Progress 02/15/01 to 09/30/06
Outputs
During the past 5 years, under the Technical Service Training Program on Nutrient Management and Land Treatment Practices, a total of 213 people have been trained by December 2006. As a result the program awarded a total of 110 CEU credit hours in soil and nutrient management. The Florida Phosphorus Index was developed and implemented that is being used throughout the state to assess the environmental risk from applied P sources. Through a regional project with USDA-IFAFS funding a study on phosphorus management determined the relative solubility of phosphorus from inorganically fertilized, manure amended and native phosphatic soils in Florida, thus providing valuable tools for environmental risk assessment. A regional comparison of the indices among 12 contiguous southern states as well as Puerto Rico through a separate project, were made and the results were published in an effort to assess the strengths and weaknesses of the tool. It was successfully determined that
sorghum sudan was efficient in recovering residual soil nitrogen in rotation with potato crop produced in northeast Florida. A 5-year project studying vegetable crop production under standard lower nutrient recommendations was successfully demonstrated on a commercial farm as viable compared to higher rates of applications by the grower in the Suwannee basin, thus aiding in formulation of Best Management Practices. Studies to determine laboratory and field procedures for determining phosphorus concentrations in soils and solution using ICP and color spectrometry and reflectoquant methods were completed. An inter-agency effort led to the development of Interim Forage Best Management Practices for successful hay production in Florida. A study compared the effectiveness of standard Mehlich-1 and Mehlich-3 extractant for major Florida soils. A preliminary study on rapid analyses techniques for soil and plant tissue analyses was successfully completed paving way for a 4-year state-wide
study. In order to better understand the extent of subsurface lateral flow of water and solute, a study was initiated in 2005 for agricultural production under seepage irrigation. A 3-year study determining the rate of nitrogen mineralization from applied poultry litter has been completed in the Suwannee basin on melon production under plastic mulch. Best results were obtained when half of the required nitrogen was supplied from poultry litter. In order to determine the critical level phosphorus requirements of grazed Bahiagrass pastures in south Florida, a multi-year field study was initiated with the premise that tissue test may be an appropriate alternative to unreliable soil test. It was successfully determined that optimum parsley production on sandy soils of Florida was possible when soluble sources of nitrogen were combined with composted municipal solid waste at a 50% rate. Two Ph.D. and one M.S. students have graduated while one Ph.D. and two Master's students are currently
enrolled pursuing the overall objectives of this project. A post-doctoral associate and an educational coordinator are also being trained to develop and implement the programs.
Impacts
A total of 830,300 acres was covered by the nutrient management plans during the past 5 years in Florida, including 65,907 acres for 2006. An estimated reduction of 79.9 million lbs of N and 12.3 million lbs of P was possible based on the soil testing programs from 2003 in a four county area. Sorghum sudan has been successfully introduced as a viable catch crop for residual nitrogen, impacting an estimated 16,000 ha of area under potato production in Florida. A savings of $3.2 million has been realized by reduced rate of nitrogen application by 40 lbs/acre to potatoes in Florida. Interim Nitrogen BMP rate of 80 lb/A/cutting of hay has impacted over 100,000 acres of hay production in Florida thus significantly minimizing the applied nitrogen. Three Ph.D. and three M.S. students, a post-doctoral associate and an educational coordinator have participated in this project. During this period, a total of 12 refereed articles (5 more under review), 7 articles in proceedings,
92 extension fact sheets, 2 regional bulletins, 3 web sites, 26 CD-Roms were published. A total of 135 hours of continuing education credits were delivered on various topics. Over 450 individuals were trained through targeted programs such as including workshops, conferences, training sessions, and CCA programs. Over 65,000 soil, water and tissue samples from producers and homeowners were analyzed and educational information on comprehensive nutrient management was distributed resulting in appropriate fertilizer applications and minimized loss of nutrients into the environment.
Publications
- Osmond, D. M. Cabrera, S. Feagley, G. Hardee, C. Mitchell, P. Moore, R. Mylavarapu, J. Oldham, J. Stevens, W. Thom, F. Walker, and H. Zhang. 2006. Comparing Southern Phosphorus Indices. Journal of Soil & Water Conservation. 61:325-337.
- Munoz, F., Mylavarapu, S. Hutchinson, C. M. Portier, K.M. 2006. Root Distribution under Seepage-Irrigated Potatoes in Northeast Florida. American Journal of Potato Research. 83:453-462.
