Over the last 30 years, potato production in the Northeast has declined by more than 100,000 acres, while production in other regions has increased steadily. So, what exactly is limiting Northeast production? Is it physical, chemical, or biological properties of the soil? Disease? Water? Or a combination of all these factors?
Several researchers are working on a project to determine just that. “We set out to identify what is constraining productivity of potatoes in the Northeast and to identify what can be done to reduce or overcome those constraints,” says Dr. Wayne Honeycutt, research leader and soil scientist. “To do this, we implemented in 2004 several different cropping systems, each designed to remove one or more potential constraints to productivity.” The systems are designed and managed as 1) Status Quo; 2) Soil Conserving; 3) Soil Improving; and 4) Disease Suppressive.
The Status Quo
According to Honeycutt, two status quo systems serve as research controls. One is a barley-potato rotation, which is typical for potato growers in the region, and the other is potato only (a non-rotation control). “A soil conserving system was designed to implement more soil conserving practices, thereby reducing certain soil limitations,” says Honeycutt. That system includes a three-year rotation of different crops. Because spring tillage is a more soil conserving practice, it is used in the status quo system instead of the traditional fall tillage.
Working With Soil
The soil improving system and the soil conserving system work hand in hand, Honeycutt says. The soil improving system adds compost in each phase of the rotation. Crops that have shown to reduce soilborne diseases are included in the disease suppressive system, specifically mustard in year one, sudangrass and winter rye in year two, and potatoes in year three.
“All of these systems are being evaluated under both irrigated and rainfed management so we can assess the interactions between cropping systems and water management,” Honeycutt says. The research team is evaluating plant growth and productivity, soil chemical-physical-biological properties, tuber, soilborne, and foliar diseases, economics, and a host of other variables.
So far, the soil improving system has increased carbon and nitrogen in the soil, while also reducing the density of the soil surface. “Most importantly, plant growth and yield responded to these changes in soil properties,” says Honeycutt. “These results indicate that management practices focused on improving the soil resulted in potato plant canopies with greater and longer lasting photosynthetic potential.”
This translates into a 23% to 51% higher yield, although Honeycutt points out that irrigation did not increase yield in the soil improving system. “These results show that management practices to improve soils can significantly increase potato yield and can serve as a substitute to supplemental irrigation in the cool, humid Northeast,” he says. “So growers have the option of either investing in irrigation or improving their soils in order to increase potato yield.”