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

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

Summary

Treatments had a significant effect on flow rate, mean flow rate was significantly higher at 12 PSI operating pressure than at 6 PSI operating pressure (23.61 and 17.96 gallons/hr/100-ft respectively).

Drip tape flow rate significantly affected depth and width of the wetted zone. Contrary to what we expected, depth and width of the wetted zone were significantly higher at 12 PSI operating pressure than at 6 PSI operating pressure. Within the range of volume of water applied (6.3 – 93.6 gallons), the relationship between mean width and volume of water applied was quadratic (mean width = -0.0007volume*volume + 0.17volume + 9.35; r-square = 0.94), and relationship between mean depth and volume of water applied was linear (depth = 0.038volume + 22.11; r-square = 0.32). Hence, reducing operating pressure reduces flow rate but the reduction depends on the type of drip tape, but increasing flow rate increases the lateral movement of water in the soil, which was contrary to what we expected.

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.

Accomplishments/Milestones

To date the work towards objectives 1 and 2 has been completed.

Outreach: The research from objectives 1 and 2 was presented at a regional meeting – 66th Annual Meeting, Southern Region of the American Society of Horticultural Sciences, in Dallas, TX.

The work for objective 3 will be completed in 2008 and 2009.

Impacts and Contributions/Outcomes

The results from this trial demonstrate that both drip tape flow rate and operating pressure and not just operating pressure influence water movement in the plant root zone.

Collaborators: