Turfgrass Soil Health: What is it and Why is it Important

Introduction

Civilization, as we know it, has only been around 6,000 years.  Plants have been around for 700 million years and fungi around 1,300 million.  They have flourished, adapted and survived long before our intervention.  It is clear that Food Web (Image 1) interactions and ecosystem diversity is a measure of soil health that have contributed to this survival mechanism.  Management systems that support microbial life such as decomposers (bacteria, fungi and microarthropods) are responsible for nutrient retention in the soil.  The interactions of decomposers with predator groups (protozoa, nematodes and certain arthropods) create nutrient cycling and retention in the ecosystem. Advances in technology are improving our understanding of microbial life and various biological functions, which are vital for overall soil health.

Practices associated with production agriculture are similar to the management of sports turf, golf, and home lawns etc., which attempt to mitigate or eradicate problem areas such as insects or diseases.  However, those practices can reduce the overall health of the turf ecosystem.  As, local, regional, state, and federal regulations are continually evaluating the environmental effects of applying chemical pesticides and fertilizers, best management practices which help sustain good soil health should be considered.   Providing a beneficial management decision for plant growth in conjunction with a good environment for microbial activity needs more attention.   While there is no one formula and no one solution, our management decisions must continually scrutinize the potential impact on overall soil health. However, soil health is relatively new to agriculture and the turf industry.  The challenge is in testing and adjusting different methods onsite to establish site-specific programs.

Management Considerations

Nutrient-based upon soil test – not too much or too little. Turf needs fertility but that only makes up 5% of their diet (digested from both organic and mineral sources) while the other 95% comes from carbon and oxygen in the form of carbon dioxide and hydrogen from water.  The organic source is a byproduct of the soil microorganisms which first digest and transform these nutrients into the available form. Plants respond to both excessive and deficient nutrient levels.  While they are unable to distinguish the nutrients from biologically released organic source and our chemical soluble source, looking at a balance between the two would reduce the feast to famine scenario of a “spoon feeding” operation. Higher cation exchange capacity due to formation and presence of stable organic humus may promote greater numbers of soil microorganisms that regulate the availability of nutrient.

pH- acidity can effect turf nutrient uptake and growth as well as potential infestations by weed species.  Microbes tend to grow best in upper pH range of 6.5-8.0.  Optimal pH will improve the rate of mineralization of nutrient.

Water- too little or too much creates stress.  Moisture is essential for microbe survival.  If too high, aeration will be limited and most microbial activity reduced.  Various forms of organic matter can hold many times their own weight in water, which can retain more dissolved nutrients that would otherwise be leaching out of the root zone.

Aeration- is essential for all aerobic microorganisms and those involved in nitrogen mineralization.  Thatch management – heavy thatch keeps soil too moist, reduces air movement and promotes both insects and disease. Aeration reduces compaction from both foot and vehicle, which allows moisture, fertility, and oxygen through the root zone.  

Cut height- management practices that include increased cutting height can reduced herbicide and fungicide applications as the greens are not as stressed compared with cutting at lower heights.

Beneficial insects- healthy turf contains beneficial insects such as ground beetles, predatory and parasitic wasps, non-pest ants.  Some prey upon harmful species or aid in recycling nutrients in soil as primary decomposers.  Unnecessary pesticides reduce beneficial insects.

Pests- Pest create damage causing many human concerns.  They can range from chiggers and ticks to raccoons in garbage cans or deer trails across the course. Treating the pest symptom may resolve the current visible issue but further investigation might lead to discovery of an imbalance in the ecosystem.  Pesticide side effects can create an imbalance in the beneficial rhizosphere microbial pool.  While plants are not defenseless, healthy plants in conjunction with soil organisms are able to withstand greater pest pressures. 

Source: Dr. Todd Lorenz – Agronomy MU Extension Professional