Nitrogen Use Efficiency
Nitrogen use efficiency (NUE) can be defined in many ways, but initially we will use the simplest calculation: the partial nitrogen balance (NUE = Nitrogen exported from field in crop products / Nitrogen applied).
This calculation relies on four values: (1) yield, (2) the percent moisture of the product, (3) the nitrogen content of the product, and (4) the quantity of nitrogen applied. We are in the process of putting together a database of values from different sources (see Table 1, below). Current data sources include USDA National Agricultural Statistics Service (NASS), the USDA Crop Nutrient Tool, USDA Chemical Use Surveys, and UCD Cost Studies. Future analysis will examine (1) how these values should be adjusted to account for crop and field-level nitrogen cycling, (2) the export of crop by-products that contain nitrogen off-farm, and (3) the integration of additional measures of nitrogen use efficiency.
This assessment will use available data to gain a broad perspective on where synthetic nitrogen is being applied and the efficiency of nitrogen use on a commodity-by-commodity basis. We will examine nitrogen use for more than 40 commodities—all that account for at least 1 percent of the total acreage, value, or production in California. We recognize efficiency will vary widely across producers and locations and thus we will calculate a distribution of potential values for each commodity.
Nitrogen Use Efficiency Across Crops (Table 1)
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This table displays preliminary data and sources for NUE calculations of 20 commodities. We will perform these calculations for more than 40 commodities—all that account for at least 1 percent of the total acreage, value, or production in California.
Questions/Comments: Contact Todd Rosenstock, Best Practices and Technical Options Fellow, [email protected]