Smart Fertilizer Provides K When and Where Needed

A new fertilizer technology developed at Penn State University offers several potential benefits for turfgrass cultivation. The new technology employs a phosphorus buffering system (PBS), which , maintains a steady phosphorus concentration in the soil solution over time. The PBS has the size and consistency of sand (Fig. 1) and can be mixed with any soil media. Once charged with phosphorus, the PBS establishes an equilibrium with the surrounding soil at a pre-established phosphorus concentration. This is useful for several reasons: • First, the PBS permits synchronization of phosphorus supply from the fertilizer and phosphorus demand by the plants. This is in contrast to traditional fertilizers, which are either immediately soluble or are released over time as a function of moisture and temperature, resulting in excess phosphorus supply soon after application and inadequate phosphorus supply some weeks later. Because the PBS is in equilibrium with the soil around it, phosphorus is released from the PBS only as it is being used by the roots. Under conditions of rapid growth and phosphorus uptake, more phosphorus is released, whereas under conditions of slow plant growth and slow phosphorus uptake, little phosphorus is released by the PBS. This occurs automatically by chemical reactions and does not require any monitoring or intervention by the grower. The synchronization of phosphorus supply with phosphorus demand assures that the plants are getting a sustained, optimal level of phosphorus nutrition over time, regardless of other environmental conditions. • Second, the PBS can be treated to maintain phosphorus at higher or lower equilibrium concentrations, allowing precise control of phosphorus supply to the roots. This is useful for turf cultivation since excessive phosphorus supply leads to reduced root growth, increased drought sensitivity, increased shoot growth, weaker leaves, lower leaf chlorophyll concentration and interference with micronutrient nutrition. Precise control of phosphorus supply via the PBS permits the grower to stimulate root growth, reduce leaf growth, improve leaf color and toughness, and improve drought Continued on page 50 Poa Annua It's been 10 years since the breeding program at Penn State introduced one of the most talked about grasses. . . .54