Progress 03/15/10 to 03/14/13
Outputs
OUTPUTS: In 2008, 2009 and 2010, we conducted field experiments to test automated sensor based drip irrigation in watermelons using Sentek TriSCAN EasyAg 50 multi-sensor capacitance probes. The objectives of this research were: (1) To demonstrate the utility of Sentek TriSCAN EasyAg 50 (Sentek Sensor Technologies, Stepney SA, Australia) soil water capacitance probe as a tool to determine soil water content for the purpose of drip irrigating watermelons according to pre-determined set points; (2) To determine appropriate set points in watermelons for automating drip irrigation scheduling in sandy Coastal Plains soils; and (3) To determine if the factory calibration of the MCP would be suitable for the southeastern Coastal Plains sandy soils. When the MCP's determined a 15% deficient of plant available water existed in the plant root zone (0-30 cm) a short duration irrigation cycle (60 min., 2008 and 30 min., 2009, 2010) was initiated. The goal was to maintain root zone volumetric moisture content (VMC) as close to field capacity without leaching into soil depths below 30 cm. A total of 345 irrigation cycles were triggered during the three years of research. The short but frequent on demand irrigation cycles of 60 minutes in 2008 and 30 minutes in 2009 and 2010 reduced water movement below the root zone as indicated by a gradual season reduction in the VMC at the 40 - 50 cm soil depth. We conducted field experiments in 2011 and 2012 comparing sensor based irrigation with typical on-farm irrigation management programs for seedless watermelon production. Many vegetable specialists in the southeast recommend as a rule of thumb that growers begin by applying approximately 1 inch (27,154 gallons) water per week for drip irrigated vegetables. Experiments were conducted to compare sensor based irrigation at 15% available water depletion to programmed irrigation programs delivering one seventh of an inch of water (3,879 gallons) per day. One program applied the daily one seventh inch water during one irrigation cycle and the second program applied the daily one seventh inch water split evenly during three daily irrigation cycles. Weekly soil nutrient solutions were drawn at 20 cm and 40 cm soil depths and laboratory analysis was performed to determine mineral and NO3-N concentrations. Laboratory analysis coupled with multi-sensor capacitance probes allowed us to monitor and document the movement and relative amounts of nutrients as influenced by the irrigation treatments. To determine the plant root zone, soil root cores were taken at 27, 56 and 86 days after planting (DAP) and root length density was determined in 15 cm increments down to 75 cm. The total gallons of water applied for each irrigation management plan was recorded by electronic flow meters. Yield and fruit quality was determined at each harvest and water use efficiency (WUE) was calculated (pounds produce per gallon water). Results have been disseminated at numerous grower meetings state wide and nationally. The most significant output and dissemination activity is the completion of a PhD dissertation and the accompanying publications being reviewed. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
On-site probe calibration showed factory calibration to be adequate for field purposes, suggesting the usefulness of the probes for the sandy Coastal Plain soil. The capacitance probes were found to facilitate triggering irrigation at pre-determined set points and simplify automation. MCPs use with short duration triggered irrigation cycles can improve irrigation efficiency versus non sensor based irrigation, reduce movement of water and solutes below the root zone and simplify management. Experimental results indicated that the water use efficiency was significantly greater with the sensor based irrigation programs compared to the on-farm irrigation programs. Total water applied for the one inch per week irrigation programs was 312,597 gallons per acre in 2011 and 384,199 gallons per acre in 2012. The sensor based irrigation program applied 166,480 gallons per acre in 2011 and 149,738 gallons per acre in 2012. Sensor based irrigation produced the greatest yield in 2011, while the irrigation program delivering 1 inch per week with 1 cycle per day had the least yield in 2011. During 2012 there were no significant differences in yield between irrigation treatments. The water use efficiency (WUE) was greatest for the sensor based irrigation treatments in both 2011 and 2012. Root length density (RLD) data indicated that the majority of roots (87% total RLD) were in the 0-30 cm soil profile and irrigation management should endeavor to reduce leaching of water and nutrients below this depth. Soil solutions taken weekly at the 20 cm and 40 cm soil depths indicate that NO3-N concentration (ppm) was greatest with the sensor based irrigation treatment at both depths. Although nutrient analysis below the 40 cm depth was not determined, a reasonable hypothesis would be a greater amount of nutrients and ions were washed below the 40 cm soil depth under on-farm irrigation treatments compared to automated sensor based irrigation with short irrigation cycles. Based on the above research we believe that automated sensor based irrigation, although innovative, is proven technology and if adopted on the farm could lead to improved yields, water conservation and greater water use efficiency. The sensor based irrigation technology has been shown to be successful in research and on-farm field trials. Because it employs technology which is new to most farmers, its success and adoption on the farm will need to be closely supervised. This grant which provided equipment and more importantly supervision of technology implementation and maintenance helped demonstrate to growers an innovative and reliable tool to help on farm drip irrigation scheduling, water conservation and reduction of nutrient leaching below the crop root zone.
