Strip-tillers who use soil tests to find where essential nutrients are located in the upper soil profile can better optimize fertilizer placement.
Basic agronomics set our minds in motion to get after soils testing and brushing up on all of us getting better about understanding the soil NP?K-S tests and results to establish the best fertility program for next year. Where we place these essentials with what our soil tests tell us as to where and how much is available in the upper segment of the soil profile is really important.
I have to ask, what did you see happening in your corn and soybeans this year, the year after the ugly drought of 2012? Hmmmm! Sulfur (S) issues? Maybe some potassium (K) issue? Soil tests values were a mite shy but nothing out of the ordinary? Last year, the year of the furnace never shutting down we observed all across the Corn Belt from 75 to 25 (east to west) sulfur depicted as a deficient nutrient and K deficient also. It is known in corn that drought stress will bring those out to the forefront and also the plants demand more K and then this year (2013) in the Western segments of the Corn Belt we saw and see K and S deficiencies.
A report from International Plant Nutrition Institute (IPNI) is stating potassium levels need improvement. Coming out of the 2010 national soil fertility study there is evidence of a decline of 4ppm K since 2005. Potassium is vital to overall plant health, many plant physiologists consider K as second only to nitrogen in importance for plant growth.
Fig. 1 Symptoms of K deficiency in corn at V7
This is because K “activates” as many as 60 enzymatic and plant hormonal reactions, regulating many physiological and biochemical processes. Potassium supports water uptake into the plant via the roots. Potassium also regulates leaf tissue openings (ie: leaf stomates) to hold onto the moisture in the plant rather than distribution through leaves. Outcome – better stalk strength and late season standability. Which we have observed this fall (2013), numerous locations in Nebraska, northern Kansas, western Iowa and southeastern South Dakota of corn breaking down before harvesters get into the field.
The good folks at Mosaic state the following; “The uptake of potassium into the plant is dominated by diffusion — moving from high concentrations in the soil to a lower concentration inthe root. This leaves the uptake process highly dependent on the stages of root development. Smaller or compromised root systems significantly limit the ability of plants to access potassium, ultimately limiting plants’ growth potential/health.”
“All this happens in a relatively short period of time. The majority of potassium uptake (as much as 80 percent) happens prior to corn tasseling, with the greatest uptake happening between leaf stages V6 and V10. At the same time, potassium is stimulating earlier and deeper root growth, to ensure season-long nutrient uptake.”
So if this is a case to consider, where does root activity take up K? And a follow-up question, at the V6-V10 stage of a corn plant, surface 4 inches or maybe it is much deeper? Corn roots are most active at the V6-V10 below 8 inches to approximately 16 inches during the biggest percentage of the time of the corn plants life span. Now placing nutrients at 16 inches is really not responsible. ut at 7-9 inches, yes we see that is a good practice for a portion of your P and K. We at Orthman are seeing great response at 9 inches for a significant portion of what we desire in the soil profile for P and K.
Putting this all into perspective with Precision Tillage/Strip-Till, myself as one of the Orthman agronomists and what we advocate with Precision placement for the corn grower – having adequate amounts of the macronutrients along with S right in the immediate vicinity of the roots makes the most sense. Last year the drought hurt many, many growers corn yields if not they were a disaster, potassium may have been depleted to a level this year (2013) and growers felt the repercussions.
Carrying out a wise soil sampling program for your fields even this fall will offer a better picture of what can be your field results in 2014. We have observed time and time again the high K soil tests values do not always mean that potassium is not needed. Soil tests values less than 150ppm usually indicates that K additions will give a response in the plant and yes potentially yield.
Fig. 2 Placing K in the soil profile - important!
So depending upon your source of K, whether dry or liquid or a combination of products; placing these materials in the root zone make a great deal of sense to maximizing the crops potential to uptake potassium and avoid diminished crop health. Here at the Orthman Research and Proving Farm near Lexington, Nebraska we are all about placement and benefits of such for sustaining high yield corn production with Strip-Till as our foundation practice. We suggest that where plants wilted or exhibited stress before other areas in your fields, check on K levels and the overall soils and plant fertility.
We feel that a great strategy is to prepare for in a dry year builds your field for a great year. Considering the 4R’s of Nutrient Management and that one about the “right place” has a big benefit for you. Having K as well as P in the root path which is taken up mainly by diffusion is what we can help you do with Strip-Tillage and the Orthman 1tRIPr.
Fig. 3 Using the 1tRIPr to precision place the lesser mobile nutrients P & K as dry products (even in Mpumalanga Provence, ZA)
Consider this relatively immobile ion, K and surface application of an inorganic form of potash that has to interact with water to become soluble in soil before the plant root can absorb it. Does it happen as well with surface broadcasting as with direct, positive placement into the soil? This is what can be accomplished with Precision Tillage – Strip-Till? A thought, doesn’t three of the 4R’s of Nutrient Management ask the same question?
We will dig deeper into the correlation of potassium and the number of issues with stalk rot in corn in another article very soon here on PrecisionTillage.com. We are fully aware that strip-tilled corn fields are exhibiting poor stalk performance this year in places.
Do not hesitate to contact us here at Orthman, www.precisiontillage.com or a trusted agronomist that considers in-the-ground placement a wise choice to fertility programs for your field or area.