WATER AND NITROGEN USE EFFICIENCY OF POTATO UNDER SPRINKLER AND DRIP IRRIGATION

• Sponsoring Institution: State Agricultural Experiment Station
• Project Status: COMPLETE
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 0194992
• Project Start Date: Jan 10, 2002
• Project End Date: Jan 9, 2005
• Program Code: [(N/A)]- (N/A)

Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001

Performing Department
BIOLOGICAL SYSTEMS ENGINEERING

Non Technical Summary
Potato growers in the Pacific Northwest face increasing challenges of limited water supplies, in addition to other challenges such as increased competition in the market and rising energy costs. Drip irrigation offers significant potential for saving water, energy, and chemicals in potato cropping systems. This study will quantify the water use differences between drip and sprinkler irrigation, and provide valuable datasets and opportunities to continue this research.

Animal Health Component

30%

Research Effort Categories

Basic

40%

Applied

30%

Developmental

30%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
405	5360	2020	100%

Knowledge Area
405 - Drainage and Irrigation Systems and Facilities;

Subject Of Investigation
5360 - Drainage and irrigation facilities and systems;

Field Of Science
2020 - Engineering;

Keywords

drip irrigation

water use

water use efficiency

nitrogen fertilizers

fertilizer application

application rate

potatoes

nitrates

sprinkler irrigation

irrigation systems

agricultural engineering

soil moisture

soil plant water relations

temperature

production economics

production costs

crop yields

crop quality

energy costs

energy conservation

water conservation

Goals / Objectives
To quantify and compare water use and "tuber zone" moisture and temperature patterns for potato under drip and sprinkler irrigation systems; Quantify the effects of drip versus sprinkler irrigation on potato yield and quality; Quantify the effects of drip versus sprinkler irrigation on potato nitrogen requirements; Quantify cost of production of drip irrigated potatoes.

Project Methods
Research plots will be located on land irrigated by a 4-span linear move irrigation system modified and automated to independently control water application rates in each half-span by means of pulsing solenoid valves controlling the flow of water to each sub-manifold. Soil is a Warden very fine sandy loam, characteristic of potato production in the Columbia Basin. A 3-year rotation will be used. Ranger Russet potatoes will be grown under span No. 4 during 2003 in a strip split plot design with 4 replications of 2 irrigation systems (drip and sprinkler) and 2 nitrogen treatments. Drip irrigation will be installed with one tube, 2-3 inches deep between two rows of potatoes. Rows will be planted 16 inches apart in double beds. Drip irrigation trials will be automated to start irrigation at -20 kPa soil water potential. Both granular matrix and capacitance sensors will be used to monitor soil moisture content. Systems will be set up with low flow tapes, emitter flow rate of 0.06 gph, and 12-inch emitter spacing. Soil samples will be taken at regular intervals following planting at 30 cm depth increments down to 120 cm. Gravimetric soil moisture content will be determined. Soil sample will be extracted in 2M KCl and the concentration of NH4-N and NO3-N will be analyzed using a rapid flow ion analyzer. Suction lysimeters will be installed at 120 cm depth to sample soil solution on a weekly interval for analysis of NO3-N. Capacitance probes will be installed under both irrigation treatments at 15, 30, 60, 90, and 120 cm depths providing water content data at these depths. Since these measurements are done on a continual basis, both within and below the root zone of potato, the water mass balance can be calculated to determine the water leaching below the root zone. The quantity of N leached below the root zone in various treatments can be calculated, using the estimate of water leaching and the concentration of NO3-N in the soil solution (from SL). Two commercially-available Bowen ratio energy balance (BREB) systems (Campbell Scientific Inc., Logan, Utah) will be installed in the study site after planting, one in the area under sprinkler irrigation and the other in the drip-irrigated area. These micrometeorological apparatus will be used to measure crop evapotranspiration. Measurements will include air temperature and humidity at two heights above the canopy, net radiation, soil heat flux, and soil temperature. In addition to the BREB measurements, soil moisture tension will be monitored using granular matrix sensors installed in the plant row at 0.3m, 0.6m and 0.9m depths and connected to data loggers. Drip irrigation will be initiated when the average soil moisture tension measured at 0.6m is equal or smaller than -20 kPa. Irrigation scheduling will be based on traditional growers' practices with a 65% management allowable deficit. Potato yield and quality will be evaluated for each research plot.

Progress 01/10/02 to 01/09/05

Outputs
The goal is to provide farmers and land managers with real-time data and information that will improve the efficiency and efficacy of their management practices. The Center for Precision Ag Services continued the development and deployment of AgWeatherNet, a system of hardware and software for real-time monitoring and reporting of weather related sensors and information. The core technology CPAS developed includes a data logger integrated with a frequency hopping spread spectrum 900 MHz radio capable of a master-repeater-slave configuration. By the end of 2003, CPAS deployed a network backbone that covers most of the two million irrigated acres of cropland in eastern Washington State. This backbone network makes it possible for growers to install slave stations configured with various arrays of sensors as desired for full weather stations, pest monitoring stations, and for soil moisture and soil temperature monitoring. The network is operated using a Java program with features to manage the radio network, monitor sensors, poll each slave, and manage the sensor data base. Java software provides weather related products on the Internet on 15 minute intervals (www.agweathernet.com). The same core technology is being integrated with other sensors or devices to create additional useful applications. By adding a load cell and low cost GPS system to our datalogger/telemetry system, we can quantitatively track manure applications in real time. The tracking system records location and load every second and reports these data to a base computer via a network backbone on a preset time interval. The manure tracking system is being beta tested on a dairy farm and will provide accurate records on manure application rates and timing needed to meet nutrient management guidelines. Another application was developed and beta tested to assist growers in frost/freeze protection by deploying this system as a local, on-farm network. Air temperature is measured and reported every minute from remote slaves via radio telemetry to a base that sequentially broadcasts the data to rover units connected to a laptop PC operating a Java software program, AgFrostNet. The AgFrostNet software displays and plots time series temperature data to a grower in real-time.

Impacts
The principal investigator resigned midyear therefore the research conducted under this project was terminated.

Publications

• No publications reported this period