The joint action of nitrogen and nematicides onPratylenchus penetrans and potato yield

The joint action of nitrogen fertilizer and nematicides onPratylenchus penetrons and yield was investigated using three potato varieties (Superior, Onaway and Russet Burbank), three rates of nitrogen (84, 168 and 336 kg/ha), five edaphic pesticides (disulfoton, aldicarb, 1,3-D + MIC, carbofuran and thiofanox), and an insecticide spray to minimize the role of foliar feeding insects In 1977, disulfoton, aldicarb, and disulfoton plus 1,3-D + MIC significantly increased the yield of Superior at all nitrogen rates. The yield increases ranged from 37–56% for Superior, 15–35% for Onaway and 13–27% for Russet Burbank. Nitrogen had no detectable influence on yield. Population densities ofP. penetrans were significantly reduced by disulfoton plus 1,3-D + MIC and by aldicarb. Superior was most susceptible toP. penetrans, Onaway intermediate, and Russet Burbank moderately tolerant. Neither the potato variety or nitrogen significantly influenced the population densities ofP. penetrans In 1978 aldicarb, 1,3-D + MIC and thiofanox significantly increased yields of Superior at all nitrogen rates. Nitrogen also significantly increased yields, but only where aldicarb and 1,3-D + MIC were applied. Total yield was increased 12–14% and 17–23% by 1,3-D + MIC and aldicarb at 168 and 336 kg N/ha, respectively. Aldicarb, 1,3-D + MIC, and thiofanox appeared to increase tuber set, while nitrogen increased tuber size. Although all of the nematicides provided some control ofP. penetrans, aldicarb had the highest degree of efficacy and gave excellent season-long control     

Efficiency of nitrogen uptake by potatoes

White Rose potatoes were fertilized with isotopically labeled ammonium sulfate at rates of 67, 134, 202 and 270 kg N/ha to evaluate N uptake efficiency. All N application increased yields above the control, however the 3 higher N rates produced the same yields statistically. All N rates which maximized yields maintained petiole levels of total N above 600 ppm. Rapid changes in petiole inorganic N occurred during the growing season. Fertilizer derived inorganic N decreased at rates ranging from 67 to 518 ppm/day during the third month after planting. Total inorganic N in petioles during the same period dropped at rates ranging from 500 to 880 ppm/ day. Tubers grown in N-fertilized plots assimilated total N in a nearly linear pattern during the period 82 to 125 days after planting. Uptake of total N ranged from 142 to 233 kg/ha. In assessing N utilization by 3 methods, good agreement was achieved between the isotope and difference method in the first and third (last) samplings, however, agreement was poor between the two in the second sampling. With N rates to 202 kg/ha the uptake efficiency was about 57% but dropped to 39% with application of 270 kg N/ha. When uptake efficiency was measured by dry matter production in relation to units of N fertilizer, the 67 kg N rate was superior to other rates. Inorganic N levels in the surface meter of soil were higher before planting and fertilizer application than after harvest. Following harvest the control plots had more N below 1.5 m than did the N fertilized plots. In control plots, the total inorganic N between 1.5 and 2.5 m depths was equivalent to 170 kg N/ha. Virtually none of the accumulated N below 1 m was due to labeled N applied in the experiment. Using 134 kg N/ha as the optimum rate, tubers removed 178 kg N/ha of which 78 kg was derived from the applied fertilizer. With total N input of 191 kg/ha (57 kg N/ha from irrigation water) the N rate required for maximum yield would pose no risk of nitrate pollution since it represents only 13 kg more than crop removal (191 vs 178 kg N/ha).     

The effect of nematicides onPratylenchus penetrans and potato yields

Aldicarb applied as Temik 10% or 15% granular at 1.68, 2.24 or 3.36 kg/ha active ingredient (a.i.) in the row at planting reduced the size of populations ofPratylenchus penetrons in experimental plots and commercial fields. Both aldicarb and the soil fumigant, Telone-II, were associated with yield increases of about 40% in Superior and Sebago potatoes in experimental plots in 1978, but there were no significant increases in yield in 1979 and 1980. A comparison was made between areas treated with aldicarb 10% granular at 2.24 kg/ha a.i. or disulfoton 15% granular at 3.36 kg/ha a.i. in 24 commercial fields. Average yields from the combined results of Kennebec, Superior, Sebago, and Russet Burbank cultivars were about 13% higher in the aldicarb treatments. Yields in six fields where aldicarb was applied at 3.36 kg/ha a.i. were not different from yields in adjacent fields treated with the lower rate of aldicarb. Superior potatoes inoculated withP. penetrons, or uninoculated, were grown in pots in the greenhouse in fine sandy loam at moisture levels of 35–55% or 70–100% field capacity. The lower soil moisture level and the nematode treatment reduced tuber weights. The nematode-soil moisture interaction was significant in one of the two experiments.     

