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Agronomic Services — Agrotips
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Scout wheat early and often this year.
Due to drought and the skyrocketing price of nitrogen, wheat producers need to count tillers in January and follow up with tissue sampling in March. With nitrogen at $320/ton (up from $180/ton last fall), no one wants to apply more than is necessary, especially when some fields may still contain nitrogen unused from the previous crop.
In areas where wheat was planted late due to drought, tiller counts may be down. At the beginning of green-up in January, 50 to 70 tillers per square foot is optimum. If the count is lower, it is appropriate to apply half of the spring topdress nitrogen right away. The application will help the crop continue to produce tillers on warm days without excessive growth. Tissue testing in the spring will indicate how much more nitrogen is needed.
- Submit soil samples for spring pasture renovation now.
Cost-share money for emergency pasture renovation is available through many local Soil and Water Conservation District offices. Contact SWCD for requirements and additional information. Cost-share funding will require recent soil test results. Growers considering spring renovation need to submit samples right away. There is typically a 6- to 8-week turn-around time for samples coming into the Agronomic Division soil lab in January.
- Test source water for tobacco seedling float beds.
Nearly half of the source water samples taken from tobacco float bed operations in North Carolina and about one in five nutrient solution samples have high alkalinity (sometimes known as total carbonates). Alkalinity values greater than or equal to 100 contribute to high pH and soluble-salt problems. When necessary, the solution analysis report provides recommendations for reducing alkalinity by 80%.
- Tips on understanding cation exchange capacity (CEC)
Many growers ask questions about the meaning of cation exchange capacity values on NCDA&CS soil test reports. In essence, CEC values indicate the ability of a soil to hold nutrients: for example, the higher the CEC value, the greater the capacity of the soil to supply calcium, magnesium and potassium for plant growth. Sandy soils tend to have low CEC values (typically 1-3 milliequivalents per 100 cubic centimeters) and low levels of nutrients. Organic and clay soils tend to have higher CEC values (up to 25 milliequivalents per 100 cubic centimeters) and more nutrients.
Note: Soil test reports from other laboratories may report CEC values in units of milliequivalents per 100 grams. These values have to be interpreted on a different scale than NCDA&CS values.
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Monitor strawberry nutrient status by tissue sampling.
The Agronomic Division recommends monitoring the nutritional status of strawberries and the efficiency of fertilizer programs by submitting a plant tissue sample at least once a month, preferably every two weeks. Sampling should begin with the first flush of growth in the spring and continue throughout the flowering and fruiting season.
Plant tissue samples should be representative of conditions in the field. A good sample includes the most recently mature trifoliate leaves (leaf blades and petioles) from 20 to 25 locations in the field. Detach petioles from the leaves as you collect them but include them in the sample. Petiole analysis is a good indicator of the nitrogen currently available for growth and development. Be sure to provide the name of the strawberry variety on the information sheet.
If tissue analysis reveals plant nutrient deficiencies, consider the following factors before taking corrective action:
- soil pH and nutrient levels,
- environmental conditions such as rainfall and temperature,
- disease and insect pressure, and
- plant appearance and stage of development.
- Check source water used in greenhouse and nursery operations and correct any SAR (sodium adsorption ratio) problems.
Water used in plant production, including greenhouse-grown tobacco transplants, should have an SAR value of 4 or less. For ornamental plants in a nursery setting, SAR values of 10 or greater are cause for concern. High SAR values are most common for water samples from coastal areas.
A high SAR value on a solution analysis report indicates an imbalance among sodium (Na), calcium (Ca) and magnesium (Mg) cations. This imbalance can cause leaf burn due to foliar uptake of Na. In mineral soils, this imbalance can also lead to poor soil structure, which hinders infiltration of water. In soil-less container media, however, this effect is negligible.
The best way to reduce SAR to the desired level is to add calcium from a source such as gypsum. To calculate the amount of gypsum needed to reduce SAR to 4, follow these steps.