- Mylavarapu, R.S. and S. Curry. 2006. Technical Service Provider Training Activities- A Florida Practicum. Proceedings Southern Plant Nutrient Management Conference, Olive Branch, Mississippi, Oct 3-4, p73-76.
- Mylavarapu, R.S., Kidder, G., and C.G. Chambliss. 2006. UF/IFAS Standardized Fertilization Recommendations for Agronomic Crops. SL129, Soil & Water Science, Cooperative Extension Service, IFAS. p9.
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Progress 10/01/04 to 09/30/05
Outputs
Minimizing the environmental impact while sustaining and improving economic yields through optimized nutrient management practices for both agronomic and horticultural crop production systems is the primary focus of this research project. Four grant-funded projects and three state funded projects were current during this year aimed at achieving the over-all objectives of this CRIS project. Second year of a new project to demonstrate the benefits of potato-cover crop research on three different fields on a commercial farm has been completed successfully. A new 4-year grant funded project was initiated funded by Florida Department of Agriculture aimed at developing rapid analysis techniques for soil and leaf tissue samples from representative sites and crops of Florida as a potential substitute for laboratory analyses. A soil archive of 2000 samples has been set up, along with a database contains all scanned and analytical properties. During the second phase of the
study, plant tissue samples and additional soil samples will be collected, scanned, analyzed for nutrient properties in the laboratory. The data will be statistically analyzed to obtain best correlations between soil properties and spectral reflectances. Another 2-year grant study funded by St. Johns Water Management District in Florida, was initiated during Spring 2005 characterizing lateral movement of subsurface water under seepage irrigated fields using Br tracer. The area is characterized by an extensive and thick hardpan underlying the surface at about 0.4 meters thus preventing vertical movement of water, which is taken advantage of for irrigating agricultural crops grown on raised beds by controlling water table levels. A total of 96 wells were installed and water samples were collected for a 6 week period on a daily interval for the first 7 days and weekly interval the remaining 5 weeks following tracer injection. Bromide concentrations in the water samples were determined to
understand the extent of lateral flow. This study will be continued for another 3 seasons. A total of 159 participants have successfully completed the Technical Service Provider training program in eight sessions being offered through a grant from the Florida Department of Agriculture and Consumer Services and a total of 40 CNMPs are being developed in the sate as a results of this program. Another grant funded study on mineralization of poultry manure in melon production under plastic mulch was initiated. Poultry manure was applied at different rates in combination with soluble fertilizer nitrogen to determine the feasibility of organic amendments for successful melon production in north Florida region. Periodic sampling of soils from the PVC cylinders buried under the plastic throughout the crop production period from treated and control plots was done and the samples were analyzed for nitrate, ammonium, and TKN values. Poultry litter in a 50:50 combination with ammonium nitrate to
provide for the recommended N dose for melons has proven to be the most effective method to supply all the crop needs. The study is being continued for another two years.
Impacts
A total of 159 participants from state agencies and private industry have received training on Nutrient Management through the Technical Service Provider Training in Florida. A total of 216,077 acres of agricultural land has been covered by Nutrient Management Plans during the FY2004 and a total of 40 CNMPs are being developed in the state at this time. A total of 38 International CEU credits have been awarded to CCAs during the two training sessions organized this year. Assuming a 50% availability rate, application of poultry litter to supply the recommended dose of N at a 50:50 ratio with ammonium nitrate for successful production of melons under plastic mulch proved to be the most effective way in maximizing the efficiency of applied N and minimizing leaching. There was very little nutrient value leftover after the manure application for the first crop of a two-crop system. A 2000 soil sample archive has been established and statistical estimates for using the NIR
spectral reflectances have been developed for certain soil physical and chemical properties in the first phase of the project. Preliminary data analysis has shown that the subsurface water movement in seepage irrigated vegetable plots was extremely slow and the study will be repeated in both wet and dry seasons to further confirm the extent of water movement. Inclusion of sorghum as a summer cover crop in the crop rotation sequence with spring potato production in north Florida proved to be the most effective method to recover residual nitrogen in the soil after potato harvest.
Publications
- Mylavarapu, R.S.nd V.L. Quisenberry. 2005. Spatial Distribution of Drainage from Uniform Soil Columns. Soil Science, 170:38-46.
- Mylavarapu, R.S., J.P.Smith and F. Munoz. 2005. Soil and Nutrient Management Influences on Collards Nutrition. HortTechnology. 15(1) 7-12.
