Different Levels Of Nitrogen Fertilization Research Articles

Influência do azoto amoniacal na emergência de Striga asiatica em milho (Planalto Central de Angola)

Influence of different levels of nitrogen fertilizer on maize to control Striga asiatica in maize (Zea mays cv. SAM3) was studied in farmer’s fields, Chianga, Huambo, between 2008 to 2010. The experiment was laid out in complete randomized design with 4 repetitions. Nitrogen levels were: (0 (Nzero), 30 (N30), 60 (N60), 90 (N90), 120 (N 120) kg N/ha). Results showed that soil nitrogen addition had a significant and positive effect on maize height, earn number and yield. S. asiatica plants per m-2 decreased with nitrogen increase dose and N(90) induced highest suicidal germination of Striga. A significant and negative correlation between the number of S. asiatica and the number of maize earns was observed Conclusion, increasing soil fertility, especially soils nitrogen content, give high crop yields and contribute to decreased S. asiatica emergence.

MAXIMIZING POTATO PRODUCTION VIA NITROGEN FERTILIZATION AND PLANT SPACING

The potato plants (Solanum tuberosum L.) vs. valor were exposed to different levels of nitrogen fertilizer (60, 100, 140, 180 kg N/feddan (4200 m2)) and in-row plant spacing (12.5, 25 and 50 cm) for maximizing the yield production to match food security needs under climate change impacts on Delta region, Egypt. The experiment was carried out during two growing seasons (2010/2011 and 2011/2012) in split plot design at El-Bossily Farm, Agricultural Research Center, El-Behira Governorate, Egypt. The vegetative growth characteristics and yield parameters were measured. The result of this study verified that increasing nitrogen level up to 180 kg N/feddan significantly increased the vegetative growth, total and marketable yields than the other N treatments. The in-row plant spacing 50 cm was significantly increased vegetative growth and yield (kg/plant), but the total yield (kg/m2) had different trend. The highest total yield /m2 was obtained by 12.5 cm treatment. The interaction effect of 180 kg/feddan of N and 12.5cm in-row plant spacing were increased the total tuber yield (kg/m2) significantly. In contrary, the best marketable yield (tubers > 35 mm) /m2 was obtained by 25 and 50 cm in-row plants. This study was concluded that the best agronomic practices for potato production obtained by application 180 kg N/feddan of with in-row plant spacing 25 cm treatment. The economical consideration of the different treatments showed that the best total net income was obtained by 180 kg/feddan N with 50 cm in-row plant spacing.

Effect of Nitrogen Fertilization on the Quality of Swiss Chard at Harvest and during Storage as Minimally Processed Produce

AbstractThe effects of different levels of nitrogen fertilization (0–50–100–150–200 kg/ha), minimal processing and cold storage (14 days at 4C) on yield and quality of fresh‐cut Swiss chard (Beta vulgaris L. var. cicla L.) were evaluated. Increasing the level of nitrogen fertilization over 100 kg N/ha, plants had a higher fresh weight, reduced their dry matter content and resulted taller and leafier. Total and marketable yield increased linearly with increasing nitrogen level. Both nitrate and ascorbic acid content at harvest increased with increasing nitrogen supply. Nitrogen fertilization negatively affected the yield of minimal processing. No effect on appearance and quality loss during cold storage was detected. Reducing nitrogen fertilization could lead to a more environmentally friendly product with no significant loss in yield and quality both for raw plant and fresh‐cut Swiss chard. Minimal processing can improve nutritional quality lowering nitrates and increasing ascorbic acid content in fresh‐cut produce.Practical ApplicationsMinimally processed vegetables have gained a lot of interest among consumers as they are easy to use and ready to eat. Leafy vegetables are the most widespread among fresh‐cut produce. In order to increase the yield and the quality of leafy crops, farmers often supply great amounts of nitrogen fertilizers. Overdoses of nitrogen may negatively affect environment and nutritional quality of raw and minimally processed vegetables. This study focused on the assessment of the dose of nitrogen that can be more environmentally friendly and can assure to the industry of minimal processing, the best quality of raw Swiss chard and the retaining of good quality during storage. The reduction of nitrogen fertilization may lead to a reduction in nitrate content of the plants and, if associated to minimal processing, determines an improvement of the nutritional quality of fresh‐cut Swiss chard.

