Nutrient Management Research Database

http://ucanr.edu/sites/Nutrient_Management_Solutions/files/212661.pdf

The California vegetable industry is in the midst of an irrigation revolution. After many years of slow growth, drip irrigation has finally taken off. Use of drip in both the Central Valley and the coastal areas is now commonplace for the production of tomatoes, peppers, celery, lettuce and other vegetables. While growers recognize that drip irrigation requires radical changes in water management strategies, the impact of drip on soil fertility management is less obvious. The most frequently discussed effect of drip irrigation on fertilizer needs is the potential for reduced N leaching losses through greater irrigation
efficiency. There are a number of other ways in which the conversion to drip irrigation may require adjustments to fertilizer strategies. The following discussion highlights some of those issues.

This proceedings from the 2004 Plant and Soil Conference discusses the issues that must be addressed when adjusting fertility management plans after converting to drip irrigation.

Topics presented include:

• Buried vs. surface drip
• N, P, K and micronutrient management
• Nutrient monitoring
• Putting it all together

While this is not a research paper, the author does make some recommendations on fertility management after a conversion to drip irrigation, including: 

• P and K fertility management should only need slight adjustments and should be based on preplant soil testing.  In the case of buried drip, testing should be done in the root zone.  
• N use could be reduced if irrigation efficiency is improved with a transition to drip, but reduced N availability for soil organic matter mineralization should also be taken into account.  
• The N fertility plan should take into account crop growth stage and can be adjusted based on in-season soil NO3-N testing of the root zone.