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Similar to conventional in many ways Organic potato needs the same nutrients as a conventional potato Physiologically the same
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Where they differ Management Organic growers have: – More advanced planning – More pest pressure – Lower yield and quality Conventional, 450 – 550 cwt/acre (22 – 28 ton/acre) Organic, 300 – 350 cwt/acre (15 – 18 ton/acre)
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What we will discuss today… Introduction to organic production Potato Variety selection Adapting fertilizer recommendations for organic production Organic fertilizer sources Cover Crops
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Organic Acronyms N.O.P. – U.S. National Organic Program – Regularly allows or prohibits materials and practices as certified organic OMRI – Organic Materials Review Institute – National List of Allowed and Prohibited Substances WSDA (Washington State Dept. of Ag.) – Also distribute a list of allowed and prohibited substances, followed by Idaho – Often more restrictive than OMRI’s list ACA – Accredited Certifying Agent – ISDA in Idaho (Idaho State Department of Agriculture)
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N.O.P. Definition for Organic An ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. Minimal off-farm inputs Management practices that restore, maintain and enhance ecological harmony
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“Organic” Chemicals containing carbon are also called “organic” – Based on this definition, urea fertilizer and most pesticides are “organic” – Different from USDA certified organic Are all certified organic practices chemically organic? – No – Manures, composts are chemically organic – Mineral compounds are not
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Why grow Organic? Because you believe in the organic philosophy – Small-scale growers – Trend toward more sustainable practices Because you want to make a higher profit from your potato fields – Large-scale growers – Trend toward less sustainable
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Week of February 26, 2014 Organic Potato $ Value, ~2.3 times greater than conventional http://www.rodaleinstitute.org/Organic-Price-Report
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Challenges for organic potato growers Lowered yields – 250 cwt. (organic) vs. 400 cwt. (conventional) Effective Nitrogen sources Weed control Finding buyers/market demand
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Transitioning from conventional to organic Three years of following organic regulations before a field is certified organic Most common method, alfalfa hay for 3-year period, then into more profitable and intensive row/grain crops for next 3 years or so Fertility issues seem to be more severe for newly transitioned field – Less organic matter? – Less microbial diversity? – Nutrients building up from manure/compost/cover crop applications?
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VARIETY SELECTION
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Advice on variety selection Resistant to local diseases and disorders – Example – Late Blight issues, consider Defender Maturity – Short-season varieties tend to require less N – Exception, Alturas (late-season but requires less N) Early and vigorous plant emergence, help with weed competition Insect resistance
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Seven potato varieties grown on a certified organic field at the UI Kimberly Research Station in Kimberly, Idaho in 2009 and 2010. Potato VarietyMarket TypeTotal Yield (cwt/acre), two year average Total Yield (ton/acre), two year average AlturasProcess26013.0 DefenderProcess/Fresh26213.1 Russet BurbankProcess/Fresh35017.5 Yukon GoldProcess/Fresh23711.8 Yukon GemProcess/Fresh33516.8 Dark Red NorlandFresh24012.0 Russet NorkotahFresh1949.7 Presented at Idaho Potato Conference. 2011. Olsen and Moore.
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Potato Variety Defoliation rating (1=healthy, 9=defoliated) Defender2.2 Yukon Gem3.2 Alturas4.2 Russet Burbank2.2 Yukon Gold3.4 Dark Red Norland5.2 Russet Norkotah2.8 Defoliation by Colorado Potato Beetle on July 8, 2009. Kimberly, Idaho. Presented at Idaho Potato Conference. 2010. Wenninger.
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Adapting fertilizer recommendations for organic production
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Petiole Nitrates UI recommends over 15,000 ppm petiole nitrates during tuber bulking Based on potatoes receiving N fertilizers We see good tuber yields but low petiole nitrates – On fields receiving manure/compost applications, – On fields following alfalfa Don’t recommend that organic growers rely on petiole nitrate values – Still useful for showing changes N status in the plant over the growing season
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Soil N – 12.0 ppm Preplant N – 119 Inseason N – 119
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Soil N – 12.0 ppm Preplant N – 119 Inseason N – 119 Yield achieved – 634 cwt/acre Yield goal – 550 cwt/acre Previous crop – Alfalfa
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Organic nutrient sources
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Animal manures and composts Mineral fertilizers Mustard/canola/soybean meals “Specialty” fertilizers
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Organic composted animal manure Composted plant and animal materials produced though a process that: (i) Established an initial C:N ratio of between 25:1 and 40:1; and (ii) Maintained a temperature of between 131 °F and 170 °F for 3 days using an in-vessel or static aerated pile system; or (iii) Maintained a temperature of between 131 °F and 170 °F for 15 days using a windrow composting system, during which period, the materials must be turned a minimum of five times.
