The water chestnut experiment was completed today. Overall, I would say that the experiment to see if water chestnuts could be grown in southern Oregon was a success.
However, the total yield was very small (~2 lbs) from the 16 initial plants (~1 lb). Many of corms are still immature, small and have not formed a “skin”, so I don’t think they will hold over the winter for replanting. We will eat those and save the largest corms for next year.
I can think of several ways to potentially improve the yield in future test plots:
1) plant earlier in the year – sprouting the corms in early May may have been too late; starting them in late March may provide the extra 45 days or so that I think would make a big difference.
2) deeper soil and water – the several inches of topsoil that I placed in the artificial bog was not enough based on my observation of the root mass. I would like to increase the soil depth to at least 6 inches of muck with 6 inches of water above it. This would provide a more stable environment during our dry summer season.
3) increase the fertility – the topsoil tests for trace amounts of N/P/K. Adding a bushel or so of well rotted/composted manure to the soil a couple weeks after planting would likely allow the water chestnuts to have even more robust growth above and below the water line. I am impressed they grew as vigorously as they did with very little added fertility.