Heritability of some quantitative characters in five varieties of maize (<i>Zea mays l.</i>,) under the influence of various levels of nitrogen

field experiment was conducted at the Kano University of Science and Technology Wudil teaching and research farm during the 2010 and 2011 rainy seasons. Five varieties of maize were studied to estimate components of genetic variance and heritability of some quantitative characters that might exist among them, under the influence of different levels of Nitrogen fertilizer. The experiment was laid out in a randomized complete block design, and replicated three times. The genotype × different levels of nitrogen fertilizer (G × N) influenced the expression of the ear height and yield component. Analysis of variance for plant height revealed highly significant differences among varieties with genotypic coefficient of variation (1.67%) which is smaller than the phenotypic coefficient of variation (1.72%). The estimate of broad-sense heritability was high (0.79), thus showing the presence of considerable amount of genetic variation in total phenotypic variation. While the analysis of variance for ear height showed highly significant differences among genotypic coefficient of variation (0.93%) which is smaller than the phenotypic coefficient of variation (1.05%). The estimate of broad-sense heritability was high (0.49) indicating the presence of considerable amount of genetic variation in total phenotypic variation. The results confirmed thefindings of other researchers on high heritability for plant height. Analysis of variance for grain yield per plot showed greater Genotypic variance than the environmental variance with genotypic coefficient of variation (5.33%) which is smaller than the phenotypic Coefficient of variation (6.24%)and the estimate of broad sense heritability (0.78) was moderately high.Keywords: Heritability, variation, ear height, genes.

Evaluation Forage Clipping Stages and Different Levels of Nitrogen on Grain and Forage Yields of TRITICALE (× TRITICOSECALE WITTMACK)

In order to reach suitable forage clipping and estimate nitrogen fertilizer to most economical proficiency, an experiment was carried out at Saatlo Station in 2008-2009 seasons. A factorial experiment was done based on the randomized complete blocks design with 4 replications. The first factor was three levels of clipping stages including non-clipping, clipping at tillering and booting stages. Different levels of nitrogen fertilizer including 0, 40, 80, 120 and 160 kg/ha were arranged at the second factor. Results showed that non-clipping and clipping at booting stage with 610.5 and 203.1 g/m2 had the most and the lowest grain yield, respectively. The highest economical proficiency (3743.06 $/ha) resulted with using 80 kg/ha nitrogen fertilizer and non-clipping. With considering both forage and grain yield, it is necessary that the clipping should be done at tillering stage with using of 120 kg/ha nitrogen fertilizer (3336.56 $/ha). At regression of economical proficiency traits of grain yield, straw and total dry matter remained at the final model. Economical proficiency had the significant positive correlation with spike per square meter (0.87**), grain yield (0.64**), total dry matter (0.65**), plant height (0.52**) and 1000-kernal weight (0.54**).

Response of new rice for Africa (NERICA) varieties to different levels of nitrogen fertilization in Zimbabwe

The new rice for Africa (NERICA) varieties were bred and released in West Africa. This rice has high yield, good quality and other agronomic traits that include adaptability to harsh environments found in Africa. Zimbabwe, recently introduced NERICA varieties, however, the best performing NERICA varieties under local conditions were not known and the optimum level of nitrogen fertilization for those varieties was unknown. A study was carried out to evaluate the response of introduced NERICA varieties to different levels of nitrogen fertilization in Zimbabwe during the 2011/2012 summer season. A four by four factorial experiment in a randomized complete block design was used. One factor consisted of four levels of nitrogen (0, 39.5, 64.5, and 89.5 kg / ha) and the other had four varieties (NERICA 1, NERICA 3, NERICA 7 and Mhara 1). Analysis of variance showed that there was no significant interaction between nitrogen fertilization rates and varieties. However, significant nitrogen effects (P < 0.05) were found on plant height, panicle length, filled grains per panicle, unfilled grains per panicle, grains per panicle and grain yield. Grain yield for level 1 (0 kg N / ha) was significantly reduced compared to nitrogen addition, but level 2 (39.5 kg N / ha), level 3 (64.5 kg N / ha) and level 4 (89.5 kg N / ha) were not significantly different. This showed that the optimum level of nitrogen fertilization is 39.5 kg N / ha. Varieties showed significant differences (P < 0.05) for days to 50% heading, plant height, filled grains per panicle, filled grain ratio, grains per panicle, 1000 grain weight and grain yield. All NERICA varieties performed better than the local check variety, Mhara 1 and NERICA 3 had the best yield followed by NERICA 7. Growing of these NERICA varieties using the nitrogen rate of 39.5 kg / ha can boost rice yield in Zimbabwe. Key words: Upland rice, new rice for Africa, nitrogen fertilization, grain yield.

