Basicities of primary arylamines and calculated amine nitrogen electronic charges

Mülliken charges on nitrogen atoms were calculated for several arylamines, utilizing the AM1 Quantum Chemistry method, relating their values to experimental amine pKa . Direct relation between pKa and nitrogen charges was found. The amines energies of protonation, calculated by the same method, also correlate directly with these charges.

Physiological cost of induced resistance in cotton plants at different nitrogen levels

Resistance induction through the use of chemical inducers often results in physiological costs to the plant. In this study, induced resistance in cotton plants was evaluated with regard to physiological costs in a cultivar susceptible to Colletotrichum gossypii var. cephalosporioides (CNPA GO 2002 - 7997). Plants were cultivated in substrates with two levels of nitrogen and received two applications of acibenzolar-S-methyl (ASM), jasmonic acid (JA) and Agro-Mos® (AM) disease resistance inducers. Plant height (H), internodal length (IL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW) and root dry weight (RDW) were evaluated. The activity of the phenylalanine ammonia lyase (PAL) and peroxidase (POX) was also determined. The plants treated with ASM presented high physiological costs with an accentuated reduction in H, SFW and SDW, whereas those treated with JA exhibited a significant increase in SDW, and did not significantly differ from H and IL. In the potting mix supplemented with nitrogen, all inducers differed from the control treatment regarding to internodal length, whereas only ASM and AM presented a significant difference between one another in the potting mix without the addition of nitrogen. Significant correlations (P=0.05) were found for most of the variables analyzed, with greater correlations observed between SFW and SDW (0.94); IL and H (0.74); SFW and H (0.70); and SDW and H (0.70). ASM induced the least amount of PAL activity, significantly differing from the remaining treatments. Greater POX activity was observed in ASM, which significantly differed from the control. AM and JA, however, presented lower activity than the control with regard to these enzymes, and it was not possible to confirm induction resistance in these two treatments.

Effect of the application of different water depths and nitrogen and potassium doses on quality of Tanzania grass

The objective of this study was to evaluate the effects of the application of different water depths and nitrogen and potassium doses in the quality of Tanzania grass, in the southern of the state of Tocantins. The experiment was conducted on strips of traditional sprinklers, and used, as treatments, a mixture of fertilizer combinations of N and K2O always in the ratio of 1 N:0.8 K2O. This study determined throughout the experiment: plant height (PH), the crude protein (CP) and neutral detergent fiber (NDF). The highest plant height obtained was 132.4 cm, with a fertilizer dose of 691.71 kg ha-1 in the proportion of N:0.8 K2O, in other words, 384.28 kg ha-1 of N and 307.43 kg ha-1 of K2O, and water depth of 80% of the ETc. The highest crude protein content was 12.2%, with the fertilizer dose application of 700 kg ha-1 yr-1 in the proportion of 1 N to 0.8 of K2O, in other words, 388.89 kg ha-1 of N and 311.11 kg ha-1 of K2O and absence of irrigation. The lowest level of neutral detergent fiber was 60.7% with the application of the smallest dose of fertilizer and highest water depth. It was concluded in this study that there was an increase in plant height by increasing the fertilizer dose and water depth. The crude protein content increased 5.4% in the dry season, by increasing the fertilizer dose and water depth. In the dry season, there was an increase of NDF content by 4.5% by increasing the application of fertilizer and water depth.

Nitrogen fertilization by deep-bedding swine production and its effects on the properties of a Quartzarenic Neosol

The objective of this study was to evaluate the effects of the nitrogen fertilization in the form of swine deep bed in the properties of a quartz-sand neosol. The organic compound used was the deep bed made with rice hulls, from a commercial swine finishing system farm. Deep bed samples have been collected at various points in the installation in order to obtain a representative composite sample which has been fractionated in a 2.0 mm sieve and submitted to a 50-day maturation period. Then, agronomic value analyses were done. The experimental design was completely randomized. The treatments consisted of 0; 75; 150 and 300 mg dm-3 of N doses of deep bed as well as an additional treatment with ammonium sulfate at a 150 mg dm-3 of N. The experimental period in the greenhouse was 45 days, where the soil was cultivated with maize. After the experiment completion, further soil properties analyses were done. From the results, it was noted that the organic fertilization with deep bed provided a significant increase in the levels of potassium, in the sum of the bases, in the effective CEC, in the CEC at pH 7.0 and in the percentage of saturation.