Publications
- Miller, G.A. (2012). Sensor based irrigation effects on root distribution and growth of grafted and non-grafted watermelons. (Doctoral dissertation). Retrieved from ProQuest Dissertations and Theses. (Accession Order No. UMI 3512153)
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Progress 03/15/11 to 03/14/12
Outputs
OUTPUTS: The three research sites located in the Pee Dee, Coastal Plains and Midlands geographical areas of South Carolina were established, maintained and monitored through the 2011 season. Total water applied by sensor based irrigation and on-farm irrigation management was recorded at each research site. In addition at the Midlands site located at the Edisto Research and Education Center (EREC) the concentration of NO3-N and other nutrients was documented at 20 and 40 cm soil depths under sensor based irrigation and typical on-farm irrigation management programs. Yield data at each site was also documented. The crop at each site was watermelon. A fourth site in the Coastal Plains was added in 2012 which includes cantaloupes. Each site; EREC, O'Neal, Jenkins and Sandifer has uniquely different soil types with field capacity levels respectively at 17.4, 16.1, 10.6 and 9.4%. At each site sensor based irrigation is being compared to the on-farm irrigation management program. Under sensor based irrigation a short irrigation cycle is initiated when 15% of the available water (field capacity - permanent wilting point) is depleted. In addition to frequent one on one conversation with cooperating growers and other growers near the research site, numerous field days, conferences and trainings have allowed dissemination of objectives, goals and purpose of this project. Watermelon Field days at the EREC in 2009 and 2010 presented foundation concepts on how plant roots grow and absorb water. The 2011 Watermelon Field Day at EREC highlighted the root distribution of watermelon grown under a plasticulture system with drip irrigation. The necessity of keeping water and nutrients in the shallow (less than 30 cm) watermelon root zone and not leaching was emphasized. At each field day growers and industry representatives were also able to see the sensor based irrigation equipment and gain a better understanding of its functionality. Presentations on sensor based irrigation have also been presented at the Georgia Watermelon Growers Association meeting, the NC and SC Vegetable Expo, SE Vegetable Expo and Trade Show and the annual SC Watermelon Association Meeting. A Watermelon Field Day at EREC is scheduled for July 12, 2012 at which 2011 results from each research site will be presented. PARTICIPANTS: Gilbert Miller is a vegetable specialist at the Edisto Research and Education Center and served as project coordinator. Seven summer students have worked on this project. Partner organizations and individuals include David Lankford, Global Director, Chief Visionary Officer, Earthtec Solutions, LLC., John Boazman, Branch Manager, W. P. Law Incorporated, Fluid Handling Professionals and the South Carolina Watermelon Association. Collaborators and contacts include Billy Jenkins who is the cooperating farmer in the Pee Dee region of SC. Bradley O'Neal is the cooperating farmer in the Coastal Plains and Phil Sandifer is the cooperating farmer in the Midlands. In addition to one-on-one training with cooperating farmers and neighbors several training opportunities have been provided. Training was provided to farmers and industry representatives at July Watermelon Field Days at EREC in 2009, 2010and 2011. Training will also be provided at the July 12, 2012 EREC Watermelon Field Day. Presentations were made at the annual South Carolina Watermelon Association meeting in January and at the Georgia Watermelon Association meeting. Presentations have also been provided at NC and SC Vegetable Expo and at the SE Vegetable Tradeshow and Expo. TARGET AUDIENCES: Our primary target audience is fruit and vegetable growers who employ drip irrigation. Industry representative who are consulted by growers and provide information to farmers are also targeted. July Watermelon Field Days held each year provide hands on experience in the equipment capabilities and the value of sensor based irrigation. Project results have been presented at several grower meetings. PROJECT MODIFICATIONS: A fourth research site was established in 2012. At this Midlands site cantaloupe are being produced. The research set up with one field being sensor based irrigated and one field using the standard on-farm irrigation management program remains the same.
Impacts
Research at the EREC site in 2011 compared sensor based irrigation triggered at 15 per cent available water deficient (AWD) to two commonly employed on-farm irrigation management programs. The sensor based irrigation management plan utilized a short irrigation cycle based on automated real-time soil volumetric moisture content (VMC). The two on-farm irrigation management plans applied the common rule of thumb recommendation of 1 inch water (27,154 gallons) per week per acre. One program applied the daily one seventh inch water during one irrigation cycle and the second on-farm program applied the daily one seventh inch water split evenly during three irrigation cycles. Nutrient solutions were collected from each irrigation treatment weekly at 20 and 40 cm soil depths. Total water applied for the two on-farm irrigation programs was 312,597 gallons (11.5 inches). Total water applied for the sensor based irrigation program was 166,480 gallons (6.1 inches). The irrigation program which delivered 1 inch water per week with single long cycles per day had the least yield (69,547 lbs per A). Yield for the on-farm irrigation program employing three cycles per day for delivering 1 inch water per week was 86,593 lbs per A. The sensor based irrigation program produced the greatest yield at 109,884 lbs per A with a WUE of 0.66. The WUE of the on-farm irrigation programs were 0.22 and 0.27 respectively for one long irrigation cycle and three short irrigation cycles per day. Weekly soil solution nutrient analysis at 20 and 40 cm soil depths indicated that the short cycle sensor based irrigation program maintained greater NO3-N ppm in the 20 and 40 cm soil depth compared to the on-farm irrigation programs. At the 2011 O'Neal Coastal Plain research site, sensor based irrigation was employed in one 17 acre field and the grower utilized their irrigation management plan in a second 17 acre field. The O'Neals employ a hand held tool for determining soil volumetric moisture content and adjust their irrigation program accordingly. Automated sensor based irrigation applied 256,760 gallons per acre while the on-farm program applied 275,069 gallons per acre. Watermelon yields were the same for both fields. At the 2011 Jenkins Pee Dee research site, two 6 acre fields of watermelons were compared. The Jenkins employ long irrigation cycles delivered irregularly based on their intuitive judgment of the crop needs. Jenkins used 147,850 gallons of water per acre and the sensor based irrigation program delivered 143,290 gallons of water. Yield of watermelon per acre for Jenkins was 69,455 lbs per A and the sensor based irrigation produced 77,541 lbs per A. Water use efficiency respectively for Jenkins and sensor based was 0.46 and 0.54. Research at each of the above mentioned sites is continuing in 2012. An additional site with commercial acreage of cantaloupes has been added for research in 2012.
