Soil and Water Research

Soil erosion

NEW: Consumer Lawn Care and Fertilizer Use in the United States 2014

Contact: Hayk Khachatryan

Summary: The results of the U.S. consumer lawn care and fertilizer study provides insights into residential landscaping practices. The information within this survey serves to assist turf and landscape professionals that are involved with lawn/landscape care. Results also provide a snapshot of consumers' fertilizer use and perceptions. Professionals involved in the fertilizer industry (development, production, packaging/marketing, regulation, etc.) could also benefit from gaining insights on current consumer behavior towards fertilizers.

Needs, Uses, Perceptions, and Attitudes towards Weather and Climate Forecast Information by Water Resource Managers in the Southeastern United States

Principal Investigator – Chris Martinez
Funded by NOAA
This project provides an assessment of the current uses of, needs for, perceptions of, and attitudes towards weather and climate information, forecasts, and derived products by water resource managers in the states of Alabama, Florida, and Georgia.  The project also identifies gaps in diagnostic and forecast information currently available.


Evaluating Compost and Lime Effects on Soil Organic Matter, Soil Microbial Communities and the Control of Fusarium Wilt in Commercial Tomatoes Grown in Florida's Sandy Soils

Principal Investigator: Dr. Amy Shober

Situation and Objectives: Florida vegetable production commonly occurs on highly sandy soils with low native fertility and water holding capacity. Fertility is managed using inorganic fertilizers and lime, while soil pests have traditionally been controlled by methyl bromide fumigation. There is a need to evaluate non-chemical methods for pest control in order to move toward a more sustainable production system. We determined the effect of compost and lime on soil organic matter, soil fertility, soil microbes, and the incidence and severity of soilborne diseases.

Research methods: Composted municipal yard waste and dolomite were applied at a commercial tomato farm. The soil is periodically evaluated for organic matter and fertility. Populations of aerobic bacteria and fungi are measured, and Fusarium oxysporum is assessed to estimate the soil treatment effect on pathogenic and non-pathogenic populations.

Potential Impacts: This research is part of a long-term effort to identify cost-effective cultural practices that reduce the need for chemical pesticides and fertilizers by improving soil conditions that enhance soil microbial populations and activity. Such practices are sustainable, environmentally benign and have practical applications for conventional and organic crop production in Florida and other southeastern states.

Evaluating composted cow manure (“cowpeat”) as a landscape amendment during the establishment of new residential landscapes

Principal Investigator: Dr. Amy Shober

The study is designed to look at the impact of compost amendments and/or tillage on soil compaction, landscape plant establishment and quality, and potential for nutrient losses in runoff and leachate. This study also includes an investigation of nutrient leaching from greenhouse plant production using cowpeat as a potting media substrate.


Evaluating Compost and Tillage Effects on New Landscape Establishment and Nutrient Losses

Principal Investigator: Dr. Amy Shober

Situation and Objectives: When land is urbanized, grading and filling operations typically disturb and/or degrade the natural soil profile. The new “urban” soil is usually not conducive to healthy plant root growth, leading to establishment and aesthetic quality problems. We determined if compost addition and shallow tillage or aeration can improve soil properties, provide a better environment for root growth, and decrease nutrient loss from new residential landscapes.

Research methods: We created a typical "urban" soil by applying 10 cm of non-compacted fill material over the top of compacted soil. Soil tillage, soil aeration, and/or compost additions were applied to determine treatment effects soil quality, plant establishment, and the potential nutrient loss.

Key findings: Compost was effective in improving soil quality and it helped improve the establishment rate and quality of turfgrass and ornamental landscape plants. Losses of N and P in the first year following addition of compost were much lower than loads associated with agriculture, even with high rates of N fertilizer.

Outputs and Impacts

  • Information from this study was used to prepare six EDIS publications and several extension presentations related to soil compaction and organic amendments. Results of this study have also been submitted for publication in a refereed scientific journal.
  • Results of this research are helping guide the development of a "Water Efficient Landscapes" ordinance in Sarasota County, FL.

