The economic impacts of disease suppressive rotations in Maine potato cropping systems

Authors: Halloran, John; Larkin, Robert - Bob; Honeycutt, Charles

Submitted to: Plant Management Network
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2008
Publication Date: 9/12/2008
Citation: Halloran, J.M., Larkin, R.P., Honeycutt, C.W. 2008. The economic impacts of disease suppressive rotations in Maine potato cropping systems. Online. Crop Management doi: 10.1094/CM-2008-0912-01-RS.

Interpretive Summary: Productivity of Maine potato cropping systems has shown little growth over the past five decades. This has placed Maine’s potato producers at a competitive disadvantage. To identify what is limiting potato yield five cropping systems were implemented. The five systems are: 1) a Status Quo system using a barley-potato rotation, a standard in the industry; 2) a Continuous Potato system as a non-rotation control; 3) a Soil Conserving system using no-tilled small grains following grass sod and then potatoes; 4) a Pest Suppressive system using crops recognized for their disease suppressive properties, green manure and potatoes; and 5) a Soil Improving system that includes composted manure in every year of the rotation. Two alternative systems showed significant increases in productivity compared to the barley-potato system. The Pest Suppressive system performed well under irrigated and rainfed conditions. The key to adoption appears to be the inclusion of rotation crops that are marketed in order to increase revenue. The Soil Improving system also showed significant gains compared to the barley-potato rotation under rainfed conditions. Rainfed production systems are the norm in Maine. In our experiments the Laboratory paid commercial landscape rates for compost, making the system unprofitable. However, studies indicate that compost can be made at greatly reduced costs indicating that the system could be feasible. In addition, compost in rainfed systems greatly reduces the level of production risk the producer faces.

Technical Abstract: Potato cropping systems in Maine show little growth in per acre productivity over the last five decades, especially when compared to other Fall potato producing states. This stagnant productivity has put Maine’s potato producers at a competitive disadvantage in the market place. In 2003 long-term field studies were initiated to identify and address the constraints of potato systems in the Northeast. Five different potato cropping systems were implemented. They are: 1) a Status Quo system using a barley-potato rotation, a standard in the industry; 2) a Continuous Potato system as a non-rotation control; 3) a Soil Conserving system using no-tilled small grains following ground cover and then potatoes; 4) a Pest Suppressive system using crops recognized for their disease suppressive properties, green manure and potatoes; and 5) a Soil Improving system that includes composted manure in every year of the rotation. Each of these systems is managed under both irrigated and rainfed conditions. With the exception of the barley-potato rotation these systems were not designed to be profitable, but rather to identify constraints to productivity, such as water management, disease problems, physical soil properties or nutrient utilization. Results of the first two complete rotation cycles indicate that the systems vary widely with respect to increasing potato yields under irrigated and rainfed situations. The Pest Suppressive system showed robustness under both water management regimes when compared to the Status Quo barley-potato rotation. The Soil Improving system showed large and significant gains compared to the barley-potato rotation under rainfed conditions. As expected, neither system consistently out performs the Status Quo barley-potato rotation in terms of net revenue. However, the results suggest that modifications that reduce their input costs could lead to increased net revenue and a reduction in production risk.