Project Number: 2096-21660-003-00
Start Date: Sep 12, 2013
End Date: Jan 28, 2015
Hypothesis 1A. Application of biofertilizers derived from agricultural bioenergy production will provide plant available nitrogen (N), phosphorus (P), potassium (K), and sulfur (S); reduce synthetic fertilizer application rates and improve weed management reduce greenhouse (gh) gas emissions and will not be a food safety problem. Laboratory, gh and field studies will evaluate and quantify the efficacy of manure-derived biofertilizers, biochar, and crystalline struvite to supplement synthetic P-fertilizers in specialty crop production. Chemical analyses will characterize N, P, K and S of each biofertilizer, soil concentration and plant-availability. Carbon (C) mineralization will be used to measure soil biological activity and soil C stability. Yield, tissue nutrient content and pre- and post-harvest root-zone soil nutrient levels will be used to assess nutrient use efficiencies. Economic analysis of amendments will be done using standard procedures for farm management cost and return estimates. Hypothesis 1B. Canopy reflectance of potato can be used as a non-destructive technique to predict water and/or nutrient stress. Gh water stress studies will be conducted. Hyperspectral images of the canopy will be measured weekly to estimate vegetative stress. Nitrogen stress experiments will be conducted at the ARS Research Field Station in south central Washington. Hyperspectral images will be acquired with a Hyperspec® VNIR camera through the growing season. Responses of potato to different spectral bands will be used to develop vegetative stress indices. Hypothesis 2.A. Soil and plant N status affect timing and amount of tuber set, size, vigor of vine growth, phytonutrient levels, ease of vine kill, and skin set following vine kill in early potato production. Bintje and Ciklamen potatoes will be grown as an early crop at the ARS Research Field Station. Petiole N samples will be taken at weekly intervals until vine kill. Total tuber yield, numbers, and size distribution will be determined at harvest. Tuber size will be categorized into < 25 cm, 25 to 38 cm, and > 38 cm diameter size classes. Phytonutrient assessments will identify N levels and vine kill methods that result in tubers with higher amounts of phenylpropanoids or carotenoids, anthocyanins, antioxidants, chlorogenic acid, aromatic amino acids, glycoalkaloids, reducing sugars and asparagine. Hypothesis 2.B. Vine kill method affects the level of vine kill, speed of skin set, resistance to skinning and phytonutrient levels in early potato. Mechanical, chemical, and combinations of the vine kill methods will be evaluated for vine kill, speed of skin set, and tuber yield, size distribution, and quality of tubers in the 25 to 38 mm diameter size classes. Mechanical treatments include flail chopping, undercutting, and rolling with a roller-crimper. Chemical desiccation tests include sulfuric acid, diquat, glufosinate, carfentrazone, and pyraflufen. Skin set will be rated after rolling tubers down a 2.2 m metal diamond grid ramp placed at a 13° angle to promote skinning. Resources in years 4 and 5 may be re-directed toward testing production of second crops following early harvested potato.