- Munoz, F., R.S. Mylavarapu and C.M. Hutchinson. 2005. Environmentally Responsible Potato Production Systems- A Review. Journal of Plant Nutrition, 28:1287-1309.
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Progress 10/01/03 to 09/30/04
Outputs
Minimizing the environmental impact while sustaining and improving economic yields through optimized nutrient management practices for both agronomic and horticultural crop production systems is the primary focus of this research project. Eight grant-funded projects and two state funded projects were current during this year aimed at achieving the over-all objectives of this CRIS project. Two Ph.D. students have completed research during this year that involved modeling nitrate movement in poultry litter amended soils for predicting nitrate risk to groundwater, and studying the influence of cover crop-potato rotation on nitrate concentration in the shallow water table in the lower St. Johns River data with supporting data collected on characterizing potato roots for N-uptake efficiency. This trial suggests that crop rotations with sorghum in late fall can be a promising alternative for scavenging nitrogen in soils during the post-potato seasons. First year of a new
project to demonstrate the benefits of potato-cover crop research on three different fields on a commercial farm has been completed successfully. In a new collaborative project, nutrient concentrations in run-off water and tail-water recovery ponds have been evaluated at the commercial nursery production sites in New Jersey. A M.S. degree student has successfully completed research during the final year of the IFAFS project, working on P solubilities of inorganically fertilized, manure-amended and phosphatic soils of Florida. Final phase of soil sampling for this is being completed at this time. A total of 120 participants have successfully completed the Technical Service Provider training program in five sessions being offered through a grant from the Florida Department of Agriculture and Consumer Services. A state funded project on comparing P concentrations based on ICP analysis and a color method has been completed that resulted in a presentation at an international conference.
Additionally two other state projects have been completed -one on a quick-test for soil P using a Reflectoquant technique as a tool for initial assessment of soil P levels and the other on phosphorus mineralization in subtropical soils amended with poultry litter. The results from the P mineralization study will be presented at an international conference by the Ph.D. student working on the project.
Impacts
Results from these research projects helped impart training to over 120 agency and industry personnel in the development of nutrient management plans for agricultural operations in the state. A total 148,500 acres of agricultural land was covered by Nutrient Management Plans during this period. Twenty five county extension agents have been trained in Quick field test for P, and over 100 CCAs have been trained through three training sessions on basic soil fertility, soil and water movement, P-Index and N & P management techniques for minimizing impacts on water quality. Mnaual for BMPs both in row crops and in vegetable crops have been developed based on the resreach work and will be implemented through Florida Department of Agriculture. Over 11,000 soil sampling reports have been supplied to Florida growers with information on appropriate nutrient management that will directly help minimize impacts on both surface and groundwater quality in the state of Florida. The
Florida P-Index has been appropriately modified to reflect findings from these projects and 67 circulars for computing P-Index for each of the 67 counties in Florida have been revised accordingly.
Publications
- Zinati, G.M., Y. Li, H.H. Bryan, R. Mylavarapu and M. Codallo. 2004. Distribution and fractionation of phosphorus, cadmium, nickel, and lead in calcareous soils amended with composts. J. Environ. Sci. Health. B39(1):209-223.
- Hutchinson, C.M., R.S. Mylavarapu. 2003. Evaluation of nitrogen best management practices for potato production in northeast Florida. Acta Hort. 619:279-283.
- Mylavarapu, R.S., H. Savoy and C.R. Crozier. 2004. Soils and Soil Fertility. In Vegetable Crop Guidelines for the Southeastern U.S. Ed. D.C. Sanders, North Carolina Vegetable Growers Association, NC, pp9.
- Sikora, F.J., R.S. Mylavarapu, D. Hardy, R. Tucker, R. Franklin. 2004. Conversion Equations for Soil Test Extractants: Mehlich-1 and Mehlich-3. Southern Regional Fact Sheet, SERA-IEG-6. http://soils.rs.uky.edu/M3vsM1.htm
- Mylavarapu, R.S. 2004. Irrigation and Household Water Test and Interpretation. 2004. SL 219, Soil & Water Science, Cooperative Extension Service, IFAS, pp4.
- Munoz, F, R.S. Mylavarapu and C.M. Hutchinson. 2004. Nitrogen Management in Potatoes through Crop Rotation in Northeast Florida. Proc. Southern Plant Nutrient Management Conference, Memphis, Oct 5-6.
