Potato yield stability under contrasting soil management strategies

Managing soil quality is recognized as a cornerstone of maintaining crop production potential. Here we show that soil management that improves soil quality characteristics can also reduce year-to-year variation in yields. Thirteen years of data from the Maine Potato Ecosystem Project were used to investigate the long-term effects of soil management, pest management, cultivar, and rotation in a factorial design on the yield and yield stability of potatoes grown in 2-yr rotations. Potato (Solanum tuberosum L.) yields in the amended soil system (manure, compost, green manure, and supplemental fertilizer) were up to 55% higher than yields in the contrasting nonamended soil system (synthetic fertilizer) in all but 1 yr. Yield stability was also enhanced in the amended system compared with the nonamended system, as demonstrated by lower CVs of total and U.S. no. 1 potato tuber yield. Stability analysis indicated that yields in the amended system were less influenced by adverse growing conditions, particularly low rainfall. Total and U.S. no. I treatment yields in the poorest-yielding year were 63 and 59% of maximum yields, respectively, in the amended system, compared with 45 and 46% in the nonamended system. Yields and yield stability were also influenced by pest management system and cultivar but not by rotation. These results indicate that management practices that improve soil quality can enhance potato yield stability by reducing the impact of adverse growing conditions.