I'm embarrassed to ask this question. Many of my vegetables require higher amounts of potassium. Most of the fertilizers indicate a NPK. So, is one of these numbers potassium usable in potash & phosphate? If not, what do I need to add to increase potassium.
dun 1 kirk, please never be embarrassed when needing answers to any gardening question, that's why Dave's garden site was set up as people of ALL types of abilities re gardening had at times became stuck with project, plant names, diseases or anything gardening or even just to admire someone's pictures of their plants.
DoGooder has answered your question and all I can add is, when growing Veg, it's a great idea at start of every season take a soil test in various areas where you grow veg, these are not costly, a few dollars from garden store, these results will tell you what you need to add, maybe lime, more Potash or whatever and it saves you overdosing with stuff already plentiful for the veg you want to grow in that area. Also Dun1 Kirk try never grow the same veg in the same bed, that way you avoid any build up diseases that ALL veg can have, over time growing the same plants in the same bed MAY cause the soil to become useless due to soil born pests / diseases building up. IT might never happen BUT, better preventing than trying to cure.
Peas and beans add nutrients to soil when you cut the dead / finished plants down leave the roots in the soil as they have little nodules of nutrients on the roots, dig them in.
other Veg like the cabbage family remove nutrients, Potatoes help to clean up the soil as they grow, you rake or pile the soil up over the green tops, this helps keep weeds away and therefore no weed seeds able to grow the onion Family helps keep away the greenfly, carrot flies etc, so I always grow the onion / garlic beside the carrots as the smell masks the sweet aroma that wafts from the lovely green carrot tops, that smell attracts the carrot fly.
Hope this helps give you ideas for help or, prevention and you have a wonderful gardening season, ask any questions you want and someone will get back to you, remember the question you need answers to are probably the same ones some other new gardener has been worrying about too so it's helping each other here.
Don't forget Dunkirk, maybe when you were at school, you never thought Chemistry would be a subject you were likely to need, My memory block is Algebra and dare I say Geometry is a thing I never new the sense of it BUT, all these things came back to bit you on the bum when later on you need answers instantly LOL. Glad you got the answers and perhaps lots of other new gardeners are enlightened too.
have a good gardening season.
I tested my soil this year and found a ph of 7 everywhere also very low on phosphorous but very high in potassium. Some of this soil has never been planted (yes, nitrogen low...hello manure). Why do I have such high potassium levels? I'm in zone 5 with slightly clay soil...is it that? Just wondering.
Gracesmom, clay soils tends to have a high cation exchange capacity: the clay particles are negatively charged, so they can grab and hold onto positively charged ions (cations). The usable form of potassium (and calcium, magnesium and many other plant nutrients) are cations, so clay soils are typically high in these.
The some of the usable forms of nitrogen (nitrate and nitrite ions) and phosphorous (phosphate ions) are negatively charged ions, so the clay particles do not hold onto them. They need organic matter to stay in the soil. Without organic matter, N and P tend to leach from soil.