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Progress 10/01/02 to 10/01/03
Outputs
Minimizing the environmental impact while sustaining and improving economic yields through optimized nutrient management practices for both agronomic and horticultural crop production systems is the primary focus of this research project. Six grant-funded projects and three state funded projects were current during this year aimed at achieving the over-all objectives of this CRIS project. A Ph.D. student has completed research on modeling nitrate movement in soils using Scenarios technique that will help in risk assessment. Nitrate levels have been monitored through field soil and groundwater well sampling and extensive soil characterization for moisture retention characteristics sampling as influenced by cropping, nutrient and manure management decisions at poultry and a dairy operation in the karst Suwannee basin as a part of a major BMP implementation study. Influence of cover crop-potato rotation on water quality in the lower St. Johns River is the main focus of
another study being conducted under a grant from Florida Department of Agriculture's Nitrate Bill program. A graduate student hired on this project has completed collecting data for two years on potato and cover crop rotations. As a part of the student research, data on potato roots has been collected and is being characterized based on applied N levels for N uptake efficiency. This trial suggests that crop rotations with legumes and non-legumes can be promising alternatives for scavenging nitrogen in soils during the post-potato seasons. A new project to demonstrate the benefits of this research on commercial farms has been initiated. At the end of the 3-year collaborative project between University of Puerto Rico and University of Florida, maximum P sorption capacities for all six soils have been determined which resulted in 2 published abstracts and a refereed journal publication. A Ph.D. student is working on analytical methodologies and P management on subtropical soils. At the
end of the third year of the IFAFS project, the graduate student has graduated after completing research on comparison of P solubilities of inorganically fertilized, manure-amended and phosphatic soils of Florida. An instant P test is also being calibrated to obtain a quick reference to extractable soil P levels. On the project developing real-time field sensors for soil P, the graduate student has completed research on spectral analyses on soil and water samples in the Okeechobee basin. A state funded project on comparing P concentrations from the ICP analysis and a color method has been initiated and two new projects have been initiated. One of the state projects aims to develop a quick-test for soil P using a Reflectoquant technique as a tool for initial assessment of soil P levels. This project has resulted in two presentations and two abstracts at the national and international meetings. The other project deals with determining the feasibility of resin extraction of soil P as an
alternative to traditional chemical soil test extractions.
Impacts
Results from these research projects helped impart training to over 100 agency and industry personnel in the development of nutrient management plans for agricultural operations in the state. Over 100 county extension faculty have been trained in N & P management techniques for minimizing impacts on water quality. Interim BMPs have been developed and implemented for Forage crops in the state. Over 12,000 soil sampling reports have been supplied to Florida growers with information on appropriate nutrient management that will directly help minimize impacts on both surface and groundwater quality in the state of Florida. The Florida P-Index is being appropriately modified to reflect findings from these projects.
Publications
- Mylavarapu, R.S. 2003. Role of an Extension Soil Testing Program in the Development of Best Management Practices: A Florida Case Study. Journal of Extension, 45(4) pp9.
- Lee, W.D., J.F. Sanchez*, R.S. Mylavarapu and Choi. 2003. Evaluation of Soil Nutrient Levels Using Spectroscopy. Transactions of ASAE, 46(5) 1443-1453.
- Sotomayor, D.R., G.A. Martinez, O. Santana, R.S. Mylavarapu and J. L. Guzman.2003. Phosphorus soil tests for environmental assessment in sub-tropical soils. Commun. Soil Sci. Plant Anal. (in press).
- Olczyk, T., Y.C. Li, E. Simonne and R. S. Mylavarapu. 2003. Reduced phosphorus fertilization effects on yield and quality of sweet corn grown on a calcareous soil. Proc. Fla. State Hort. Soc.
- Sanchez, J.F. and R.S. Mylavarapu. 2003. Cacao crop in Ecuador: soils and production. Soil and Crop Science Society of Florida Proceedings 62, 92p.
- Sanchez, J.F. and R.S. Mylavarapu. 2002. Leach-m performance in sandy soil of North Florida. Annual Meetings Abstracts, ASA, SSSA and CSSA. Sanchez, J.F. and R.S. Mylavarapu. 2002. Impact of different organic manure fertilization strategies on soil water retention characteristics. Annual Meetings Abstracts, ASA, SSSA and CSSA, Indianapolis, Nov 11-14.