Publications
- http://www.epageflip.net/i/56600/21 2012
- http://www.growingproduce.com/article/26541/improved-irrigation-sched uling 2012
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Progress 03/15/10 to 03/14/11
Outputs
OUTPUTS: As indicated in the project time table, Year 1 (2010 - 2011), will primarily involve implementation and trouble shooting. We have successfully established three functioning research sites. The research sites are located in the Pee Dee, Coastal plains and Midlands geographical areas of South Carolina. Site one in the Pee Dee is located in a ten acre watermelon field. Site two in the Coastal plains is situated in a fifty acre watermelon field. At both sites, one half of the field is being irrigated with the farmer's standard irrigation management plan and the other half is being irrigated using real-time soil moisture data recorded by capacitance probes which initiate irrigation at determined soil volumetric moisture depletion points. The above procedure has been in place and functioning at the Coastal plains site since April 21, 2011. The later planted Pee Dee site began functioning May 3, 2011. Each site has uniquely different soil types with very different water holding capacities. The third Midland site is located at Clemson University's Edisto Research and Education Center (EREC) in Barnwell, SC. Twelve watermelon research plots have been established at this site. Three irrigation management programs with four replications are being tested. Each of the twelve plots has two capacitance sensors. One irrigation program is as described above with capacitance sensors triggering irrigation at available water depletion set points. The other two irrigation management programs are similar to on-farm programs in South Carolina. In each of the twelve research plots at EREC, Sentek SoluSensors are located at 20 and 40 cm depths. Weekly, solutions are drawn at both depths in each plot and laboratory analysis is performed to determine mineral and NO3-N concentrations. Laboratory analysis coupled with the capacitance probes ability to measure soil salinity should allow us to monitor and document the movement and relative amounts of nutrients as influenced by the irrigation programs. At all sites yield and produce quality will be determined for all irrigation management plans. The total gallons of water applied for each management plan is being quantified by electronic flow meters. The nutrient movement and quantity at 20 and 40 cm depth is being quantified by laboratory analysis and capacitance sensor readings at EREC and will be quantified with capacitance sensor readings at Pee Dee and Coastal plains research sites. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
At each research site the cooperating grower has received near weekly training since early March in the installation, maintenance and functionality of the sensor based irrigation equipment. The concept, objectives and purpose of this research project have been discussed at numerous field days, conferences and one-on-one meetings with growers. A July 9, 2009 Watermelon Field Day at EREC provided educational programs to growers on plant roots and how they grow and absorb water. The July 8, 2010 Watermelon Field Day presented information on nutrient absorption by plant roots. At both field days the necessity of keeping water and nutrients in the root zone and not leaching was emphasized. During the January 2009 and 2010 South Carolina Watermelon Association meetings presentations were made during the grower educational sessions on Sensor Based Irrigation. Presentations on sensor based drip irrigation management have also been presented at the 2010 Georgia Watermelon Growers Association meeting, the NC and SC Vegetable Expo and the SE Vegetable Expo and Trade Show. During the July 7, 2011 Watermelon Field Day at EREC, the preliminary results from the EREC midlands site will be presented. Growers will be able to see the equipment and gain a better understanding of its functionality. Field days at the Pee Dee and Coastal plains sites are planned for 2012. Following the conclusion of the first year of this project, we anticipate being able to show growers from commercial type research/demonstrations that automated sensor based irrigation is possible on the farm. Not only possible but we also predict showing a reduction in the total amount of water needed to produce the crop with short sensor based irrigation cycles and a reduction in the amount of water and nutrients leached below the crop root zone. This hands-on type of research on the farm coupled with in depth research at EREC should provide quantifiable results which will provide impetus toward a change in knowledge on the farm in regards to drip irrigation management. Over time we anticipate key growers to adopt and use the new methods and improved technology of sensor based irrigation which could lead to a reduction in the application of irrigation water, a reduction of nutrients leaching below the root zone and possibly a decrease in total nutrient application in the future.
Publications
- No publications reported this period
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