Archive | January 2016


Dear Geke,

Evaporation 24 to 31st January 4, 3, 3, 6, 5-4, 2-15, 2-9 We were heading to being the driest total to the end of January in the 65 years of records that I have, but that late rain means we are only the second driest. 2002/03 was worse, but had good February rain, so we ended up with a reasonable total. I don’t know if we will be so lucky this time as the consensus of my weather sites is that the rain will go away this week. The situation for power remains poor and the UK weather office has just issued a forecast for the next 5 years – POSSIBLY lower temperatures in 2017 (IF a La Nina forms) but more record temperatures in 2018-20. You may have heard that Peterhouse (my old school) had 500mm in 24hrs – I passed that on to a friend in the Lake District and she pointed out that Storm Desmond dumped 380mm in 24hrs and 760mm in 72 hours on Keswick. With wetter and steeper hills and more built up valleys, I am sure their 380mm did more damage than Peterhouse’s 500.

One way we can reduce the catastrophic effects of this extreme weather is to plant more trees. A tree I have been interested in for a long time is Millettia pinnata – from South East Asia – and it is now available in Zambia. Ben Warr has imported some improved grafted trees from India and is looking for farmers willing to plant them. The trees are a legume to fix nitrogen, the leaves can be browsed, they yield more oil per ha (under intense conditions, for biodiesel) than oil palm, the cake can be used (sparingly) for stockfeed or the nuts can be burned directly (as green coal). If you are interested in planting some (particularly in the triangles between center pivot circles) get in touch with Ben – in 6o years time (when they stop bearing enough nuts) our children can cut the trees for firewood.

The Troy Nicolle heat exchanger is up and running. It cost me $2,500 in steel plus some welding rods and labour. It isn’t perfect yet (needs a few modifications) but it burns firewood beautifully and is MUCH better at holding my temperatures than my old boiler radiator. If anyone wants that boiler and 6 1.4m x 1.4m radiators they are welcome to take them away. I think the boiler/radiators would still run a tunnel or chongololo adequately but (a) need the radiators installed differently from the way I had them and (b) a proper hot water pump – which I never had.

Best4now, Bruce


Rabies and capacitors

Dear Fiona,

Evaporation 17 to 23rd January 3-6, 3-1, 5, 5, 6, 5, 5 With evaporation figures like that we should all be looking carefully at our remaining dam water. My ‘budget’ starts from the 1st March, but there is a real possibility that our dams will be lower by then than they are now and I am fully expecting one of my dams to be dry by August.

I had to put my youngest dog down on Saturday night. She was half Australian Blue Healer half Jack Russell and was one of the sweetest dogs I have owned. But my three have been involved in two fights with rabid dogs since Christmas. After the second one I decided to re-vaccinate them all (they were due again in April). But I was not aware that the pup should have had a repeat vaccination 3 months after her first. It seems that she may therefore not have had sufficient protection. Although she never developed obvious symptoms, there was quite a bit of ‘smoking gun’ evidence and putting her down definitely seemed the wisest option. I have heard that there have been two human cases of rabies in Choma and Kalomo recently so please keep your dog and cat vaccinations up to date.

Still a lot of uncertainty over this Power Factor correction issue. There are three options: correct individual motors, install Variable Speed Drives, install a variable Capacitor Bank. Which one you choose depends on the situation but they ALL contain capacitors, which makes them ALL dangerous (you MUST discharge the capacitors before poking around there with a screwdriver) and ALL attractive to lightning. So, install good lightning arrestors at the same time – and remember that your arrestors are only as good as your earthing. I see that, of the original 8 earthing rods I installed 35 years ago, only 3 are still connected – the other 5 have had their wires stolen. Finally, remember that this PF equipment will also save some of your diesel cost when you are having to run your generator – which we will be having to do more and more as 2016 progresses.



Enjoy it while it lasts

Dear Estelle,

Evaporation from 10 to 16th January 5-1,7, 4, 5, 5-2, 4, 2-17 My historic average evaporation for January is 2.3mm a day, so we were still experiencing evaporation much higher than ‘normal’.

