Assessment and Demonstration of the Sustainability of Long vs. Short Potato Rotations

Assessment and Demonstration of the Sustainability of Long vs. Short Potato Rotations

Summary

Comparisons of sustainable Best Management Practices or BMPs (based on judicious inputs focusing on environmental and economic sustainability) to Maximum Yield Management or MYM (based on “insurance inputs targeting maximum yield) were completed in the Pacific Northwest fields. The average BMP market yields were slightly less than the MYM (average 13 cwt/a increase), but, similar to the previous year, the cost of additional chemical and fertilizer inputs outweighed the yield increases in four of five fields evaluated (average $75/a loss). These results and the growers practicing BMPs were highlighted at three field days and several radio and trade publication interviews.

Objectives/Performance Targets

The objectives of this project are to quantify the effects and educate growers concerning the long-term impacts of short vs. long periods of time between potato crops with regard to:

*nematodes
*wireworm
*bacteria:fungi ratios
*Rhizoctonia (Rhizoctonia solani)
*silver scurf (Helminthosporium solani)
*white mold (Sclerotinia sclerotiorum)
*pink rot (Phytophthora erythroseptica)
*Pythium leak (Pythium species)
*Verticillium wilt (Verticillium dahliae)
*powdery scab (Spongospora subterranea subsp. subterranea)
*weed seed bank/numbers
*herbicide-resistance development
*soil microbial activity
*soil carbon and inorganic nutrient conc.
*soil depth, density, & aggregate stability
*water infiltration rate
*biomass yield
*tuber yield, size, grade, solids, and defects
*net economic return
*cost per rotational acre
*cost per potato acre and per cwt

Accomplishments/Milestones

Twelve fields were surveyed by taking late-season measurements, yields, and post-storage measurements. The containerized soil study and the early-season measurements were not able to be completed due to the lateness of funding notification, but the container portion of the study will be completed next spring. The field pairs were selected by choosing fields in close proximity to each other and with similar soil, topography, and management with the exception of rotation history. Fields with short rotation had potatoes every other year with small grains as the rotation crop in each case. The long-rotation fields had potatoes every four years, again with small grains as the rotation crops. The results of the yield differences show substantial decreases in total and US No. 1 yield with decrease in years between potato crops. Differences in size categories included a 53 cwt/a decrease in the 6-10 ounce size category when years between potato crops are decreased. Other size and grade category differences were less than 13 cwt/a for each. No statistical analysis is available due to the small sample size for this survey (statistical analysis will be performed at the end of the three-year trial).

Impacts and Contributions/Outcomes

No definitive impacts have been made to date as this project is in its initial phase. However, several workshops have been conducted and more are scheduled where growers will learn about the importance of rotation frequency and participation in this project.

2005 REFERENCES FOR THE ROTATION PROJECT

State Presentations:

Hopkins*, B.G., J.M. Alvarez, S.L. Hafez, P.J.S. Hutchinson, J.S. Miller, P.P. Patterson, and M. Thornton. June 28, 29, 30 and July 25, 26, 27; 2005. Potato Production Frequency BMPs. Invited Lecture. Trade Adjustment Assistance Training. Nine presentations given at Blackfoot, Burley, Idaho Falls, Pocatello, Rexburg, and Twin Falls; Idaho. (225 attendees)

Proceedings:

Hopkins, B.G., P.P. Patterson, P.J.S. Hutchinson, J.S. Miller, M. Thornton, S.L. Hafez, and J.M. Alvarez. 2005. Cropping Sequence and Rotation: Impact on Potato Production and Soil Condition. Trade Adjustment Assistance Training Workshop Workbook. University of Idaho. Moscow, Idaho.

Newsletters:

Fritz, M. and B.G. Hopkins. 2006. Model Potato Growers Maximize Profits through Best-Management Practices. Ag Knowledge. University of Idaho. Moscow, Idaho (In Review).

Fritz, M. and B.G. Hopkins. March 2005. Best Management Practices for Potato Production. Extension Trends. University of Idaho. Moscow, Idaho.

Web:

Hopkins, B.G., J.C. Stark, S.L. Hafez, P.J.S. Hutchinson, P. Patterson, J. Miller, M. Thornton, and J.M. Alvarez. 2005. Field Selection, Crop Rotations, and Soil Management web page. http://www.ag.uidaho.edu/potato/production/files/soil%20management%20and%20crop%20rotation%20and%20sequence.pdf

Radio:

Scott, B. May 20, 2005. Potato Rotations. Today’s Idaho Ag News. Interview quotes broadcasted on 64 radio stations.

Collaborators: