Seed Bank Composition

Samples are taken from each of the 5 sampling stations in each treatment replicate in the Main Cropping System Experiment at the LTER Main Site (7 trts * 6 reps; in 1994 the forested sites were added to the sampling regime). The sampling location is 1 m to the southwest of the sampling flag; 10 cores (1 inch diameter) to a depth of 15 cm are taken from a quadrat area of 25*25 cm. Cores are uniformly distributed in the quadrat.

Each core is divided into 2 depth intervals: 0-5 cm and 5-15 cm. The 10 cores from each quadrat are composited and placed in separately labeled paper bags. Each bag is labeled with the trt/rep/sample location and depth. The 2 bags from each sample location are placed in a ziplock bag. Samples are stored in the dark at 5 degrees C until elutriated following methods in Gross and Renner (1989). Storing the samples at cool temperatures should prevent germination and facilitate elutriation as the samples will not form " peds" as a consequence of drying.

Microplots:

A single location is sampled from the center of each of the 4 microplots (+/- fertilizer; +/- herbicide) at 30" row spacing in all reps of trts 1 and 2 (Conventional and No-till). In the no fertilizer treatments, the samples are taken from the middle of the first 6 rows to avoid areas that were accidentally fertilized in 1989. All other samples are taken form the center of the 12 row microplot.

Comments:

Treatment 8 was not sampled. Treatment 1 (conventional till) will be resampled after it is plowed to determine how tillage effects the distribution and viability of seeds in the seed bank. If these samples are taken more than 2 weeks after the main site sampling was done, the no-till plots will be resampled f or a comparison of time effects.

References:

Gross, K.L. and K.A. Renner. 1989. A new method for estimating seed numbers in the soil. Weed Science 37:836-839.