This is the last regularly scheduled ginseng crop update for the 2012 growing season. Updates will be provided as required over the fall and winter, and begin on a weekly basis in spring 2013.
Ginseng continues to senesce in all ages of gardens. With the recent heavy rainfall and more in the forecast, this may be your first opportunity this year to examine fields for drainage issues. Water pooling in the field for longer than a day can cause problems with root rot. This should be corrected before the winter, when standing water is more likely.
The fall is a good time to have your soil analyzed for nutrients in fields to be prepared for seeding next year. Phosphorus and potassium levels remain relatively constant over the winter, and therefore, fall levels provide a good indicator of the need for supplemental fertilizer the following year. Soil nitrogen tests are not recommended in the fall, because the available form of nitrogen (nitrate) is highly mobile in the soil and will leach out of the soil over the winter, and most nitrogen is tied up in organic matter and will not be available to the crop.
Both pH and buffer pH can also be analyzed in the fall, which will indicate the need for liming next season. A pH of 6.5 is ideal for ginseng. Values lower than 6.0 should be raised by adding lime. The amount of lime required to bring soil pH to 6.5 can be calculated using the buffer pH. For more information consult Table 2-3 in OMAFRA Publication 610 – Production Recommendations for Ginseng. Soil pH values higher than 7.5 could predispose ginseng roots to disease. Lowering pH from these values is not practical.
Magnesium is the other nutrient normally included in a basic soil fertility test. Magnesium is only an issue if it falls below 20 ppm. Dolomitic lime is the least expensive method to increase magnesium levels in the soil.
Information on interpreting soil tests is available in Publication 610.