Nutrient Management Research Database
General Information
Research Title
Link to File
Research Specifications
Authors
Summary/Abstract from Original Source
- Tissue analysis can have merit for organic production
- Conventional P and K sufficiency standards should apply to organics, but some modification necessary for N status
- Developing your own database across years most useful
Research Highlights
Design and Methods
This presentation includes the following sections:
- Differences in soil test interpretation for organic as compared to conventional
- How does organic management change soil fertility
- The theory of nutrient balance
- What can you infer from a soil test about soil nitrogen status?
- Tissue analysis in organic production
- Petiole and whole leaf sampling
Results
1. Differences in soil test interpretation for organic as compared to conventional
Same interpretation for pH, extractable P, extractable K, cation saturation, and micronutrients. However organic matter and N status require adjustments for organic systems.
2. How does organic management change soil fertility
Organically managed soils often have higher Olsen-P and exchangeable K levels.
3. Nutrient Balance
Crops can actually handle a wide range of nutrient ratios, and the economics of attempting to achieve nutrient balance often make it unrealistic.
4. Inferring from soil tests
Soil organic matter is related to total soil N and N mineralization potential. Nitrate-N values need to be interpreted in light of when during the season the samples were taken.
5. Tissue analysis
Nutrient sufficiency/deficiency can usually be predicted with soil test results, so tissue testing is secondary. Organic crops take up the same forms of N and process it identically to conventionally grown crops.
6. Petiole and whole leaf sampling
Tentative petiole nitrate-N levels of 5,000 ppm at early flowering and 2,000 at full bloom are useful for determining sufficiency. Whole leaf sampling is useful for organic production, with a level of 4% at first flower and 3.5% at full bloom indicative of sufficiency/deficiency.