Soil

Gypsum to reduce potassium

Would the application of agricultural gypsum help in reducing high potassium levels in soil?

Gypsum is calcium sulfate (CaSO4). Addition of gypsum to soil would not reduce the soil test measure of potassium. Potassium salts are highly soluble so there is no way to precipitate excess potassium in the soil through addition of mineral salts.

Uptake of potassium by the plant is affected by the relative amount of calcium, magnesium and potassium in the soil. By adding more calcium to the soil using gypsum I would expect the amount of potassium uptake by plants would tend to decrease. Potassium deficiencies have been documented on calcareous soils that soil test indicates have sufficient potassium from this process.

John A. Lory
Environmental Nutrient Management Specialist

Soil analysis

I would like to have an analysis done on a can of garden soil. To what address should I send it? How much does it cost?

I assume you want to submit your soil sample to evaluate its fertility. First of all, be sure you have a representative sample. The reliability of the results and recommendations depend on the sample submitted.

Take soil at random spots in your garden
Collect soil to a depth of 6 inches
Mix well
Mail about 1.5 cups to the lab

You can submit the sample at your county extension center with the MP555, Horticulture Soil Sample Information Form.

You can also mail the sample to the

MU Soil and Plant Testing Lab
23 Mumford Hall
Columbia, MO 65211

The cost to test a sample for regular fertility status and provide fertilizer recommendations is $9. Check should be made out to MU Soil Testing Lab and mailed with the sample.

Additional information on how to submit a soil sample, fee structure, and sample information forms can be obtained from the MU Soil and Plant Diagnostic Services Web site.

Manjula Nathan
Director
MU Soil Testing and Plant Diagnostic Servicese

Pigeon manure

My neighbor has offered me the droppings from a pigeon coop. Can I use this to fertilize my garden? Is it considered the same as poultry?

This could be a good source of fertilizer similar to poultry manure.

Charles Fulhage
Department of Biological and Agricultural Engineering

Anhydrous ammonia

What is anhydrous ammonia made of and how does it affect crops?

Anhydrous ammonia is a nitrogen fertilizer commonly used on crops such as corn. The ammonia is kept in pressurized tanks that maintain it in a liquid form. The liquid ammonia is then injected into the soil as a fertilizer. The farmer must be sure to inject the ammonia into the soil or it will be lost to the air as ammonia gas. This sometimes happens if the injection slits fail to close after the injectors allowing ammonia to escape from the point of injection.

Due to the chemistry of anhydrous ammonia, the injection band initially is toxic to plant growth because of high pH. In a relatively short period of time after injection into the soil the ammonia is converted to nitrate and the pH of the injection band decreases. Nitrate is the primary form of nitrogen used by corn from the soil. At this point the corn plant can use the fertilizer and provide higher yields.

Nitrogen nutrient most limiting corn yield on most fields. Nitrogen is needed by the plant because it is a critical component of protiens. Deficiencies affect all aspects of crop growth including chlorophyll production. Plants short on nitrogen are stunted and have a light green color. Farmers often apply 100 to 200 pounds of nitrogen per acre to meet the nitrogen need of the corn crops. The exact amount of fertilizer needed depends on the productivity of the soil. Nitrogen fertilizer is not typically applied to soybean. Soybean is a legume plant with the capability of fixing atmospheric nitrogen to meet its nitrogen need. Consequently, farmers do not need to apply fertilizer nitrogen to grow this crop in most cases.

John A. Lory
Environmental Nutrient Management Specialist
Commercial Agriculture Program

Nitrogen and phosphorus

How many pounds of nitrogen and phosphorus are in a ton of 18/46/0?

The formulation represents the percentage of nutrients in the fertilizer on an N, P₂O₅, K₂O basis. In this case the material is 18 percent Nitrogen, 46 percent P₂O₅ and 0 percent K₂O.

In one ton (2,000 pounds) of fertilizer there will be

360 pounds of N (2,000 x 0.18)
920 pounds of phosphate (P₂O₅)fertilizer (2,000 x 0.46)
405 pounds elemental P(P₂O₅ x 0.44 = P)

Phosphorus can be confusing. Fertilizer recommendations and fertilizer products are on a phosphate or P₂O₅ standard. I assume that is the value you want. I included the elemental P value because you stated phosphorus. If you are unsure, use the phosphate values.

John A. Lory
Environmental Nutrient Management Specialist
Commercial Agriculture Program

Updated 5/16/06