Deep tillage can have a positive and significant impact on the quality and health of potato crops according to Dr. A.J. Bussan, a potato and vegetable specialist with the University of Wisconsin at Madison.
“Deep tillage effects vary with conditions but, in general, the process allows for larger plants, deeper roots and better water drainage,” he says, adding it is especially valuable in compacted fields that are prone to flooding and in seasons when there are frequent periods of water and heat stress. Compacted soils restrict the depth of rooting and limit the nutrients available to the plants. That, in turn, limits the potatoes’ growth.
Dr. Bussan has been involved in a number of recent deep tillage studies and experiments conducted in Wisconsin. In these studies, while the majority of control plot potato root systems were above the 12-inch mark underground, deep tilled potato plant roots sank 30-inches down.
As for sugar responses, Bussan notes that in areas of deep tillage, the level of sucrose at the stem end decreased while the glucose component increased. At the bud end, the sucrose level was even lower while the glucose levels remained unchanged.
In storage, the incidence of pink eye and other diseases were lower for potatoes grown in deep tillage areas and there were 70 per cent fewer rotten tubers, Bussan says.
“We saw a size increase in the deep tillage areas and three of the six growers we worked with reported increased yields.” Of the remaining growers, one reported a reduction in yield while the other two didn’t notice any difference.
As for timing, Bussan says the growers involved in the studies first tried the deep ripping method during the spring – but ran into problems when the wheels of the ploughs created furrows.
“They shifted to a post-planting tiller. They also put the furrows right below the plants, running shanks 20-inches into the soil. They used row markers to help keep the furrows uniform.”
A couple of growers also used guidance systems on their tractors for more precise ripping.
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