Teaching Organic Farming and Gardening

Soil Tests and Amendments

Unit 1.11 | 37

F. The challenges of accurate nitrogen budgeting in organic farming systems:
Factors influencing the release of nitrogen from organic matter

1. 99% of the N in most soil is tied up in soil organic matter (SOM), the release of which is
   dependent on soil conditions such as temperature, aeration, and moisture, which are in turn
   dependent on weather/air temperature, tillage, rainfall, and irrigation practices


2. The quality and quantity of existing soil organic matter and organic matter inputs. The C:N
   ratio, the presence of lignins and tannins, soil biological activity, and the placement of organic
   matter amendments in the soil profile all influence the mineralization rate of organic matter.
   The accuracy of the mineralization rates listed in the Nitrogen Budgeting Worksheet must be
   understood in this light and represent only a rough estimate.


3. Discuss long-term budgeting and nutrient management. The use of this nitrogen budgeting
   exercise, combined with annual soil analysis report data, can give a grower an indication of
   either the accumulation or depletion of soil nutrients. With such information, the grower
   may make adjustments to the system in order to balance nutrient inputs with outputs,
   
   thereby both assuring nutrient availability and avoiding the problems associated with excess
   soil nutrients.

Instructor’s Demonstration 3 Outline