English

The study was carried out to show the effect of different levels of nitrogen fertilizer 0, 20, 40 and 60 kg urea/ha, and two seeding rates 15 and 30 kg/ha. The study was conducted at Bakrajo research field during the winter season 2011-2012 to some growth characteristics of Egyptian clover, such as plant height, dry leaf weight percent, dry stem weight percent, leave stem ratio, fresh yield t/ha, dry yield t/ha and dry matter percent. The experiment was designed as (R.C.B.D). The results can be summarized as follow; significant differences were observed between all three cuts, and the third cut was superior in almost characters especially in the forage yield. The application of 40 and 60 kg urea gave maximum yield. Using 15 kg seeds/ha showed superior value due to fresh yield in compare to 30 kg for all cutting, while the dry yield responded non-significantly to seeding rates.

Effects of pyridoxine and different levels of nitrogen on qualitative and quantitative yield of Physalis alkekeng

Alkekengi (Physalis alkekengi) is a medicinal plant from Solanaceae family which contains some important alkaloid compounds including Physalin. To evaluate the effect of pyridoxine and different levels of nitrogen fertilizer on yield of the alkekengi medicinal plant used the randomized complete block design with three nitrogen levels (included total application of 100 (control), 150 and 200 kg N ha-1) in the main plots and three pyridoxine treatment included 0 (control), 0.02% and 0.04% in subplots in three replications. Results of this study shows that both pyridoxine and nitrogen treatments have significant positive effects on yield of alkekengi. According to the results, 0.04% pyridoxine and 150 kg N ha-1 treatment resulted in maximum values for yield, as compared to other treatments. The lowest yield was obtained by application of 100 kg N ha-1 and no pyridoxine (control treatment). * Corresponding Author: Atefeh Khoshlahjeh  a.khoshlahjeh@yahoo.com

Growth and Grain Yield of Pearl Millet (Pennisetum glaucum) Genotypes at Different Levels of Nitrogen Fertilization in the Southeastern United States

Pearl millet (Pennisetum glaucum [L.] R. Br) has the requisite characteristics for dry land production in the southeastern USA in comparison to the traditional grain crops while requiring less input. The purpose of this study was to identify the genotypes that produce the highest yield and seed quality at different rates of nitrogen. Four pearl millet genotypes (2304, LHB08, 606A1*2304 and 707A1*4280) were cultivated on secondary land and treated with 4 different nitrogen rates: 0, 40, 80 and 120 kg ha-1. The genotypes were evaluated for agronomic parameters including booting, number of tillers, plant height, plant weight, number of heads, head length and yield. Nitrogen rate did not have any significant effect on the head length, number of tillers and plant (dry) weight among the genotypes. Plant height ranged between 96 and 111 cm and was significantly different among the genotypes. However, numerically, genotype LHB08 produced the longest heads (42 cm) and highest seed yield (6,159 kg ha-1) across all treatments. Overall, nitrogen rate did not produce significant difference in yield among the genotypes. Since grain yield obtained in this study is comparable to those reported elsewhere, it can be inferred that pearl millet has the potential as a new grain crop for the southeastern United States. Furthermore, results demonstrated that pearl millet can be grown with limited N-input. As N-fertilization is the major cost of producing any crop, pearl millet offers special opportunity for large number of limited resource farmers in the region.

Proteomic Analysis for Low and High Nitrogen-Responsive Proteins in the Leaves of Rice Genotypes Grown at Three Nitrogen Levels

Nitrogen (N) is an essential nutrient for plants. Increase in crop production is associated with increase in N fertilizers. Excessive use of N fertilizers and the low nitrogen utilization efficiency by crop plants is a major cause for environmental damage. Therefore, to reduce the N-fertilizer pollution, there is an urgent need to improve nitrogen use efficiency. Identification and/or development of genotypes which can grow and yield well at low nitrogen levels may provide a solution. Understanding the molecular mechanism of differential nitrogen use efficiency of the genotypes may provide some clues. Keeping the above facts in mind, in this study we have identified the high N-responsive and low N-responsive contrasting rice genotypes, out of 20 genotypes that were grown at low (1 mM), moderate (10 mM), and high (25 mM) levels of N (KNO(3)). Proteome analysis of leaves revealed that the proteins involved in the energy production/regulation and metabolism in plant leaf tissues are differentially expressed under N treatments. Moreover, some disease-resistant and stress-induced proteins were found to be overexpressed at high levels of N. The present study could be useful in identifying proteins responding to different levels of nitrogen fertilization, which may open new avenues for a better understanding of N use efficiency, and for developing new strategies to enhance N efficiency in cereal crops.