- Calculate the amount of calcium required in parts per million (ppm).
Ca needed = 0.004725 Na² – 1.64 Mg – Ca,
where Na, Mg and Ca are the ppm concentrations listed on the Solution Report.
- Calculate the appropriate rate of gypsum (22% Ca) to apply by inserting the Ca needed value from step 1 into the following equation.
Ca needed × 0.0607 = ounces gypsum per 100 gallons of water
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Remember, you can check the status of your agronomic samples online.
Current turn-around times for samples are posted online. These estimates are based on the total number of samples awaiting processing and the date that samples arrive at the lab—not the date they are mailed or dropped off at an extension office! To check on samples, go to www.ncagr.com/agronomi. Look in the left column of the Agronomic Division home page and click on "Find Your Report." The current turn-around time for each type of sample is listed at the top of the page.
If you scroll down the page to the "Access Reports" heading and click on "Grower," you can check the status of your own samples. You must enter your last name or the farm name exactly as you spelled it on the information sheet submitted with your samples. If your samples are not listed, that does not necessarily mean that they have not arrived at the lab. They are probably in line for processing but have not been opened yet. Samples are not listed as "logged in" until the shipping container is opened. Once this occurs, the report(s) should be available in two weeks or less.
- Test for nematodes before planting vegetables.
Nematodes pose a major threat to nearly all vegetable crops in all soils. Unless you intend to apply a preplant fumigant, it is a good idea to collect soil samples for nematode assay before seedlings are planted and mulched. Any steps to prevent nematode problems must be taken long before the crop is established. For information on collecting and submitting samples for nematode assay, visit www.ncagr.com/agronomi/uyrnem.htm.
- Now is the time to collect tissue samples from wheat.
Depending on where you live, you may need to sample now (eastern counties) or wait until late March (western counties). The best time to take tissue samples is when the wheat is at Zadoks Growth Stage 30 or Feekes Stage 4–5. At these growth stages, stems are upright and tillering has stopped. To collect a sample, break wheat plants off about 1/2 inch above the ground. Each sample should consist of about two handfuls of wheat—a composite gathered from 10 to 20 areas throughout the field. A pictorial guide to tissue sampling is available online at www.ncagr.com/agronomi/pictorial.htm.
- When growing peanuts, use agronomic tests to monitor zinc levels in the soil.
Growers who value the prime farmland where peanuts are produced should consider using alternate sites for waste application. Peanuts are very sensitive to certain metals found in waste, particularly zinc. Soils with NCDA&CS zinc index (Zn-I) values as low as 300 can be toxic to peanuts, even though other crops can tolerate levels up to Zn-I=2000.
In some areas, soil test data for peanut land already appear to show increases in zinc levels, indicating that waste is being applied to these fields. An important aspect of managing sites where waste is applied is to maintain a pH of 6.0–6.5. Low soil pH increases the availability and toxicity of metals.
- Liming according to soil test results is important this time of year.
Have soil tested well in advance of planting so you can apply lime early enough to adjust soil pH. Liming soils to the target pH of the intended crop increases availability of plant nutrients already in the soil and supplies additional calcium and/or magnesium. Since liming can take up to 6 months to adjust pH, it is important to apply lime as far in advance of planting as possible. In addition, soil test reports provide sound fertilizer recommendations for the crops indicated.
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Check your crop's sulfur needs.
Before planting, study your soil test report carefully. Throughout North Carolina, soil levels of sulfur can be critically low. This plant nutrient moves easily out of the root zone in sandy coastal plain soils or sandy bottom lands in the western part of the state. In the piedmont, heavy clay soils may restrict root growth and limit access to sulfur reserves. Your NCDA&CS soil report indicates whether application of additional sulfur is necessary. If heavy rains occur early in the season, it is advisable to check sulfur levels again.
- Use plant tissue and solution analyses to manage fertility of greenhouse tomatoes.