Dry-matter production,and nutrient uptake and removal bySolanum andigena in the Peruvian Andes

A Field experiment withSolanum andigena (cv. Renacimiento) at three levels of fertilization was conducted in the Mantaro Valley (Central Sierra) of Peru during the 1967–68 growing season. Dry matter and nutrient accumulation in tops and tubers of Renacimiento potatoes were determined at 3-week intervals between 72 and 172 days after planting (42 and 142 days after emergence). Tuber initiation took place during the interval 116–137 days after planting, and top growth reached its maximum shortly thereafter. Total growth rates of 200 kg/ha/day⁴ (178 lb/a/day) where estimated under medium and high fertilization, and tuber dry matter accounted for 70–75% of the total dry matter produced. Final tuber yields (fresh, 21% dry matter) ranged from 10m.t./ha (89 cwt/a) without fertilizer to 41 m.t/ha (366 cwt/a) when fertilized with 160 kg each of N, P₂O₅ and K₂O/ha (143 lb/a). Under high fertilization, total N, P, and K accumulation was estimated at 141, 19, and 403 kg/ha (126, 17 and 359 lb/a), respectively, with 77 kg (68 lb/a) of N, 14 kg (12 lb/a) of P, and 224 kg (200lb/a) of K being removed in the tubers.     

Direct application of reduced rates of aldicarb to potato seedpieces

Aldicarb was applied directly to potato seedpieces at 0.3, 0.6, 1.1, 2.2 and 3.4 kg AI/ha at planting and at 2.24 kg Al/ha over the plants at crop emergence. All seedpiece treatments resulted in superior early season protection from Colorado potato beetle,Leptinotarsa decemlineata (Say). Lower seedpiece rates lost effectiveness by early July, while higher rates protected foliage into early August. In a second study, plots treated with 1.1 kg AI/ha to the seedpiece produced crop yields as high as those treated with additional aldicarb at crop emergence. It is suggested that low rates of aldicarb applied directly to the seedpiece at planting could offer effective early season insect control while reducing the risk of groundwater contamination.     

THE EFFECT OF THE TIME AND LEVEL OF INJECTION OF ANHYDROUS AMMONIA ON THE PRODUCTIVITY OF GRASSLAND

Four levels of nitrogen, 188, 285, 358 and 392 kgJ.ha (150, 225, 285 and 350 units/ac) supplied as anhydrous ammonia were injected on each of four occasions, 18 Dec, 5 Feb., 12 Mar. and 16 Apr. DM and CP yields were estimated at each of three harvests taken on 4 June, 19 July and 28 Sept Total DM yields showed only a 10% difference between the highest yielding injection date, 12 Mar., which yielded 12270 kg/ha (10946 Ib/ac) and the lowest, 16 Apr., which yielded 11169 kgJ.ha (9963 Ib/ac). Early injection of ammonia promoted growth during the late spring and later injections resulted in increased yields at the two later harvests. The responses per kg fertilizer N were 11.9 kg DM (10.8 lb/unit) and 3.6 kg CP (3–3 Ib/unit). It was concluded that ammonia should be applied to grassland before April and, preferably, during March, for maximum yields of DM and CP.     

AMMONIA AS A SOURCE OF NITROGEN FOR GRASS SWARDS

Aqueous ammonia was injected to a depth of 10 cm into small grass plots in late winter at rates equivalent to 200 and 400 kg N per ha. The effect on yield of DM, seasonal distribution of yield and uptake of N in the herbage was compared with that of single or split applications of ammonium nitrate. Two levels of supplementary irrigation were given in summer. The method of injection minimised damage to the sward and loss of ammonia by volatilization.
Aqueous ammonia and ammonium nitrate (single application) gave similar yields of dry matter, uptake of N and distribution of yield over the season. Ammonia was no more effective than ammonium nitrate under dry conditions. A single application in February of 200 kg N/ha as ammonium nitrate gave a greater total annual yield than the same quantity of N as ammonia or as a split dressing of the solid fertilizer. At 400 kg N/ha, split application gave the highest yields. The uptakes of N in the harvested grass was similar, in each irrigation treatment and at each level of N, for the three methods of applying N, The apparent recovery was low.
Aqueous ammonia, efficiently injected, was a satisfactory form of N for grass at the first cut, but it did not provide a continuing supply of N for crops harvested later in that season.     

