A recent UC Davis study about nitrate contamination in underground water supplies throughout California’s Central Valley and the Salinas Valley revealed that agricultural fertilizers were principally responsible for the contamination.

However, the general public may not realize that the problem of nitrates draining into drinking water tables has been a complex issue that agriculture has been tackling for many years.

Regarding the UC Davis study highlighting the problem, the fertilizer industry acknowledges the importance of dealing with the problem of nitrates seeping into California’s groundwater, and the industry has not been sitting idly by and not doing anything about it.

Granted, the new study did note the scope of the problem and the numbers of those people affected by nitrate pollution, along with pointing out financial remedies to deal with the situation, but general readers might not know that the industry has been working hand-in-glove with agriculture and state agencies to reduce nitrate loads on croplands.

It is even accurate to state that had it not been for the research and education funded by the fertilizer industry and the improved farming practices over the last many years to deal with the nitrate issue, UC Davis researchers may have reported numbers that greatly exceeded their findings about the extent of the problem and the amount of those residents impacted.

To put the nitrate issue into context, it should be pointed out that during the past 30 years the fertilizer industry in California has self-funded research on the issue working in tandem with the California Department of Food and Agriculture.

More specifically, CDFA’s Fertilizer Research and Education Program (FREP) has concentrated on developing extensive “best management practices (BMPs)” to mitigate contributions from fertilizers. Over the years, with the support of the fertilizer industry, CDFA/FREP has contributed millions of dollars in grant funds to combat the nitrate problem.

Through nutrient management projects, farmers are implementing BMPs that optimize the efficiency of fertilizer usage by matching nutrient supply with crop requirements and to minimize nutrient loses.

Over the years there have been changes in farming practices to reduce nitrate leaching. These include split applications of nitrogen fertilizer which involves the proper amounts of nitrogen and other plant nutrients for vigorous crop growth based on soil and plant tissue testing. Soil moisture sensors are now available that allow for the continuous monitoring of soil water status in the soil profile. Fertigation (fertilizer mixed into irrigation methods) has become more popular for its efficient use of water and nutrients, tremendously reducing leaching and runoff of nitrates.

And, more recently, there have been new technologies developed, such as the remote sensing of in-season nitrogen status of crops for supplemental fertilization involving corn and wheat, and is presently in development for stone fruit crops and almonds. Crop-specific and sometimes even variety-specific algorithms allow for precise and spatially variable application of the optimum nitrogen rate. Also, progress is being made to determine nitrogen management zones guided by aerial imagery, photography to detect nitrogen stress, and sensors to calculate nitrogen application rates while travelling across the field. As this new technology becomes more established and affordable, its adoption in California will be widely accepted.