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2022 Midwest Vegetable Guide

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20 Midwest Veg Guide 2022 Soil Fertility and Nutrient Management ground limestone reacts with soil more quickly than normal limestone. In fluid lime, 100 percent of the liming material must pass through a 100-mesh screen, and nearly 80 to 90 percent must pass through an even smaller 200-mesh screen. The principles of effectiveness of ground agricultural lime also apply to fine or fluid lime. Lime suspensions do not possess any special capabilities compared with conventional agricultural lime that contains a high degree of 60-mesh or finer particles. Pelletized lime, or pell-lime, is finely ground lime that has been formed into pellets for easy application. Because it is finely ground, it will react quickly in the soil. Unlike regular ag lime, it will not provide residual liming activity over a few years. Liming Recommendations Fields usually require lime every few years because Ca and Mg are removed in harvested portions of the crop, leached out of surface soil by rainfall, and lost from the field when soil erodes. Lime is also needed to neutralize acidity produced by acid-forming fertilizers. Growers sometimes need to add lime to correct subsoil acidity. In that case, apply enough lime to bring the surface soil to pH 6.8. The subsoil pH will increase only if you maintain the surface pH near 6.5 or more. Over time, rain will leach the Ca and Mg into the subsoil, raising its pH. Because this downward movement takes several years, the sooner the lime is applied, the better. In most cases, make split applications when the recommendation is more than 4 tons per acre. This will achieve a more thorough mixing with the acidic soil. Apply half the lime before plowing and half before soil fitting. For best results, apply the lime at least six months before seeding a legume. If you have a recommendation for a maintenance application of 2 tons per acre or less, you can apply it at any time in the cropping sequence. Plant Tissue Analysis Plant tissue analysis for nutrients is a useful tool in managing plant health, and a tissue test is usually required to confirm a diagnosis of nutrient deficiency. Tissue testing can be especially helpful when growing a new crop or a familiar crop in a new production system. Regular tissue tests, especially early in the growing season, will provide early notice of nutrient imbalances so they can be corrected before yield or quality is affected. With high value greenhouse crops regular tissue testing is often a standard part of production. Concentrations of nutrients in plant tissue that are normal, deficient, or excessive have been identified for most vegetables. The concentrations depend on the plant part and stage of growth. Before collecting plant tissue, contact a tissue testing lab and request instructions for collecting and submitting samples. The specific plant part to collect for tissue analysis varies depending on the crop; often it is a recently mature leaf. The stage of crop growth is important because normal tissue nutrient concentrations change as the crop develops. If the tissue test is being used to diagnose a specific symptom, collect separate samples from each of these groups: • Symptomatic plants • Healthy plants • Plants with minor symptoms Comparing the results of these three samples, along with results of soil tests, can help in determining the problem. For assistance in interpreting plant tissue tests, contact your local extension vegetable specialist. Chemigation Management Chemigation is the process of applying an agricultural chemical (pesticide or fertilizer) to the soil or plant surface through an irrigation system. Depending on the type of agricultural chemical, chemigation may be referred to as fertigation, insectigation, fungigation, etc. For chemigation applications, you can only use pesticides that display EPA approval for such applications on the label. Each chemigation and irrigation system also must use the safety equipment specified on the EPA label as well as any equipment required in your state. Some states also may require a system or operator permit before you can apply any product with chemigation. Chemigation can be an effective application option for some labeled pesticides if the irrigation system can apply the chemical/water solution uniformly over the target area with the correct water depth. Some pesticides work best with less than 0.25 inch of water per application. Most late-model center pivot and linear move systems provide adequate distribution but some may not be able to apply a small enough volume of water. Solid set sprinkler systems may be effective for some pesticides but require close timing of chemical movements to get complete and uniform coverage of the field. Drip irrigation can be used effectively to apply certain pesticides and fertilizers. Traveling gun and hand move systems do not provide water distribution that has high uniformity and are not recommended. Product labels provide more information about appropriate water application amounts and which irrigation systems are recommended.

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