이앙 및 수확시기에 따른 녹원찰벼의 녹색정도와 수량변화

녹원찰벼를 이앙시기와 질소시비 조건을 달리하여 재배한 후 수확시기별로 녹색정도 및 수량성의 변화를 구명하여 녹원찰벼의 녹색정도 및 수량성을 고려한 재배기술을 확립하고자 수행하여 얻어진 결과는 다음과 같다. 1. 출수기는 이앙시기가 늦어질수록 지연되었고, 질소시 비량별로는 차이가 없었다. 2. 이앙시기에 따른 녹색미 비율은 6월 10일 이앙에서 높았으며, 질소시비량별로는 유의적인 차가 인정되지 않았다. 3. 녹색 현미수량은 6월 10일 이앙까지 이앙시기가 늦어질수록 증가하였으나 6월 15일 이앙에서는 감소하였고, 질소시비량이 많아질수록 증가하였다. 4. 녹색 현미수량 향상을 위한 적정 이앙시기는 6월 4일~6일, 적정 질소 시비량은 9 kg/10 a 이었다. 5. 수확시기에 따른 녹색 현미수량은 출수 후 37일 수확에서 가장 많았으며, 출수 후 37일 이후 수확에서는 급격히 감소하였다. 6. 녹색 현미수량 향상을 위한 적정 수확시기는 출수 후 35~37일이었다. This study was conducted to investigate the yield and greenness of "Nogwonchalbyeo" on the basis of different date of transplanting and harvesting. Delay in heading was observed in the plants transplanted later but no effect on heading was observed due to different levels of nitrogen fertilizer. Percentage of green color in dehusked rice was higher in the grains of rice transplanted on 10th June. An increasing trend was observed in the yield with the delay in the date of transplanting, maximum yield was observed in the rice planted on 10th June but a decrease in yield was recorded if transplanted after 15th June. Similarly, yield also increase as the days for harvesting increased until 37 days after heading but beyond 37 days decreasing trend was observed in yield. Based on the above findings it can be suggested that 4~6 June and 9kg/10a are the optimum dates of transplanting and amount of nitrogen while 3 5~37 days after heading is the best time for harvesting of "Nogwonchalbyeo".

Influence of Nitrogen Fertilizer on Ash, Organic Carbon, Phosphorus, Potassium, and Fiber of Forage Corn Intercropped by Three Cultivars of Berseem Clover as Cover Crops in Semi Arid Region of Iran

Supplementation of animal feeds with high quality needs new agriculture management, like intercropping system. In order to determine qualitative characteristics of forage corn intercropped by berseem clover cultivars in different levels of nitrogen fertilizer, an experiment was conducted in 2010 at Research Farm, Faculty of Agriculture, Islamic Azad University, Khorasgan Branch, Esfahan. A factorial layout within randomized complete block design with 3 replications was used. Cultivars were Karaj, Sacromont and Multicut, and nitrogen levels were included 0, 40 and 60 kg/ha. The nitrogen fertilizer was provided from urea source (46% pure N). Cultivar had significant effect on ash percentage, P, organic carbon of soil and soil nitrogen percentage. Nitrogen had significant influence on ash, K, organic carbon of soil, soil nitrogen percentage, light transmission, solar radiation absorption and extinction coefficient. Organic carbon of soil and soil nitrogen percentage just significantly influenced by cultivar and nitrogen interaction. In this experiment the highest ash percentage, organic carbon of plant, ENDF was obtained in forage corn intercropped by Multicut. The maximum organic carbon of soil and soil nitrogen percentage also related to forage corn and Multicut intercropping. The highest ash percentage, organic carbon, ENDF, organic carbon of soil, soil nitrogen percentage and solar radiation absorption was obtained in forage corn and Multicut intercropping.

Effect of sowing date and different levels of nitrogen fertilizer on yield and essence of flower in medicinal plant of Calendula officinalis L.

