Effects of rate, source and distribution method of nitrogen fertilizer on seed potato production

Abstract

Seed potatoes are grown on the high plateaux of northern Israel where it is cool enough for a summer crop. The seed are used for winter production of ware potatoes in southern Israel. Irrigation is essential because of the arid summers. It is customary to apply much of the N fertilizer through the irrigation system in numerous small doses. Total N rates have ranged between 300 and 400 kg/ha. In 1975 various aspects of N, P, K fertilization for seed potato (Solanum tuberosum L., var. Up-ToDate) production were examined. There were no responses to P or K fertilizers so only the N fertilizer responses are reported here. MATERIAL AND METHODSThe experimental site was on a plateau which is 900 m above sea level. The soil, an alluvial Brown Mediterranean clay loam, was derived from tunic and basaltic materials. The surface soil pH in 001 M-CaCl 2 was 5-5 and contained 1*4% organic matter. Soil tests indicated that available P and K levels were very high which explains the lack of response to P and K fertilizers.The N treatments were all combinations of two rates (175 and 350 kg N/ha), two sources (urea and ammonium sulphate), and two distribution methods (all at planting and split). Split N was applied in equal amounts: at planting, 23, 37, 50, 62 and 74 days after the start of growth. Each split N application was broadcast just previous to a scheduled irrigation. An overall dressing of 50 and 166 kg/ha of P and K as ordinary superphosphate (8 % P) and K g SO 4 was applied prior to planting. The latter and at-planting N fertilizer was broadcast and incorporated to a 20 cm depth by rotovation.Plots were 3-6 x 13 m and consisted of four rows. The in-row seed spacing was 25 cm. The centre two rows were used for sampling and yield measurements. Treatments were randomized and replicated in five blocks. The at-planting fertilizer applications and planting was done in dry soil. The start of growth was counted from 13 May with the application of 70 mm of water. Soil moisture was maintained near optimum without excessive leaching by sprinkler irrigation using evaporation pan data. Water was applied when moisture tension approached 0-6 bars at 30 cm below the ridges. Standard cultural and pesticide practices for seed potato production were followed.Plant samples, consisting of the total aboveground growth (canopy) and tubers in 1 m of row, were procured at 91 days after the start of growth which was close to the peak canopy growth stage. Haulms were chemically desiccated 130 days (19 September) after growth initiation and the tubers were dug for final yields 16 days later. Tubers were separated into seed (3-6 cm) and ware potatoes (> 6 cm). RESULTS AND DISCUSSIONThe final yields (Table 1), although not always statistically significant, showed certain definite trends. The lower N rate, the (NH 4 ) 2 SO 4 source and the split application of N resulted in higher yields than their counterparts. The treatment (low rate of split applied ammonium sulphate) with the 0021-8596/80/2828-3710 801.00

Growth, nitrogen uptake and partitioning within the potato (Solatium tuberosum L.) crop, in relation to nitrogen application

“…The sampling of field experiments has usually been too infrequent to establish accurately the time of tuber initiation, but Dyson & Watson (1971) reported that nitrogen slowed the early growth of tubers. Since high rates of nitrogen application stimulate excessive canopy dry-matter production, Baker, Ben Heyuda & Kafkafi (1980) suggested that dividing the application of fertilizer into six equal dressings applied at regular intervals during the season might increase tuber yield by increasing dry-matter partitioning to the tubers. In the present study, withholding half the fertilizer nitrogen until after tuber initiation had no effect on either nitrogen uptake or tuber yield, except when comparing the divided and single applications of 20 g N/m a in 1984.…”

Threshold Value for Chlorophyll Meter as Decision Tool for Nitrogen Management of Potato

“…Millard and Marshall (1986) showed that potato can take up more N than is needed to satisfy immediate requirements for growth. High rates of N application stimulate excessive canopy dry‐matter production (Baker et al, 1980).…”