What Soil Amendments do we need?

Do you really need to put 18 different things on the garden before you plant something? It must be time for the Jerry Baker PBS specials. People listen to Jerry, decide they like what he says and then call me to get the details. In the interest of full disclosure, let me say I am envious of the large amount of money Jerry has made off such a small amount of knowledge. If I could make as much money per knowledge, I would be a multimillionaire. I haven't figured out the appeal of putting 18 different things on the soil so I started asking the people calling in. They don't know either but they still wanted Jerry Baker information.

One person offered the opinion that Jerry gave simple advice. Maybe to them but it takes me a while to remember any list of 18.

Another person who came in the office told me she liked Jerry Baker because he used things she had around the house like chewing tobacco. This person didn't look like she chewed tobacco but I managed to keep my mouth shut.

Do you need to put 18 things in the ground to get plants to grow? Actually, two amendments will suffice. We will look at a few items suggested by Jerry Baker, who is not related to Cooperative Extension's Master Gardener Volunteers. The majority had no rhyme or reason for being in our gardens while a few could help under certain circumstances. We will also look at some products used by local gardeners. Some work and some don't

The first thing you need in Cabarrus County is something to adjust the ph. Lime raises the pH. 90 lbs. of lime per 1000 square feet is a good start. A soil test would be more accurate. Plants need the correct pH so the plant nutrients are available.

Compost is the other thing I would like to use. Compost contains nitrogen, phosphorus and potassium. There are other ways to get these chemicals but compost also provides bacteria, fungi and a carbon source for them to live on. Two inches of compost tilled in the garden would be ideal but I have never had that much available in real life.

Lime and compost are all we need to add to the soil but let's look at a few other common ingredients people use for soil improvement.

Cow, sheep, horse, or pig manure, poultry litter, alfalfa meal, soybean meal, fish meal, and crab processing byproducts. These are good products with nitrogen, phosphorus, potassium, and carbon source. Manures already have soil life. Manure may have high zinc and copper levels due to feed additives. This is not a problem the first few tons per acre. These products can be substituted for compost. Peat moss is an organic material but it holds water and our clay already holds enough water. When peat moss is used as packaging or container media, I will add it to the soil but otherwise don't use it. Milk is another organic product with nitrogen, phosphorus, potassium, and carbon source to sustain bacteria. It is too expensive for general use, but if some goes to the bad, I pour it on the garden instead of down the drain.

Ammonia. This is a nitrogen source with high burn potential compared to compost. It cost more than some fertilizer sources but it will work. The first number on a fertilizer bag is nitrogen. So any fertilizer with more than zero in the first space has some nitrogen. Some, like Miracle Grow or Jobe tree spikes, cost a lot more per pound than ammonia but I have found several that cost less.

Bone meal. Bone meal is a good phosphorus source but no better than many other phosphorus sources. Phosphorus is the second number in the fertilizer bag.

Wood ashes. These add potassium which is the third number on the fertilizer bag. Wood ashes are probably the best of the materials to add potassium but they raise the pH.

Granite dust from Vulcan materials (Gold Hill Plant or Poplar Tent Plant). This product has mixed reviews but I have seen results. Granite doesn't break down that fast which is why we use it for tombstones and buildings. Still, the grit will kick off some potassium. It can be used as a potassium source but don't use a rate high enough to change the soil structure. Greensand is a product mined in New Jersey with similar characteristic. Greensand has more trace elements but we have plenty of trace elements in our soil.

Gypsum. Gypsum is calcium sulfate. Again the sulfur of our soils is generally okay so we don't need gypsum for that reason. Calcium is normally low in our soils. Gypsum adds calcium without raising the pH. Lime adds calcium and raises the pH. Use the lime until the pH gets to 7.0. In high sodium soils, gypsum fluffs up the soil which is why Californian garden writers swear by this material. We don't have high sodium soils so that doesn't mean anything. Gypsum is called landplaster by peanut growers. They use it because sandy soils can't hold calcium. Our clay soils can hold calcium, so again the advantages of using gypsum here are not that much.

Epsom Salts. This is magnesium sulfate. Both magnesium and sulfur are needed for plant growth but we have plenty of sulfur in our soils. The availability from Epsom salt might be a little better but it is not worth the extra magnesium. Our soils have too much magnesium. I would be tickled if I could take 66% of the magnesium out of some soils, so I have never used this product.

Lye. Lye is used around pecan trees and I have seen results. There are two possible reasons. First, is the fact that lye will raise the pH. This shouldn't be helpful if you use enough lime. The other possibility is trace minerals including zinc from the can that is normally buried along with the lye. Pecans are heavy users of zinc and occasionally our soils test marginal for zinc. I suggest solving this by using a zinc fertilizer once or twice over the life of the tree. My soil is high enough in zinc and I use plenty of lime so I don't plan to use the lye.

Chewing tobacco. This is a potent pesticide although it would be illegal to use it as such. I have never figured out what soil born insects might be a preplanting problem other than cutworms. If I ever have a problem with cutworms, Sevin would kill them a lot easier and safer to me and the environment than chewing tobacco.

Perlite dust from the plant in Gold Hill. Why? It has the inadvertent effect of keeping the soil cooler by turning it lighter color and there have been high boron levels in some batches.

PermaTill. (Also called VoleBloc.) This light weight product is expanded slate. It is manufactured in Rowan County and reduces weight in concrete but is also sold as a soil amendment. I haven't seen the scientific experimentation on this product but don't think it is going to be that useful for the average gardener. It may have uses in high traffic areas and I am still curious to see if it can protect against the voles.

Beer. I don't have data on this one. I don't know of any good it does and I am sure our plants can grow without it. I have never heard of any place in nature where beer rains down from the skies, not that the natives would be willing to share that information.

Diet Soft Drink. Generally, when I have seen plants watered with soft drinks in school projects, the student uses too much soft drink. This creates pH problems. Students sometimes use regular soft drinks and the extra sugar creates nitrogen tie-up problems. Diet drinks may have the ability to make plants more disease resistant at very low rates (One pint per acre). More recent research has disputed this claim so we still need to sort some things out. Compost will also promote disease resistance so there could be a chemical in the diet drink that mimics something in the compost. Diet drinks are not a part of our official recommendations and there is no on going research. This will probably sit around for several years as a reminder that we don't know it all.

Soap. Soap is another potential pesticide. The home made versions are illegal.  Plus there is no reason to use a pesticide unless there is a pest to kill.

Slag. Slag is mostly trace elements, but they are readily available.

Ash from the local sewage incinerator. This product is not normally available. It is mostly iron so I wouldn't expect any benefits.

The kitchen sink. Since Jerry Baker listed 18 items I was trying to list 19 items. A sink doesn't really help the soil, but it won't hurt the soil. Besides, lot of artists display their junk so you might as well display yours.



Article was written by David Goforth Agriculture Extension agent North Carolina Cooperative Extension Cabarrus County Center.  Visit my homepage http://cabarrus.ces.ncsu.edu/ or http://cabarrus.ces.ncsu.edu/index.php?page=lawngarden or my blog http://gardeninggurugoforth.blogspot.com/

Contact me at David_Goforth@ncsu.edu.  Reviewed 2007.