The weather overall cooperated again this past week. Soils are warming and perhaps and while some of the area received over an inch of rain, other areas were able to make progress. Corn should/must go in the ground now. However as this is written, an unsettled pattern is supposed to be upon us. Wheat is jointing and progressing with the good air temperatures over the last week. We are in “Goldilocks” territory for temperatures – not too hot and not too cold. One last note – while not found yet in Barton County. Rust is being found on wheat in several Kansas counties so attention for possible treatment is in order. Last week’s column discussed fertilizer application and was about what are termed macronutrients – nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. This week’s discussion will focus on the “wee” things, which can may a large difference in crop yield and quality – micronutrients.
These nutrients are termed micro as they are needed in significantly lower amounts than the macronutrients. The positively charged nutrients, cations, are iron, copper, zinc, manganese, and nickel. The negatively charged nutrients, anions, are boron, chlorine, and molybdenum. There isn’t much space here so let’s be brief and to the point.
• There are soil tests for these nutrients, some are good and some not so much. Often, if you suspect a deficiency, plant tissue samples are the only way to see what you have.
• In many cases the deficiency isn’t a lack of the nutrient in the soil, it can be for something like zinc and boron, but due to soil chemical conditions. Some are present but unavailable at high pH while others become unavailable at low pH (very acid soils). Some like chlorine move easily in the soil and can leach with heavy rains on lighter (sandy) soils. Some are found primarily with organic matter so low levels can create deficiencies.
• What is challenging with micronutrients compared to the macronutrients is there is for many a fine line from deficiency to sufficiency to toxicity. Meaning that over application can result in damage to or even the death of the plant. A producer must be careful to know for certain they need the nutrient and not to over apply it to the soil or as a liquid for foliar applications.
• Deficiencies are occurring for several reasons. We have depleted the natural occurring amounts in the soil. Crop yields continue to increase, taxing the soils ability to supply them. Finally, producers used to get them for free when purchasing other fertilizers. Today N-P-K fertilizers are much purer. One last thing, it wasn’t terribly long ago we were still identifying what these essential nutrients were. Nickel was determined in the last twenty years and while we know it is necessary for a plant to grow and complete it’s lifecycle, we don’t know had to really determine sufficiency amounts or soil deficiencies accurately. And too much nickel is bad, potentially very bad for plants. There may be more identified, we just don’t know.
• Finally for today, sometimes there is a quick easy fix for a deficiency, sometimes we can’t easily correct the deficiency and have to do things like other crops or specific cultivars.
Next week’s column will discuss the likely micronutrient problems in Kansas and how to address them.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.