Fertility, Soil & Irrigation Management
In organic crop production, natural sources of fertility are used to provide crop nutrition. There are many sources available to organic producers including animal manures, incorporated legume cover crops, mined nutrients such as potassium, as well as commercially formulated blends of nutrients. The number of fertility products with guaranteed nutrient analysis has increased in recent years. These newer products take some of the guesswork out of calculating application rates and reduce the risk of under- or over-application of nutrients; nitrogen and phosphorus in particular.
Soil quality is an important consideration on organic farms. Although the definition of a “quality soil” varies by location, most researchers agree on what parameters should be included. Minimally, a quality soil is one that is chemically balanced, biologically active, and is structurally sound. Producers interested in assessing the quality of their soil should refer to the database of alternative soil testing labs listed below.
Many of the nutrients present in organic soil amendments must be transformed by soil microorganisms before they can be utilized by crops. Therefore, the soil environment must be suitable for these organisms to facilitate efficient nutrient cycling. Tillage, excessive moisture or drought and lack of carbon-based amendments are detrimental to soil carbon stores and deplete the energy reservoir needed by microorganisms. A suitable soil environment is also important to support a variety of predators and parasites of insect, diseases and nematode pests that dwell in the soil.
Crop nutrient management programs in organic systems are ultimately site-specific. There is no “cookbook” approach to designing an organic fertility program. Producers are advised to follow University of Florida fertilizer recommendations. One caveat to this is that organic fertility sources release nitrogen slowly. Because of this, many producers preplant incorporate the full nitrogen rate at the beginning of the season for crops that mature in 60-70 days.
Maintaining good records of irrigation, soil amendments, timing, rate and method of application of inputs and crop response will provide a history to which management programs can be fine-tuned. Producers should not underestimate the value of a good crop and soil nutrient monitoring program. Experience is the best method to determine what works best to produce optimum yields while maintaining soil and water quality.
For more information about nutrient management in organic crop production, please see the resources listed here or contact your localUF-IFAS County Extension office.
- Management Overview
- How are Organic Farming Inputs Evaluated?
- Fertilization of Sweet Corn, Celery, Romaine, Escarole, Endive, and Radish on Organic Soils in Florida
- Irrigation for Small Organic and Conventional Farms
- Producing Garden Vegetables with Organic Soil Amendments
- Reduction of the Impact of Fertilization and Irrigation On Processes in the Nitrogen Cycle in Vegetable Fields with BMPs
- Compost and Animal Manures
- Cage Layer Manure: An important resource for land use
- Guidelines for Purchase and Application of Poultry Manure for Organic Crop Production
- Large Scale Utilization and Composting of Yard Waste
- Diagnostic Resources
- UF/IFAS Extension Soil Testing Laboratory
- Organic Soil Amendments
- Composting on Organic farms, North Carolina State University
- Organic and Conventional Management Effects on Biologically Active Soil Organic Matter Pools--University of California
- Organic Soil Amendments for Sustainable Agriculture, University of Hawaii
- Small-Scale Vericomposting, University of Hawaii
- Soil Fertility Management for Organic Crops, University of California
- Soil Fertility on Organic Farms, North Carolina State University
- Soil Management
- Fertigation Applications and Costs in Organic Vegetables - Washington State University
- Crop Rotation on Organic Farms: A Planning Manual - SARE
- Building Soils for Better Crops, 2nd Edition - SARE
- Conservation Tillage on Organic Farms, North Carolina State University
- Organic Fertilizer Calculator-Oregon State University Small Farms
- Soil Management and Soil Quality for Organic Crops, University of California
- Soil Quality Considerations for Organic Farmers, North Carolina State University
- USDA Natural Resources Conservation Service (NRCS)
- Databases and Resource Guides
- NCAT's List of Alternative Soil Testing Laboratories
- Sources of Organic Fertilizers and Amendments--ATTRA
- Return to Organic Production