California Department of Food and Agriculture

Office of Environmental Farming & Innovation

Nutrient Management

California produces many diverse agricultural crops that provide a nutritional food supply to feed a growing global population. Plant nutrients, especially nitrogen, are essential elements for plant growth and food crop production. Soils in California used for growing food crops lack sufficient amounts of nitrogen. Therefore, synthetic and organic (e.g., manure) nitrogen fertilizers are applied to the soil to provide agricultural crops with the adequate amount of nitrogen to ensure sufficient crop yields.

It is well understood that applied soil nitrogen goes through the microbial cycle. Microorganisms in soils convert the nitrogen to nitrate, a soluble form of nitrogen suitable for plant uptake. Some of the nitrate can move to water systems including groundwater over many years if not taken up by plants or further processed by soil microorganisms. High nitrates in drinking water is a public health concern. The State Board of Food and Agriculture recently had a forum "to discuss innovations, approaches and stewardship related to the nitrogen cycle." Download more information on the board meeting, including presentations. (PDF)

Nutrient management plans or nitrogen budget worksheets are an important tool that growers can use to address nitrogen movement to waters of the state, including groundwater. These plans help growers understand how much nitrogen is left over after considering the plant requirements, how much was added to the soil, how much nitrogen was removed from the field with harvest as well as several other important variables. CDFA believes that this tool is a sound science-based "front-end" solution to reducing nitrogen movement off irrigated agricultural lands and into groundwater systems. CDFA has established several new initiatives under the leadership of Secretary Ross. These initiatives are listed below.