Summer 2012 Volume 2, Issue 3

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1 Rutgers Cooperative Extension of Mercer County Meredith Melendez, Sr. Program Coordinator, Agriculture 930 Spruce Street Trenton, NJ (609) In This Issue Fertigation of Vegetable Crops Bill Lamont, Penn State Page 1 Center For Food Safety Wes Kline Page 2 Are You Watering Enough? Page 4 Upcoming Events Page 5 The Mercer County Grower is a publication from Rutgers NJAES Cooperative Extension of Mercer County. All Rutgers NJAES Cooperative Extension educational programs are offered without regard to race, sex, age, handicap or disability, color or national origin. Rutgers NJAES Cooperative Extension is an equal opportunity employer. Mercer County Summer 2012 Volume 2, Issue 3 Fertigation of Vegetable Crops Bill Lamont, Penn State Extension Soluble fertilizers can be added to the drip irrigation water to provide uniform crop fertilization. A simple "hozon brass siphon mixer" venturi injector draws soluble fertilizer from a bucket or jug into the line at a preset ratio (usually 1:16 or 1 gallon for every 16 gallons of water flowing through the line). However, the hozon injection system, is suitable only for one-third to onehalf acre plantings or less. Other venturi units are available in sizes up to two inches in diameter. More expensive injectors with greater capacity and accuracy use an electric or hydraulic "pump" to inject fertilizer solutions from a stock tank into the line. A hydraulic device, called a Dosatron, placed in the mainline can be set at various dilution rates and operates with water flowing directly through it. Use only high quality, soluble fertilizers that completely dissolve. All fertilizer injections should be made ahead of either the main filters on the line or the secondary filters if placed closer to the field, so that any contaminants are filtered out. Fertigation is used most commonly to supply nitrogen and potassium, because they are highly soluble and move easily through soils to roots. Phosphate and micronutrients are best applied prior to planting and Grower not injected through the irrigation system. Other chemigation applications may include pest control measures, but check label restrictions on use in chemigation applications. If any fertilizer or chemicals are applied through the system, a check valve or proper back-flow prevention devices are required to ensure that no contamination of the water source is possible. Preplant Fertilizer Take a soil test to know what level of fertility is in your soil. Use a starter fertilizer, a small amount of fertilizer, either liquid or dry, that is applied in the bed in drip irrigated crops. This fertilizer would contain all of the phosphorus (P) and micronutrients and up to percent of the nitrogen (N) and potassium (K). On soils testing very low in P and K, the starter can be broadcast or banded in the bed. If only small amounts of P and micronutrients are required, then it would probably be better to band these materials two to four inches below the bed surface and to the side of the plant row, but not between the drip tube and the row. In most cropping situations, approximately 20 to 30 pounds per acre of N and K would be sufficient in the starter fertilizer mixture. In situations where the soil test index for Continued on page 3

2 The Produce Safety Alliance Wes Kline, Agriculture Agent Rutgers NJAES Cooperative Extension of Cumberland County There are a large number of projects and organizations involved in food safety research and education. The Center for Produce Safety (CPS) is unique in that it is a collaborative effort among industry, government and the scientific community and focuses on the practical questions that affect the produce industry. They try to identify gaps in food safety knowledge and provide funding to search across the United States. In three years, they have awarded $9.2 million and funded 54 one to two year research projects at 18 universities and organizations. These applied projects must come up with answers in a short time that is directly applicable to the industry. The following are examples of projects which were recently discussed at their annual meeting: How far will E. coli 0157:H7 travel in the air from cattle production areas to a leafy green field Ways to reduce E. coli in irrigation water Evaluation of risks for Salmonella contamination in irrigation water from a mixed produce farm Risk assessment of Salmonella preharvest internalization in relation to irrigation water quality standards for melons and other cucurbits (squashes) Pathogen transfer risks associated with specific tomato harvest and packing operations Developing and validating practical strategies to improve microbial safety in composting process control and handling practices Evaluation and optimization of postharvest intervention strategies for reduction of bacterial contamination on tomatoes Improving produce safety by stabilizing chlorine in washing solutions with high organic loads These are just a few of the presentations that are directly applicable to New Jersey growers. The more we can find out about how pathogens contaminate produce the better the chance is to focus on those areas. This will help reduce the need for some recordkeeping and make food safety plans simpler. More articles on these topics will follow in the subsequent newsletter issues. Page 2

