Implementing the 4 Rs of nutrient management for berry crops can be beneficial to all!
Most berry growers should have heard of the 4Rs of nutrient management practices by now. There have been guidelines on how to implement the 4R best nutrient management or stewardship program in many states. For example, in Ohio, where I work, specific laws and rules have been passed recently requiring fertilizer applicators to be certified. New laws and regulations may sound like pain, but the 4Rs of nutrient management can be beneficial to all!
What are the 4Rs of nutrient management or stewardship? Greg LaBarge, a field specialist of Ohio State University (OSU) Extension, wrote in the 2012-40 issue of C.O.R.N. Newsletter that “4R Nutrient Stewardship is an industry driven concept of looking at soil nutrient application. The program utilizes a science based approach to nutrient use in crop production.”
The concept of 4Rs is actually not complicated and it refers to the right source of fertilizer, applied at the right rate, at the right time, and in the right place. I’d like to show you how you can put these principles into action.
Soil testing, in conjunction with tissue testing, is used to identify the right source of fertilizer. Soil testing should be done every 2 to 3 years to determine soil pH, lime index and nutrient levels such as phosphorus, potassium, magnesium, and calcium. You can request additional tests. I encourage you to check with your testing lab for more information. Soil nitrogen is not typically tested for fruit crops since there is very little in the soil.
Ryan Slaughter, a horticulture research assistant at OSU South Centers in Piketon, OH and a market gardener in Chillicothe, OH, takes soil samples on a regular basis. With soil sampling, he normally takes 12 to 15 cores at a depth of 6 inches in a zig-zag pattern to ensure a representative sample.
Fertilizer application rates have been established for almost all of our common fruit crops. According to Penn State University soil test recommendations, the standard nitrogen application rate for brambles is 75 pounds per acre. The optimum soil phosphorus level ranges from 25 to 50 ppm. At 25 ppm of soil phosphorus, the phosphorus recommendation will be 70 pounds of P2O5 per acre. The optimum soil test potassium level ranges from 125 to 160 ppm. At the 170 ppm soil potassium level, the potassium recommendation is 75 pounds of K2O per acre.
You should conduct tissue testing on a regular basis to reveal how much nutrients the plants take up. Tissue testing results will also be used to determine fertilizer application rates. According to the Penn State University soil testing lab, the recommended ranges for nitrogen, phosphorous, and potassium in brambles are: nitrogen tissue levels (% dry weight) are 1.80 (low), 2.00 (normal), 3.00 (high) and 3.50 (excessive). Phosphorus levels (% dry weight) are 0.23 (low), 0.25 (normal), 0.40 (high) and 0.50 (excessive). Potassium levels (% dry weight) are 1.45 (low), 1.50 (normal), 2.50 (high), and 3.00 (excessive).
The proper time to take tissue samples is mid-July for blueberries, July 15 to Aug.1 for strawberries, and Aug. 1 to Aug. 20 for brambles. I would take at least 60 leaves. Only leaves on non-fruiting canes are selected on brambles. Only the most recently full-expanded leaves without any mechanical, disease or insect damage, should be selected.
Right Time and Right Place
Time and place for proper fertilizer application is crop dependent. Please refer to Extension publications in your state for more information.
According to Penn State’s soil testing lab, with brambles, “broadcast fertilizer over entire bed as soon as possible in spring before new growth starts. If new growth has started, drill the fertilizer in between the rows, but no closer than 6 inches from plant stems. If fall-bearing cultivars are being grown, apply 60 pounds per acre actual nitrogen in the spring and additional 30 pounds per acre in mid-July.”
With blueberries, “Nitrogen: for new plantings, apply 25 pounds per acre actual nitrogen one month after planting. For 2- to 3-year-old plantings, apply 30-35 pounds per acre actual nitrogen. For plantings older than 4 years, apply 40 to 50 pounds per acre actual nitrogen. The preferred nitrogen fertilizer is ammonium sulfate. Broadcast fertilizer, as soon as possible in the spring (March), in a 2-foot-wide band along each side of the row, but no closer than 6 inches from plant stems.”
Combining soil and tissue testing should help berry growers select the right type of fertilizer, applied at the right rate, right time and right place. Growers can achieve desired fruit yields and quality without wasting money on fertilizer or labor on application, while protecting our water and soil for many generations to come.
Finally, I’d like to take a moment to thank you. It has been fun for me to respond to your inquiries. My fan club is growing. Hope this article finds you in a beautiful berry growing season!