Progress Report on Microirrigation
in Iowa, 2004.
Title: Microirrigation: Technologies for protection of natural resources and optimum production.
Personnel: Henry G. Taber
Department of Horticulture
Iowa State University, Ames,
IA 50011
Objectives:
Iowa research was carried out on the following 2 objectives of the four in the project.
1. To evaluate and refine microirrigation management strategies to promote natural resource protection and optimal crop production.
4. To promote appropriate microirrigation technologies through formal and informal educational activities.
Accomplishments:
Objective 1
The research was conducted at the Horticulture
Station (central Iowa, glacial, upland soils). This site is a well-drained
loam (fine-loamy, mixed, mesic Typic Hapudolls) with 18-24% clay, organic
matter of 2.3% and AWC of 2.5-inch/foot.
Two varieties of sweet bell peppers, Lafayette and Aristotle, grown in twin-rows on black plastic mulch were the test crop to evaluate 2 irrigation scheduling strategies; 1) soil tension measurement with tensiometers where irrigation event triggered when daily readings of a 6-inch tensiometer reached 25 kPa. Water amount applied determined as 25% depletion of AW and brought back to field capacity. And, 2) daily (ETr – rainfall) * crop canopy. Only rainfall amounts > or = 0.01 inch were recorded. Irrigation initiated when value was > or = 0.75 inch.
As with studies the past three years, both scheduling methods, when properly managed, produced equivalent marketable yields of bell peppers, 1260 bushels/acre. This year both methods provided water at 80% of growing season ETr. Variety response to water management differed as the later maturing Aristotle variety significantly (P < 0.03) responded to ET replacement as compared with the tensiometer method, a 12% or 235 bushel increase.
Objective 4
Presentations specifically related to
this project were given at the Iowa Fruit and Vegetable Growers conference,
January 30, and summer field day, July 12
Impact of Work:
An undergraduate student, Lucas Cox-Richard
completed an internship on this project.
Grants from vegetable grower associations
of approximately $12,000 were received over the 4-year project. For
various reasons, vegetable growers are reluctant to utilize irrigation
scheduling management tools. They rely almost exclusively on empirical
methods. Overcoming this barrier would improve profitable yields and environmental
sound production practices.
Publications:
Taber, H. G. and V. Lawson. 2003. Scheduling methods for bell pepper irrigation on sandy soils. In: Annual Fruit/Vegetable Progress Report. Taber, H. G. (Ed.) Iowa State Univ. Coop. Ext. FG-601, p 23-27.