BEST MANAGEMENT PRACTICES
program . The evaluation criteria should include nutrient content and quality , release rates , cost , ease of handling and distribution , offensive smell or odor , infiltration rate and any tendency to stain shoes and clothing .
PREDICTING / IDENTIFYING NUTRIENT DEFICIENCIES Predicting or identifying nutrient deficiencies can be done using the following tools : Visual assessment Soil analysis Plant tissue analysis Fertilizer response evaluation
VISUAL ASSESSMENT Visual assessment is a valuable first step for identifying nutrient deficiencies in plants . However , these symptoms are less specific in turfgrass compared with most other types of plants . It is also noteworthy that when avoiding urea application under hot , humid and / or windy conditions there is often “ hidden hunger ” with no visible symptoms .
In general , nutrient deficiencies cause a reduction in chlorophyll , which results in chlorosis ( yellowing ) that can progress to necrosis ( dead tissue ). In many plants , the various nutrients show distinct patterns in terms of age of tissue and type of chlorosis that help in deficiency identification . However , in turfgrass , mowing and relatively thin shoots can make it difficult to see these patterns .
In most instances , when chlorosis occurs , it is usually a result of nitrogen deficiency , although sulfur , iron and potassium deficiencies are also relatively common causes . Deficiencies in most of the
Source : Hopkins et . al 2020 . other nutrients can also cause chlorosis , although these instances are rare . It is somewhat common for soils that are excessively wet for prolonged periods to exhibit chlorosis due to problems in soil chemistry . Phosphorus deficiencies are an exception . If severe , these deficiencies result in plant tissues turning dark green or even red / purple . Visual assessment needs to be coupled with the other assessment tools to effectively diagnose deficiencies .
SOIL ANALYSIS Soil analysis is a tool that can help customize fertilizer needs in turfgrass with estimates of nutrient availability predicting plant response to an applied nutrient . Although a reliable tool , soil testing is not a perfect science . Some nutrients have been more thoroughly researched than others and some tests are more highly correlated to plant response than others . The most reliable tests indicate native soils high in silt and clay are somewhat resistant to change in nutrient and pH levels , and therefore soil testing may only need to be conducted every one to two years ( and no less than every five years ), unless monitoring corrective action ( such as liming an acid soil ). Sand-based soils are less resistant to change in nutrient status or pH , and thus may require relatively more frequent sampling such as once per year .
For soil analysis to be effective , accurate and representative samples are needed . Each field should be sampled separately , with about 12-15 cores per sample ( typically about a pint in total volume ). Within a field , if there are areas that are behaving differently , these samples should be segregated . Laboratories and other organizations / businesses dealing with soils can provide sampling instructions . Sampling depth for turfgrass is generally recommended at 3 ” to 4 ”. It is imperative to take separate samples from areas with varying soils and / or management . In addition , soil samples should not be collected following fertilization .
A laboratory with a record of sound QA / QC should be selected to conduct soil testing . Laboratories can provide documentation of their data quality , such as participation in proficiency testing . It is a good management practice to track data trends over time , which is sportsfieldmanagementonline . com February 2023 | SportsField Management
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