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Progress 10/01/01 to 10/01/02
Outputs
Minimizing the environmental impact through optimized nutrient management practices in both agronomic and horticultural crop production systems is the central focus of this research project. Currently there are six grant-funded and one state funded projects that are either on-going or being initiated to achieve the project's objectives. Nitrate levels are being monitored through both field and lab sampling as influenced by cropping, nutrient and manure management decisions in two phases of the project at a crop farm and at a poultry and a dairy operation in the karst Suwannee basin. As a part of the graduate student's research on this project, an understanding of nitrate movement through karst soils and the resulting effect on water quality will be developed through modeling. Influence of cover crop-potato rotation on water quality in lower St. Johns River is the main focus of another study being conducted under a grant from Florida Department of Agriculture's Nitrate
Bill program. Second year data from this trial suggests that crop rotations with legumes and non-legumes can be promising alternatives for scavenging nitrogen in soils during the post-potato seasons. A student has been hired on this project to look at potato root systems and N uptake efficiency. A new project to demonstrate the benefits of this research on commercial farms has been funded. During the second year of the collaborative project between University of Puerto Rico and University of Florida, maximum P sorption capacities for all six soils have been determined and the results were published as an abstract and were presented at national meetings. A comparison of specific P-Index for each state will be made to validate a field approach for the methods. A Ph.D. student has joined this project and will be working on analytical methodologies and P management on subtropical soils. During the second year of the IFAFS project, soil samples have been collected to 2-meter depth from
four dairy sites in the basin and are being analyzed for extractable and sorptive capacities of P. An instant P test is also being calibrated to obtain a quick reference to extractable soil P levels. A graduate student hired on this project is developing the relationships among Mehlich-1, -3 and water soluble phosphorus in inorganically fertilized, manure amended and phosphatic soils of the basin. A state project has been initiated to study the impact of reduced phosphorus fertilizer additions on tomato production in marl soils of Miami-Dade county. A new project was initiated aiming at developing real-time field sensors for soil P in the Okeechobee basin. A state funded project on comparing P concentrations from the ICP analysis and a color method has been initiated.
Impacts
Interim BMPs have been developed from the preliminary results of the potato project and the Suwannee project on crop, dairy and poultry operations in the Suwannee basin. Results from other projects will also be used to develop optimum nutrient, water and manure management practices for commercial agricultural operations that will directly help minimize impacts on both surface and groundwater quality in the state of Florida.
Publications
- Hutchinson, C., R.S. Mylavarapu, and F. Munoz. 2002. Utilization of legumes in crop rotation programs to reduce nitrate leaching from potato production into the lower St. Johns River watershed. Proceedings of Southern Soil Fertility Conference, Memphis, Oct 8-9, p78-82.
- Sanchez, J.F. and R.S. Mylavarapu. 2002. Leach-M performance in sandy soils of North Florida. Annual Meetings Abstracts, ASA, SSSA and CSSA, Indianapolis, November 10-14. Sanchez, J.F. and R.S. Mylavarapu. 2002. Impact of different organic manure fertilization strategies on soil water retention characteristics. Annual Meetings Abstracts, ASA, SSSA and CSSA, Indianapolis, November 10-14.
- Mylavarapu, R.S., D. Sotomayor, E.D. Kennelley and J.A. Nguyen. 2002. Evaluation of Environmental Impacts through Phosphorus Sorption Capacities of Soils. Annual Meetings Abstracts, ASA, SSSA and CSSA,Indianapolis, November 10-14.
- Zinati, G. M., H. H. Bryan, R. McSorley and R. S. Mylavarapu. 2002. Sustainable cropping systems for tomato production in south Florida. Acta Hort.
- Munoz, F. and R.S. Mylavarapu 2002. Effect of Soil and Nutrient Management Practices on Collards Performance. Annual Meetings Abstracts, ASA, SSSA and CSSA,Indianapolis, November 10-14.
- Herrera, D.A. and R.S. Mylavarapu. 2002. Relationship between Water Soluble and Mehlich1 Phosphorus in Manure Attended and Inorganically Fertilized Soils. Annual Meetings Abstracts, ASA, SSSA and CSSA, Indianapolis, Nov 11-14.
- Hutchinson, C. M., R.S. Mylavarapu and F. Munoz. 2002. Evaluation of BMPs for potato production in Northeast Florida. Annual Meetings Abstracts, ASA, SSSA and CSSA, Indianapolis, November 10-14.
- Hutchinson, C.M. and R.S. Mylavarapu. 2002. Evaluation of nitrogen best management practices for potato production in northeast Florida. American Journal of Potato Research (in press).
