Identifying Constraints to Potato Cropping System Sustainability.

Potato yield in the Northeast U.S. has remained constant for over 50 years, despite increased inputs of pesticides, nutrients, and water. Consequently, a key question is: What is limiting potato system sustainability? We established Status Quo, Soil Conserving, Soil Improving, and Disease Suppressive cropping systems under both irrigated and rainfed management to address this question. Each system was evaluated for plant growth and productivity, soil chemical-physical-biological properties, tuber diseases, soilborne diseases, foliar diseases, economics, and their interactions. The Soil Improving System resulted in increased soil aggregate stability, lower soil bulk density, and less soil resistance to penetration. Under rainfed management, highest Leaf Area Index (LAI) was obtained in the Soil Improving System, and lowest LAI was observed in the Status Quo Continuous Potato System in 2006 and 2007. Similarly, highest Leaf Area Duration was found in the Soil Improving System. These results indicate that management practices focused on improving the soil resulted in potato plant canopies with greater and longer lasting photosynthetic potential. This translated into higher yield, where the Soil Improving System under rainfed management increased potato yield by 23% in 2006, and 51% in 2007. 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.