Reducing nutrient loss below the root zone of drip-irrigated vegetables using low-pressure, increased irrigation time

2008 Annual Report for GS07-063

Project Type: Graduate Student
Funds awarded in 2007: $9,966.00
Projected End Date: 12/31/2010
Grant Recipient: University of Florida
Region: Southern
State: Florida
Graduate Student:
Major Professor:
Bee Ling Poh
University of Florida

Reducing nutrient loss below the root zone of drip-irrigated vegetables using low-pressure, increased irrigation time


As an attempt to reduce nutrient leaching and irirgation water needs, the effect of low pressure, N rate and irrrigation rate on tomato yield was assessed with tomato grown with plasticulture in the Springs of 2008 and 2009 at the North Florida Research and Education Center near Lvie Oak, FL. Total tomato yields were 874 and 2,030 25-lbs cartons/acre in 2008 and 2009, respectively. In both 2008 and 2009, total tomato yields were not significantly different for the twelve management regimes (combinations of operating pressures of 12 and 6 PSI, fertilizer rates of 100%, 75% or 50% IFAS recommended rates and two irrigation rates of 100% or 75% IFAS rates). These results suggest that reduced pressure may be a new strategy to keep nutrients in the root zone of tomatoes. Reducing operating pressure reduced drip tape flow rate. This resulted in a possible reduction of irrigatio nwater needs, but have some practical implications. First, tomato receiving less irrigation had a smaller, less dense canopy, potentially increasing the risk of fruit sun scald. Second, low pressure may reduce uniformity of water application and be insufficient to close self-flusing caps.

Objectives/Performance Targets

1. To measure flow rate and uniformity of water application under low pressure.
2. To determine the effect of reduced operating pressure on the size and shape of the wetted zone.
3. Effects of fertilizer and irrigation water management treatments on plant nutrient status, soil moisture levels, nutrients in the soil and fresh market tomato marketable yields.


To date the work towards objectives 3 had been completed for two years of study. The work for objectives 1 and 2 had been completed for one year of study and would be repeated in the Fall of 2009.

Impacts and Contributions/Outcomes

Yield results showed that with the lower pressure (6 PSI) and reduced flow rates, it is possible to use less fertilizers and water to achieve the same yields as when using conventional pressure (12 PSI) and flow rates.


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