I'm in the San Joaquin valley. Our soil tends to be alkaline. Well, at the elementary school, we have a Life Lab (hands on science w/garden plots). I have a few teachers who want to grow potatoes. My gardening book says that pototoes need acidic soil but not to use lime. How else do I get the soil to move to the acidic side? We're about 7.5 to
8.0.Thanks Nicole
Plant in plenty of compost/manure. Potatoes are generally not fussy about soil types, they're one of the easiest things to grow, always recommended for the beginner and for children. Further to an earlier thread, I would recommend chitting them before planting, i.e put them in boxes in the light so they start to sprout. Kids will especially like this part of the process.
Isn't the San Joaquin valley in California? I don't know anything about frost conditions there, but they should be planted out when there's not too much danger of frost. Once they're showing, if a frost is forecast, bury the tips with an inch or two of soil, and that will protect them.
Incidentally, I think it's great that you're getting the kids interested from an early age, I'm not sure that many schools here in UK do much in that department.
Steve
Manure like Steve suggests is probably one of the best ways so long as it is thoroughly decomposed. In any case, you wouldn't use lime to make the soil more acid. Lime would make it even more basic than you are already. For quick drops in pH, aluminum sulfate is usually recommended. Powdered sulfur should drop it over the long run along with the added compost. Manure itself would help buffer the pH and not really acidify the soil but maybe help neutralize it on top of the other benefits supplied by the organic material including moisture retention. I hope the kids get a good crop. Gary
Yes, lime is to make soil alkaline. I think you should consider other crops because the potatoes will be miserable. Changing the pH on the fly is easier said than done and you may ruin the whole plot for a while by applying too much sulfate. Onion, chard, beet, and just about any brassica (broccoli, cabbage, collard, kale) will grow well in alkaline conditions. Kale will give you something edible in six weeks if the weather cooperates.
You still have to add a little organic matter and fertilizer to make them happy. If you apply manure, it will provide both. In your conditions, one of the best organic amendments are wood chips, that will lower pH (they are acid), give you good mulch and good humus. You have to add some nitrogen fertilizer (a single bag will be good for the whole school garden). On the other hand, wood chips are OK only if you plant little plants or big seeds like squash. You cannot seed directly things like kale (many small seeds) on wood chips until they have decomposed.
Make a Google search and you should find a few more crops that will be happy above 7.0. I am guessing, for example, that lettuce, garlic, beans, peas and tomatoes will manage with that soil. Various squashes and cukes might be a little less happy but still manage. Potatoes are really the only big no-no.
I agree with all the comments and advice you give, except the use of aluminium sulfate to lower pH. Aluminium salts have been linked with health problems, in particular, increasing the development of Alzheimers disease. My suggestion for lowering pH (beyond the excellent ones of compost and powdered sulfur) is to add citric acid, which you might be able to get in pharmacies or even ethnic food shops, or pine needles are very acidic if I recall correctly. In terms of ease of finding and cost, sulfur might be the best, but it is apparently easy to add too much and end with very acidic soil.
I agree with you that aluminum has been implicated in the progression (possible cause?) of Alzheimers disease but there is no proof or indication that the aluminum comes from salts in the soil absorbed by plants. How many people cook in aluminum cookware including high temp frying pans? How many take megadoses of Maalox (magnesium aluminum hydroxide) for upset stomach?
8% of the earth's crust is alum>> Manure like Steve suggests is probably one of the best ways so long as it
Have you looked at the potato growing information at the Santa Clara County Master Gardeners website? They have a good way of growing potatoes in a half-barrel where you can use packaged soil and not have to worry about these issues. Also, potatoes can be prone to certain plant diseases that can make the soil unsuitable for other crops later (such as strawberries). Using a half-barrel should avoid that problem.
I suggest using their pile method--a half barrel with a wire cage over the top that you keep heaping straw upon to create a higher and higher stack throughout the growing season, that becomes rife with potatoes. The wire cage keeps the straw from falling off--anyway the details are at their website.
the plots are individual so no worries about ruining everything. I'll plant
4 x 20 of pototoes. Hopefully, the weather will cooperate.It's too late to grow any of the cool season vegetables here. In fact, I've had broccoli bolt already. I'm familiar with most veggies and flowers for this area. I'm a master gardener which is offered thru UC Davis. Taught life science and gardening for 4 years. the pototoes are a special request so I'm doing it for 2 of the teachers. For some bizarre reason, the current teacher knows nothing about horticulture.... makes no sense but oh well Thanks again
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