Agronomy and Curing, finding solutions

Evaporation: I am afraid there isn’t any this week, The Thirsty Ox got at the evaporation pan and I did not have time to get it refilled etc. However, my rain witchcraft still works. I decided to irrigate my October crop on Wednesday; it actually took me until Thursday morning to re-prime my pumps and, 20 minutes later, down came a very welcome 24mm of rain. So, I have, from 10th to 16th January:
?, ?, ?, ?-1, ?, ?-24, ?.

Those of us who visited Nick and Tim’s crop on Tuesday got a nasty wake up call. Despite all our knowledge and experience tobacco can still go seriously wrong on us, given the wrong conditions. Tim suspects his borehole water might be contributing to his problems and it is certainly worth testing. (Although I had had my borehole water ‘tested’ (by UNZA) I now suspect that there was something in that borehole water that affected my float beds several years ago, and caused me to give up on them.)

As a result of that visit, I re-did the calculation that I did several year’s ago, and for every 100mm of irrigation you apply to a field, you apply 10,000 (sq meters) x 0.1 (depth of applied water in meters) x 1000 (weight of a cubic meter of water, in kgs) = 1,000,000 kgs. So, if you apply 600mm of water containing 1ppm of Boron, that is equivalent of 6kg Boron per ha, or nearly 30kg/ha of Solubor. (In looking up the B content of Solubor I found a recommendation that irrigation water should only contain 0.02ppm Boron. So, if you are sending samples for testing, check that your lab can check to ppb – parts per billion!) Boron is pretty soluble and likely to be easily leached so it is unlikely to be the cause of Tim and Nick’s problem, and very little of Nick’s crop had been irrigated.

Thanks to Ian Taylor’s plant pulling, we saw that both crops showed no sign of growth below the original seedbed roots – all the root growth was horizontal feeder roots above the seedbed plug. It suggested some sort of “chemical pan” and I hope both Nick and Tim take some soil samples from that level, to find out what is preventing the roots from growing downwards. I feel both fields are crying out for trials – I would even give Liquid Lime a go. ANYTHING to try to find out what those crops need. Tobacco IS an amazing crop and, with the right corrective treatment, they could still pull a reasonable crop.

Two sources have told me (Chris Aston and Chris Cairns) that, to avoid K and Z, I should dry my leaf at no more than 45C. Easier said than done in a continuous curing system. I am packing my tunnel with less tobacco (so able to have a slower cure), and have shut down the air to about 30% of the capacity of the fan. I still need 70C inlet temperature (in order to dry the stems) but I hope that, with less air, the temperature will drop quickly to around the 45 level. In my new 9 barn chongololo I was planning to use one extra barn for longer cures and one for longer conditioning, but I have decided to use both extra days for curing and hoping that the slower cure will reduce the K and Z. I would love to know how other continuous system farmers deal with this problem. Just as Nick and Tim have to find out what is wrong with their soil I HAVE to find out how to cure this variety.

Finally, on a different subject. The Chinese Restaurant has asked me to inform you that they can now make their own Tofu. They will be looking for several hundred kgs of soybeans once you get to harvesting this year’s crop. I had their Tofu with cucumber which even I (a boarding school food ignoramus) enjoyed very much. If you like to use Tofu in your own cooking, I am sure they will prepare a tub for you. (They also had some imported Chinese mushrooms, but the flavor didn’t do it for me; nor did they bring me any unusual dreams.)




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