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My Father-in-Law, let’s call him Joe - because that’s his name - is a great sports fan. He enjoys all kinds of sports, but he is especially a student of baseball. One of the things he’s taught me is the old idiom “you can’t tell the players without a scorecard.” The same is true about the nutritional status of your potato crop. We can watch the crop grow all day long and even though we can notice things from a macro-view, without a good regimen of sampling we will probably not know what is really going on in the crop. Soil and tissue sampling gives us the scorecard we need to really understand what is going on and to help us better manage the “players”.
Soil sampling gives us a snapshot of the amounts of mineral nutrients that are physically found in the soil; they can be measured in pounds or parts per million (PPM) of N, P, K and so on. What a soil test does not necessarily tell us is the form of the specific nutrients and their availability to the plant. For instance, a soil sample can tell us how many PPM of manganese are in the soil, but it doesn’t tell us the valence of the manganese, whether Mn++, Mn+++, or Mn++++. This can have great consequence in your potato crop being to take up manganese, as only Mn++ is taken up by the plant, but depending on the soil pH, the Mn that the soil test identified might be Mn+++ or Mn++++. The availability of manganese increases 100-fold with a one unit drop in pH. This is just one example of how unintentionally misleading a soil sample can be, and it is a perfect example of why in-season tissue sampling is so important.
Stripped petioles. Photo: Yara UK.
In potatoes the reference standard tissue analysis is weekly petiole sampling. Weekly samples show nutrient trends in the crop and can help to identify potential instances of “Hidden Hunger” before deficiencies rob your crop of yield and quality. Potatoes have a large compound leaf, and so the sampling procedure consists of pulling the youngest fully developed leaf (usually the fourth or fifth leaf from the terminal), stripping off the individual leaflets and submitting just the petiole to the lab for analysis. About 25-50 petioles taken randomly from representative areas of the field constitutes a sample. There are certain steps we can follow to make sure that our petiole sample gives us a consistent and representative analysis as to what is going on across the field.
Megalab is Yara’s crop nutrient analysis system and is the world’s largest privately held nutrient analysis database. Megalab has been an online resource since 1992 and has served farmers and retailers in dozens of countries and on dozens of crops. Megalab takes the local lab’s analysis and compares those numbers with our prescribed guidelines according to growth stage and delivers to farmers detailed recommendations on Yara’s complete line of crop nutrients. This process removes all the guesswork in your crop’s nutrition program.
To find out if your lab is associated with Megalab, ask your Yara representative.
Jimmy Ridgway - Crop Manager, Potato
Greetings Potato Enthusiasts!
I want to introduce you to TopPotato Newsletter brought to you by Yara North America. The intention is to bring production and market insight to light for all members of the potato value chain, from seed and commercial producers, to input providers, packers and processors. We know how busy you all are, so we will keep each edition brief and to the point so you can get on with your day; however, if the information you receive here raises your curiosity please feel free to reach out to us and we will be happy to discuss each topic at length.
Enjoy and share TopPotato Newsletters with others. If you have any comments or suggestions for topics, please email me.
Thanks and have a productive year!
Crop Manager, Potato - Yara North America