.F. 2013 Nitrogen fertilization of Black Walnut ( Juglans nigra L.) during plantation establishment. Morphology and production efficiency For. Sci. 59 453 463 Guajardo, J. Saa, S. Camps, R. Besoain, X. 2017 Outbreak of crown and root rot of walnut caused
Javiera Morales, Ximena Besoain, Italo F. Cuneo, Alejandra Larach, Laureano Alvarado, Alejandro Cáceres-Mella and Sebastian Saa
C.A. Mullins, R.A. Straw, B. Pitt Jr., D.O. Onks, M.D. Mullen, J. Reynolds and M. Kirchner
`Silver Queen', `Incredible', and `Challenger' sweet corn (Zea mays L.) cultivars were evaluated at different nitrogen (N) fertilization rates at Springfield, Tenn., in 1993, 1994, and 1995. `Incredible' was more productive than `Silver Queen' and `Challenger'. Of the three cultivars, `Silver Queen' had the tallest plants, longest ears, and most attractive ears. Nitrogen fertilization rates were 0, 50, 100, and 150 (100 lb/acre at planting and 50 lb/acre sidedressed) lb/acre (0,56, 112, and 168 kg·ha-1). The 100 lb/acre rate of N applied at planting appeared to be sufficient for producing sweet corn in soils with an annual cropping frequency. Height of plants and ear diameters were larger at the higher fertilization rates, but differences among treatments were not great and were usually not significant. The cultivars of different genetic types did not differ in response to N fertilization rates. Cultivar × year interactions were significant for most factors evaluated, but most other interactions were not significant.
Mark A. Smith, George C. Elliott and Mark P. Bridgen
The effects of Ca and N on cut flower production of Alstroemeria were determined in separate greenhouse experiments. Calcium was supplied as Ca(NO3)2 and CaCl2 at 0, 1, 2, 4, 8, and 12 mmol·L-1 added to tap water containing Ca at ≈0.2 mmol·L-1. Nitrogen was supplied as KNO3 and Ca(NO3)2 providing total N at 0, 3.5, 7, 14, 28.5, and 57 mmol·L-1 in tap water containing N <0.2 mmol·L-1. Nutrient solutions were applied at 7- or 10-day intervals to plants growing in a soilless medium in 2.6- or 5.5-L containers. Flowering stems were harvested when the primary florets opened. Total N concentration was measured in leaf tissue from the upper portion of flowering stems. Flower production was not affected by Ca supply, but increased with N supply to a maximum of about four stems per plant on a weekly basis at 28.5 mmol·L-1, then decreased to less than three stems per plant at 57 mmol·L-1. Nitrogen concentration in leaf tissue on a dry mass basis was maintained at 45 ±3 g·kg-1 in plants supplied with N at 28.5 mmol·L-1, 52±5 g·kg-1 at 57 mmol·L-1, but <40 g·kg-1 with N supply of 14 mmol·L-1 or lower. Nitrogen fertilization of Alstroemeria should be managed to maintain leaf tissue N close to 45 g·kg-1.
Kebede Woldetsadik, Ulla Gertsson and Johan Ascard
Two field experiments were conducted with shallot (Allium cepa var. ascalonicum Baker) on heavy clay soil to evaluate growth and yield response to mulching and nitrogen fertilization under the subhumid tropical climate of eastern Ethiopia during the short and main rainy seasons of 1999 with rainfalls amounting to 240 and 295 mm, respectively. The treatments included wheat straw, clear and black plastic mulches, and an unmulched control, each with nitrogen rates of 0, 75, or 150 kg·ha-1. Straw and black plastic mulches increased soil moisture while clear plastic reduced it considerably. Weed control was best with black and clear plastics in the short season and with black plastic or straw mulch in the main season. Both plastic mulches elevated soil temperature, especially clear plastic, which also caused most leaf tip burn. Yield increased nearly three-fold with the black plastic mulch in the short season and by one fourth in the main season compared to the bare ground. The straw and clear plastic mulches increased yield during the short sea son, but slightly reduced yield in the main season. The growth and yield of shallot were related to the weed control and soil moisture conservation efficiency of the mulches. Mulching did not alter the dry matter and the total soluble solids contents of the bulbs. Nitrogen fertilizer increased leaf numbers, plant height, mean bulb weight, bulb dry matter, and total soluble solids while reducing marketable bulb number, but did not significantly affect yield, leaf tip burn, or weed abundance.
