Weed Supression with Winter Annual Cover Crops in Potato

Weed Supression with Winter Annual Cover Crops in Potato

Summary

Integration of cover crops is scarce in conventional agriculture today. With the use of pesticides, fertilizer, and crop rotation, most major production problems can be overcome. However, more growers are beginning to consider the use of cover crops as they reflect on the importance of soil retention, soil quality and environment quality, as well as alternate methods for fertility management and pest control. Cover crops are heavily relied upon in organic and sustainable agriculture systems. These systems continue to increase in acreage each year with North Dakota ranked second in acreage for organic crops. Weed control in organic potato production relies on the effectiveness of cultivation, harrowing, and weed suppressing varieties. Unfortunately, in the Red River Valley, regular precipitation and slow soil drying due to the heavy soil texture, makes timely cultivation difficult and often impossible. A potential alternative, which utilizes early season weed suppression, is through the use of winter annual cover crop species. Unfortunately, cover crop research in the Northern Plains region is limited. The proposed research will determine the effectiveness of cover crop species and kill methods on weed suppression in potato. Cover crop performance will be evaluated with respect to cover crop biomass accumulation, soil water content, nitrogen cycling, weed suppression, subsequent potato yield and grade. The expected outcome of this research will provide greater awareness among producers of the benefits of cover crops, expand the use of cover crops, and demonstrate the benefits and limitations when incorporating a cover crop into a sustainable potato production system. Results from this project will be made available regionally to potato growers through extension articles and websites, grower meetings and field days; and nationally as publications in scientific journals.

Objectives/Performance Targets

Short-Term Outcomes: The cover crop weed suppression project in potatoes has the ability to greatly impact the weed control knowledge of growers currently producing organic potatoes in North Dakota and Minnesota. Grower’s knowledge of this research will expand the interest in organic potato production and show others new technology and science that should improve their operations. This project will be the initial step taken to resolve the issue of weed control, the major obstacle in organic potato production for this region. The awareness of cover crop benefits should increase the interest of adopting cover crops in other production systems.
Intermediate-Term Outcomes: This project will demonstrate the ability of cover crops to bring the nitrogen towards the soil surface for plant use and to reduce weed establishment. It will provide a new method of weed control for organic potato producers in this region and most likely increase yield and quality without increasing external inputs. It is anticipated that we will be able to build on the success of this project to show other producers the benefits of cover crops to the soil and thereby increase profitability and sustainability in their production system.
Long-Term Outcomes: The ultimate goal of the cover crop for weed suppression project is a positive effect to the whole system of organic agriculture. Not only would potato growers in North Dakota and Minnesota be impacted by the research, but growers throughout pertinent potato growing regions in the United States and other countries as well. Systemic changes could be achievable with the success of this research. The organic potato industry would have greater success with higher yields using cover crops for weed control as well as increasing soil quality and sustainable production practices. In organic agriculture, pests and nutrient deficiencies of all sorts have the potential to decrease yields and create major production problems for growers. Cover crops are the link which could serve multiple purposes in organic agriculture. A great aspect of this potential research is its ability to add knowledge to an integrated cover crop system for growers that have been content with conventional production practices, paving the way for more sustainable practices and the future of organic agriculture.

Accomplishments/Milestones

The first field season of this research began September, 2009 and was completed October, 2010. The final year will conclude with potato harvest in 2011. Two sites were initiated the first year. The dry land site was at Fargo, ND and the irrigated site was at Oakes, ND. Data collection for the first year included cover crop dry biomass, soil available nitrogen, weed species identification, weed counts, weed weights, and potato yield. The study is being replicated in 2011 with both the dry land and irrigated sites at Carrington, ND. The results from 2010 were promising. The difficult task of growing potatoes in high residue, sometimes no-till field conditions presented a challenge. Soil type needs to be an important factor for future consideration of these methods for growers, as heavier soils tend to be less compatible with potato planting into high residue cover crop soils. Cover crops did not present any noticeable negatives compared with the no cover crop, high tillage treatment which served as the conventional check, a big positive result. Several cover crop treatments provided higher weed control percentages than the weedy check. The second year of research will solidify the results and allow for comprehensive insight into the accomplishments of this research.

Impacts and Contributions/Outcomes

The first year’s research, summer 2010, was presented at the North Central Weed Science Society’s annual meeting in Lexington, Kentucky on December 14th, 2010. At that time the research was presented to a wide audience of weed specialists, where it was complimented and critiqued during the questions segment. The 2010 results were also published in the Oakes Irrigation Research Site’s Annual Reports for 2010. This report is an extension publication circulated widely to a major potato producing region of North Dakota. This region, south central North Dakota, has the potential to benefit from the research as organic production progresses there.

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