BEST MANAGEMENT PRACTICES be detrimental to compaction potential and infiltration rate in sand-based fields .
Salinity and sodicity are important considerations where greywater is used for irrigation , as well as in certain arid zones where irrigation waters / soils can be natively high in salts . It is important to understand that there can be an overall salt problem ( salinity ) and / or specific ion toxicities ( sodium , chloride and boron are the most common ) when irrigating with greywater .
When a soil test shows that the electrical conductivity used to measure salts is above 4.0 dS / m , the soil is considered “ saline ” although plants can experience stress before the salt concentration in soil gets this high . In this case , it does not matter which salts are present — as all contribute to the overall salt effect . Plants need salts for their metabolic processes and while all fertilizers are salts , excessive salts in direct contact with plant tissues will burn the foliage . In the soil , salts bind to water so strongly that plants can desiccate even when there is ample soil moisture . Saline soils are corrected by ensuring adequate drainage followed by irrigating to excess with reasonable quality water to move the salts below the rootzone .
Specific ion toxicities occur when nutrients and other chemical elements are excessively high . Chloride and boron are both essential plant nutrients , but they are sometimes present in excessive amounts , usually in the irrigation water , which can kill plants . Again , soil testing can identify these toxicities . These are potentially corrected through leaching below the rootzone .
Similarly , sodium is a beneficial nutrient ( not essential ) found in all soils and most irrigation waters . It can become a problem when its ratio relative to calcium and magnesium is high , creating a “ sodic ” soil . This is relatively more common in arid regions , but also with some reclaimed irrigation waters . Sodic soils have an Exchangeable Sodium Percentage > 15 % and / or a Sodium Adsorption Ratio > 13 , but preventative action should be taken before reaching these levels . Sodicity results in the soil structure being destroyed as clay-based aggregates disintegrate , which is not a problem in sand-based fields . Sodic soils are remediated similar to saline soils except that a soluble calcium source ( most commonly gypsum ; limestone should not be used in alkaline soils ) needs to be applied prior to leaching .
PLANT TISSUE ANALYSIS Visible plant symptoms and soil testing can offer helpful clues in diagnosing nutrient deficiencies but can also be confusing and misinterpreted . Tissue testing is an effective way to determine precisely what nutrients are in plant tissue at a particular point in time . While that data is beneficial , it does not necessarily reflect why the nutrient is at a deficient or excessive level . It is important to pair tissue testing with soil testing data to best determine nutrient management strategies and closely follow the lab ’ s guidelines for how to sample and prepare the tissue samples to get meaningful results .
Tissue testing can help to adjust nutrient management programs in these ways : Confirm a suspected nutrient deficiency or toxicity . Monitor plant nutrient concentrations for sufficiency . Pair tissue tests with soil tests for troubleshooting .
Plant tissue samples can be easily taken in turfgrass from fresh mowed clippings — taking them from multiple locations throughout the field . However , careful cutting with clippers may be needed when sampling small areas with visual symptoms for comparison to areas that appear to be healthy . ( Soil samples should be taken from the same areas for comparison .) Samples should not be taken within a few days of a fertilizer or amendment application . For micronutrient analysis , plant samples should be rinsed lightly and quickly to remove any dust or soil particles and then air dried or oven dried at temperatures below 150 ° F ) before being placed in clean paper bags and sent to the laboratory .
For diagnostic samples , plant tissue samples should be collected as soon as symptoms appear . Plants showing symptoms of severe deficiency are often the most difficult to interpret correctly , since a deficiency of one element may result in deficiencies or excess accumulation of other elements if uncorrected . Plants under prolonged stress of any kind ( temperature or moisture extremes , pests , flooding , mechanical damage , etc .) can have unexpectedly high or low nutrient levels due to the stress . As with soil testing , plant tissue analysis is a useful tool but is not always certain in its findings .
FERTILIZER RESPONSE EVALUATION Another tool for managing nutrients , especially for correcting suspected , but unconfirmed deficiencies is the application of fertilizers to small test areas to observe whether greenup occurs . Application of a complete fertilizer containing all of the nutrients can help determine whether the problem is nutritional or related to some other stress . Application of individual or paired nutrients can help isolate which nutrient is deficient . sportsfieldmanagementonline . com February 2023 | SportsField Management
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