Ratoon sugarcane yield integrated drip-irrigation and nitrogen fertilization

The aim of this study was to compare the use of water and nitrogen on ratoon sugarcane during irrigated and rain-fed conditions, and to assess the production potential of stalks and sugar with different rates of N-fertilizer on the subsurface drip-irrigated management. The experimental design was a randomized block with four replications for each experiment and treatments: (T1) irrigated, 0kg N ha-1; (T2) irrigated, 70kg N ha-1; (T3) irrigated, 140kg N ha-1; (T4) irrigated, 210kg N ha-1; (T5) not irrigated, 0kg N ha-1, and (T6) not irrigated, 140kg N ha-1. Biometric, technological, dry matter and yield variables were analyzed among the treatments. The irrigation system together with the application of N-fertilizer at 140kg ha-1 presented significant differences in dry matter accumulation of shoots, and for the production of stalks and sugar, respectively 94, 105 and 106%, higher when compared to the not irrigated, without N-fertilizer (T5). There was a positive and synergistic effect of irrigation with N-fertilizer on the productivity of stalks and sugar. Ratoon sugarcane irrigated with subsurface dripping had the highest yield (22Mg ha-1 of sugar) with the dosage of 140kg ha-1 N.

Nitrogen fertilization by deep bedding swine production and its effects on dry matter production and accumulation of nutrients by maize

The goal of this study was to evaluate the nitrogen fertilization as deep litter for pigs in order to produce biomass and accumulate nutrients by the corn. A deep litter made of rice husk as organic compound, from a commercial pig farm during finishing phase, was used. After three consecutive batches of pigs, the deep litter was subjected to a maturation period of 50 days, and samples of this material were taken for analysis of agronomic value. The experimental design was completely randomized with five replicates. The treatments consisted of doses of 0, 75, 150 and 300mg dm-3 of N of deep litter, as well as an additional treatment with ammonium sulfate, with a dosage of 150mg dm-3 of N. After 45 days, corn plants were harvested in order to evaluate the total dry weight and nutrient concentrations of their aerial parts. Dry matter increases were found with more application of deep litter. Regarding control fertilization, the use of increasing dosages of deep litter allowed accumulation of K, reduced the availability of P, Ca, Mg, Zn and B and did not alter the concentrations of N, Cu, Fe and Mn.

Removal of nitrogen, phosphorus, copper and zinc from swine breeding waste water by bermudagrass and cattail in constructed wetland systems

This work aimed to study the agronomic performance and capacity of nutrient removal by bermudagrass (Cynodon spp.) and cattail (Typha sp.) when grown in constructed wetlands systems (CWSs) of vertical and horizontal flow, respectively, used in the post-treatment of swine breeding wastewater (ARS). The average yield of dry matter (DM) of bermudagrass in sections of 60-day interval ranged from 14 to 43 t ha-1, while the cultivated cattail produced in a single cut after 200 days of cultivation between 45 and 67 t ha-1 of DM. Bermudagrass extracted up to 17.65 kg ha-1 d-1 of nitrogen, 1.76 kg ha-1 d-1 of phosphorus, 6.67 g ha-1 d-1 of copper and 54.75 g ha-1 d-1 of zinc. Cattail extracted up to 5.10 kg ha-1 d-1 of nitrogen, 1.07 kg ha-1 d-1 of phosphorus, 1.41 g ha-1 d-1 of copper and 16.04 g ha-1 d-1 of zinc. Cattail and bermudagrass were able to remove, respectively, 5.0 and 4.6% of the nitrogen and 11.2 and 5.4% of the phosphorus applied via ARS, being less efficient in extracting N and P when the initial intake of these nutrients is evaluated.

