Nitrogen Recovery and Potato Tuber Yield Response to Various in-Season Nitrogen Sources for Organic Production.
Amber Moore and Ashok Alva. USDA ARS, 24106 Bunn Rd., Prosser, WA 99352
Potatoes require numerous applications of nitrogen throughout the growing season. Organic potato growers face challenges in selecting effective sources of certified organic liquid nitrogen fertilizers, with little information available on yield and nutrient uptake effects. The objective of this study is to compare tuber yields and nitrogen recovery rates of potato plants with pre-plant manure fertilizers and in-season organically-certified fertilizers to conventional inorganic pre-plant and in-season fertilizers. Alturas and Umatilla varieties of Russet potatoes were grown in a greenhouse setting in a Quincy fine sand. Poultry litter, litter mixed with dairy manure compost, and urea were applied as pre-plant N fertilizers. Fish emulsion, organic liquid urea, NaNO3, feather tea, distilled water, and conventional urea-ammonium nitrate were applied weekly for 10 weeks. Total nitrogen rate for pre-plant and in-season fertilizers was 175 mg N kg-1.