Effect of nitrogen,phosphorus, and potassium fertilizers on yield components and specific gravity of potatoes

Netted Gem potatoes were grown at four levels of N, three of P, and two of K fertilizer in metal lysimeters protected from rain by an automatic shelter. The first two increments of N fertilizer, 200 and 400lb/acre (224 and 448 kg/ha), successively increased yields by increasing the number of tubers produced. The first increment also increased the average tuber weight. With 800 lb N/acre (896 kg N/ha), tuber yield and grade of potatoes were reduced from those of the 400-lb/acre (448-kg/ha) treatment becuase the average weight per tuber was reduced. P fertilizer increased yield by increasing the average tuber weight. The increased yield due to N and P fertilizers was almost entirely in the form of Canada No. 1 potatoes. K fertilizer did not affect number or weight of tubers in this high-K soil.     

Influence of cultivar,harvest-date and soil nitrogen on sucrose,specific gravity and storage stability of potatoes grown in Michigan

The cultivars Atlantic, Belchip, Denali, Monona, Norchip and Russet Burbank were harvested at weekly intervals from early August to early October in 1980–81 and analyzed for the following attributes: 1) sucrose rating (SR) (mg sucrose/g fresh tuber) 2) specific gravity (Sp.G.); 3) total yield and 4) chip color. At the final harvest, samples of each cultivar were stored and analyzed for color to determine chipping ability after storage. All varieties achieved a SR below 1.0 by 145 days of growth. Higher nitrogen levels reduced the total yield for early harvests but had no significant effect for later harvests. Changes in sucrose levels as tubers matured were helpful in evaluating the chemical maturity of more recently developed cultivars in relation to established chipping varieties.     

Relations between specific gravity,dry matter content and starch content of potatoes

Summary Published relations between specific gravity, dry matter content and starch content are summarized in the form of regression equations and a diagram. It is suggested that, for the potato literature, uniformity of presentation of results and of conversion equations used would be desirable.     

Nitrogen and potassium fertilization of potatoes: Yield and specific gravity

Potassium and N fertilization is often required for maximum potato (Solanum tuberosum L.) production. Nitrogen, K, and K-sources (KCl, K₂SO₄ are known to affect yield and quality of potatoes but N and K interactions as affected by K-source have not been defined. This study evaluated the N*K and K-source interactions on Russet Burbank tuber yields and specific gravity (SG) in two irrigated field experiments. Nitrogen rates of 0, 112, 224 or 336 kg ha^-1 were combined with selected K rates of 0,112, 224 or 448 kg ha^-1 as either KC1 or K₂SO₄ in an incomplete factorial. A multiple linear regression model was fit to the data and used to predict yield and SG for a complete factorial for each K-source. Both N and K applications increased yields independent of K-source. Nitrogen decreased yields at the 336 kg ha^-1 rate. Potassium increased yields up to 448 kg K ha^-1. Both K-sources decreased SG a similar amount with N application; without N, KC1 decreased SG but K₂SO₄ did not. Nitrogen also decreased SG. Petiole NO₃-N and K concentrations were positively related to yields and negatively to specific gravities. The petiole K concentration 100 days after planting should be above 4.5 for highest tuber yields. The N*K*K-source interaction was important for yields at low available N and for SG at adequate N availabilities. This study showed that N or K fertilizers can be applied according to their respective soil test concentration and the crop’s requirement, generally without consideration of K-source.     

Sources of fertilizer nitrogen and phosphorus for potatoes in Atlantic Canada

The performance of ammonium, nitrate, ammonium plus nitrate, and urea as sources of nitrogen in combination with superphosphate, monoammonium, and diammonium phosphates for potato production was measured on two soil types in New Brunswick. No N or P sources produced any indication of abnormal plant growth. Yields, specific gravity of tubers and N, K and Mg contents of plant petioles were similar for all N and P combinations. The P content of the plant was higher with ammonium nitrate or urea as N source and with monoammonium or diammonium phosphate as P source. Ca content was higher with N from sodium nitrate and P from superphosphate. It was concluded that availability and costs of fertilizer materials could become a dominant factor in selectng N and P carriers. With no significant cost differential, a preference was indicated for low-risk materials as reflected by reports of damage to developing seedlings and of reduced yields.