3 Fertigation of Vegetable Crops cont. P is high or very high, then no P would be added to the soil. Note on phosphorous and micronutrients. In general, simultaneous application of P and micronutrients is not recommended in drip irrigation systems. This is because of precipitation events that can happen between the fertilizers or between the P and the calcium or magnesium in the well water. If application of P is required during the season (such as during cold periods), it should be injected as phosphoric acid alone, in separate applications. Acidification of the irrigation water to ph 4.0 to 5.0 might be needed to keep the P in solution during this fertilizer application. Acidification can be achieved by using phosphoric, sulfuric, hydrochloric, or other acids to reduce the ph of the water. Concentrated acids always must be added to water, never the reverse. Similar problems also occur for micronutrient injection. The key is to avoid precipitation. If micronutrients must be injected, then soluble forms, less subject to precipitation, such as chelates, should be used. Like P, micronutrients should be injected alone. Injected Fertilizer Rates. In most situations, injected fertilizers will consist only of N and K. The amount of N to use is determined basically by the N requirement of the particular crop. This amount of N is recommended for each crop for each season. The current recommendations for opensoil culture can serve as "starting points" for developing local plasticulture recommendations. The amount of K to be injected is based on the soil-test predicted requirement of K for the crop minus the portion of this requirement that is applied in the bed as a starter. For example, if the soil tested medium in K, perhaps only 100 pounds per acre of fertilizer would be required for the season. If 20 percent of this K, i.e., 20 pounds, were applied in the bed as starter fertilizer, then 80 pounds would be injected through the season. Sources. Several sources of N and K can be used for drip irrigation injection, but all sources must be highly water soluble to be effective. Nitrogen sources include ammonium nitrate, calcium nitrate, various N solutions, and urea. Potassium can come from potassium nitrate, potassium chloride, or potassium sulfate. Frequencies. It is most convenient to think of rate of injection in terms of pounds of a particular nutrient per acre per day or week. For example, the recommended schedule of N injection for a particular crop might be to start out early in the season with l pound N per acre per day and finally inject 2.5 pounds per acre per day when the crop is at its peak growth rate. The general rule is that the amount of N and K injected per day or week starts out low and peaks with the crop demand for the nutrients. It is tied to the stage of crop growth or development. Nutrients can be injected into the system in various frequencies. Basically, the frequency of injection, whether once a day or once every two days or even once a week, depends on system design constraints, on soil type, and on grower preference. Research has shown that the frequency, even up to once per week, is not as important as achieving a correct rate of application of nutrients to the crop during a specified period of time. With computer control of drip irrigation systems, some growers find it easy to inject more frequently, such as once every day. This may have a slight advantage logistically. For example, injecting fertilizer on a more frequent basis would reduce the chances that nutrients were leached from the beds during a heavy rain storm or excessive irrigation compared to injecting larger amounts on a less frequent basis. If the chances for leaching losses are extremely low for any particular field, then injection once per week would be satisfactory. In any case, it is extremely important that the nutrients applied in any irrigation event are not subject to leaching either during that same irrigation event or by subsequent irrigation events. This is why knowledge of the crop root zone is important for optimum fertilizer management. It is critical to monitor the application of water and to realize that fertilizer application is linked closely to water application. To be a good fertigator, a grower first needs to be a good irrigator. When injecting fertilizer in noncontinuous (bulk) fashion, such as once per day or once per week, it is important to keep in mind a few pointers about the operational sequences for the injection events. The drip irrigation systems always should be brought up to operating pressure prior to injecting any

