ABSTRACT Phosphorus (P) fertilization in low P retention soils can result in P leaching to ground... more ABSTRACT Phosphorus (P) fertilization in low P retention soils can result in P leaching to ground water. This study evaluated the effect of P application rate on orthophosphate leaching (OP) and its relationship with plant P uptake. Floratam St. Augustinegrass (SA) (Stenotaphrum secundatum (Walt) Kuntze cultivar Floratam) and Empire Zoysiagrass (EZ) (Zoysia japonica cultivar Empire) were grown in an uncoated sand soil with very low extractable P and low P retention capacity. Phosphorus was applied every 4 weeks at a rate of 0, 0.14, 0.28, 0.56 and 1.12 g m-2. Each treatment was replicated four times. Phosphorus uptake, plant dry matter accumulation, and Mehlich I extractable P were determined biweekly during 120 days (May to August, 2008). In addition, large plastic lysimeters were used to collect leachates, and the amount of OP leached was measured weekly. A decrease (p-value < 0.05) in OP leached with increasing P application rate was observed in SA while OP leached in EZ plots increased with greater P application. Under the conditions of this study, a cumulative P application of 3.75 g P m-2 and 1.5 g P m-2 in SA and EZ, respectively, did not result in an increase in OP leached in comparison to the no P application treatment. Phosphorus uptake rate of SA across treatments and sampling dates was higher (p-value < 0.0001) than in EZ. Root biomass in SA and EZ was not different (p-value = 0.920); however, root length density in SA was greater than in EZ (p-value < 0.0005).
Vegetable production in Southwest Florida is dynamic and responsive to new technology, market tre... more Vegetable production in Southwest Florida is dynamic and responsive to new technology, market trends, consumer demands and social pressures. Area growers want to continue to produce in the area and they seek the latest technology and knowledge to help them produce our food efficiently. Environmental concerns demand low-input, efficient operations which ultimately save money and energy and protect the environment.
ABSTRACT: Land area used for citrus (Citrus sinensis L. Osbeck) production in Southwest Florida h... more ABSTRACT: Land area used for citrus (Citrus sinensis L. Osbeck) production in Southwest Florida has expanded. The location of this expansion is a concern of water use and environmental regulatory agencies. Citrus requires well-drained conditions for optimum growth, but the soils in the region are primarily poorly to very poorly drained with seasonal high water tables. Drainability is the major factor which determines soil suitability for citrus production. The objectives of this study were to use the DRAINMOD soil water management/drainage model to 1) simulate water table behavior for artificially-drained flatwoods, slough, and de-pressional soils, 2) determine differences in soil drainability using an index calculated by DRAINMOD, 3) categorize soils as to suitability for citrus production, and 4) evaluate the accuracy of the method. Mean SEW30 of depressional soils was higher (indicating lower drainability) than flatwoods or slough soils. Empirical water table data from citrus gro...
Citrus trees planted in alkaline soils typically show iron (Fe) deficiency chlorosis. Currently, ... more Citrus trees planted in alkaline soils typically show iron (Fe) deficiency chlorosis. Currently, Fe-EDDHA (ethylenediiminobis-2-hydroxyphenyl acetic acid) chelate is the most effective source of Fe for high pH soils. Iron humate (FeH), a by-product of the drinking water decolorization process, was compared with Fe-EDDHA for Fe deficiency correction on nonbearing `Ambersweet' orange and `Ruby Red' grapefruit Citrus paradisi Macf., and bearing `Hamlin' orange Citrus sinensis and `Flame' grapefruit trees, all on Swingle citrumelo rootstock, planted on high pH (>7.6) soils. Iron humate was applied under the tree canopy in spring at rates from 2 to 200 g Fe (nonbearing trees), or 22 to 352 g Fe (bearing trees) per tree per year. Application of FeH to nonbearing trees decreased twig dieback rating and increased flush growth, flush color rating, tree size, and leaf Fe concentration. Addition of urea or ammonium nitrate to FeH did not increase Fe availability. Iron amendm...
Blueberry plants fertilized at 3-week intervals with nitrogen (N) throughout the year and protect... more Blueberry plants fertilized at 3-week intervals with nitrogen (N) throughout the year and protected from freezing temperatures avoid dormancy and produce an off-season “winter” crop. Southwestern Florida offers a climate where this production system can be implemented without undue fear of freezes. `Sharpblue', `Gulfcoast', and `Warmabe' southern highbush blueberry cultivars have been planted at high density (10,000 plants/ha) to determine the feasibility of successfully establishing an evergreen production system for blueberry. Three rates of N fertilization (84, 168, and 252 kg·ha–1) and the use of peat or municipal solid waste (MSW) compost as soil amendments are being evaluated in this study. Initial data on plant growth indicate that, during the first 9 months of the planting, 168 kg N/ha will produce plants similar in height, but with significantly less volume, to those receiving 252 kg N/ha. MSW compost appears to be a beneficial soil amendment for blueberry estab...
