Written by Mike Hamilton, CCA & President of Turf Dietitian
The standard testing methods to determine the nutrient content of the soil have been around for many decades. The lab data from testing soil for the nutrient reserve is information that practically every Superintendent in the world knows how to analyze. However, guidelines and target ranges for testing soil reserve were established in the 1950s on soils from Midwestern farms that were nutrient-rich, received adequate rainfall, and cultivated one or two times per year. I don’t know many golf courses that fall under that category. Yes, the information from testing soil reserve is valuable, but it is only one piece of the puzzle.
Although every piece of data on the soil reserve report is essential in putting the puzzle together, the physical data is probably the most important factor when growing highly manicured turf.
The organic matter and saturation index give us critical information on soil structure, while pH and CEC are essential for determining nutrient uptake.
Most of the nutrients in soil reserve come from the water that falls or flows across the property. Nutrients can also enter the soil reserve through organic matter decomposition, animal decomposition or waste, mechanical application, or directly from the atmosphere. Although a large amount of nutrients get stored in the soil reserve, only a tiny amount of that nutrient bank is immediately available to the plant.
The best analogy for nutrient reserve is this: there is a cabinet full of canned food, but you have no can opener. Getting to the food in those cans will take some physical reactions.
Even though much of the nutrient reserve is tied up and unavailable for plant consumption, chemical reactions, electrical charges, and hydrolysis free up some of the nutrient reserve, allowing the nutrient to move into soil solution.
At Turf Dietitian, we analyze the reactions in the soil to understand plant needs and nutrient availability.
Nutrients in Soil Solution
Analyzing soil solution is a more modern science than measuring soil reserve. The data we get from studying soil solution is just one more piece to the puzzle, but it holds valuable information that was not accessible to us until a few years ago. Knowing anions in solution and nutrient availability helps Superintendents determine the most efficient source of raw materials to use to balance the plants’ diet.
Soil solution is capillary, or gravitational water that occupies a percentage of the sore pore space. Soil solution participates in physicochemical and biochemical reactions, the cycle of matter in the soil, and plant nutrition. The composition of soil solution isn’t easily determined. Soil-forming processes, vegetation, general climatic conditions, the season, weather, and man’s activity, such as adding fertilizers, can all affect soil solution composition. The amount of available nutrients for plant consumption depends on the soil’s moisture content.
The best analogy I have for soil solution is this: it’s a variety of food on the plate ready for consumption.
However, just because the food is on the plate doesn’t mean the plant will eat it. If you think all the food on your kid’s plate gets eaten because it’s clean, take a look at the rolled-up napkin in the middle of the garbage can. It might just be full of vegetables.
Turf Dietitian examines soil solution to help Superintendents develop strategies and nutritional programs that are efficient and supply a balanced diet so plants can overcome nutrient tie-up and soil imbalances.
Plant Nutrient Consumption
Plant tissue testing provides the most accurate data to indicate what nutrients the plant has consumed. Although most of what the plant takes up is through the mass flow of nutrient-rich gravitational water, a small amount of nutrients absorbs through the plant tissue by atmospheric nutrients and sugar or amino acid nutritional products.
Turf Dietitian owns and operates a private certified tissue testing lab. We provide a weekly service to determine what nutrients were consumed by the plant, and we make recommendations on balanced weekly nutrient applications.
Trying to determine plant reactions from any of the above-mentioned factors is like putting together a 1,200-piece puzzle with 200 pieces. Using 1/6 of the pieces may give you an idea of what the puzzle looks like, but it’s nowhere near complete. With all 200 pieces added, the puzzle becomes more apparent. But, use all 1,000 pieces, and you’ve got a beautiful picture that can be hung on the wall.
