BEST MANAGEMENT PRACTICES
CALCIUM AND MAGNESIUM Although calcium and magnesium are essential to plant function , they are ubiquitous in the environment and , thus , rarely have documented deficiencies . Soil and irrigation water tends to be very high in these nutrients . Although much of the calcium and magnesium is found in solid form in soils , equilibrium chemistry assures that there is ample found dissolved in soil solution . When deficiencies do occur , they are typically on acidic sandy soils with no or minimal irrigation or with very pure irrigation water . Testing for and maintaining an appropriate pH with dolomitic limestone , which contains both of these nutrients , is generally enough to provide for healthy plant growth as both pH and nutrition is managed . Excess amounts of these nutrients are common and not typically concerning , although unwarranted applications are wasteful and potentially detrimental due to excessive salts .
MICRONUTRIENTS Micronutrients are typically found in relatively low concentrations in plant tissues , although they are just as essential for proper turfgrass health as macronutrients . They play a variety of roles in turfgrass biology , including photosynthesis , enzyme catalysis , protein synthesis , and a wide variety of other physiological activities and structural components . However , they are often found in ample concentrations in soils and turfgrass rarely shows response to their application . For example , nickel and molybdenum are needed in extremely minute quantities and there are no documented deficiencies in fieldgrown turfgrass . Although rare , deficiencies of the other micronutrients have been documented . These are far more likely to occur in sand-based fields with low organic matter .
Generally , there is ample chloride in irrigation water and soils . It is also included with the most common source of potassium fertilizer which is “ potash ” ( potassium chloride ). Chloride deficiencies are more likely to occur in non-irrigated , high-rainfall areas when potassium chloride fertilizer is not utilized .
Boron , zinc , manganese , copper , and iron are more likely to be deficient in alkaline soils due to poor solubility . In the past , iron chlorosis ( yellowing ) was somewhat common . However , modern varieties have been bred to mostly avoid chlorosis , especially with Kentucky bluegrass . Regardless , it is common to do a foliar iron spray a few days before high-visibility sporting events . This doesn ’ t necessarily improve plant health , but the practice typically results in visual response of greening .
Rates of micronutrient fertilizers are relatively low and should follow label recommendations . It is relatively easy to cross over from deficient to toxic given the fact that these are needed in such low quantities . This is especially true for copper and boron . In most cases when one or more micronutrients are needed , a single application annually will suffice . However , in severely deficient situations more frequent , generally foliar , applications are warranted . This is especially true for newly established sand-based fields . SFM sportsfieldmanagementonline . com January 2023 | SportsField Management
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