Insecticide control of the potato tuberworm in late-crop potato foliage

The systemic insecticides, Dasanit^®, carbofuran (Furadan^®), phorate (Thimet^®), aldicarb (Temik^®) and disulfoton (Di-Syston^®) were applied in the planting furrow at 2–3 lb actual/acre for potato tuberworm (Phthorimaea operculella (Zeller)) control in Irish potato foliage. None of these compounds gave entirely satisfactory results. Dasanit was the best with slightly over 80% decrease in the number of mines and was followed closely by carbofuran; all treatments needed to be supplemented by foliage sprays for satisfactory tuberworm protection. Azinphosmethyl (Guthion^®) gave consistently outstanding results as a foliage spray at 0.5 lb/acre with over 99% tuberworm reduction. Other foliar-applied insecticides giving at least 98% tuberworm control included: Monitor^®, monocrotophos (Azodrin^®), phosphamidon, Orthene^®, Torak^®, methomyl (Lannate^®) and Dursban^® (all at 0.5 lb/acre) and Phosvel^® (1 lb/acre).     

THE EFFECT OF CUTTING HEIGHT AND NITROGEN LEVEL ON THE YIELD, IN VITRO DIGESTIBILITY AND CHEMICAL COMPOSITION OF ITALIAN RYEGRASS SWARDS

Three cutting heights, 2±5, 7±6 and 12±7 cm (1, 2±5 and 5 in.) and three levels of fertilizer N, 168, 280 and 392 kg N/ha (150, 250 and 350 Ib N/ac) were imposed on a sward of Italian ryegrass (Lolium multiflorum) cv. Irish. Lowering the cutting height and increasing the level of applied N increased the yield of herhage DM. Increasing the level of applied N had a greater effect on the chemical composition of the herbage than altering the cutting height     

POTENTIAL PASTURE PRODUCTION IN THE UPLANDS OF WALES

Study of the growth of heavily fertilized swards of S23 perennial ryegrass (Lolium perenne) at a hill and a lowland centre in mid-Wales during 1968–69 demonstrated that lower productivity in the uplands could only be partially attributed to a shorter growing season and poorer summer growth conditions. Comparison of yields with potential transpiration estimates indicated that winter damage had an important bearing on production during the following year. In 1969, the adverse combination of a mild autumn and a severe winter led to a spring tiller density which was less than 25% of normal at the hill centre. With an annual fertilizer input of over 500 kg N/ha (480 lb N/ac) total DM production in 1968 and 1969 was 10.6 and 4.4 t/ha at the upland site compared with 14.8 and 10.1 t/ha in the lowlands (9450, 3920, 13,190 and 9000 lb/ac).     

Effect of fertilizer,fumigants, and fungicides on leafroll-net necrosis in Russet Burbank potatoes

A total of 112 combinations of 13 fumigants, fertilizers, and a fungicide was tested in replicated plots in eastern Washington in 1963 and 1964 to determine their effects on the net necrosis produced in Russet Burbank potatoes by the leafroll virus. Plots treated with Telone^® (dichloropropenes) or Telone+chloropicrin had significantly fewer tubers discolored with leafroll net necrosis than untreated plots; plots treated with lower rates of various chlorinated propenes and propanes or ethylene dibromide had fewer discolored tubers than plots treated with higher rates of these chemicals; and plots treated with higher rates of various combinations of dichloropropenes with methyl isothiocyanate or 3-bromo-1-propyne had fewer discolored tubers than plots treated with lower rates of these chemicals. An interaction took place between the chemicals and the leafroll virus that either increased or decreased the amount of net necrosis in the tubers. Other types of internal discoloration (OID) in the tubers were significantly increased by Telone treatments in some tests. Telone treatments showed no effects on OID in other tests compared to untreated tubers. Also, nitrogen, at 100 lb/acre and over, significantly increased the other types of discoloration over no nitrogen, but potassium at 0 to 150 lb/acre and pentachloronitrobenzene (PCNB) at 0 to 30 gal/acre showed no significant effect.     

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.     

