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Management of rice production systems to increase productivity

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1. Crop reproductive yield, Crop vegetative yield, Crop<br />

reproductive N content, Crop vegetative N content; OR<br />

2. Crop <strong>to</strong>tal dry matter, Crop <strong>to</strong>tal N content; OR<br />

3. Crop reproductive yield, Harvest ratio, Crop reproductive N<br />

content, Crop vegetative N content<br />

Determining Crop Available N: Once the amount <strong>of</strong> N is calculated for<br />

the target yield, NuMaSS calculates the amount <strong>of</strong> N available <strong>to</strong> the plant<br />

from the soil (NSoil), manure (NManure) and organic amendments<br />

(NResidue), and green manure crops (NResidue). The equation used <strong>to</strong><br />

calculate crop available N is:<br />

Crop available N = NCrop(available_<strong>to</strong>) = NSoil + NManure + NResidue<br />

Determining Soil N: There are four different methods that you can use<br />

<strong>to</strong> determine the amount <strong>of</strong> N supplied by the soil (NSoil). The program<br />

au<strong>to</strong>matically selects the method for calculating NSoil based on the data<br />

availability. The hierarchy for determining NSoil is outlined below. If<br />

sufficient data is available for Method 1, then that is the method used.<br />

However, if there is insufficient data the program will continue sequentially<br />

checking for available data until a method can be found. The precision for<br />

calculating NSoil changes as the program moves through the methods.<br />

Method 1 is the most precise calculation <strong>of</strong> NSoil, Method 4 is the least precise.<br />

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