... HUATING DOU,1* SHELLEY JONES, THOMAS OBREZA2 AND BOB ROUSE2 1Florida Department of Citrus Cit... more ... HUATING DOU,1* SHELLEY JONES, THOMAS OBREZA2 AND BOB ROUSE2 1Florida Department of Citrus Citrus Research and Education Center ... fertilization rate increases vitamin C in lemons, oranges, and grapefruit (Embleton and Jones, 1966; Reitz and Koo, 1960; Smith ...
Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetab... more Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetable and Agronomic Crop Water Quality/Quantity Best Management Practices Manual was adopted by rule in the Florida Administrative Code in 2006 and describes cultural practices available to tomato growers that have the potential to improve water quality. By definition, BMPs are specific cultural practices that are proven to optimize yield while minimizing pollution. BMPs must be technically feasible, economically viable, socially acceptable, and based on sound science. The BMP manual for vegetables endorses UF-IFAS recommendations, including those for fertilization and irrigation. Current statewide N fertilizer recommendations for tomato provide for a base rate of 224 kg/ha plus provisions for supplemental fertilizer applications 1) after a leaching rain, 2) under extended harvest season, and 3) when plant nutrient levels (leaf or petiole) fall below the sufficiency range. An on-farm projec...
Journal of the American Society for Horticultural Science
Growth and nitrogen (N) accumulation relationships based on tree size, rather than age, may provi... more Growth and nitrogen (N) accumulation relationships based on tree size, rather than age, may provide more generic information that could be used to improve sweet orange [Citrus sinensis (L.) Osbeck] N management. The objectives of this study were to determine how orange trees accumulate and distribute biomass and N as they grow, investigate yearly biomass and N changes in mature orange trees, determine rootstock effect on biomass and N distribution, and to develop simple mathematical models describing these relationships. Eighteen orange trees with canopy volumes ranging between 2 and 43 m3 were dissected into leaf, twig, branch, and root components, and the dry weight and N concentration of each were measured. The N content of each tree part was calculated, and biomass and N distribution throughout each tree were determined. The total dry biomass of large (mature) trees averaged 94 kg and contained 0.79 kg N. Biomass allocation was 13% in leaves, 7% in twigs, 50% in branches/trunk, ...
Resource soil scientists with the USDA Natural Resources Conservation Service have rated the soil... more Resource soil scientists with the USDA Natural Resources Conservation Service have rated the soils that are delineated by map units in the Ocala National Forest area; parts of Marion, Lake, and Putnam counties Soil Survey Report1 for their potential for leaching and runoff of pesticides. The rating criteria are given in a companion publication entitled "Soil Ratings for Selecting Pesticides
Leaching of phosphorus (P) from agricultural soils, especially those that are sandy, is adversely... more Leaching of phosphorus (P) from agricultural soils, especially those that are sandy, is adversely impacting P-limited ecosystems like Florida's Everglades. A more developed understanding of P and water management strategies and their effects on P leaching is needed to achieve reductions in subsurface P losses, especially from intensively managed dual cropping systems under plastic mulch in shallow water regions. We compared the effects of conservation P and water management strategies with traditional practices on P transport to groundwater. A 3-year experiment was conducted on hydrologically isolated plots with plastic-mulched successive cropping systems to compare high (HEI) and soil test based recommended (REI) external input (water and fertilizer P) systems with traditional sub-irrigation (seepage), and REI with a potential water conservation subsurface drip irrigation system (REI-SD) with regard to groundwater P concentrations above and below the low conductivity spodic hor...
Laboratory experiments were conducted to determine the mineralization rates of 1,3-dichloropropen... more Laboratory experiments were conducted to determine the mineralization rates of 1,3-dichloropropene (1,3-D) in surface and subsurface soil samples collected from three sites in Florida with different histories of 1,3-D exposure. Mineralization rates of uniformly labeled (1)C-1,3-D in surface and subsurface samples collected from two of the three sites, one of which was treated with 1,3-D only once and the other which had not been treated with the chemical for 5 years, were similar to the corresponding samples collected from untreated plots, and the rates generally decreased with soil depth. Initial mineralization rates in surface and subsurface samples collected from the site that had repeatedly been treated with 1,3-D at least 6 of the past 12 years were more rapid than those in either the corresponding untreated samples or in samples collected from the two other sites. Not only were the initial mineralization rates in soil samples collected from this site greater, but also the disa...