- Hutchinson, C.M. and R.S. Mylavarapu. 2002. Utilization of legumes in rotation with potato to reduce nitrate leaching in Florida watersheds. HortScience (in press). Hutchinson, C.M. and R.S. Mylavarapu. 2002. Utilization of legumes in crop rotation programs to reduce nitrate leaching from potato production into the upper St. Johns River watershed, report on the first year results. Hastings Research and Education Center, University of Florida, HAS2001-7. 7 pp.
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Progress 10/01/00 to 10/01/01
Outputs
Minimizing the environmental impact through optimized nutrient management practices in both agronomic and horticultural crop production systems is the central focus of this research project. Towards this goal, four grant funded and four state funded projects were undertaken. Nitrate levels are being monitored through both field and lab sampling as influenced by cropping, nutrient and manure management decisions in two phases of the project at a crop farm and at a poultry and a dairy operation in the karst Suwannee basin. As a part of the graduate student's research on this project, an understanding of nitrate movement through karst soils and the resulting effect on water quality will be developed through modeling. Influence of cover crop-potato rotation on water quality in lower St. Johns River is the main focus of another study being conducted under a grant from Florida Department of Agriculture's Nitrate Bill program. First year data from this trial suggests that at
high nitrogen rates, nitrate can be under- utilized by the potato crop which may be lead to losses by leaching. Lysimeters have been established to obtain nitrate concentrations leaving the rootzone, particularly to document inefficiencies of subsurface seepage irrigation. This project will be continued for a total of 3 years. A collaborative project between University of Puerto Rico and University of Florida entitled `Towards Development of Environmental Soil Phosphorus Critical Levels in Agricultural Soils of Puerto Rico' was funded by USDA-CBAG. This study aims to identify a method for environmental impact assessment of P for predominant soil types in Puerto Rico and Florida. P sorption studies for all six soils included in the study and a comparison of different P extractants for Puerto Rican soils have been completed and the results presented at national/international meetings. Studies will be continued to establish sorption maxima for the soils and a comparison of specific
P-Index for each state will be made to validate a field approach for the methods. Under a new 4-year project funded through USDA-IFAFS, soils in the Suwannee basin extending from south Georgia to north central Florida will be characterized for leachability of P. Soil samples have been collected to 2-meter depth from four dairy sites in the basin and are being analyzed for extractable and sorptive capacities of P. An instant P test is also being calibrated to obtain a quick reference to extractable soil P levels. A graduate student hired is developing some of the analytical methods and will also be developing educational modules from the project results. A high correlation between Mehlich-1 and -3 was obtained from analyses of 519 acid soil samples collected from throughout Florida under a state project. In another state project, Loss on Ignition method for soil organic matter was found to be suitable for most Florida soils. Methods for low-level P analyses critical for sensitive
ecosystems in Florida are being studied as a part of another project. A state project has been initiated to study the impact of reduced phosphorus fertilizer additions on potato production in marl soils of Miami-Dade county.
Impacts
Results will be used to develop optimum nutrient, water and manure management practices for commercial and homeowner agricultural sites that will directly help minimize impacts on both surface and groundwater quality in the state of Florida. Development of best management practices based on the findings will secure optimum economic and environmental sustainability.
Publications
- E. D. Kennelley and R.S. Mylavarapu. 2002. Low-level Phosphorus Analysis in the Presence of Silicate. Proceedings of International Soil & Plant Analysis Council Conference, July, 2001, Edmonton, Canada. Communication in Soil Science & Plant Analysis. (Accepted).
- Mylavarapu, R.S. and C. M. Hutchinson. 2001. Utilization of legumes in crop rotation programs to reduce nitrate leaching from potato production into the lower St. Johns River watershed. Proceedings of Southern Soil Fertility Conference, Memphis, Oct 9-10, p44-48.
- Li, Y., S. O'Hair, R. Mylavarapu, T. Olczyk and M. Lamberts. 2000. Demonstration of phosphorus fertilizer management for potato grown in a calcareous soil. Proc. Fla. State Hort. Soc. 113:237-239.
- Mylavarapu, R.S., J.F. Sanchez, J.H Nguyen, and J. M. Bartos. 2002. Evaluation of Mehlich-1 and Mehlich-3 Extraction Procedures for Plant Nutrients in Acid Mineral Soils of Florida. Communication in Soil Science & Plant Analysis. (In press).
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