And Pasakdee said growers also need to “know the water.” She recommends testing irrigation water to determine nitrate and salinity levels. Groundwater, she said, has “somewhat higher” nitrogen levels.

Pasakdee said it’s also important to “know your fertilizer,” the types and sources being applied and the methods of application.

She cited a “4R nutrient stewardship concept”: using the right source (whether soil or foliar); using the right rate (perhaps splitting applications over time); applying to the right place (the roots); and applying nutrients at the right time.

Kaomine Vang, project manager at CIT, talked of the benefits of using fertilizer and of the effects on drinking water, which is a significant health concern in San Joaquin Valley and elsewhere.

He said one way to prevent leaching of water and nutrients is to use soil moisture sensors to monitor water movement through the soil.

Vang said sources for information on evapotranspiration and crop coefficients include and


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