Hi @Ecompost, great info for a new farmer, I'm really enjoying the reading.
1 question...."Ca in the right ratio with Mg is critical" What would that ratio be? I've seen others mention 5-1, and read 3-1 somewhere else too.
Thanks for the feedback, in answer, hold on to your hat.... since it rather depends on your growing medium buddy. Are you in soil and if yes what base??
Here is my gen for that....Soil users should really avoid the marketing of ideal ratios of cal mag in bottles, since it (Cal/Mag) seldom limits plant growth so long as pH is maintained.
If you are growing in soil, I personally dont recommend calcium inputs in order to meet any such suggested ratio.
The calcium to magnesium ratio is merely a statement of the relative proportions of available calcium and magnesium in the soil. It does not give any information about the actual levels of these elements. For example, one soil may have exchangeable calcium and magnesium levels of 250 and 50 lb/a, respectively,while another soil may have 2,500 and 500 lb/a of exchangeable calcium and magnesium. Both have identical Ca:Mg ratios. However, in the first soil mentioned, both nutrients would be marginally low, and in the second soil, they would be present in adequate amounts.
The matter is exchangeable calcium really, when I say ratio I should be more clear.
Ca:Mg ratios can be misleading in other ways. For example, a low Ca:Mg ratio reflects one of two possible situations: (1) a soil with low exchangeable calcium and normal magnesium, or (2) a soil with normal exchangeable calcium and high magnesium. It is impossible to distinguish between these two cases using only a ratio. On the other hand, a high Ca:Mg ratio means there is either (A) too little magnesium relative to calcium, or (B) calcium is excessive relative to magnesium.
The idea that a proper Ca:Mg balance is necessary for good plant growth was conceived by New Jersey researchers in 1901: They recommended a total Ca:Mg ratio of about 5:4.However, soil scientists soon recognized that total element analysis is difficult and not necessarily a good measure of the amount of these nutes available. Measuring the amounts of exchangeable elements is the best way to know what might be available to a plant for example, but this is media dependent largely based around the total amount of clays
For example, the New Jersey study determined that the “ideal alfalfa soil”should have 65% of the cation exchange sites occupied by calcium, 10% by magnesium, 5% by potassium and 20% by hydrogen. However, further research has shown that these percentages can vary considerably without affecting crop yields. For example, the percent of exchangeable sites occupied by calcium
can range from 55 to 75% without yield reduction, as long as magnesium and potassium are present in adequate amounts.
Sorry this isnt more definite but I do hope it helps explain the matter. Based on the ratio you are presenting, I would anticipate a high loam content, fairly silt based soil. Those in more sandy soils need to pay more attention to the K rates and a ratio for
CalMag in sandy media would be about 1.5:1. If you are in soil-less, I see no reason 1.5:1 or 1:1 would not work well. Again soil less media requires attention is paid to the ratio relative to K+ and H+ so pH is more critical here. ranges from 6.0 to about 6.4 will work in soil less to maintain exchangeable elements