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| IF the seed is firmed sufficiently into moist soil at the bottom of the furrow, then closing by covering the seed with loose material is preferrable over closing by packing. The discontinuity of moisture films between the loose soil and undisturbed soil actually slows drying at seed depth. Lyle Carter did a huge amount of work studying this. Read his summary quote here: http://exapta.com/knowledge/library.html (and the full text if you can stand the download time). This effect is real, and I've seen it many times. Seeds with loose soil over the furrow actually emerge sooner than those with packed soil above them -- *if* the seeds were sufficiently firmed into the bottom of the trench. Doesn't matter if we have high temps and drying winds after planting, so long as the firming of the seed in the bottom of the furrow was adequate.
As for the design and action of the various closing wheels discussed in this thread, there are substantial differences. Some of that is described here: http://exapta.com/products/thompson.html and the Thompson wheel provides the best combination of sidewall breakage with very little risk of disrupting seed placement (in our opinion, and in the opinion of many customers who have tried a number of different brands/designs).
Hope this helps. | |
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slots splitting back open
