GIVE

Dr. Kelly Morgan

Extension: Soil and Water Science

The objectives of the extension program are to use science-based information to educate Florida growers about improved soil fertility and water management methods through publications and presentations of research data and demonstrations of BMPs so they will be able to sustain yields while protecting water quality.

Specific goals of the extension program encompassing citrus, vegetables, and sugarcane are the teaching and demonstration of:

  1. Nutrient-related BMPs
  2. Improved irrigation management and grower decision aids.

Situation
Situation
Competition of an increasing population for land and water resources has increased concerns for the environmental health of the watersheds and water bodies throughout Florida. Therefore, implementation of BMPs designed to maintain or improve water quality is essential to the sustainability of Florida’s citrus, vegetable and sugarcane industries. The implementation of these BMPs will greatly impact the local environment in a positive way. However, BMPs may negatively impact crop production if growers are not sufficiently educated on how the BMPs should be implemented. Thus, information on irrigation and nutrient use efficiency is needed by growers to support implementation of BMPs that will reduce agricultural impacts on the environment and at the same time reduce production costs for commercially-viable yields.

In addition to environmental pressure, low commodity prices and high production costs are requiring citrus, vegetable and sugarcane growers to closely examine all production inputs. Fertilizer inputs are typically 30 to 35% of non-labor farm costs depending on commodity. Due to leaching of N from sandy soils, N uptake efficiency in Florida is relatively low (i.e. 40 to 60%) depending on the type of fertilizer, application rate, timing, and placement. Improving N uptake efficiency is also a priority of state environmental regulators. Implementation of practices that keep N in the crop root zone and improve N uptake efficiency would increase growers profits through greater efficiency of fertilizer inputs.

Another environmental issue in Florida is P loading to surface waters. Reduction in P loading has become an important goal of selected BMPs. As with N, any improvement in P use efficiency would also benefit the growers financially and help protect the environment by reducing the leaching and runoff of surplus fertilizer nutrients to Florida's limited and environmentally vulnerable water resources. To reduce the impact of fertilizer applications on the environment, fertilizer and irrigation practices must be evaluated. Application rate and timing of soluble fertilizers, controlled release fertilizers, and irrigation scheduling (provided by soil moisture sensors and models) are technologies that growers must implement to adhere to BMPs and/or improve overall soil nutrient management.

The presence of two bacterial diseases (i.e. canker and Huanglongbing, or greening), has created an interest in higher performing citrus grove designs and cultural systems. These improved citrus production systems are based on higher tree densities and drip fertigation to promote greater growth in the early years after planting. Increased tree planting density and size will improve early productivity and increase returns to offset potential losses from these diseases. A system of intensive irrigation and nutrient management (i.e. open hydroponics, a.k.a. Advanced Production Systems) should accomplish these goals and allow complete grove replacement as a result of tree loss from disease with time on a more profitable basis. Drip irrigation and fertilizer injection is currently used by a small percentage of vegetable growers and not used at all by sugarcane growers. Using drip fertigation practices similar to those being developed for citrus will conserve water and can potentially improve nutrient use efficiency compared with current seepage irrigation practices.

Weather and climate data are important for many management decisions that impact water and nutrient efficiency. Data from the Florida Automated Weather Network (FAWN) have been under-utilized due to the lack of integrated tools available to growers. The number, reliability and accuracy of tools and models available to growers as decision aids must be improved with time if greater strides in improving nutrient and water use efficiency are to be made. These decision aids will have to be robust, easily integrated into current management structures, and user friendly. Collection of weather data and other information for these decision aids must be seamless to the growers and nearly effortless.

Nutrient Related BMPs
Nutrient Related BMPs

The objective of the crop nutrient extension program is to promote the implementation of water quality-related BMPs by providing a framework of knowledge that allows growers to understand the benefits of BMPs to their economic status as well as the benefits to their surrounding environment. Using the logic model outlined in Table 1, stakeholders, overall needs, resources and products were identified. Gains in grower knowledge are built through the dissemination of pertinent research results on management techniques. To this end educational material and classroom instruction has been developed for growers throughout the state. Information has been instilled to citrus, vegetable, and sugarcane growers through demonstration projects, participation in grower meetings and workshops, and publication of BMP manuals, bulletins, trade magazine articles and EDIS publications. Thus, the goals of the crop nutrition extension program for citrus, vegetable and sugarcane growers are:

  • Improve agricultural production efficiency and prevent water resource impairment by increasing grower knowledge and understanding of plant nutrient management and nutrient use efficiency, and
  • Shepherd the implementation of nutrient-related BMPs by Florida growers.
Improved Irrigation Management and Grower Decision Aids
Improved Irrigation Management and Grower Decision Aids

The irrigation management extension program has focus on improved crop nutrient accumulation and improved water use efficiency. Improved irrigation management can improve nutrient accumulation and reduce leaching of fertilizer nutrients to the environment. Low volume irrigation practices (e.g. microsprinkler and drip) conserve both water and energy through increased water use efficiency compared with seepage irrigation. The use of seepage irrigation (i.e. the elevation of the water table by seepage of water from perimeter and field ditches) requires large volumes of water and may lead to nutrient leaching. Currently, nearly all citrus utilizes microsprinkler irrigation, while most vegetable growers and all sugarcane production utilize seepage irrigation. Ongoing vegetable seepage and drip management research will lead to increased adoption of this irrigation practice in the future and greater extension efforts. The current extension program in irrigation management emphasizes practices to further improve water use efficiency in the citrus industry.

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Professor, Soil and Water Science