Given the excessive rainfall in the northeastern US last year and the continued snow, rain and sleet this winter, the timing seems appropriate to develop a checklist for spring. “This too shall pass,” a wise person once told me. With warmer weather around the corner, turf managers must quickly evaluate the extent of plant survival after snow and ice melt. What was status last fall and leading up to dormancy, and how might this year’s winter weather affect the potential for turf loss? Here are ways to determine the extent of winter damage, options to improve drainage so fields can handle more water, what to do when it inevitably gets hot and dry, and identify when and why sports turf managers most often fertilize.
Don’t wait to get in the field and determine the extent of turf injury and/or loss. Check problem areas first, including low lying, poorly drained, heavily trafficked, compacted, and/or those that were established the previous fall. If an area looks lost, cut out a core and bring it inside to determine how much crown tissue and stolons remain viable. It may take a couple of weeks to see the extent of the damage. In areas that incurred turf loss, prepare to renovate or inter-seed. Avoid seeding too early however; depending upon you location, it’s possible for winter weather to reoccur, setting back immature plants. Consider turf selection very carefully during establishment. This provides an opportunity to incorporate desirable species and cultivars going forward. Prioritize the most important turfgrass traits for your site and use, for example texture, wear tolerance, cold tolerance, or shoot density.
As temperatures warm, any renovation has occurred, you’ve smelled cut grass, and the first fertilizer has been applied, consider where and how to improve drainage. Focus on soil physical properties that affect soil air/water ratios, and the structure that provides stability, drainage and anchorage for plants. For fields on heavier soils, it’s important to maximize drainage for improved turfgrass vigor, including rooting, but also to promote better surface characteristics, less compaction, and improved traffic tolerance. Recall that soil texture influences drainage, extent of compaction, and firmness (all important factors for playability) but it also affects nutrient holding capacity and thus the effectiveness of turf nutrition programs. Soil compaction remains a function of both soil texture and moisture. Most compaction occurs at the surface and can lead to internal drainage problems if not corrected. Choose options to improve water infiltration and hydraulic conductivity based on the extent of the problem, resources, and budget.
Aeration replaces soil oxygen with atmospheric oxygen for plant root and microorganism consumption and provides additional exchange of carbon dioxide to the atmosphere. Aerate using hollow coring, solid deep tine, hydroject and aggressive vertical mowing. Core aeration produces macro channels, allowing better movement through the soil profile. These channels may be filled with sand to amend the soil and further improve percolation. Routine and continued aeration also reduce thatch, minimize compaction, and offer better plant rooting long term.
Broadcast sand for general maintenance and fill hollow tine coring holes with sand to dilute soil organic matter and thatch. Routine sand topdressing applications firm the playing surface, minimize devoting potential, and reduce compaction. Recall that sand particles do not compact like silt and clay, therefore modifying the rootzone with sand over time will offer better overall hydraulics and reduce standing water. Sand topdressing can be expensive, both the sand and the labor to apply it, however it offers many benefits so figure out a way to incorporate this key cultural practice into your management plans.
What to do when it’s hot and dry
So you’ve dealt with the spring checklist and improved drainage, now guess what? Of course it’s going to get hot and dry, right? Here are some considerations for summer because, as we all know, the fields will continue to see play throughout environmental stress.
Focus on rooting. Plants with deeper, more fibrous roots systems will acquire limited soil available water. Turf species and time of year largely determines the extent of the root system, however you can encourage rooting by applying moderate doses of soluble nitrogen (N) at the correct time, aeration, spiking, vertical mowing, and judicious irrigation. Do not over apply N; shoot growth at the expense of root growth, particularly in the late spring for cool season turf, will negatively affect turf vigor and stress tolerance because carbohydrate reserves can become depleted.
Do you have access to irrigation or rely on natural rainfall? If you irrigate, how is the water quality? If you are fortunate enough have to ability to control water inputs, you have the advantage to control soil moisture and speed establishment by supporting microbial activity and nutrient release. Do not overwater. If feasible, hand watering offers more control and the option to syringe. Assess turf vigor by how it responds to a fertilizer application and/or recovers from mechanical stress, lack of water, and/or divoting. Reduce soluble N during drought stress. Ensure optimum tissue potassium (K) 2-3% to further increase drought stress tolerance. Finally, consider spraying known osmotic adjusting amino acids such as proline and glycine-betaine. These normally come as part of a nutrient formulation and should be applied preventatively, prior to water deficit. These osmotic adjusters, or compatible osmolytes, work at the cellular level to improve plant water status.
Wetting agents and surfactants will promote water infiltration and/or uniform movement of the applied water. Use on sites where water does not easily penetrate the soil surface or on sand based systems where hydrophobicity/water repellency has resulted in localized dry spots. Surfactant chemistries differ in their mode of action and application for use and have the potential to cause phytotoxicity, so always read labels and apply for the appropriate reason.
