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With the abundance of organic materials in the autumn season and directly applying leaves or garden refuse to an area prior to tillage, there is always a question about adding too much organic material to a soil. Standard organic materials can be added in fairly large quantities without many problems developing. It helps if the materials are partially decomposed (composted) or finely shredded so that they can begin the process of decomposition rapidly. Where we can get into difficulty is in organic materials that have a high nutrient concentration. Usually this comes in the form of animal manures- especially concentrated manures- where high rates of application can be too much. High nutrient levels or imbalances of nutrients can cause plant production problems the next season. In addition, high levels of nutrients can leach into groundwater or surface waters. Some concentrated manures contain levels of salt that can become excessive for certain flower and vegetable plants. The salt problems become compounded in dry seasons when natural leaching of salts through the soil is slowed down and salts accumulate.
As a general rule, use caution when applying concentrated manure organic materials without a soil test and/or a general recommendation as to application rates per unit area. Also, be careful about multiple year applications. In some cases, we may need to wait 2-4 years between applications.
For general soil improvement in terms of looseness and work ability of the soil, application of composted yard waste ( leaves, grass clippings, and similar materials) work much better than applications of animal manures- especially concentrated manures.
As soon as the garden chrysanthemums are done flowering, cut the plants back to 2 to 3 inches high. After the ground has become frozen, apply a layer of mulch over the top. Mums should not completely dry out during the winter. It may be necessary to water occasionally if sufficient rain or snow has not fallen. (WU)
Though there are high pH soils in most parts of the state, soils tend to be more alkaline in the central and western regions of Kansas. These high pH soils can cause problems for plants by reducing the availability of certain micronutrients. For example, most Kansas soils have more than adequate amounts of iron. However, a high pH can make iron unavailable resulting in a condition called iron chlorosis. Iron chlorosis reduces the health of plants by reducing photosynthesis. Lowering the pH of such soils will eliminate iron chlorosis.
Now would be a good time to have a soil test done to see if your pH is too high. If so, sulfur can be added either now or in the spring to lower the pH. Different textures of soil require different amounts of sulfur to lower the pH. A sandy soil needs 7 pounds of sulfur per 1000 square feet to lower the pH one point. A loam soil needs 11 pounds and clay needs 17 pounds to do the same. For example, if you wished to lower the pH from 8.5 to 6.5 on a loam soil, you would need 22 pounds of sulfur per 1000 square feet.
Unfortunately, adding sulfur to lower pH is not as clear cut a solution as we would like. Here are some other factors to keep in mind.
Free Calcium Carbonate: Some soils have free calcium carbonate, actual particles of limestone mixed in the soil. These "calcareous" soils normally have a pH of 7.3 to 8.5, with 8.2 to 8.3 being most common. In order for us to lower the pH with sulfur, all free calcium carbonate must be neutralized first. A recent soil test showed 6.7 percent free calcium carbonate. One pound of sulfur is needed to neutralize three pounds of calcium carbonate. Assuming 80 pounds for a cubic foot of soil, you would need about 1.75 pounds of sulfur per square foot just to neutralize the free lime. Additional sulfur would be needed to lower pH. Adding this much sulfur to a soil at one time is not recommended.
Not all high pH soils are calcareous. Perform this simple test to see if your soil contains appreciable amounts of free lime. Apply one drop of vinegar to dry soil. A vigorous fizz usually means the soil contains at least 3 percent calcium carbonate. A mild fizz suggests a calcium carbonate of between 1 and 2 percent and a fizz that can only be heard suggests the soil has a calcium carbonate content less than 1 percent.
How Sulfur Works: Elemental sulfur does not lower pH directly. It must first be oxidized to the sulfate form with the result being sulfuric acid. The sulfuric acid produces hydrogen, which acidifies the soil and lowers pH. The oxidation takes place primarily through microbial activity.
Oxidation Takes Time: Microbial oxidation of elemental sulfur takes time and depends on:
- number of sulfur oxidizing bacteria present
- temperature (75-104 degrees optimum)
- moisture content of soil (too wet or too dry will slow down process)
- size of sulfur particles (the smaller the better)
A single sulfur application normally takes at least 2 years for most the sulfur to react and form sulfuric acid. This, of course, depends on the above factors.
So, what do you do about calcareous soils? That will be a topic for next week. (WU)
Now would be a good time to check on the location of foliage houseplants to be sure the plants don't get too cold this fall or winter. Plants next to windows and in entry ways near outside doors are at the greatest risk. Plants very sensitive to cold temperatures include Chinese evergreen (Algaonema), flamingo flower (Anthurium), croton (Codiaeum), false aralia (Dizygotheca), and ming and balfour aralia (Polyscias). Monitor and maintain temperatures above 65 degrees F for the false aralia and above 60 degrees for the rest of the list. Many other indoor plants prefer temperatures kept above 50 degrees. If needed, move plants farther away from the windows or door entrances to reduce cold temperature exposure. It may be necessary to move some plants from window sills before shades or drapes are pulled, especially in the evening. (WU)
Contributors: Ward Upham, Extension Associate; Chuck Marr, Vegetables
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