My title refers to electricity – not to rainfall. It seems we are no longer being subjected to the full 8 hours a day power cuts, yet the Zambezi flow is still well below average and we currently have 60 days generating capacity in Kariba (and 90 on the Kafue). Add to that the decision to delay the Power Factor penalty to April and keeping the tariff for domestic consumption at the old price and we seem to have done everything possible to make sure we run out of electricity as soon as possible. The website shows that (apart from Mwinilunga itself) the rest of the Zambezi catchment above Kariba is not exactly flush with moisture. Kafue the same. So, those of us who are lucky enough to have irrigation water (not me) are unlikely to have adequate power to irrigate with.

Some more good news (genuine, to go with last week’s news of a 100mkg shortfall in Brazilian tobacco): Chris Aston reports that his VFDrives have reduced his diesel consumption from about 24 litres an hour to about 16. He reports that learning how to use VFDs is not easy, but it is obviously a technology that we are going to have to get to grips with. Also in the paragraph on good news is the fact that (after 35 years – Duh) I think I have finally come up with a solution to water hammer in my irrigation pipes. It really needs a diagram (which I will try to prepare for next week) but it involves putting the pressure relief valve under water on the suction side. This enables it to be set at a much lower pressure (so that it releases the hammer quickly) but also it then doesn’t matter if it leaks slightly as it cannot suck air into the system. With water being so short we CANNOT afford leaking pipes any longer and managing water hammer should help reduce those leaks.

Finally on water; I did mention about 5 years ago (when I was last critically short of water) that it was important to calculate our profit per megaliter of water. Time to dust off and update those figures. As Chris Aston pointed out (at the time) it is important to include the evaporation losses. A simple look at how much we pump onto irrigated tobacco, might suggest that it gives a better return than wheat. But, by the time we have irrigated our tobacco our dams have lost a lot more through evaporation and wheat, using the water earlier, might actually have been the better option.




Some Good News

Dear Denise,

Evaporation 3rd to 9th January, 6-2, 9, 9, 9, 11, 5-6, 7-1, The average evaporation I have for January is about 2.5, so you can see we are way above normal. That 11 is even very rare in October.

But the good news is Brazil is expecting to be about 100m kg short (as is Zimbabwe, though they don’t know it yet). I suspect quite a bit of the Zimbabwean/Brazilian crop is also going to be severely droughted, so the price for our better styles should be firm.

I am still trying to find out the longer term forecast. I probably mentioned that a friend of Sally’s said we were locked into four El Nino’s in a row – but Ant Ford had heard that next year is forecast to be wetter. I certainly feel we should be prepared for the worst and use our water as carefully as possible. Those of you who are dependent on boreholes should start recording the water levels NOW – it might give you early warning of how well your boreholes are coping.

Finally, the reason this is late is because I didn’t have access to the Internet over the weekend. I think the server at Siachitema Mission (from whence I get my signal) wasn’t working as all my equipment worked fine in town. So the people in the Airtel container opposite Barclays gave me the number of their Mr. Daka 0978981027 – you might want to keep that number handy if you use Airtel in remote areas.

May it be a wet one,




All change

Dear Caroline,

Evaporation 27 Dec to 2 Jan 5-4, 5, 6, 6, 8, 9, 7, 6-2

I don’t know how many of you read about the North Pole which was 35 degrees warmer than normal on Wednesday 30th December. When I saw the article, I thought it must be a misprint in the headline; it must surely have been 3.5 degrees. But no, the article explained that, whereas the North Pole in mid-winter should be 30 degrees C below freezing, it was actually 5 degrees above. Add to that the fact that I stayed with Tony and Sue Orr over the weekend and they reported that, although the Zambezi HAS come up by half a meter, it is still about 3 meters down from ‘normal’. Finally my sons tell me that a friends of Sally’s tells her that El Nino is ‘locked in’ for four years. I am not sure how this friend (a meteorologist) knows this (and I am trying to find out from the Internet, what the scientists are thinking about further El Ninos) but I am certainly beginning to think that we are going to have to re-think the way we farm.

I think soybeans will probably no longer be a suitable crop for Choma, as El Nino seasons tend to be too short to fill the pods in April. I think we will be planting tobacco on the flat, at much lower populations, surrounded by mulch. Cassava might be a more drought resistant source of carbohydrate than maize. It is difficult to run experiments to find out the best solutions, because the conditions in 2016 may not be the same as the conditions in 2020. But, as a book written after the Kyoto Agreement states: we must adapt or die.

Best for 2016,