Research on the use of controlled-release fertilizers (CRF) in California vegetable production has been conducted for more than 30 years. Since Lorenz et al. (1972) evaluated CRF for potato ( Solanum tuberosum ), tomato ( Solanum lycopersicum
nodules have commercial potential in nursery production and urban landscapes ( Kratsch and Graves, 2004 ). Slow-release fertilizer and CRF gradually deliver mineral nutrients (mainly N) to plants and have been widely used in nursery production ( Adams et
, 1993 ). Controlled-release fertilizer can be used to provide plants with adequate nutrition and minimize runoff because CRFs release nutrients gradually ( Broschat and Moore, 2007 ; Cox, 1993 ) and are less prone to leaching than water
combination of preplant CRF application and in-season N fertigation. There has been a significant evolution over recent decades in cultural practices used and in cultivars grown; yields have increased 140% over the past 50 years ( Shaw and Larson, 2008 ) and
container. The CRF was layered 1 inch under the top of the substrate. We use a randomized block design with 12 plastic 18-gal rectangular tubs (large storage tubs) filled with rainwater from surface ponds at the research center to create a submerged growing
more slowly available sources, such as CRFs, provides an alternative management practice to reduce nutrient movement. Unlike WSFs, CRFs release nutrients in smaller quantities over longer periods of time ( Shuman, 2002 ). Past research indicates
delivery strategies used included CLF, CRF, and PF treatments. Constant liquid fertilization is the standard industry practice for greenhouse production, whereas CRF and PF provide alternative approaches. Controlled-release fertilizer refers to a fertilizer
structures ( Handreck and Black, 2002 ; Wulfsberg, 2000 ). Consequently, they both have a high potential for moving with water once dissolved. Nitrogen leaching from CRF formulations depends on the dissolution and transport of nutrients through a polymer
the physiological requirement ( Oertli, 1980 ). Recent studies have shown that controlled-release fertilizer (CRF) applied as part of a citrus fertilization program could reduce N leaching on Florida sandy soils ( Alva and Tucker, 1993 ; Dou and Alva
controlled-release fertilizer (CRF; referred to collectively as S/CRF) release N, and in some cases, other fertilizer elements, at different rates and through different mechanisms ( Sartain et al., 2004 ). These release mechanisms will be discussed below