Nutrient Management Research Database

Fertilizer use in California agriculture has been under recent scrutiny regarding its impacts on air, surface water and groundwater quality. In June 2007, we surveyed almond growers to assess their plant nutrition practices, identify opportunities for improvement, and target reseach and extension needs. The majority of respondents, particularly those with large almond acreage, used fertigation to apply nitrogen; applied nitrogen coincident with periods of maximal plant demand; and collected annual tissue samples for analysis. While the survey results suggested broad compliance with the best-available management practices and are likely to indicate good nutrient-use efficiency, they also suggested that growers are uncertain about current practices to monitor orchard nutrient status and would value additional information to enable greater precision in fertilization rates and timing.

• This research surveyed 1800 growers in 18 counties of California.
• Based on a set of best management practices derived from existing knowledge, the surveys asked growers about:
  • their fertigation practices,
  • timing of applications, and use of tissue samples to monitor plant nutrient levels.

• Results of the survey showed that 69.7 % of growers apply some or all of fertilizer N with fertigation, while 16.7% could use fertigation but do not and 13.7% could not use fertigation at the time of the study.
• The growers surveyed applied some or all of N to 91.2% of the acres accounted for in this study, while 3.1% of the acres surveyed were not equipped for fertigation and 5.7% were capable of fertigation but did not.
• 61.3% of respondents stated that they were satisfied with their current nutrition management practices
• 29.5% considered UC critical values to be fully adequate in ensuring maximum productivity.
• The percent of growers who applied nitrogen with fertigation differed significantly depending on whether they were first or second generation almond growers (81.3% and 72.4% of first and second generation growers respectively; P=0.051) and by acreage (94.1% and 63% of growers who grew on greater or less then 250 acres, respectively; P<0.001).