4 Fertigation of Vegetable Crops cont. fertilizer or chemical. After the system has been pressurized fully, the fertilizer can be injected. Following the completion of the fertilizer injection, the drip irrigation system should be operated for a period of time to ensure flushing of the nutrients out of the tubes and into the soil. This period might be the next irrigation cycle of the day, if that water will not contain fertilizer. With these operation constraints in mind, it becomes very important to design the drip irrigation system so that fertilizer injection can be achieved in a reasonable amount of time without running the risk of overwatering the crop to get the. crop to get the fertilizer applied. This means that injection pumps, pipe sizes, and injection rates must be adjusted properly to apply the nutrients in the desired amount of time, so that the system can still be flushed without applying excess water during the injection and subsequent cycles. In some systems, fertilizer is injected continuously (concentration injection) so that all irrigation water applied contains nutrients. This system is acceptable as long as no irrigation cycle is excessive, causing nutrients to be leached below the root zone. It should be apparent from the above discussions that water application and fertilizer application are linked inextricably. Are You Watering Enough? Tianna DuPont, Penn State Extension Photo credit: Tim Coolong, U of Kentucky In dry weather like this it is important to irrigate sufficiently if you can. Vegetable crops need an inch to an inch and a half of water per week. So how much is an inch of water? One acre inch of water is 27,154 gallons! You may be surprised at how long it takes to give your plants an inch of water. For example, if you are using standard drip irrigation tubing with a flow rate of 0.45 gallons per minute per 100 feet it would take just under six hours to apply one inch of water with one line of irrigation per bed (6ft centers). If you have two lines per bed it would take less about 3 hours. Penn State s Elsa Sanchez and Bill Lamont give more details about determining how long to run drip irrigation for vegetables here. Are You Watering Enough? Tianna DuPont, Penn State Extension What the blog?? Free timely information via the web and your . Sign up today! links to Rutgers NJAES experts Quick links to online resources Archived blog posts Commercial production recommendations NJAES Ag program calendar Just click on the Subscribe to Updates in the top right corner to enter your address to automatically receive new blog posts when they are made. Vegetable blog: Field crop blog: Fruit blog:

5 Upcoming Events July /18 21 Burlington County Farm Fair 7/21 NJ Christmas Tree Association, Elk Twp Recreational Park Monroeville info /24 NE Weed Science Survey and Student Weed Contest, Rutgers Snyder Research Farm 7/25-29 Monmouth County Fair 7/28-29 Mercer County 4H Fair August /1 Farm Service Agency, Last day to file County Committee election nomination forms (FSA-669A) 8/3-4 Pennsylvania Organic Farm Fest, Center County Grange Fair Grounds 8/6-12 Middlesex County Fair 8/8-10 Somerset County Fair 8/14-16 Penn State Ag Progress Days, Russell E. Larson Agricultural Research Center or call /22-26 Hunterdon County Fair 8/29 Great Tomato Tasting, Rutgers Snyder Research and Extension Farm $7 njaes.rutgers.edu/rsvp/tomato or call September /30 Farm Service Agency, NAP closing for Barley, Clover, Grass, Mixed Forage, Rye and Wheat. Final date to report value loss crops for 2012: ornamental nursery, Christmas trees, aquaculture, ginseng and turfgrass sod. Mercer County 4-H Fair Saturday, July am to 8 pm Sunday, July am to 4 pm Free Admission, Free Parking Join us for the fair's fifth year at Howell Living History Farm! The fair includes 4-H animal shows and exhibits; food and homemade ice cream; hay rides; pony rides; music; farm tours and demonstrations; milking demonstrations; spinning, felting, and fiber demonstrations; children s crafts and activities; and displays by organizations such as the Master Gardeners of Mercer County, Mercer County Board of Agriculture and the Mercer County Equestrian Center. For more info visit: Page 5

6 NJAES Cooperative Extension Rutgers, The State University of New Jersey Rutgers Cooperative Extension of Mercer County 930 Spruce Street Trenton, NJ Mercer County Grower The Mercer County Grower Newsletter provides local information from Rutgers Cooperative Extension and collaborating organizations which represent the diverse nature of agriculture within Mercer County. To receive this newsletter via please contact Meredith Melendez at: Rutgers Cooperative Extension of Mercer County welcomes this opportunity to send you this newsletter for your information and use. Please send all inquires to the editor. Rutgers Cooperative Extension of Mercer County 930 Spruce Street Trenton, NJ (609) Fax: (609) Meredith Melendez Senior Program Coordinator Agriculture