Tomatoes and other greenhouse crops benefit from intensive management. Have source water samples tested before nutrient solutions are mixed so you can identify and correct any potential problems. After mixing nutrient solutions, submit samples to make sure injectors are working properly and target concentrations are being achieved. Finally, collect plant tissue samples weekly to monitor the crop's nutrient status and adjust fertilizer rates accordingly.
- Fertilize Christmas trees.
Each spring, apply 1/2 ounce of nitrogen uniformly over a 5×5-ft area around each tree. If trees were transplanted the previous fall and the potassium recommendation was 100 lb/acre or more, apply the remainder of the recommended potassium.
- For effective bermudagrass sprayfield maintenance, remove winter annuals.
Harvest on time, even if weather is less than ideal. Remove the overseed at the "boot" stage of growth-prior to emergence of seed heads from the sheath. For rye, this is usually early April but varies with species and weather. In some years, follow-up harvests of the winter annual may be needed.
Early April is seldom a good time to dry hay in the field, so plan to remove the winter annual as chopped or baled silage. Timely harvest of the winter annual permits bermuda to emerge from dormancy and develop leaf area before summer annual grasses and weeds germinate. If annual ryegrass was sown, plan on multiple harvests. A herbicide may be warranted for heavy regrowth.
- Submit soil samples for lawns and gardens (and some crops) now.
Now is a good time for horticulturists and homeowners to prepare for their spring gardening and landscape projects by taking soil samples. Warm-season grasses and many landscape plants will benefit from lime and fertilizer applied in the coming months. If you haven't already done so, there is still time to take samples from fields where you intend to plant late spring crops like burley tobacco, cotton, and bermudagrass pastures. In April, the lab can normally process samples within two weeks. When you receive your report, pay particular attention to lime recommendations and make application as soon as possible for maximum effectiveness.
- Use waste analysis to manage land application of farm by-products (crop residues, manure, lagoon liquid and sludge, poultry litter, and composts).
Organic wastes provide essential plant nutrients and improve soil physical properties, such as water infiltration, aeration and nutrient-holding capacity. Before application, samples of the waste should be submitted to the NCDA&CS Agronomic Division for testing. A basic waste analysis costs $5 per sample and measures concentrations of essential plant nutrients. Special tests for heavy metals, liming equivalent, or distinguishing types of nitrogen are available for an extra $10 per test per sample.
The Waste Analysis Report estimates the rates at which nutrients will be available during the first growing season. With this information, you can apply wastes to meet the specific nutritional needs of a crop. Supplemental applications of commercial fertilizer may be necessary, depending on rate of nutrient availability or other factors.
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Sidestep the high cost of fertilizer by using animal waste as a plant nutrient source.
Farm-generated wastes are a widely available and inexpensive alternative to commercial fertilizers. Animal wastes provide essential plant nutrients and also improve soil physical properties, such as water infiltration, aeration and nutrient-holding capacity. Before applying waste material as fertilizer, send a sample to the NCDA&CS Plant/Waste/Solution section. This laboratory tests for levels of plant nutrients and, when necessary, can measure pH, lime value and soluble salts. Based on analytical results, the Waste Analysis Report provides estimated rates of nutrient availability for the first growing season. With this information, you can figure out how much waste it will take to meet the specific nutritional needs of a crop. Supplemental applications of commercial fertilizer may be necessary, depending on rate of nutrient availability, cropping system, environmental guidelines and other factors.
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Tissue sampling improves crop production.
For high-value crops, in particular, plant tissue analysis is a valuable tool for optimizing monetary inputs and yield. It is a way to monitor the effectiveness of an ongoing fertilization program. It is a way to identify existing or potential nutrient problems. It can also be a way to gauge plant readiness for harvest.
