The threat of bad weather at planting prompts companies like Nunhems to keep a two-year supply of planting seed on hand. However, that reserve, said Schroeder may not cover all varieties growers want, if there is widespread replanting.

Drip irrigation has had a tremendous impact on virtually every crop produced in the state since it was introduced into California more than 35 years ago. Drip was embraced first by permanent crop growers. It soon moved into high value vegetable crops like processing tomatoes. Over 90 percent of processing tomatoes on the West Side of the SJV are drip irrigated.

Drip has not only saved water, increased yields and generally fine-tuned pesticide and fertilizer use, it has all but eliminated irrigation surface runoff.  This runoff has been a major regulatory focus for the past couple of years as agriculture comes under state and federal clean water acts.

(See related, Groundwater nitrogen dilemma in California)

However, that water quality focus has shifted to groundwater within the past year as a statewide assessment of water points a finger at nitrate-tainted drinking water.

“Conversion to drip has solved the runoff issue, but it has not solved the nitrogen in the groundwater problem,” University of California, Davis vegetable crops specialist Tim Hartz told the tomato growers.

Legislators and regulators are moving rapidly toward regulating nitrogen use in the wake of a scathing UC groundwater study that cited widespread high nitrate in drinking water.

The regional water quality control boards established to monitor and mitigate surface water degradation are now focusing on groundwater. In the coastal areas, the regulatory hammer has been of the sledge variety. Regulators there are demanding growers use and harvest all the nitrogen applied or available. They want no N left behind in the field after harvest. That is called 1.0, but those regulations are on hold for now.

Dairies were the first agricultural segment to come under the groundwater nitrate regulatory microscope in the central valley. They are targeted for 1.4, which means a nitrogen application target of 1.4 times a forage crop’s N uptake to minimize N leaching.

The regional water quality control board governing California’s Central Valley has now turned its groundwater attention to crops and is developing data on potential groundwater N pollution for major valley crops based on current practices. Tomatoes are not in the initial list of crops to be evaluated, said Hartz. However, they will eventually come under scrutiny.

Hartz provided guidelines on how growers can dodge the bullet now by paying closer attention to nitrogen use.