THE EFFECT OF NITROGENOUS FERTILIZER ON THE RATE OF GROWTH OF ITALIAN RYEGRASS

In an experiment described earlier (13), the N content of Italian ryegrass in spring reached a high value one or two weeks after applying N and then fell quickly at first and then more slowly. After 10 weeks average N content (in DM) was 0.6% from an application of 25 lh N/ac (28 kg/ha), 0.9% from 75 lb N (84 kg/ha), and 12% from 125 lb N (140 kgJha). Nitrate-N content fell more abruptly and tben remained fairly constant. Percentage nitrate–N (in DM) fell below 0.10% during the second week after an application of 25 lb NJac, during the third week after 75 lb N, and during the fifth week after recciriag 125 lb N. The yield of N increased during the first 5 or 6 weeks, remained fairly constant for 3–5 weeks, and then hegan to fall. During the ninth and tenth weeks, the crop lost an average of 9 lb N/ac per week (10 kg/ha) after an application of 75 Ib N/ac and 12 lb N/ac per week (13 kg/ha) after 125 Ib N.     

GRASSLAND RESEARCH ON BLANKET PEAT IN IRELAND

The results from 10 years of grassland research at the Peatland Experimental Station, Glenamoy, are summarized.
Grass and legume species were introduced by surface seeding, without cultivation or by direct seeding after rotavation, depending on the specific situation. The rate of establishment was dependent on pretreatment and the management of grazing animals before and after sowing.
The most suitable species were Trifolium repens, Lolium perenne, Festuca arumlinacea, Festuca rubra and Holcus lanatus .
A level of fertility suited to the introduced species must be reached initially and subsequently maintained. The requirements (per/ac) for Ca, P, K, N, Cu and Co were: 2240 lb (1016 kg) ground limestone, 36 lb (16 kg) P, 112 lb (51 kg) K, 20 lb (9 kg) N, 20 lb (9 kg) CuSO₄ and 2 lb (0–91 kg) CoSO₄ at sowing, with 27 lb (12–25 kg) P and 56 lb (254 kg) K annually.
Dry–matter yields of 6000 lb/ac (6720 kg/ha) were obtained from grass–clover swards without fertilizer N, and approximately twice this quantity where 400 lb N/ac (448 kg/ha) had been applied annually. A liveweight gain of 526 lb/ac (589–12 kg/ha) and a starch equivalent output of 2946 lb (3299–5 kg) were obtained with sheep. The relationship between these results and those on peat soils abroad are discussed.     

A COMPARISON BETWEEN A PADDOCK SYSTEM AND A 'WYE COLLEGE' SYSTEM OF GRAZING FOR MILK PRODUCTION

Two grazing systems, a paddock system and a ‘Wye College’ system, were compared in two 20-week experiments nsing 16 and 20 spring-calved Ayrshire cows in 1970 and 1971, respectively. A sward of S23 perennial ryegrass was used, and an average of 342 kg N/ha (305 lb N/ ac) was applied per annum. The paddock system had 28 separate paddocks; one paddock was grazed each day in rotation and occasionally topped in mid-season. The Wye College system had 4 plots of equal size and the cows were offered 1/7 of one plot each day; no back fence was used and surplus herbage was neither cut nor topped. The stocking rate on hoth systems was 1 cow per 0.20 ha (0.49 ac) in 1970 and per 0.16 ha (0.40 ac) in 1971. The mean daily milk yields per cow on the paddock and the Wye College systems were 16.2 and 15.3 kg (35.7 and 33.7 lb), respectively, in 1970; and 18.1 and 18.4 kg (39.9 and 40.6 lb) in 1971. The average annual output of milk was 13,500 and 13,150 kg/ha (1200 and 1170 gal/ac) on the paddock and Wye College systems, respectively. The fat and solids-not-fat (S.N.F.) contents of the milk were not significantly affected by the grazing system. It is concluded that the Wye College system was as effective as the paddock system in producing a high output of mUk per ha, but at a lower cost and with far fewer management decisions.     

THE EFFECT OF SHOOLY LARVAE (DIPTERA) ON GRASS YIELD

Elimination of shooly larvae increased grass yields daring the September feeding period. Increases were usually less than 10% bat in one case, where growth was abnormally slow, die increase was over 30% and in another, where the larval population was atypically dense, it was almost 60%. The effects of damage were not cumulative daring the feeding period; and at the end of this period insecticidreated plots sometimes gave lower yields than untreated plots. Fertilizer increases had a much greater effect on yield than did control of larvae and, where N was applied at 75 kg/ha (67 lb/ac) in spring, the additional effect of larval control was usually negligible. It is suggested that shoot-fly damage may be more serious in other localities. When turf containing shoot-fly larvae was ploughed, Oscinella spp. re-established themselves more successfully than others in seedling ryegrass bat did not damage the new sward appreciably.     