Clinton C. Shock, Erik B. G. Feibert and Lamont D. Saunders
Onion (Allium cepa L.) production in the Treasure Valley of eastern Oregon and southwestern Idaho has been based on furrow irrigation with 318 kg·ha-1 N fertilizer and average yields of 70 Mg·ha-1, but these practices have been implicated in nitrate contamination of groundwater. Drip irrigation, introduced in the early 1990s, has several advantages, including reduced leaching losses. Since onion plant populations and N fertilizer rates can affect economic returns, studies were conducted in 1999, 2000, and 2001 to determine optimum plant populations and N fertilizer rates for subsurface drip-irrigated onion. Long-day onion (`Vision') was subjected to a combination of seven nitrogen fertilization rates (0 to 336 kg·ha-1 in 56-kg increments applied between late May and early July) and four plant populations (185, 250, 300, and 370 thousand plants/ha). Onion was grown on silt loam in two double rows spaced 0.56 m apart on 1.1 m beds with a drip tape buried 13 cm deep in the bed center. Soil water potential was maintained nearly constant at -20 kPa by automated irrigations based on soil water potential measurements at a 0.2-m depth. Onion bulbs were evaluated for yield and grade after 70 days of storage. Onion yield and grade were highly responsive to plant population. Onion marketable yield increased, and bulb diameter decreased with increasing plant population. Within the range of plant populations tested, gross returns were not always responsive to plant population. Returns were increased by the increase in marketable yield obtained with higher plant population, but higher plant population also reduced the production of the largest sized bulbs which had the highest value per weight. Onion yielded 95 Mg·ha-1 with no applied N fertilizer, averaged over plant populations and years. Onion yield and grade were not responsive to N fertilizer rate or interaction of N fertilizer rate with plant population. Preplant soil available N, N mineralization, and N in irrigation water all contributed N to the crop. Onion N uptake did not increase with increasing N fertilizer rate.
Paolo Sambo*, Daniele Borsato and Giorgio Gianquinto
Research at Padova Univ., Italy, during Summer 2003, was carried out to determine the effect on nitrogen fertilization on yield and canopy reflectance of sweet bell pepper (Capsicum annuum). Pepper var. Tolomeo LRP 4993 (Syngenta) was transplanted into plots (24 m2) on 20 May, maintaining 40 cm between plants and 75 cm between rows (3.3 plant per m2). The experimental design was a randomized block with four replicates. Treatments were 6 nitrogen fertilization rates ranging from 0 to 300 kg·ha-1. Nitrogen was distributed at planting and as top dressing, 44 days after planting. All other production techniques were typical of pepper production in the Veneto region. Beginning the second week after transplanting, canopy reflectance was measured weekly using a multispectral radiometer MSR 87 (Cropscan Rochester, Minn.). Fruits were harvested at breaking color stage starting from 21 July to 9 Oct. (8 harvests). At harvest, total and marketable yield, fruit averaged weight and nitrogen content were determined. Maximum yield was recorded at the 120 kg·ha-1 nitrogen treatment, while higher rates proved ineffective at increasing production. Nitrogen rates positively affected fruit weight. The nitrate content of fruits also increased with the nitrogen rates although it remained below the level dangerous for human health. Canopy reflectance was able to detect the different nitrogen treatments only during the late stages of the growth cycle making difficult its use as a tool to drive nitrogen fertilization.
