Nutrient Management Research Database

General Information

Research Title

Strategies for germinating lettuce with drip irrigation

Link to File

http://ucanr.org/sites/uccemontereycounty/files/85308.pdf

Research Specifications

Crop: Lettuce

Soil Type: Not Specified

County, State: Monterey, California

Year: 2007

Authors

Cahn, M.D., Smith, R., Fennimore, S., Ajwa, H.A., Young, A.

Summary/Abstract from Original Source

This presentation summarizes a number of research trials. The objectives were: 1. evaluate strategies for enhancing lateral movement of moisture around drip tape and maximizing germination; 2. Compare water use and nitrate leaching between drip and sprinkler germination; 3. Evaluate weed control under drip germination. Field trials and observation took place in 2005 and 2006 at Hartnell College and in 2006 USDA-ARS Spence Farms and in 5 commercial fields. Field trials at Hartnell in 2005 tested the effect of tape discharge rates on soil wetted-width, soil moisture, germination, residual soil nitrate at different depths in the soil profile. At Hartnell in 2006, cultural strategies including tape discharge, emitter spacing, and tape depth were evaluated for their influence on germination and water movement. At USDA Spence farms, drip and sprinklers were compared based on water use and germination. Commercial field trials evaluated the effect of subsurface drip, surface drip and sprinkler on mineral N loss, marketable yield and number of marketable plants.

Research Highlights

Design and Methods

At the Hartnell trial in 2005, a soil flocculant, SoilFloc 300E, a linear polyacrylamide (PAM), was applied at rates of 0, 20, 40 and 60 ppm.
Tape discharge rates of .22, .45, and .67 gal/min/100ft were evaluated.
A preplant fertilizer of 300lb/acre 34-0-0 was broadcasted. At Hartnell in 2006 tape discharges of .3 and .5 gal/min/100ft, emitter spacings of 8 and 12 inches and tape depths of 1.8 and 3.1 inches were evaluated.
At USDA Spence in 2006, beds were mulched and rolled, tape discharge was .5 gal/min/100ft, emitter spacing was 8 inches and tape depths evaluated were surface and 2.5 inches.
At the commercial drip field trials, tape discharge rates of .34-.53 gal/min/100ft, emitter spacing of 8 and 12 inches, and tape depths of between 2.5 and 3.36 were compared in both head and romaine lettuce systems.

Results

At Hartnell in 2005, the use of different concentrations of linear polyacrylamide (PAM) did not result in significant differences in wetted widths.
Increasing tape discharge rates resulted in higher average wetted-widths and germination rates, and lower residual soil nitrogen.
At Hartnell in 2006, shallow tape depths resulted in higher soil moisture and wetted-width, while emitter spacing did not have a significant effect on either soil moisture or wetted-width.
At USDA-ARS Spence in 2006, drip irrigation resulted in higher initial and second germination counts, although significant differences were not determined.
In commercial trials, water use, nitrate losses, and germination rates were similar for drip and sprinkler irrigation.
However, sprinkler irrigation resulted in higher marketable yields, although differences could not be evaluated for significance.
Best practices for drip germination appear to be mulched beds, shallow placement of tape (2-3 inches), medium flow tape and 8 inch emitter spacing, a drip system with a high application uniformity, compact beds with a weighted roller and slightly deeper plantings.