 |
| How do I soil sample |
| for SCN? |
| Once a field is infested with SCN, soil samples do not need to be collected each year. Soil samples from these fields should be collected before SCN-susceptible varieties are grown again or once every 3 years if resistant varieties are grown in a rotation. |
|
| While soil samples for SCN may be collected at any time, the ideal time to sample is as close to soybean harvest as possible. SCN numbers tend to be highest when the plants are almost mature to shortly after harvest. | |
| Sampling near harvest allows sufficient time for the nematode laboratory to process the sample and provides you with information and enough time for variety selection or choosing alternative crops for the next year. | |
| Soil samples
collected for soil fertility analysis can be split into: |
|
 |
1for fertility |
|
1 for SCN analysis |
| However, remember to place the nematode sample in a plastic bag, not in a paper soil test bag, and keep the sample out of direct sunlight! | |
| Large fields
may be subdivided into sections and a single composite sample from
the different sections submitted for analysis. If the crop row is
identifiable, place the soil probe within 2 inches of the row when
collecting the soil core. Placement of the soil probe is not important
for samples collected from cultivated fields or fields where soybeans were drilled. The importance of getting a representative soil sample of the area under consideration (whole field, section of field, area where plants show symptoms of crop injury) cannot be overemphasized. |
|
| How
to deal with hot spots Soil samples should be collected from the area between the damaged plants and the "healthy" plants. Do not collect the sample from the center of the affected area because these plants usually have severely stunted root systems that cannot support SCN. Thus, the sample may show that SCN numbers are low when in fact there are high numbers present in the areas where plants are “healthy.” |
|
| How
to sample fields that have never been checked for SCN The first time a field is checked for SCN, sample areas where SCN is likely to establish first. This includes near a field entrance, along fence lines, areas that have been flooded, areas where weed control isn't quite as good, areas of high soil pH (greater than 7) or areas where the yield seemed to be a little low last season. |
|
| Nematode diagnostic laboratories usually have special forms to be submitted with soil samples. Even if such a form is not available when you sample, you should provide the following information: | |
| • your
name, address, and phone number • the county in which the field is located • the date when the field was sampled • the number of acres represented by the sample • crop history (previous 2 to 4 years) • the name or number of the field • pesticide applications for current and previous years. |
|
| Procedure for collecting soil samples: |
|||
| 1 | Use a cylindrical soil probe to collect soil samples | ||
| View Photo 1 | |||
| 2 | Collect 10 to 20 soil cores in a zig-zag pattern across the entire area to be sampled. | ||
| View Photo 2 | |||
| 3 | Collect soil cores from areas of similar soil texture and cropping history. If different soil textures occur in the same field, sample them separately. | ||
| View Photo 3 | |||
| 4 | Collect to a depth of 6 to 8 inches. | ||
| View Photo 4 | |||
| 5 | Bulk the cores in a container (bucket) and mix. | ||
| View Photo 5 | |||
| 6 | Place approximately 1 pint of mixed soil in a plastic bag and label the outside of the bag with an indelible marker. | ||
| View Photo 6 | |||
| 7 | Store the sample away from sunlight in a cool area until it is shipped to the laboratory. | ||
| View Photo 7 | |||
| Note: If you are sampling on a 2.4 or 2.5-acre grid, you can collect 2 extra cores from every 8 or 9 grid cells for SCN analysis. | |||