M. Meheriuk, D.-L. McKenzie, G.H. Neilsen and J.W. Hall
Four green apple (Malus domestica Borkh.) cultivars, `Granny Smith', `Mutsu', `Newtown', and `Shamrock', were subjected to a factorial experiment of two rates of nitrogen fertilization and three concentrations of foliar urea sprays for 4 years. The higher rate of N (160 kg N/ha) had no effect on ground color or fruit quality relative to the lower rate of 80 kg N/ha. Urea sprays enhanced green pigmentation in `Granny Smith' and `Newtown' at harvest and retarded yellowing of fruit in all cultivars during air storage at 0C. Response was similar for urea at 0.5% and 1%, and urea sprays did not adversely affect quality. Urea sprays increased fruit N by 23% and 47% for the 0.5% and 1% concentrations, respectively.
Mark V. Yelanich and John A. Biernbaum
A model constructed to describe nitrogen dynamics in the root zone of subirrigated container-grown chrysanthemum was used to develop and test nitrogen fertilization strategies. The model predicts the nitrogen concentration in the root zone by numerical integration of the rates of nitrogen applied, plant nitrogen uptake, and nitrogen movement to the medium top layer. The three strategies tested were constant liquid N fertilization, proportional derivative control (PD) based upon weekly saturated medium extraction (SME) tests, or PD control based upon daily SME tests. The optimal concentration of N to apply using a single fertilization concentration was 14 mol·m–3, but resulted in greater quantities of N being applied than if PD controller strategies were used. The PD controllers were better able to maintain the predicted SME concentration within 7 to 14 mol·m–3 optimal range and reduce the overall sample variability over time. Applying 14 mol·m–3 N at every irrigation was found to be an adequate fertilization strategy over a wide range of environmental conditions because N was applied in excess of what was needed by the plant.
Bielinski M. Santos and James P. Gilreath
A 2-year field study was conducted in two locations in the Dominican Republic to determine the influence of various support systems and nitrogen fertilization programs on passion fruit (Passiflora edulis var. flavicarpa) yield and economic returns. Three trellis systems were used: 1) single line, where a single wire was placed along the planting rows at 2 m high; 2) double lines, where two wires were established along the planting rows at 2 and 1 m high, respectively; and 3) crossed lines, with wires at 2 m high, allowing the vines to grow both along and across the planting rows. Nitrogen (N) fertilization rates were 13, 26, and 52 g/plant of N every 20 days. Plants trained with the single- and double-line support systems combined with 52 g/plant of N had higher marketable yield and had the lowest proportion of non-marketable fruit/plant per year. Partial budget analysis indicated that the single-line support system had a marginal return rate of 36% compared to the double-line support system.
N. Tremblay and C. Bélec
The necessity of achieving appropriate nitrogen fertilization of vegetable crops relates to both economical and environmental sustainability. Split nitrogen applications have been shown to improve N-use efficiency, in line with the aforementioned objective and should therefore be encouraged. Given the variation in the amount of N naturally provided to, or uptaken by, the crop, strategies are required to tailor supplementary fertilization to actual crop needs, keeping in mind the absolute requirement for optimal yield in quality and quantity. It is suggested that the fertilization rates applied at sowing or later in the season can be figured in two manners. The first relies on modelling; the second on measurements. The modelling (N budget) approach, mostly linked to initiatives on the European continent, would be most applicable to the determination of the first fertilizer dressing. When a plant stand is established, however, canopy-based measurements made either directly or remotely could be developed to make use of the capability of the plants to integrate the properties of the soil environment and to decide upon further top-dressed applications. For this purpose, a fully fertilized “reference plot” has to be introduced in the field in order to overcome the variability induced by season, site and cultivar. With the emergence of “precision farming” and “remote sensing technologies” it is now possible to adjust fertilizer inputs not only at the field level but also within fields based on actual, localized requirements.