The weather was mixed the previous week. Some parts south of Great Bend didn’t receive much rain and even rated as dry. However, much of the area receive well over an inch last Sunday night and rains occurred throughout the past week. This combined with cool temperatures resulted in wet soils and little progress in fieldwork. Corn planting is now officially late and if the forecast is correct, unsettled weather should continue through at least midweek. The Wheat Tour predicted an average yield for the state of a little under fifty bushels per acre, found nitrogen and sulfur deficient fields in South Central and Southwest areas of the state, the wheat is behind the average in terms of development, and leaf diseases are starting to show up. Producers are not late with soybeans and grain sorghum but work is stacking up. Finally, the rule of thumb is the first alfalfa cutting should occur around mid-May at about 1/10 bloom. This is normally the largest cutting and the one preferred by horse owners. Now, to finish last week’s topic on micronutrients (iron, zinc, copper, manganese, nickel, molybdenum, boron, and chloride).
These nutrients, needed in small amounts are becoming more important as producers work to increase yields and natural soil stores are drawn down. So how do producers determine what they need and how to address the problems?
• For the macronutrients, we have adequate soil tests for nitrogen, potassium, phosphorus, calcium, magnesium, and sulfur. However, work is still being done to determine effective soil tests to relate soil levels to actual nutrient availability for the crop. The best we can do for many is place the level in a broad range and determine deficiency, sufficiency, or excess. For example, chloride levels are determined in a range and applied based on the range they fall in. Not such a big deal with nutrients like chloride where a bit too much is of little concern. However, with some, like manganese, an excess could harm the crop. For some nutrients, like iron, an important bit of information is the soil pH where a high pH is the cause of the deficiency and not the actual iron concentration in the soil.
• For some producers farming on lighter, i.e. sandier soils, an initial diagnosis of a deficiency of soil chloride and/or zinc for corn, tells them what they need to know. A simple yearly, moderate application of the nutrient is needed without further testing.
• The best test for many micronutrients doesn’t involve the soil at all but plant tissue testing. For young plants it’s typically whole plant samples. As the plant grows, there are instructions for what plant part to take, from where, and how big a sample to collect. Sometimes, you can correct the deficiency that season while for certain nutrients it’s too late but at least the producer knows for next season.
• Once you have identified the deficiency there are a variety of options based upon the deficiency, soil conditions, and plant growth stage.
Next week’s column discusses common micronutrient deficiencies for Kansas crops and how to address these issues.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.