lines marked with an * needs to be provided.
Information about an input or output field can be accessed by clicking on
.
Field-Specific Input
Crop*:
Region*:
Planting date*:
Expected harvest date*:
Expected yield*:
Previous crop:
Residual nitrate in 1st ft:
Residual nitrate in 2nd ft:
Nitrate in irrigation water:
Irrigation System*:
Preplant/starter fertilizer:
Soil organic matter*: %
Soil type*:
Nitrogen Uptake and Applications
Nitrogen from soil and water includes residual nitrate, N mineralized during the growing season and N applied with irrigation water.
The graph and the calculations are based on average values from commercial fields in California. Weather conditions, management and variety selection all can affect N uptake and availability. It is therefore important to monitor the N status of the field during the season with soil or leaf analyses. More information about soil and leaf sampling can be found here.
Nitrogen Budget
Estimated N uptake:
In-season N mineralization:
Available residual nitrate:
Nitrate in irrigation water:
Preplant/starter N available:
Assumed fertilizer N use efficiency:
In-season fertilizer N needed:
Alfalfa provides additional N credits to subsequent crops, not incluced in the calculation.
In field trials across California,
alfalfa’s N contribution to a irrigated wheat crop ranged from 50 to 125 lb N/ac. Stand vigor
and height of the alfalfa plants at termination, as well as soil properties and climate can affect
N credits to subsequent crops.
For more information, see Putnam, D.H. 2016. Nitrogen Dynamics in Cropping Systems – Why Alfalfa
Is Important.