Glacier FarmMedia – Nitrogen, phosphorus, zinc, boron, potassium are all the buzz words for the foundations of proper crop management.
They may get all the headlines, but more and more attention is getting paid to proper copper nutrition.
“Copper nutrition was discovered in 1931, so don’t let people tell you copper nutrition is new,” said Dan Owen, director of market development and agronomy for ATP at a recent nutrient summit in Lethbridge, Alta.
Read Also
Kioti expects autonomous tractors in near future
Kioti has plans that could see it become a much bigger player in the agricultural sector, specifically, the introduction of fully autonomous tractors.
“There’s been a lot of work done in this arena, it just means it’s the new shiny object. Last year it was boron, the year before it was potassium. If we get stuck in a rut and we think it’s not important, we ignore it. We’ve got to learn how to manage it better because currently we’re stuck in the past. We put it in the soil and we forget about it.”
Why it Matters: With 16 nutrients needed in photosynthesis, copper often takes a back seat to others in soil and plant management for crops, where its deficiencies can lead to a lot of yield being left on the table for growers.
Copper deficiencies can lead to poor pollination, reduced standability and increased ergot infection.
Cereals are the most sensitive to copper deficiencies alongside pulses such as beans, lentils and chickpeas for rhizobium production.
Owen assured farmers if they are doing a program surrounding soil-applied copper only, they are leaving yield on the table. There are 16 nutrients and two structurals involved in photosynthesis. Copper activates enzymes, stimulates proteins and metabolizes carbohydrates, aiding respiration and breaking down sugars.
“You know what the yield loss can be from carbon deficiency? Fifty-plus per cent, you fail. Because at the end of the day, if you’d have done a soil test, if you did tissue tests, would we be here?” questioned Owen.
There are several factors that can affect copper deficiency. It is greater in coarse-texture soils that can be excessively leached, along with soils that have increasing pH (alkaline).
“Copper solution, or solubility of copper, decreases with an increase in pH,” said Owen.
Optimum conditions are near neutral to slightly acidic (5.5-7.0) because acidic soils do not massively hurt copper availability compared with other nutrients.
The 16 nutrients Owen spoke of have to work in synergy because applying high levels of zinc, iron, manganese or phosphorus can depress the crop’s ability to absorb copper. The increased growth response to increased nitrogen may end up being greater than copper uptake, diluting the concentration in the process. This can cause low lignification and the crop falling over.
“That can antagonize copper uptake in the plant that will have high levels. So this is why we talk about soil analysis. We need to understand how to interpret those results. It’s not just red, green and yellow. It’s what are the interactions between these nutrients. We’ve got to start thinking a little differently,” he said, adding increased nitrogen can impede copper movement from the older to the newer leaves.
Soil and tissue testing throughout the season can serve being proactive to compacting copper deficiencies affecting yield. Twisted leaves/heads can be the first sign of copper deficiency, but can often be mistaken for herbicide injury, and by then it would be too late to save yield.
Copper sulfate can be used to address copper deficiencies, but if you are dealing with higher organic matter, a complex/chelated sulfate is recommended so it will not be tied up. Owen stressed avoiding copper oxides if you are looking to address deficiencies.
“What it will do is it’ll have no impact on the plant, but your soils will look better because it’s insoluble,” said Owen on the lack of overall nutritional benefit.
After applying plant-available, soil-applied copper, farmers are often hesitant about foliar application for fear of leaf burn (phytotoxicity). But because copper has limited mobility in soils, it can be beneficial if done carefully in timing (BBCH 31 and BBCH 45), safety and with yearly soil programs to increase yields. He cited wheat studies (Marschner 1996 and Malhi 2005) showing timed copper foliar applications netted noticeably higher yields, with a greater emphasis in future research on proper timing.
“How long does a foliar last … a couple of weeks? How long is the gap between 30 and 45? Probably more than a couple of weeks, isn’t it? This is why, when we dig into these types of programs, we need to think about this staged approach as to how we add the nutrient,” said Owen, recommending a foliar rate of 0.5 litres per acre with a minimum 10 gallons of water per acre as well.
He cautioned to be careful with stroby fungicides when mixing with your foliar copper applications.
“We still have to be cognizant of what it is sharing the tank with. Strobilurins, I would say, are the harshest ones to put with copper. SDHIs (succinate dehydrogenase inhibitor) would be my second warmest, and generally most triazoles are OK,” said Owen.
“The only triazole I would be a little nervous about would be any form of generic triazole that is still using the EW formulation that has the oils in there. That is a desiccant. Great product, but if you don’t know how to use it, you’ll make a mess.”