Hydrologic and biogeochemical modeling of cattle pastures in the Lake Okeechobee watershed

Principal Investigator: Chris Martinez, Agricultural and Biological Engineering

This project involves modeling the cycling of nutrients in pastures and in-pasture isolated wetlands and the effects of hydrologic regime on nutrient export to Lake Okeechobee.

Linking Terrestrial Nutrients to Red Tide Incidences in the Tampa Bay: A Preliminary Investigation

Principal investigator: Gurpal Toor
Other investigators: Amy Shober, Geoff Denny, Chris Martinez, Sabine Grunwald, Soil and Water Science Department

Faculty members of the Center for Landscape Conservation and Ecology have received a Research Innovation Fund grant of nearly $50,000 to investigate potential links between nutrient runoff and red tide, the toxic algae bloom, in Tampa Bay.

The goal of the study is to provide information that will help develop solutions to manage Tampa Bay’s red tide problems, by exploring the relationship between nutrient distribution in the landscape and stream water quality parameters. The research team hopes to answer the question “What is the impact of rapid urbanization on soil and water quality in a coastal watershed already subject to red tide outbreaks?”

The investigating team will use remote sensing and geographic information system (GIS) tools to develop relationships between nutrients stored in different areas of landscape, such as residential, commercial, agriculture, and forest areas, and nutrients flowing in selected segments of the Alafia River. The area targeted in this exploratory study is the North Prong Drainage Basin of the Alafia River watershed. Land use in the Alafia River watershed is predominantly urban (thirty-eight percent), followed by agricultural (thirty-three percent) and conservation land (seventeen percent).

Red tide has become increasingly common throughout Florida’s coastal waters, including Tampa Bay. Several studies have linked population growth and the associated increase in nutrient runoff with an increase in the frequency and extent of algal blooms throughout the world.

As Florida’s population continues to rise, land is being converted from traditional agricultural and other rural uses to residential and commercial developments at an alarming rate. This land use conversion adversely affects the physical, chemical, and biological properties of soils, reducing the ability of soil to act as a natural buffer able to remove nutrients from runoff waters.

At the same time, the increase in pavement and other impervious surfaces that comes with urbanization means that a great amount of runoff is created. And this runoff can rapidly transport nutrients from land to water bodies. The resulting increased nutrient transport may lead to red tide events that last longer and can occur more frequently, which may threaten recreational uses of coastal waters and severely affect Florida’s important tourism industry.

Nitrogen Fertilizer Requirements of Ornamental Landscape Plants Growing in the Landscape

Principal Investigator: Dr. Amy Shober

Situation and Objectives: Emphasis on landscape Best Management Practices has created a demand for increasingly sophisticated fertilizer recommendations. Trees and shrubs may have different fertilization requirements compared with perennials, annuals, vines and groundcovers. The objective of this research was to verify the accuracy of the Florida Green Industries BMP N fertilizer recommendations across a wide range of landscape plants.

Research methods: Warm season annuals, cold season annuals, perennials, ground covers, vines and woody ornamental plants are being evaluated under five N fertilizer treatments (0, 2, 4, 6, and 12 lbs N 1000 ft²). Plants are being evaluated to determine the N fertilizer requirement for acceptable aesthetic quality when grown in subsoil fill material (common in new residential landscapes).

Key findings: Preliminary results suggest that the N requirements of ornamental plants fall within the current UF/IFAS recommendations for most landscape plants, but some species of annuals may require up to twice the recommended N rate.

Outputs and Impacts

  • The findings of this research for warm season annuals have been published in the Southern Nursery Association Research Conference proceedings.
  • Results of this project will be used to update UF/IFAS Environmental Soil Testing Laboratory and Florida-Friendly Landscaping™ Program recommendations for N fertilization of ornamental landscape plants.
  • Results will be used to screen additional ornamental plants for classification into N fertilizer categories (e.g., high, medium, low), which will allow zoning of landscape plants to reduce overall N fertilizer load to mixed landscapes.
  • Pending further horticultural evaluation, high N users (e.g., Vinca) may be removed from the Florida-Friendly plant list.

