Soil heterogeneity and potato fertilizer recommendations

Each of 24 field experiments ranging from. 23 to 3.1 acres in size was divided into small rectangles. Each rectangle was soil sampled and each sample was analyzed separately for phosphorus and potassium. In some experiments separate samples were taken from both the top and the second foot of soil. The means, standard deviations, coefficients of variation and the percentage of the experimental area which fell into one of five nutrient level classifications were calculated. Soil test results showed that fertility varied greatly within plots located in Washhington's Columbia Basin. The extreme soil variability is a factor that affecsts the method of soil sampling and the fertilizer recommendation. Thus, soil variability must be evaluated before a fertilizer program can be built. The use of soil testing to determine α specific fertilizer need for a field is not practical if the variability of the field is large. However, soil testing can assist in assessing the variability of a field and determining fertility trends over the years if properly used.     

Alternative sources of nitrogen and phosphorus in potato fertilizer

Urea and diammonium phosphate were compared with ammonium nitrate and triple superphosphate, in all combinations, as sources of N and P in fertilizer on two soil types important in potato production in Ontario. Greenhouse experiments with these soils and a peat:vermiculite:sand mixture gave very varied root and shoot development which followed no constant pattern. The same combinations of fertilizer in the field gave no differences in emergence, appearance, or senescence, but there was one yield difference and minor, inconsistent differences in specific gravity and cooking quality.     

Some pointers on potato storage

American Journal of Potato Research -     

Some studies on carbohydrates in potato tubers

Summary Starch and pulp were isolated from three cultivars of potato tubers grown in four localities. The starch content in the pulp was determined by an enzymatic method which is shown to be more accurate than a polarimetric method. On an average, 94% of the starch was isolated and 5% remained in the pulp. The change in low-molecular weight carbohydrates in the potato tubers during storage for 2, 4, 7 and 11 weeks at 9 C was studied. Generally there was an increase of sucrose, glucose, fructose andmyo-inositol during the first 2–4 weeks of storage, followed by a diminishing decrease.