Application of response surface methodology to study the biological removal of nitrogen from effluent of cattle slaughterhouse in a sequencing batch reactor

The aim of this study was to evaluate the efficiency of a sequencing batch reactor (SBR) on biological removal of nitrogen from cattle slaughterhouse wastewater by nitrification/denitrification processes. The effects of initial concentration of ammoniacal nitrogen were investigated at 100; 150 and 200 mg L-1 and air flow rate at 0.125; 0.375 and 0.625 L min¹ Lreactor-1 on the nitrogen compounds removal, by a Central Composite Rotational Design (CCRD) configuration. There were variations from 9.2 to 94.9%, 4.0 to 19.6% and 20.8 to 92.0% in the conversion of ammoniacal nitrogen to nitrate and nitrite concentration and removal of total nitrogen, respectively. The increase of air flow rate and decrease of the initial concentration of ammoniacal nitrogen resulted in higher efficiencies of total nitrogen removal, as well as the conversion of ammoniacal nitrogen to nitrate. During the pre-established intervals of this study, the removal and conversion efficiencies of nitrogen compounds above 85% were achieved in air flow rate variations from 0.375 to 0.725 L min-1 Lreactor-1 and initial concentration of ammoniacal nitrogen from 80 to 200 mg L-1. On denitrification process, we obtained efficiencies from 91.5 to 96.9% on the removal of nitrite/nitrate and from 78.3 to 87.9% on the removal of organic matter.

Ammonia nitrogen desorption from sanitary landfill leachate in filling towers

Sanitary landfill leachates present high concentrations of carbonaceous and nitrogenous materials. The crucial point is that carbonaceous materials are of difficult biodegradation, what compromises the performance of biological treatment processes, while nitrogenous materials, such as ammonia nitrogen, probably preclude the use of biological treatments. Therefore, the aim of this work was to study the desorption process of ammonia nitrogen from sanitary landfill leachate in filling towers. Desorption was carried out in filling towers of 35 L capacity. The leachate was collected from a sanitary landfill located in João Pessoa, Paraíba State, Brazil. Desorption efficiency for the pH values ​​adopted in four treatments was 93% minimum and 95.5% maximum, with aeration mean time ranging from 3 to 6 hours. The limiting factors of ammonia nitrogen desorption from sanitary landfill leachates in filling towers are associated with the use of alkalizer species for pH correction, and electricity costs for aeration.

Leaf concentrations of nitrogen and phosphorus in phaseolus vulgaris l. Plants under high CO2 concentration and drought stress

This study aims to evaluate the leaf concentration of nitrogen and phosphorus correlated to the production of photoassimilates in beans plants (Phaseolus vulgaris L.) under high [CO2] and drought stress. The experiment was conducted in Viçosa (Brazil), during the period from April to July 2009, by using open-top chambers equipped with CO2 injection system. The drought stress was applied, through the irrigation suspension, during the period from flowering to maturation. The experimental design was randomized blocks in split-plot scheme with four replication, where the plots with plants grown in [CO2] of 700 mg L-1 and [CO2] environment of 380 mg L-1 and the subplots with plants with and without drought stress. The results were submitted to ANOVA and Tukey test (p < 0.05). In the plants under high [CO2] with and without drought stress, the photosynthetic rate increased by 59%, while the dry matter presented an increment of 20% in the plants under high [CO2] without drought stress. Reductions in [N] and [P] occurred in plants grown under high [CO2], resulting in greater efficiency in nitrogen use for photosynthesis. The high [CO2] increase only the total dry matter and not the total mass of grains. The drought stress reduces the dry matter and mass of grain, even at high [CO2].

Irrigation with domestic treated sewage and nitrogen fertilizing in sunflower cultivation

The objective of this study was to evaluate the productive performance of sunflower plants irrigated with different levels of domestic treated sewage and groundwater well with different doses of nitrogen. It was used randomized blocks design in split-split plots with four replications. In the plots, we evaluated the effect of two types of irrigation water, in the subplots we evaluated the five irrigation levels expressed as 25, 50, 75, 100 and 125% of the Class A pan Evaporation (CAE), and in the sub subplots, we evaluated the effect of four different doses of nitrogen (25, 50, 75 and 100 kg ha-1). The irrigation of sunflower with domestic sewage produced greater yield potential of grain and oil. The use of water from treated wastewater can replace up to 50 kg N ha-1 without affecting productivity. It is recommended for the commercial production of sunflower the use of treated sewage water with irrigation depth relative to 100% of CAE (296.64 mm) and nitrogen of 25 kg ha-1.