BEST MANAGEMENT PRACTICES
Incorrectly calibrated equipment can cause fertilizer burn . Credit : B . Hopkins .
FERTILIZER TYPES LIQUID VS . DRY Turfgrass is unique among most fertilized plants . Each individual plant has a very narrow cylinder root contact with soil . As such , uniformity of fertilizer application is very important .
Dry fertilizers are relatively inexpensive , especially when purchasing common forms in bulk from agricultural suppliers . However , these can result in poor nutrient uniformity . Fertilizers with a high size guide number ( SGN ) ( i . e ., larger particle size ) result in some plants getting excess fertilizer and others getting none . Conversely , fertilizers with a smaller SGN more uniformly deliver nutrients to all plants .
Liquid fertilizers , when properly applied using an accurately calibrated sprayer , can provide improved nutrient distribution — with every plant receiving nearly identical rates . However , liquid fertilizers do have some disadvantages . The liquid has direct and immediate contact with the shoots , which can have a high burn potential if the rate is high and / or the environmental conditions are hot , dry and / or windy . Liquids can also have chemical reactions in spray tanks , hoses , nozzles and other equipment . This can result in plugging that can be very costly to clean . This is particularly a problem with phosphorus due to its low solubility and highly reactive nature with calcium , magnesium and other cations in the water and / or fertilizer blend . If the liquid is being injected into the irrigation system , distribution uniformity problems related to irrigation water distribution may arise . Finally , liquid fertilizers tend to be more costly if they are shipped already mixed , although some products , such as urea , ammonium sulfate , potassium chloride , etc . can be purchased inexpensively in dry form and then dissolved .
NUTRIENT APPLICATION PROGRAMS AND STRATEGIES Stewardship that considers the impact of nutrient applications with respect to the environment , economy and society , includes the following “ 4R ’ s ”: Right fertilizer sources Right rate Right timing Right placement
Applying a quick-release fertilizer at high rates on a hot , windy day near impervious surfaces is a good example of ignoring the 4R ’ s rule . This example represents a waste of natural and facility resources , results in contamination to the environment , and may result in poor plant health as well . Poorly managed fertilizer usage has resulted in some instances of serious environmental contaminations and adoption of regulatory requirements by many state or local agencies . Sports field managers need to be good environmental stewards to avoid further problems and additional regulation . A one-size-fits-all approach to nutrient application is not possible , given all the variables of turfgrass species , sports , traffic intensity , soil , climate , budget and equipment available . Some strategies , such as Minimal Level of Sustainable Nutrition strategy , can be used . Using the information presented in the SFMA BMP guide and consultation with Extension specialists can help managers develop an appropriate site-specific nutrient management plan .
FERTILIZER APPLICATION EQUIPMENT AND CALIBRATION Dry fertilizers are typically spread with a broadcast spreader ( or a drop spreader in rare situations ). Liquid fertilizers are applied with a sprayer or injected into the irrigation system .
The selection and calibration of application equipment is an important aspect of nutrient management , as not all fertilizers can be applied with every spreader . For example , coated fertilizers can crack , and their control release properties can be destroyed when handled roughly , such as with certain drop spreaders equipped with an agitator .
Accurately calibrated sprayers and spreaders are essential for proper fertilizer applications . Incorrectly calibrated equipment can result in an application of too little or too much fertilizer , resulting in deficiencies or toxicities , excess costs , and greater potential for nutrient pollution . In keeping with the BMPs for equipment washing , spreaders should always be thoroughly cleaned after each use to remove salt residue that corrodes metal parts of the spreader . Many universities have publications on proper calibration methods . SFM
16 SportsField Management | February 2023 sportsfieldmanagementonline . com