ABSTRACT Phosphorus (P) fertilization in low P retention soils can result in P leaching to ground... more ABSTRACT Phosphorus (P) fertilization in low P retention soils can result in P leaching to ground water. This study evaluated the effect of P application rate on orthophosphate leaching (OP) and its relationship with plant P uptake. Floratam St. Augustinegrass (SA) (Stenotaphrum secundatum (Walt) Kuntze cultivar Floratam) and Empire Zoysiagrass (EZ) (Zoysia japonica cultivar Empire) were grown in an uncoated sand soil with very low extractable P and low P retention capacity. Phosphorus was applied every 4 weeks at a rate of 0, 0.14, 0.28, 0.56 and 1.12 g m-2. Each treatment was replicated four times. Phosphorus uptake, plant dry matter accumulation, and Mehlich I extractable P were determined biweekly during 120 days (May to August, 2008). In addition, large plastic lysimeters were used to collect leachates, and the amount of OP leached was measured weekly. A decrease (p-value < 0.05) in OP leached with increasing P application rate was observed in SA while OP leached in EZ plots increased with greater P application. Under the conditions of this study, a cumulative P application of 3.75 g P m-2 and 1.5 g P m-2 in SA and EZ, respectively, did not result in an increase in OP leached in comparison to the no P application treatment. Phosphorus uptake rate of SA across treatments and sampling dates was higher (p-value < 0.0001) than in EZ. Root biomass in SA and EZ was not different (p-value = 0.920); however, root length density in SA was greater than in EZ (p-value < 0.0005).
Vegetable production in Southwest Florida is dynamic and responsive to new technology, market tre... more Vegetable production in Southwest Florida is dynamic and responsive to new technology, market trends, consumer demands and social pressures. Area growers want to continue to produce in the area and they seek the latest technology and knowledge to help them produce our food efficiently. Environmental concerns demand low-input, efficient operations which ultimately save money and energy and protect the environment.
ABSTRACT: Land area used for citrus (Citrus sinensis L. Osbeck) production in Southwest Florida h... more ABSTRACT: Land area used for citrus (Citrus sinensis L. Osbeck) production in Southwest Florida has expanded. The location of this expansion is a concern of water use and environmental regulatory agencies. Citrus requires well-drained conditions for optimum growth, but the soils in the region are primarily poorly to very poorly drained with seasonal high water tables. Drainability is the major factor which determines soil suitability for citrus production. The objectives of this study were to use the DRAINMOD soil water management/drainage model to 1) simulate water table behavior for artificially-drained flatwoods, slough, and de-pressional soils, 2) determine differences in soil drainability using an index calculated by DRAINMOD, 3) categorize soils as to suitability for citrus production, and 4) evaluate the accuracy of the method. Mean SEW30 of depressional soils was higher (indicating lower drainability) than flatwoods or slough soils. Empirical water table data from citrus gro...
Citrus trees planted in alkaline soils typically show iron (Fe) deficiency chlorosis. Currently, ... more Citrus trees planted in alkaline soils typically show iron (Fe) deficiency chlorosis. Currently, Fe-EDDHA (ethylenediiminobis-2-hydroxyphenyl acetic acid) chelate is the most effective source of Fe for high pH soils. Iron humate (FeH), a by-product of the drinking water decolorization process, was compared with Fe-EDDHA for Fe deficiency correction on nonbearing `Ambersweet' orange and `Ruby Red' grapefruit Citrus paradisi Macf., and bearing `Hamlin' orange Citrus sinensis and `Flame' grapefruit trees, all on Swingle citrumelo rootstock, planted on high pH (>7.6) soils. Iron humate was applied under the tree canopy in spring at rates from 2 to 200 g Fe (nonbearing trees), or 22 to 352 g Fe (bearing trees) per tree per year. Application of FeH to nonbearing trees decreased twig dieback rating and increased flush growth, flush color rating, tree size, and leaf Fe concentration. Addition of urea or ammonium nitrate to FeH did not increase Fe availability. Iron amendm...
Blueberry plants fertilized at 3-week intervals with nitrogen (N) throughout the year and protect... more Blueberry plants fertilized at 3-week intervals with nitrogen (N) throughout the year and protected from freezing temperatures avoid dormancy and produce an off-season “winter” crop. Southwestern Florida offers a climate where this production system can be implemented without undue fear of freezes. `Sharpblue', `Gulfcoast', and `Warmabe' southern highbush blueberry cultivars have been planted at high density (10,000 plants/ha) to determine the feasibility of successfully establishing an evergreen production system for blueberry. Three rates of N fertilization (84, 168, and 252 kg·ha–1) and the use of peat or municipal solid waste (MSW) compost as soil amendments are being evaluated in this study. Initial data on plant growth indicate that, during the first 9 months of the planting, 168 kg N/ha will produce plants similar in height, but with significantly less volume, to those receiving 252 kg N/ha. MSW compost appears to be a beneficial soil amendment for blueberry estab...
