Management of rice production systems to increase productivity

Determining Crop N: The first step is to determine the total crop N
need. The equation for this determination is:
Where:
Total Crop N Needs = Yr * Ncr = Yg*%Ng + Ys*%Ns
Yr = Total dry matter;
Ncr = Nitrogen concentration in the total plant;
Yg = Reproductive yield;
%Ng = Nitrogen concentration in the reproductive portion of the crop;
Ys = Vegetative yield;
%Ns = Nitrogen concentration in the vegetative portion of the plant.
The input information necessary to determine the amount of N that the
crop needs is entered in the Diagnosis section of NuMaSS. The amount of
additional N needed to produce the targeted yield that you want is a function
of the capacity of the soil to supply N and the total amount of crop N needed.
In order to determine the total crop demand for N and fertilizer N
requirement, it is important to have a target yield in order determine the
amount of N fertilizer needed. Better results are obtained by entering either
the total amount of dry matter or a realist attainable grain yield. If this
information is absent, a default value may be obtained from the database for
the specific location, sub‐region, or region. Total crop N is a function of both
total crop dry matter and the N content. If information for N content is not
available, again a default value may be obtained from the database. For
NuMaSS to run, the minimum data set that must be entered (or pulled from
default values in the database) in the Diagnosis section of NuMass are:
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