The part of the plant to be sampled and the time of sampling vary by crop. Visit www.ncagr.com/agronomi/pictorial.htm for specific sampling instructions for several major crops. Samples can be dropped off at the NCDA&CS Plant/Waste/Solution lab in Raleigh, mailed through the U.S. Postal Service, or shipped via UPS or Fed Ex. Basic tissue testing costs $5 per sample, and results are typically posted on the NCDA&CS Agronomic Division Web site [www.ncagr.com/agronomi] two business days after samples arrive at the lab. Special tests to measure chloride, molybdenum or petiole nitrates cost an extra $2 per test per sample.
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Spring and summer are the best times to take soil samples from established lawns and gardens.
It is always a good idea to take soil samples several weeks before planting a garden or renovating a lawn; then if lime is needed, you have time to apply it properly and let it begin to work before planting. For established plantings, spring and summer are good times to submit routine samples because that is the laboratory's off-season and reports are available in about 10 days. If you want to use soil samples as a tool to identify a suspected nutrient problem, collect samples whenever you observe the problem and be sure to fill out the (orange) Diagnostic Soil Sample Information sheet instead of the white Soil Sample Information sheet.
Soil sample boxes and information sheets are available from all county Cooperative Extension offices and from the Agronomic Division office in Raleigh. Information sheets, sampling instructions, and completed reports are also available online at the Division's Web site.
- Collect petiole samples from vinifera vineyards during full bloom.
To monitor the nutrient status of vinifera grapes, collect a tissue sample during full bloom. The sample should consist of at least 50 petioles collected from leaves opposite the first or second bloom cluster from the bottom of the shoot. Collect petioles randomly from throughout the entire vineyard. Do not collect more than two petioles per vine. Place the sample in a paper bag or envelope. The plant analysis report—available in a few days—will let you know if your fertilization program is meeting your crop's needs.
If you want to use tissue analysis to diagnose a suspected nutrient problem, collect a petiole sample as soon as you see symptoms. Don't delay—time is critical when correcting nutrient problems. To troubleshoot a problem, you should collect four different samples: 1) a petiole sample from symptomatic leaves, 2) a similar petiole sample from healthy plants, 3) a soil sample from the problem area and a soil sample from the healthy area. Send all samples along with a completed Plant Sample Information sheet and Diagnostic Soil Sample Information sheet to NCDA&CS Plant/Waste/Solution Section. There is a $7.00 processing fee for each grape petiole sample.
- Select fertilizer grade based on soil test results.
The three numbers in a fertilizer grade designation refer to percent content of nitrogen (N), phosphate (P2O5), and potash (K2O) on a weight basis. For example, the fertilizer 15-0-14 contains 15% N, 0% P2O5, and 14% K2O, so 100 pounds of it contains 15 pounds N, no P2O5, and 14 pounds K2O.
If your report recommends using a 15-0-14 grade, you don't necessarily have to use that exact grade, but you should look for a fertilizer with a similar ratio—that is, little or no phosphate and roughly equal amounts of nitrogen and potash. Once you find a fertilizer with a similar ratio, then recalculate the rate based on the amount of nitrogen and potash recommended for your crop or landscape area.
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Prepare for a fall vegetable garden by soil testing.
If you are thinking about planting a fall vegetable garden in July or August, then you need to take the first step in June. Soil test! The test is free, and sampling instructions are available online at www.ncagr.com/agronomi/pdffiles/samhome.pdf. Sample boxes and information sheets are available at all county Cooperative Extension offices. Within two weeks, you should have all the information you need to apply lime and fertilizer for a productive garden.
- Test source water for irrigation systems.
Before you turn on that drip or overhead irrigation system, it is a good idea to collect samples of your source water and have it tested by the NCDA&CS Agronomic Division. Chemical problems with source water can affect plant growth and quality. By testing water now, you can correct any problems before you start irrigating your crops.
Solution analysis is a service that measures the chemical properties of water that affect plants. In eastern North Carolina, high alkalinity is a potential water problem. Irrigating with highly alkaline water can lead to an increase in soil pH that can limit availability of some essential plant nutrients, especially micronutrients.
