From Jerad Minnick, Maryland Soccer Foundation: Now let’s explore our approach to nutrient management used in our journey towards producing strong, durable and healthy turfgrass.
Our nutrient management thoughts break down into 2 parts.
1) Maintaining nitrogen in consistent, low levels
2) Using nutrients for are essential for plants under heavy traffic
Maintaining nitrogen in consistent, low levels
Nitrogen is one of three key macronutrients required for maintained plant growth and health. Because nitrogen is key in producing proteins, it should always be present.
However, excessive nitrogen leads to faster growth, which is a factor in turfgrass destruction on high-traffic fields. The faster growth actually weakens cell walls of the plant. Just as an adolescent child who is growing quickly can have weak bones, the plant’s cell walls become weak. The weak cell walls are easily invaded by pathogens and punctured and/ or ruptured by traffic.
Just 1 weekend play of moderate play (10-15 matches) on lush, fast growing turfgrass will lead to widespread damage via ruptured cell walls. Following the weekend, the turf will be very matted down and appear “smashed” and weak. Within 2-3 days, the turf will begin to turn to a straw color and thin out. This is especially true on referee lines and around the bench areas where the continuous foot pounding first ruptures the leaf blades.
So then comes the big question of “how much nitrogen”??
The approach we take to that answer that question is approaching nitrogen feeding on a weekly basis. The maximum amount of plant available nitrogen in 1 week that SoccerPlex grass (Patriot bermuda or Kentucky bluegrass) is to receive is .125 (1/8) of 1 lb. During the heat of the summer, bermudagrass is given up to .125 while the bluegrass is reduced to around .05 (1/2 of 1/10th) . Then spring and fall release goals are reversed- bluegrass to receive up to .125 and the bermudagrass cut back to .05.
At the end of the growing season (approx. 8 months), both grasses will average somewhere between 3.4 lbs of total nitrogen. The nitrogen comes from slow release granular sources that give us such control and from foliar sprays that include nitrogen, also giving us control.
Monitoring estimated nitrogen release (ENR) potential from the organic in the root zone is also important in reaching the desired weekly nitrogen release amount. Native soil fields that have high levels of organic matter containing carbon. As summer temperatures rise and soil microbial activity increases, organic matter breaks down and releases the carbon into the soil as a natural nitrogen source.
Nutrients Essential for Plants Under Heavy Traffic
Maintaining adequate levels of all other plant essential nutrients outside of N, both macro and micro, is also important. Soil testing at least 4 times a year allows us confirm that our root zone is balanced. But our K management, in conjunction with Ca, Si, and Mn has played the biggest role in producing turfgrass plants that withstand heavy traffic.
Potassium (K) is key for plant strength and durability during times of drought and heat stress. K also aids in balancing other elements in the plant when sodium, chloride, and bi-carbonate levels get high in the soil due to poor irrigation water and lack of drainage in native soil fields. K release for Kentucky bluegrass during the 4 stressful summer months is .2 lbs of K/ week. (Note that this is higher than our N release levels). Year end totals for K are equal to N on a 1:1 ratio.
Si, Ca and Mn also all add to plant strength and health through frequent application in plant available amounts. Potassium silicate allows us to reinforce our cell walls to withstand the traffic and stress by producing a rigid, strong leaf blade and strong, fibrous roots. Calcium works hand-in-hand with the K and Si aiding in cell division and stress resistance, while manganese is essential in the photosynthetic process, especially for a plant under traffic and stress.
Between maintaining nitrogen in consistent, low levels in conjunction with using plant essential nutrients for heavy traffic, we are able to maintain strong, durable and healthy turfgrass. The strong plants also require less water because of deeper roots and less fungicide because of a strong immune system and reinforced cell wall protecting against invasion. So in the end, the strong, durable and healthy plants allow us to decrease inputs all the way around.