Travis Beckett and Dr. Brian G. Hopkins, Plant and Wildlife Sciences
Introduction
Potato production is an integral part of the agricultural economy of the northwest United States. Under recent pressure to increase profits, growers have been practicing shorter potato rotations—leaving a fewer number of years between potato crops in a given field (Myers et al., 2008). This practice leads to increases in pest and pathogen populations, thus threatening the yield and quality of future potato crops, and the overall sustainability of the field (Keller, 1989).
This project is part of a larger USDA-funded study, which seeks to improve profitability and sustainability among Northwest potato growers (Hopkins et al., 2005). The objective of our project was to quantify the effects of shorter rotations by growing potatoes in a greenhouse environment, and measuring various factors. Our experimental design included two unique elements: (1) the soil samples were taken from a wide geographical area; and (2) these soil samples were from fields with an established rotation history of twelve or more years.
As an undergraduate student, working on my first major research project, I was allowed to make many important decisions regarding experiment design and implementation. Many difficult situations arose regarding seed preparation, irrigation methods, and experimental measurements. Under the mentorship of Dr. Hopkins, I gained valuable experience in effective research methods as I worked to find solutions to these situations.
Materials and Methods
For this experiment, fifty-four 5-gallon soil samples were gathered from various locations across the Pacific Northwest. Twenty-seven samples were from short-rotation potato fields, and twenty-seven were from long-rotation fields. The soils were brought to the greenhouse at BYU, and Russet Burbank potato plants were planted in each sample. Plant growth, progression, and senescence (when the plant starts to die back and the potatoes begin to bulk) were monitored throughout the following months. Four months later, potatoes were harvested and weighed. Soil samples were also taken for future testing for potato-specific diseases.
Results
The potato plants grown in short rotation soils began senescence an average of 16 days earlier than those in long rotation soils (Shiffler et al., 2008). In short-rotation soils, the shorter period of plant growth meant that the potatoes had less energy available for the bulking period. Accordingly, the potatoes in long rotation soils had significantly higher tuber size, yield, and number of U.S. No. 1 potatoes (an industry-wide measure of top quality). Further results are expected once the pest and pathogen tests are completed by the spring of 2009.
Discussion
These preliminary results confirm the hypothesis that short rotations lead to a lower yield and quality of harvested potatoes. Based on the delay of senescence (16 days), tuber yields in short rotation fields would be predicted to be 12 Mg ha-1 less than tuber yields in long rotation fields. An article summarizing these data and results was published in the September 2008 issue of Potato Grower (Shiffler et al., 2008). In addition, poster presentations were made at the 2008 Utah Conference for Undergraduate Research (UCUR), held at Utah Valley State College, and at the 2008 Sustainable Agriculture Research and Education National Conference in Kansas City Missouri. Conference oral presentations planned for 2009 include the next UCUR meeting and the Western Regional Honors Conference on Preservation, Sustainability, and Renewal.
References
- Keller, E.R., (1989). Crop rotation — an important aspect in integrated potato production. In: Vos, J., Van Loon, C.D., Bollen, G.J. (Eds.), Effects of Crop Rotation on Potato Production in the Temperate Zones. Dordrecht, The Netherlands: Kluwer Academic Publishers. pp. 291–301.
- Myers, P., McIntosh, C. S., Patterson, P. E., Taylor, R. G., and Hopkins, B. G. (2008). Optimal Crop Rotation of Idaho Potatoes. American Journal of Potato Research, 85, 183-197.
- Shiffler, A. K., Beckett, T. J., and Hopkins, B. G. (2008). Delayed senescence through rotation. Potato Grower, 39(9), 18.
- Hopkins, B. G., Alvarez, J., Bauscher, R., Esplin, K., Hafez, S., et al. (2005). Assessment and Demonstration of the Sustainability of Long vs. Short Potato Rotations. Retrieved from http://www.sare.org/reporting/report_viewer.asp?pn=SW05-067