The solution analysis report indicates whether alkalinity is a potential problem and, if so, provides helpful advice to correct it. Some other potential source water problems include high soluble salts, iron, boron, sodium or chloride. Once identified, these problems can either be corrected or effectively managed to prevent plant growth problems.
- If crop plants are stunted and/or discolored, check for nematodes.
The best way to find out if nematodes are responsible for an area of poor crop growth is to collect and submit two sets of soil samples: one for nematode assay and one for fertility analysis. An accurate diagnosis during the growing season provides a sound basis for effective management in the future.
For nematode assay, collect samples at the margins of affected areas where symptoms are moderate to severe. Avoid areas where plants are already dead or dying. For each nematode sample, collect at least 20 cores from the top 8 to 12 inches of soil, mix them together, and then fill a one-quart plastic bag about three quarters full. Be sure the sample includes at least a small handful of roots from the affected plants. Send a completed Nematode-Problem Diagnosis Information sheet along with the samples as well as the appropriate fee ($3 per sample). For fertility analysis, use excess soil to fill a standard soil test box. Fill out the orange information sheet designated for problem soil samples.
Package and address soil test and nematode assay samples separately so they will arrive at the correct laboratory. Use the Mail Service Center address when sending samples through the U.S. Postal Service. Use the physical address only when sending samples via a private carrier, such as Fed Ex or UPS.
- Fertilize centipedegrass lawns in June.
The nitrogen fertilization rate and schedule for centipedegrass are different from those of other warm-season grasses. Centipede requires only 0.5 pound of nitrogen per 1000 square feet per year, and all of this amount should be applied in June. The majority of centipede growth problems that are fertility related result from applying too much lime and phosphorus or inadequately maintaining soil potassium levels. These problems can be prevented by soil sampling and following recommendations. If you have not taken a soil sample in the last two or three years, you may want to do so to find out your lawn's fertility needs. When filling out the soil information sheet for your sample(s), remember that centipedegrass has its own crop code (022).
Important Reminder: Do not fertilize cool-season lawn grasses—fescue, ryegrass and bluegrass—during the summer. Wait until September.
- If crops look stunted or discolored, collect soil and tissue samples for nutrient problem diagnosis.
Soil samples are normally collected before a crop is planted to assess the lime and fertilizer needs for the upcoming season. However, soil samples and matching plant tissue samples collected during the cropping season are excellent for diagnosing a wide range of nutrient problems. The best approach is to collect both soil and tissues samples from "bad" areas, and then to collect both types of samples from "good" areas. Label the samples so you know which are the "good" ones and which are the "bad" ones. Do not collect tissue samples from dead plants.
- Summer is a good time to submit soil samples from lawns & gardens.
Summer is the off-season for the NCDA&CS soil testing lab, and samples can be processed quickly-usually in about ten days or less. Homeowners and landscapers are urged to submit samples at this time, but some farmers can take advantage of the off-season as well. Farmers who are maintaining cool-season pastures can submit soil samples to be ready for late summer or fall, which is an excellent time to apply phosphorus and potassium to get pasture grasses ready for winter.
- Any Plant/Crop
If plants are discolored, stunted or exhibiting poor growth, collect matching soil and plant tissue samples from both good and poor areas. Submit them to the NCDA&CS Agronomic Division to find out if the symptoms are due to a nutritional problem.
- Corn
In eastern counties, collect soil samples for nematode assay. Although it is too late for treatment this season, it is an excellent time to check population levels and plan management for next season.
- Cotton
Collect tissue samples (MRMLs + detached petioles) weekly beginning at early growth (pinhead squares) and continuing for three to four weeks after first bloom. Collect tissue and soil samples any time and as soon as abnormal growth is noted.
- Home & Garden
Take soil samples now to prepare for fall planting projects such as vegetable gardens, tree and shrub installation and renovation/maintenance of cool-season lawns. Do not wait until fall to submit soil samples for home landscape projects.
- Nursery Crops
Collect leaf tissue samples from plants exhibiting nutritional disorders and send them to the lab. Correct problems based on test results.
- Tobacco
Collect tissue samples five to ten days before each anticipated leaf harvest to determine ripeness. An appropriate samples consists of 10 to 12 leaves from the appropriate stalk position.
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Collect soil samples now to prepare for fall renovation of cool-season lawns (including fescue!) and pastures.
This year’s dry weather has been hard on cool-season lawn grasses and pastures. Many will need to be reseeded this fall. To be ready, submit soil samples in August and follow the lime recommendations on your report as soon as possible. That will provide several weeks for soil pH to adjust before seeds are planted in September or October.
- Submit soil samples now, if possible. Avoid the busy season.
Everyone who expects to need a soil analysis this fall is urged to submit samples now. This is especially important for homeowners, golf courses, landscapers, and others who do not have to take samples based on the timing of crop harvest. As soon as farmers begin harvesting, large numbers of soil samples will be coming into the Agronomic Division's soil testing laboratory. Send in your samples now so you will have results back in time to apply lime as needed this fall.
- At the end of the season, investigate causes of crop growth problems.
As the growing season comes to a close, you may notice weak areas where crops have not grown well. Don't be left wondering if soil fertility or nematodes were an issue. Take soil samples from good and bad areas for comparison and to help identify the source of the problem. Submit the samples (labeled as problem samples) to the Agronomic Division's soil and nematode assay laboratories for testing. Complete the appropriate information sheet(s) for problem sample diagnosis. If you need advice on how to take and submit problem samples, contact your NCDA&CS regional agronomist for assistance.
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Don't fertilize grass during drought.
Fall is usually the time to fertilize cool-season grasses, including hay and pasture crops. This year, however, fertilization should be delayed until drought conditions ease up. Moisture is needed for grasses, like fescue and orchardgrass, to begin fall growth.
Without moisture, fertilizer application is likely to be a waste of time and money. In the case of forage grasses, it could also be dangerous. High levels of nitrates can be fatal to cattle.
Rain does not necessarily mean the drought is over. Visit www.ncdrought.org to keep up with the drought status for your area.
- Focus on strawberry fertility.
Take soil samples and apply any recommended lime as soon as possible. Generally, strawberries need 100–120 lb of nitrogen per acre per season. Prior to building the beds and laying plastic, apply 30–60 lb of nitrogen along with any phosphorus or potassium recommended on the soil report. Even when soils are high in phosphorus, an additional application of 30 lb can be beneficial for root growth in the fall. Other nutrients that may have a beneficial effect at this time are sulfur and boron (1 lb/acre).
- Remember to check for nematode problems during crop harvest.
Plant-parasitic nematodes are common in all field crop soils and often lower yields without being very apparent. Fall is an excellent time to find out if nematode populations are high and, if so, to develop a plan to manage them. When the weather is good for harvest, it is also good for collecting soil samples for nematode assay.
Nematode populations peak at the end of the growing season so samples assayed at this time provide an accurate description of potential hazards. If you submit samples in the fall, you will have time to plan a management strategy.
If you noticed localized areas of poor growth during the growing season, it is a good idea to collect separate soil samples from good and poor areas. Submit two samples from each of these areas-one for nematode assay and one for soil fertility. Comparison of results from good and poor areas and from nematode assays and soil tests is helpful in pinpointing a problem.
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Use these tips when submitting soil samples.
Processing of soil samples at the NCDA&CS lab goes more efficiently when growers take care to: 1) place information sheets in plastic, zip-lock bags to prevent moisture problems; 2) use the soil lab's specially designed shipping carton when sending large numbers of samples; and 3) address and label shipping cartons completely and correctly. Visit this Web page for specific information.
- Fall is an ideal time to apply lime.
Fall liming is an excellent way to prepare for the spring growing season. Whether you are renovating your yard, preparing a new landscape planting or readying your fields for the next crop, fall is the best time to apply lime. However, lime should only be applied according to the recommendations from a recent soil test report.