Effect of rate and time of fertilization on nitrogen and yield of Russet Burbank potatoes under center pivot irrigation

Applying less N on Russet Burbank potatoes (Solanum tuberosum L.) at planting time may reduce the potential loss of N from sandy soil by wind erosion and leaching early in the season. The objective of this study was to evaluate the effect of rate and time of N fertilization on potato production. Potatoes were grown in outdoor pot cultures with N rates of 75,150 and 300 ppm and in field plots with N rates from 112 to 448 kg N/ha applied in single and split applications. The results from pot cultures harvested after one month’s growth showed that yield of tops increased and tuber yield decreased as applied N at planting increased from 75 ppm to 150 or 300 ppm. Field results showed that the yield of potatoes was as high or higher when N applications were split between planting and when plants were 15 to 20 cm tall (early tuberization) as with the same amount of N applied at planting. Generally 112 kg N/ha at planting time was sufficient when additional N was applied after emergence. Split application of N resulted in more second growth on tubers than when all of the N was applied at planting.     

THE EFFECTS OF CUTTING AND FERTILIZER TREATMENTS ON THE YIELD AND BOTANICAL COMPOSITION OF CHALK TURF

Annual factorial applications of N and K fertilizers, with or without mowing, to Festuca rubra turf on a chalk rendzina at Swyncombe, Oxon, had large effects on yield and botanical composition over a period of 10 years. The yield of herbage was increased markedly hy N, and less by K, but the N × K interaction was significant. Mean yields of herbage DM for tbe 10-year period were: no N or K, 730 kg/ha per year; N, 1967; K, 1013; N+K, 2794 kg/ha per year (651, 1755, 904 and 2492 lb/ac per year). N caused an increase in DM production by F. rubra; the NxK interaction was a result of increased growth of species other tban F. rubra. Unmown plots became extremely matted, and undecomposed litter of F. rubra leaves and stems accumulated, especially if N, or N and K together, were given. F. rubra turf seems to he unusually stable, apparently because it forms a mat in which other more demanding species cannot establish themselves.     

Planting date and nitrogen management interactions in irrigated maize

It is becoming increasingly important to develop economically and environmentally sound nitrogen fertilizer management practices. The objective of this experiment was to determine the optimum N application time-crop planting time combination(s) at two N rates which would maximize N fertilizer use efficiency (NFUE) and maintain high grain yields of irrigated maize (Zea mays L.) in the western Corn Belt of the USA. Maize was planted three times at biweekly intervals during 1979–1981 on a Typic Argiudoll in eastern Nebraska. The ¹⁵N-depleted (NH₄)₂SO₄ was applied at rates of 90 or 180 kg N/ha in a band midway between maize rows at planting, or at the 4-, 8-, or 16-leaf growth stage during 1979–1980. Control plots (no N fertilizer applied) were maintained in each planting date. No N was applied during 1981 to allow study of residual treatment effects. Grain dry-matter yield and total N and fertilizer N (FN) contents of grain were determined, and NFUE was calculated as the fraction of FN in grain to applied FN.Very high N supply by the soil resulted in small effects of FN on yield and NFUE during the first year of treatment. According to the response surface analysis, greatest NFUE (52%) in concert with high grain yield (11.2 Mg/ha, the predicted maximum) would have been achieved by applying the low N rate at the 13- to 14-leaf growth stage to maize planted during the week before the average date of 10 May. Due to lower soil N supply the 2nd year of treatment, most corn with 90 kg N/ha did not produce near-maximum grain yields. However, yields within 10% of maximum were obtained when 90 kg N/ha was applied to the early planting at the 14- to 16-leaf stage, and NFUE was 67–71% with this treatment. Maximum NFUE with the application of 180 kg N/ha was only 44%. Recovery of residual FN in this silty clay loam soil was an important factor in the improvement of NFUE with delayed N applications the second year of treatment. In 1981, recovery of residual FN generally increased with a previous delay in N application time and was not greatly influenced by planting time. Early planting in combination with a modest rate of N applied very late during vegetative growth provided maximum recovery of FN in harvested grain, while maintaining high grain yields.     

The effect of phosphorus fertilization on the chemical quality of Katahdin potatoes

The influence of phosphorus fertilization on the content of ascorbic acid, lipids, total nitrogen, protein, and non-protein nitrogen of Katahdin potatoes was investigated. Phosphorus in the form of mono ammonium phosphate was applied at rates of 0, 56, 112, and 168 Kg/ha (0, 50, 100, and 150 lb/acre). Ascorbic acid, total nitrogen, protein and non-protein nitrogen content were significantly increased (p<.01) and the phospholipid content was significantly reduced (p<.01) by phosphorus application.