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Composted Animal Manure Benefits Certified organic compost can be applied to crops any time Rich in P, K, S, and micronutrients Even field application (relatively) Drawbacks P accumulation in soils Poor source of N for newly transitioned organic fields ○ Stable organic N compounds need several years to mineralize into plant available forms
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Raw Animal Manure Raw animal manure must be composted unless it is: (ii) Incorporated into the soil not less than 120 days prior to the harvest of a product whose edible portion has direct contact with the soil surface or soil particles; or (iii) Incorporated into the soil not less than 90 days prior to the harvest of a product whose edible portion does not have direct contact with the soil surface or soil particles;
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Raw Animal Manure Benefits More N than composted manure Rich in P, K, S, and micronutrients Drawbacks P accumulation in soils Can not be used for short season potato varieties Raw manure not considered as an organic practice in some overseas markets
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Mineral fertilizers Sodium nitrate—use is restricted to no more than 20% of the crop's total nitrogen requirement. – Good for getting over the nitrogen deficit hump – Sodium toxicity and accumulation – Not considered organic by some overseas markets
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Russet Burbank yields in 2009 and 2010. Potatoes grown on an organic production field in Kimberly, Idaho. Chilean nitrate applied in-season at 48 lb N/acre. Dairy compost applied at 10 ton compost/acre in the fall of 2008 and 2009.
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10 ton dairy compost 10 ton dairy compost
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Other mineral fertilizers Rock Phosphate – Do not dissolve well on alkaline soils Elemental Sulfur Gypsum (Calcium sulfate) Potassium Chloride (KCl) Sulfates Carbonates Confirm that fertilizer is organic
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Oilseed meals Mustard, canola, soybean meals Rich in nitrogen – (4 – 7 % N) Up to 60 % of N is plant available in first growing season Expensive, competition with animal feed markets
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Russet Burbank yields in 2009 and 2010. Potatoes grown on an organic production field in Kimberly, Idaho. Dairy compost applied at 10 ton compost/acre in the fall of 2008 and 2009. 10 ton dairy compost 10 ton dairy compost
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Specialty Fertilizers Benefits Some have very high N (3% or greater) Drawbacks Can be cost prohibitive Can be ineffective, especially if low N
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COVER CROPS AND CROP ROTATIONS
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Legume rotations Alfalfa, clover, winter peas Nitrogen fixing rhizobia in root nodules Convert nitrogen gas to ammonium compounds that can be used by the plant Alfalfa combined with soil N 155 and 240 lb N/acre (Westerman and Crothers, 1993) Most organic potato growers in Southern Idaho include 3-5 years of alfalfa in their rotation
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Pink coloring in dissected legume root nodules indicates an active population N-fixing rhizobia bacterium. Photo taken of hairy vetch root nodules in Aberdeen, Idaho.
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Winter Wheat (spring harvested in Aberdeen)
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Hairy Vetch (spring harvested in Aberdeen)
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Austrian Winter Pea (spring harvested in Aberdeen)
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Daikon Radish (fall harvested in Aberdeen)
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Austrian Pea and Winter Wheat Shoshone
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http://www.extension.uidaho.edu/nutrient/CC_Calculator/Cover%20Crop%2 0Calculator%207/Cover%20Crop%20Calculator%207.htm
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Photo courtesy of Nick Andrews, and Dan Sullivan, Oregon State University.
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Equations and calibration data supporting the University of Idaho Cover Crop Calculator, which estimates plant available nitrogen (PAN) in the soil over a growing season for spring-tilled green manure crops or crop residues on irrigated cropland in Southern Idaho.
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Pest Control Well-spaced rotations – Optimum – 7 years between potato rotations – Minimum – 4 years between potato rotations Include biofumigant crop in the rotation Avoid nutrient deficiencies Field Isolation
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Weed control Intensive tillage and cultivation – Alternatives to improve tillage Roller/crimper Rotate with no-till/strip-till crops Hand weeding Timing and crop rotations Prepare for weed pressure in late season
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July 20 th, 2010
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August 23rd
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September 8 th, 2010
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Insect control Colorado Potato Beetle – Spinosad – Most effective control method Timing is critical – Pyrethrum – Neem
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July 7 th, 2010 (edges that did not receive applications of spinosad)
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July 8 th, 2010
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Bottom Line Variety selection can help to avoid anticipated issues with organic production – Pest pressure – Low nitrogen fertility Petiole nitrates may not be an optimal tool for organic growers
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Bottom Line Nitrogen, difficult to get enough for good potato yields – Annual fall applications of compost, build of slow release N – Apply higher N fertilizers during transition and when N is low (above 4% N) Keep up with organic regulations – Confirm that nutrient sources and practices are organic
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Bottom Line Include legumes in rotation – Free nitrogen! Consider cultivation for early weed control
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Amber D. Moore, Ph.D. University of Idaho Twin Falls Research & Extension Center 315 Falls Ave., Evergreen Bldg. PO Box 1827 Twin Falls, Idaho 83303-1827 Phone: 208 736-3629 Email: amberm@uidaho.eduamberm@uidaho.edu Website: www.extension.uidaho.edu/nutrientwww.extension.uidaho.edu/nutrient
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