Management of chemical fertilizers application is very important in their effect on environment and plant yield especially in arid and semi-arid region. In order to determine the effect of different sowing date and levels of nitrogen fertilizer on yield, morphological characteristics and essence of Calendula officinalis a field experiment was conducted using split plot on the basis of randomized complete block design with three replications at Agriculture Research Center of Sistan, Iran during 2008-2009. Main plots were consisted of sowing date in 3 levels, 1th, 15th and 30th of April and sub plots included levels of nitrogen fertilizer in 2 levels (50 and 100 kg/ha) (to be consistent with the rest of the work). The evaluating factors were weight of stem, the number of flower in 5 plants, weight of fresh flower, weight of dry flower and essence content. The results of main effects of compound variance analysis including sowing date and nitrogen fertilizer showed that sowing date on April 1st and 50 kg/ha of nitrogen fertilizer had the most effect in increasing these factors. Also, interaction effects of sowing date nitrogen fertilizer was significant at 5% probability level on all factors. In general, the results of this research demonstrated that using of suitable sowing date along with consumption of 50 kg/ha nitrogen increase yield and essence of C. officinalis. Key words: Calendula officinalis, sowing date, nitrogen fertilizer, yield, essence.

Influence of different levels of nitrogen, phosphorus and potassium on yield and yield components of flax seed oil (Linum usitatissimum L.) variety Lirina

In order to study the effect of different levels of nitrogen, phosphorus and potassium on the quantitative characteristics of oil flax seed oil an experiment was conducted in agricultural research farm Abouraihan Tehran University, at 2009. The experiment was designed as factorial based on randomize complete block (RCB) with three replications. Different levels of nitrogen fertilizer consisted of three levels (N1=30, N2=60, N3=90 kg.ha-1) and three levels of phosphorus fertilizer (P1=40, P2=80, P3=120 kg.ha-1) and three levels of potassium (K1=40, K2=80, K3=120 kg.ha-1), were applied respectively. Traits, branch number, capsules number, number of seeds per capsule, weight of 1000 seed and seed yield was studied in this experiment. The results showed that 90, 120, 80 kg.ha-1 of nitrogen, phosphorus and potassium significantly increased the branches number, capsules number and seed yield. Based on the results mean grain yield was obtained (2384.28 kg.ha-10). Key words: Nitrogen, phosphorus, potassium, seed yield, flax.

Cultivar Differences in Nitrogen Use Efficiency of Field Grown Rice Plants at Different Levels of Nitrogen Fertilizer

Cultivar Differences in Nitrogen Use Efficiency of Field Grown Rice Plants at Different Levels of Nitrogen Fertilizer

Weed control strategies and yield response in a pepper crop ( Capsicum annuum L.) mulched with hairy vetch ( Vicia villosa Roth.) and oat ( Avena sativa L.) residues

Organic mulches could be a part of a wide strategy of integrated weed management in vegetable production systems. A 2-year field experiment was carried out in Central Italy with the aim of assessing the effect of grass and legume mulches, coming from winter cover crops, combined with herbicide or mechanical hoeing on weed control, on weed community (density and aboveground biomass of each species), and yield of a pepper crop. Hairy vetch ( Vicia villosa Roth), oat ( Avena sativa L.) and their mixture were sown in early autumn and suppressed in May. The cover crop aboveground biomass was cut and arranged in strips which were used as beds for pepper seedlings transplanted in paired rows. A conventional treatment kept bare during the cover crop growing season with two different levels of nitrogen fertilizer on pepper (0–100 kg ha −1 of N) was also included. Three weed control treatments were applied between the paired pepper rows 30 days after transplanting: a weed free treatment, glyphosate or mechanical hoeing. Dry matter production at cover crop suppression ranged from 5.3 t ha −1 in oat to 7.1 t ha −1 in hairy vetch/oat mixture and the N accumulation ranged from 56 kg ha −1 in oat to 179 kg ha −1 in hairy vetch. Within the pepper paired rows, mulch treatments reduced weed density and biomass throughout the pepper cropping season. At harvest, weed density and aboveground biomass within the pepper paired rows ranged from 1.7 to 4.6 plants m −2 and 28 and 133 g m −2 of DM, respectively. Oat mulch had the highest weed suppression ability and the lowest species richness, Shannon’s index and Shannon evenness. Between the pepper paired rows the mulch treatments had the highest species richness and the most diverse weed community in chemical compared to mechanical weed control. The densities of Portulaca oleracea L. and Polygonum aviculare L. were the highest under chemical and mechanical control, respectively. The weeds did not hinder pepper production in hairy vetch and hairy vetch/oat mixture where the yield was similar to that obtained in a conventional weed-free system fertilized with 100 kg ha −1 of N. Therefore the use of hairy vetch mulches in combination with reduced mechanical or chemical weed control could be a feasible strategy in order to control weeds and to produce high yields in a pepper crop.

