When it comes to field grown (as opposed to container grown) vegetable gardening, I consider limestone a more important soil amendment than manure.
There are a few things I need to preface in this post. A little couple of definitions to clarify my terminology and a little chemistry for a frame of reference. Acids are chemicals that can donate a proton, frequently bind to metals and can neutralize bases. They have a pH of less than 7 (on a scale from 0-14). A base receives a proton or can donate a pair of protons and can neutralize acids and has a pH of greater than 7. A salt is the result of a acid-base neutralization and are always soluble in water. They have two parts one is an anion, one is a cation. They are separable when they are in a non-neutral pH range and then can react with other ions or can oxidize or reduce other molecules. Fertilizers are salts.
I live in New England (a specific part of Northeast USA). Our soil is very rocky and and acid rich for the lion's share of the region. We have a granite bedrock for the most part. This is unlike most of Europe and other regions of N and S America where many of our vegetable plants are native. Europe has mostly a limestone bedrock that buffers the soil pH. A soil of 6 is a good compromise for the majority of our veggies. Our native plants have developed adaptations to mitigate the affects of acidic soil. I have one example that might put things in perspective. Turf grasses are just about all native to Europe and love limestone rich soil so a foolish landscaper will lime the soil to no end with the old legend that you cannot over lime a lawn. The foolish landscaper will also apply the maximum fertilizer recommendation on the bag he bought at Home Depot as well each spring. The lawn looks great but the hundred year old sugar maple has chlorotic leaves and looks like it is fertilizer deficient because the pH is wrong for the New England native.
So if I put a bunch of fertilizer, maybe a boring old 10-10-10, (4 lbs N per 1000 sq ft is a 'bunch' fyi) into my naturally acidic soil (average acidic is soil is about 5), this is what will happen. The nitrogen will not be affected much but will be slightly less available to the plants than a nice pH 6 soil. The phosphate will bind to metals in the soil like Fe and Al and be much less available to the plant's roots. The potassium in your fertilizer will be in the form of a salt of potash (K2O). Salts of potash, when dissolved in water are basic. Ooo great! that will neutralize my soil! Not quite, potassium will neutralize some of that acid by binding itself to its conjugate acid thus reducing its availability to the plant. And do not even get me started on micronutrients girl, damn. You can kiss those goodbye. They are needed in trace amounts but their availability is very dependent on soil pH. If you are shopping for inorganic fertilizers, make sure they have micronutrients in it, its more expensive but worth it. When we add limestone to our soil, it raises the pH (makes it less acidic) and works as a buffer. In chemistry, a buffer is a chemical that set the pH of a solution and prevents the change of pH with the addition of an acid or base. Another bonus of limestome and proper pH is that if your soil is polluted with heavy metals like lead or mercury, they will be incorporated less into your veggies.
Limestone is one of two things naturally dolomitic or calcitic. Calcitic lime is all calcium carbonate is best for tomatoes since tomatoes are very sensitive to calcium deficiencies ranging from acidic tasting fruits to poor crop yield all the way to blossom end rot. Dolomitic lime is a mix of magnesium carbonate and calcium carbonate with varying proportions but are usually listed on the bag. Your local availability of limestone type is governed by your proximity to the nearest mine and what type of vein it is. Here in Connecticut, dolomitic is the cheap and abundant limestone at only $2 per 50 lb bag since the nearest mines in Upstate NY are dolomitic veins. Calcitic lime is available but more expensive; I think most of it comes from the Poconos in Pennsylvania. Quicklime or burntlime is available too. It is kiln cooked to be more soluble in water and acts faster but is almost 5 times the price.
You can get you soil tested from an Ag experiment station or by a decent landscaper and you will be advised with how much lime should add. If you have never limed your garden, you can do 80 lbs per 1000 sq ft and 40 lbs every following year until you get a soil sample. Spread it before you till or plow or you can rake it into the first couple inches after tilling.
If you want to do it really dirty, when you plant your tomato, eggplant, and pepper transplants, add a 1/4 cup of dolomitic lime to the hole and stir it into the soil and plant your plant into it. Though I seriously doubt that it will damage other veggie plants, I can't recommend it for them since I've never tried it. I know that the nightshade family is generally full of calcium junkies. I have done this myself on the recommendation of a former co worker who said the would give his tomatoes to his construction crew and they loved it since it makes the tomatoes sweeter and less acidic. I found they seemed less acidic and I started harvesting many more tomatoes. Now I till the lime into the soil each year. I have recommended the dirty method to a few friends and family, only the ones who are true tomato people. Everyone of them told me the following August that "I have so many tomatoes! I did what you said and now I don't know what to do with them all! My freezer is full, I jarred sauce....."
So the moral of this fable is the addition of limestone adds the valuable mineral calcium to the soil, raises the pH to make it less acidic while buffering the pH from other acids. A soil pH of about 6 is ideal for most plants to access the nutrients in the soil. This makes your time working the soil and your investment of fertilizer more valuable. It saves you time and money and time is money so it saves you money and money.
This is the week we should start our tomato and eggplant seeds. Chile peppers should have been done last week or earlier but its not too late to start them now.
I'll do a post soon on getting our soil ready for the main season crops including our options for fertilizing, organic and inorganic. I'm a little biased toward a hybrid method. I think it might be a multiphase operation for that topic.
I realized my posts so far can be wordy and textbook-like so I bold-ed the parts that are very important if you want the reader's digest version.
I am listening to:
Chillin' by Dirtyloud
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