... HUATING DOU,1* SHELLEY JONES, THOMAS OBREZA2 AND BOB ROUSE2 1Florida Department of Citrus Cit... more ... HUATING DOU,1* SHELLEY JONES, THOMAS OBREZA2 AND BOB ROUSE2 1Florida Department of Citrus Citrus Research and Education Center ... fertilization rate increases vitamin C in lemons, oranges, and grapefruit (Embleton and Jones, 1966; Reitz and Koo, 1960; Smith ...
Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetab... more Florida tomato growers generate about $600 million of annual farm gate sales. The Florida Vegetable and Agronomic Crop Water Quality/Quantity Best Management Practices Manual was adopted by rule in the Florida Administrative Code in 2006 and describes cultural practices available to tomato growers that have the potential to improve water quality. By definition, BMPs are specific cultural practices that are proven to optimize yield while minimizing pollution. BMPs must be technically feasible, economically viable, socially acceptable, and based on sound science. The BMP manual for vegetables endorses UF-IFAS recommendations, including those for fertilization and irrigation. Current statewide N fertilizer recommendations for tomato provide for a base rate of 224 kg/ha plus provisions for supplemental fertilizer applications 1) after a leaching rain, 2) under extended harvest season, and 3) when plant nutrient levels (leaf or petiole) fall below the sufficiency range. An on-farm projec...
Journal of the American Society for Horticultural Science
Growth and nitrogen (N) accumulation relationships based on tree size, rather than age, may provi... more Growth and nitrogen (N) accumulation relationships based on tree size, rather than age, may provide more generic information that could be used to improve sweet orange [Citrus sinensis (L.) Osbeck] N management. The objectives of this study were to determine how orange trees accumulate and distribute biomass and N as they grow, investigate yearly biomass and N changes in mature orange trees, determine rootstock effect on biomass and N distribution, and to develop simple mathematical models describing these relationships. Eighteen orange trees with canopy volumes ranging between 2 and 43 m3 were dissected into leaf, twig, branch, and root components, and the dry weight and N concentration of each were measured. The N content of each tree part was calculated, and biomass and N distribution throughout each tree were determined. The total dry biomass of large (mature) trees averaged 94 kg and contained 0.79 kg N. Biomass allocation was 13% in leaves, 7% in twigs, 50% in branches/trunk, ...
Resource soil scientists with the USDA Natural Resources Conservation Service have rated the soil... more Resource soil scientists with the USDA Natural Resources Conservation Service have rated the soils that are delineated by map units in the Ocala National Forest area; parts of Marion, Lake, and Putnam counties Soil Survey Report1 for their potential for leaching and runoff of pesticides. The rating criteria are given in a companion publication entitled "Soil Ratings for Selecting Pesticides
Leaching of phosphorus (P) from agricultural soils, especially those that are sandy, is adversely... more Leaching of phosphorus (P) from agricultural soils, especially those that are sandy, is adversely impacting P-limited ecosystems like Florida's Everglades. A more developed understanding of P and water management strategies and their effects on P leaching is needed to achieve reductions in subsurface P losses, especially from intensively managed dual cropping systems under plastic mulch in shallow water regions. We compared the effects of conservation P and water management strategies with traditional practices on P transport to groundwater. A 3-year experiment was conducted on hydrologically isolated plots with plastic-mulched successive cropping systems to compare high (HEI) and soil test based recommended (REI) external input (water and fertilizer P) systems with traditional sub-irrigation (seepage), and REI with a potential water conservation subsurface drip irrigation system (REI-SD) with regard to groundwater P concentrations above and below the low conductivity spodic hor...
Laboratory experiments were conducted to determine the mineralization rates of 1,3-dichloropropen... more Laboratory experiments were conducted to determine the mineralization rates of 1,3-dichloropropene (1,3-D) in surface and subsurface soil samples collected from three sites in Florida with different histories of 1,3-D exposure. Mineralization rates of uniformly labeled (1)C-1,3-D in surface and subsurface samples collected from two of the three sites, one of which was treated with 1,3-D only once and the other which had not been treated with the chemical for 5 years, were similar to the corresponding samples collected from untreated plots, and the rates generally decreased with soil depth. Initial mineralization rates in surface and subsurface samples collected from the site that had repeatedly been treated with 1,3-D at least 6 of the past 12 years were more rapid than those in either the corresponding untreated samples or in samples collected from the two other sites. Not only were the initial mineralization rates in soil samples collected from this site greater, but also the disa...
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