Soil Amendments for Mitigation of Compacted Soils

Principal Investigator: Michael Dukes

Compaction of soils commonly occurs during construction by heavy equipment. This results in reduced porosity and infiltration rates which lead to increased runoff. To determine the potential of two soil amendments (compost and fly ash) to mitigate compaction, 21 lysimeters were filled with each two soils (Orangeburg Sandy Loam and Arredondo Sand) for a total of 42 lysimeters. The soils were compacted to levels representative of observed compaction levels as a result of construction activity in North Central Florida. Runoff volumes and rates were monitored from both natural and simulated rainfall events. Amendment treatments (amendments: null, compost, fly ash; depths: 0, 15 and 30 cm) were then applied to the lysimeters. Runoff volumes and rates are recorded. In addition, runoff and leachate water samples were collected for constituent analysis to determine potential water quality impacts. As a precursor, a column study analyzing leachate from various for ratios of soil and amendment was conducted to determine potential runoff and leachate analytes for the lysimeter study. This research will evaluate the potential for these amendments to mitigate compacted soils in Florida.

A Tool for Slow-Rate Land Application System Storage Determination

Principal Investigator: Chris Martinez, Agricultural and Biological Engineering
Other investigators: Bin Gao, Agricultural and Biological Engineering

The purpose of this project is to develop a tool for the permitting and design of slow-rate reclaimed water land application systems in the state of Florida. The tool will determine off-line wet-weather storage requirements and will provide an estimation of annual nitrate loading to groundwater.

The tool will contain a database of precipitation and reference evapotranspiration for the state of Florida that will be used for water balance calculations to determine the storage required for a ten-year recurrence interval as required by Florida law. According to Florida law the tool must use a minimum of 20 years of data to estimate the ten-year recurrence interval. The availability of ground-based solar radiation measurements in the state is relatively sparse and generally does not meet this minimum requirement.

To provide reference evapotranspiration estimates for each weather station in the database, methods that require temperature only will be used. These temperature-based calculations will be calibrated to reference evapotranspiration estimates provided by the United States Geological Survey (for the period 1995-2004) using solar radiation obtained from Geostationary Operational Environmental Satellites (GOES) to correct bias/error in the temperature-only estimates.

Use of Seasonal Climate Forecasts to Reduce Risk in Regional Water Supply Management

Principal Investigator: Wendy Graham, Water Institute
Other investigators: Chris Martinez; Jim Jones, Agricultural and Biological Engineering

This project will develop a methodology for incorporating seasonal climate forecasts into water supply management for the Tampa Bay region. Rainfall and temperature variability profoundly affect water demand fluctuations and supply availability. In support of effective water resource management and efficient groundwater/surface water source rotation, Tampa Bay Water must develop more robust climate forecasts and simulation techniques. This study will characterize the value, uncertainties, and risks associated with using seasonal to annual probabilistic climate forecasts for water management decisions within Tampa Bay Water’s jurisdiction.

Use of Short- and Medium Range Weather Forecasts in Regional Public Water Supply Management

Principal Investigator: Chris Martinez, Agricultural and Biological Engineering
Other investigators: James Jones, Greg Kiker, Agricultural and Biological Engineering. Wendy Graham, Mark Newman, Water Institute.

This project will evaluate 1–2 week retrospective precipitation forecasts ("reforecasts") produced by the Climate Diagnostic Center of the National Oceanic and Atmospheric Administration. "Reforecasts" are sets of historical forecasts that allow us to know and quantify the error of the forecasts compared to historical observations. Quantification of the error allows for bias-correction of future forecasts to improve their accuracy. This study will evaluate the usability of these 1–2 week reforecasts in generating forecasts of water demand, streamflow, and groundwater levels in operational decision making by Tampa Bay Water. A comparative decision/risk analysis using these operational forecasts and longer term (monthly to annual) climate forecasts will be implemented by evaluating alternative scenarios and multi-criteria decision analysis to determine the value, both economic and environmental, and reliability of using these forecasts in making decisions.