For general maintenance, you should apply complete and balanced nutrient formulations. Focus on N application timing and dose. Deliver more soluble N when plants are actively growing—spring and fall for cool season turfgrass species and summer for warm season turfgrasses.
Before feeding the grass, calibrate the spreader or sprayer to ensure optimum delivery without waste. Without calibration, you run the risk of over or under-applying nutrient, which can compromise plant growth and development, risk environmental contamination, and waste money. Some fertilizer products contain pesticides, increasing the requirement for calibration.
Let’s face it, sports fields get beat up. They often host multiple sports throughout the growing season and during adverse environmental conditions. As a result, managers have little opportunity to promote turfgrass recovery. To maintain field uniformity, seed must be continuously introduced in hopes that plants survive with vigor. How do you provide the best chance for survival?
Choose the correct turf species
Provide a seedbed/limit compaction
Irrigate, if possible
Fertilize; focus on slow release N throughout the season to ensure adequate soil N and supplement with soluble N after seedlings have emerged and reached the 4-5-tiller stage.
When a lull in the schedule does exist, be prepared to implement a recovery program. Increase the height of cut and target soluble and insoluble N inputs; however, limit urea applications to permeable surfaces to reduce leaching losses. Focus on phosphorus (P) and minor nutrients to maximize energy production and photosynthesis. Discontinue the use of plant growth regulators. Soluble N will encourage rooting, tillering and stolon/rhizome growth, while the insoluble N mineralizes slowly, releasing plant available N over an extended period of time; thus enhancing turfgrass vigor longer term.
In the spring, do not try to push bermudagrass with heavy doses of soluble N, which can have a dramatic negative affect if you encounter extreme cold in late March or April. Apply more foliar micronutrients and Mg in the spring and fall when the sun angle is lower to maximize photosynthesis. Raise the height of cut going into winter. Maintain a balanced fertilization program in the fall and limit N fertilization.
For cool season turf, supply low doses of soluble N (≤ 0.25 lbs./1000 ft2) in the mid-fall to increase carbohydrate storage in the roots and increase winter hardiness. Limit high rates of potassium (K) (>1 lb. K/1000 ft2) prior to winter for warm and cool-season turfgrasses.
Many factors influence turfgrass N requirements. Warm season grasses, in general, require higher nutrient inputs than cool season grasses used for sports turf. More specifically, Kentucky bluegrass often requires much higher nutrient inputs, specifically N, compared to perennial ryegrass in the first couple of years, until fully established. Soil physical properties and organic matter also affect plant requirements. For example, compacted soils will require higher N rates than non-compacted, better draining, soils.
Fortunately, turf mangers have technologically advanced fertilizer options – from slow release granule formulations that can be applied at higher rates, to liquid, or foliar, options generally applied frequently and in low doses. The latter, referred to as ‘spoon feeding’, allows turf managers the ability to ‘meter’ nutrient inputs. Foliar fertilizers’ effects are more pronounced on sand soils, during environmental stress, or when root growth is compromised.
Concepts of Best Fertilizer Management
Beyond understanding the broad plant/soil community and collecting soil test data, best fertilizer management (BFM) includes selecting the correct fertilizer and applying it at the correct time. The concepts focus on fertilizer use and fate with the goal to maximize plant use of nutrient and minimize loss to the environment. BFM requires an integrated approach and using all available options. Most fertilizer programs start with N because plants require it in the highest amounts, and it should be the focus of a successful program. Maximize efficiency and minimize environmental losses by supplementing soil targeted slow release fertilizer applications with low dose and soluble foliar nutrition and, as always, become a keen observer and trust what you see!
Gordon Kauffman III, PhD, is turf and ornamental technical manager for BRANDT® visit www.brandt.co or www.grigg.co
Wear tolerance testing
In 2017, BRANDT worked with Dr. Gerald Henry at the University of Georgia to develop and test nutrition and soil conditioning programs designed to improve soil physical properties and increase turfgrass wear tolerance. We evaluated a rotational program of liquid fertilizers, including BRANDT iHammer’s Upplause® Plus (10-0-0) and two of BRANDT’s premier GRIGG brand specialty soil fertilizers: GRIGG™ Rhizonify™ (6-4-4 + minors) and GRIGG Bio Blend™ (10-0-0 5Ca). This rotational program improved turfgrass quality, including increased soil volumetric water content. The program also significantly increased Tifway ‘419’ Bermudagrass shear strength compared to the nutrient and untreated controls. These formulations provide nutrients for turf color and tillering, and the organics to improve the physical properties of the soil. The efficacy and delivery of these are further enhanced by the anionic surfactant that ensures uniform delivery to the soil profile.