Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 15, 2008
Publication Date: January 30, 2009
Citation: Griffin, T.S., Larkin, R.P., Honeycutt, C.W. 2009. Delayed tillage and cover crop effects in potato systems. American Journal of Potato Research. 86(2):79-87. Interpretive Summary: The short rotations, intensive tillage, and low crop residue return of potato systems put conservation practices at a premium. A standard potato rotation, which included fall tillage after grain harvest along with other tillage in preparation for planting, was compared to a 2-yr rotation which limited tillage to only those operations associated with the potato crop. In the latter, the primary tillage operation was delayed until spring, immediately before potato planting. This delay in tillage resulted in nearly 100% soil coverage for both late fall and spring, when soils are likely to be saturated and are prone to runoff and erosion. The inclusion of underseeded red clover or perennial ryegrass with the barley crop increased ground cover slightly in some rotation cycles. Total tuber yield was not affected by cover crop, and was reduced by delaying tillage in only one out of six rotation cycles. These treatments had small affects on soil-borne diseases, with red clover suppressing both Rhizoctonia and common scab signficantly in some rotation cycles. This research demonstrates that alterations in tillage system, which have a large conservation benefit, can be implemented without reducing tuber yield and quality.
Technical Abstract: Delayed tillage and the inclusion of cover crops can substantially reduce erosion in intensively tilled potato systems. Both of these practices can potentially impact potato (Solanum tuberosum L.)yield and quality via changes in soil temperature and soil water status, and suppression or enhancement of soil-borne diseases. Research was conducted over six rotation cycles at two Maine locations to evaluate the effects of timing of primary tillage (fall vs. spring) and cover crop [none, red clover (Trifolium pratense L.), ryegrass (Lolium perenne L.), or winter rapeseed (Brassica napus L.)] on grain yield, ground cover, and tuber yield and quality within the context of 2-yr barley (Hordeum vulgare L.)-potato rotations. Delaying primary tillage until spring, immediately before planting potato, resulted in higher soil water content early in the growing season (before or immediately after planting) in some rotation cycles, and also provided nearly complete ground cover during potentially erosive periods in fall and early spring. The inclusion of clover or ryegrass cover crops also had small, positive effects on ground cover in both tillage systems. A significant tillage effect on total tuber yield was seen in only one rotation cycle, when delaying tillage until spring reduced yield by about 12%. Cover crop treatments had no effect on total tuber yield, and neither tillage or cover crop affected the proportion of marketable tubers. Tillage did not affect tuber diseases, but black scurf (caused by Rhizoctonia solani Kuhn) and common scab (Streptomyces scabiei) were significantly reduced by red clover in some rotation cycles. This research shows that conservation practices can be implemented while maintaining potato yield.