Take advantage of dry fall weather to apply lime as soon as possible. If you delay, wet weather may prevent the application even longer. The earlier you put out lime, the sooner soil pH will be adjusted to meet your planting needs.
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Become familiar with the new fees for agronomic tests.
By now, many of you are aware that most agronomic tests (nematode assay and plant/waste/solution analyses) cost one dollar more than they did last year. Soil tests are still free! However, for certain samples that require special tests, fees have increased by more than a dollar.
Tissue tests for the following crops will always cost $7 for the indicated reason:
alfalfa — requires special test for molybdenum
broccoli — requires special test for molybdenum
cabbage (all kinds) — requires special test for molybdenum
cauliflower — requires special test for molybdenum
collards — requires special test for molybdenum
cotton — requires petiole analysis for nitrate nitrogen
kale — requires special test for molybdenum
poinsettia — requires special test for molybdenum
spinach — requires special test for molybdenum
strawberry — requires petiole analysis for nitrate nitrogen
turnip greens — requires special test for molybdenum
vinifera grape — requires petiole analysis for nitrate nitrogen.
Other special services, such as soil test for heavy metals ($25), tissue test including chloride ($7), and waste analysis that differentiates between types of nitrogen ($15) will be performed only upon request.
- Give appropriate care to plants you bring indoors for the winter.
By November, most houseplants should be brought inside to protect them from cold temperatures. Indoors during the winter, plants need less fertilizer and may get too much or too little water. Fertilizing once every four to six weeks with a soluble or time-release fertilizer should provide plenty of nutrients. Fertilizing too often can stress plants as excess fertilizer salts build up in the media.
Check plants frequently to see if they need water instead of watering on a schedule. Overwatering can be a problem in winter months when light is low and growth is slow. Underwatering can also occur as increased use of the home furnace tends to dry both the air and potting media at the same time.
- Check source water used for agricultural purposes.
Water used for agricultural purposes-such as irrigation or fertigation, livestock and poultry watering, aquaculture and fish production-should be analyzed every year. Testing is especially important after an extended wet or dry period. For a fee of only $5 per sample, solution analysis measures concentrations of 13 minerals plus pH, electrical conductivity, alkalinity and hardness. The solution report indicates whether any of these parameters could lead to production problems (such as clogged nozzles or reduced medication efficiency) and provides recommendations to correct any apparent problems.
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Use agronomic testing to optimize fertilization of greenhouse crops.
Greenhouse crops-like tomatoes, peppers, lettuce and cucumbers-require intensive management of fertilizers, environmental conditions, and disease and insect problems. One way growers can maximize yields is to keep abreast of any potential nutritional problems. Several tests available from the NCDA&CS Agronomic Division can help.
- Soil test—Sample media prior to filling pots or bags to verify that pH and soluble salts are within the desired ranges.
- Solution analysis—
- Submit samples of source water to determine if there are any problems that need to be corrected, such as high alkalinity, high soluble salts, or high mineral concentrations.
- Submit samples of nutrient solutions to verify that the injector is working properly and that plants are receiving the targeted nutrient concentrations.
- Plant tissue analysis—Submit samples every couple of weeks to monitor nutrient concentrations in the crop. This test predicts nutrient deficiencies or excesses before symptoms appear so growers can correct the problem quickly with as little reduction in yield as possible.
- Annual soil tests are required for all fields used for waste application. Now is the time to take care of this requirement if it hasn't already been done.
Many swine and poultry growers throughout the state are permitted through the N.C. Department of Environment and Natural Resources due to legislation addressing animal waste issues. These permits require annual soil testing of all fields used for waste application. Failure to have a yearly soil test report for a given field upon annual inspection may result in a notice of violation. Growers are encouraged to remember this fact and submit required soil samples before the end of the current year, ideally before the end of December.
Last Update
January 4, 2008
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