Growth index in massai grass under different levels of nitrogen fertilization

This study aimed to evaluate the growth index of massai grass during two regrowth cycles in a greenhouse under five levels of nitrogen (0, 150, 300, 450 and 600 mg N/dm3 of soil) and eight growth ages (5, 8, 11, 14, 17, 20, 23 and 26 days) in a split-plot design with five replications. The following variables were evaluated: net assimilation rate, herbage growth rate, relative growth rate, leaf area ratio, leaf weight ratio and specific leaf area. The effect of nitrogen was detected on the variables net assimilation rate (regrowths 1 and 2), leaf area ratio (regrowth 1), leaf weight ratio (regrowths 1 and 2), specific leaf area (regrowths 1 and 2) and herbage growth rate (regrowths 1 and 2). The growth ages influenced the relative growth rate (regrowth 2) and the net assimilation rate (regrowth 2). The net assimilation rate presented linear effect, estimated in 0.70 and 2.86 g/m2 leaf.day-1 for the 0 and 600 mg N/dm3 soil, respectively (regrowth 1). For each milligram of N/dm3 added, the leaf area ratio was reduced in 0.0000258 m2 leaf/g plant (regrowth 1). The herbage growth rate was estimated in 1.38 and 37.02 g/m2.day-1 (regrowth 1), and 4.37 and 32.20 g/m2.day-1 (regrowth 2) for the 0 and 600 mg N/dm3 soil, respectively. The massai grass' growth is favored by nitrogen fertilization, and little do the growth ages affect the growth index of the plants.

Review and Model-Based Analysis of Factors Influencing Soil Carbon Sequestration Beneath Switchgrass (Panicum virgatum)

A multi-compartment model was developed to summarize existing data and predict soil carbon sequestration beneath switchgrass (Panicum virgatum) in the southeastern USA. Soil carbon sequestration is an important part of sustainable switchgrass production for bioenergy because soil organic matter promotes water retention, nutrient supply, and soil properties that minimize erosion. A literature review was undertaken for the purpose of model parameterization. A sensitivity analysis of the model indicated that predictions of soil carbon sequestration were affected most by changes in aboveground biomass production, the ratio of belowground-to-aboveground biomass production, and mean annual temperature. Simulations indicated that the annual rate of soil carbon sequestration approached steady state after a decade of switchgrass growth while predicted mineral soil carbon stocks were still increasing. A model-based experiment was performed to predict rates of soil carbon sequestration at different levels of nitrogen fertilization and initial soil carbon stocks (to a 30-cm depth). At a mean annual temperature of 13°C, the predicted rate of soil carbon sequestration varied from −28 to 114 g C m−2 year−1 (after 30 years) and was greater than zero in 11 of 12 simulations that varied initial surface soil carbon stocks from 1 to 5 kg C m−2 and nitrogen fertilization from 0 to 18 g N m−2 year−1. The modeling indicated that more research is needed on the process of biomass allocation and on nitrogen loss from mature plantations, respectively, to improve our understanding of carbon and nitrogen dynamics in switchgrass agriculture.

Effect of Fertilization on Growth and Wood Properties of Thinned and Unthinned Midrotation Loblolly Pine (Pinus taeda L.) Stands

Abstract Growth and wood properties were measured on breast height cores collected from two stands, New Bern and Bertie, located in the lower Coastal Plain of North Carolina. The New Bern site was thinned before fertilizer application, and the Bertie site was not. The study was laid out in a randomized complete block design with each treatment replicated in four blocks at New Bern and two blocks at Bertie. The treatments were different levels of nitrogen fertilization: control (no nitrogen) and 112, 224, and 336 kg/ha. In addition, 28 kg/ha of phosphorus was included with each treatment. The objective of this study was to examine the response in growth and wood properties to midrotation fertilization in a thinned versus an unthinned stand. A significant decrease in latewood specific gravity was observed following nitrogen fertilization in the thinned stand but not in the unthinned stand. Whole ring width, latewood width, and earlywood width significantly increased following nitrogen fertilization at New Bern but not at Bertie. Whole ring specific gravity, earlywood specific gravity, latewood percentage, and earlywood:latewood ratio did not show any change due to fertilization in either stand. Responses in both growth and wood characteristics lasted for 2–3 years following fertilization and depended on the amount of fertilizer applied and whether or not the site was thinned. The response to nitrogen application was significant for the thinned stand only.

Improving Yield and Quality of Sugar Beet Using Boron at Different Levels of Nitrogen Fertilizer

Improving Yield and Quality of Sugar Beet Using Boron at Different Levels of Nitrogen Fertilizer