Nitrogen fertilization management in no-tillage maize with different winter crops

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Digestibility and nitrogen balance of lambs fed sugarcane hydrolyzed under different conditions as roughage in the diet

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nitrogen fertilization (15NH4NO3) of palisadegrass and residual effect on subsequent no-tillage corn

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

MORPHOGENESIS AND PRODUCTION OF TANZANIA, MOMBACA AND MULATO GRASSES UNDER NITROGEN FERTILIZATION

A field trial was conducted designed in a completely randomized block in a 4 x 3 factorial arrangement to evaluate the application of nitrogen doses (N) (0, 40, 80 and 160 kg/ha) on the morphogenical characteristics and dry matter partition of three forage grasses (Panicum maximum cvs. Mombasa and Tanzania and Brachiaria sp. Hybrid Mulato). The leaf appearance (LAR, leaf/day) and stretching (LER; mm/day) rates, the number of green leaves per tiller (NLT) and the average weight of tillers (MTW; g) presented s positive linear response to the N dose while the phyllochron (Phil; day/leaves) showed a negative linear response. The highest LER, IAL and final leaf length (FLL; cm) occurred in the Mombaca and Tanzania grasses, while the highest LAR occurred in the Mulato grass. There was a negative quadratic effect of the N dose on the stem elongation rate (SER; mm/day) and LF. The Mombaca and Tanzania grasses presented the highest SER; however, in just two forages. The production of total dry matter (TDM; kg/ha), leaves (LDM; kg/ha) and stems (SDM; kg/ha) increased linearly and quadratically with the N dose, respectively, for the Mombaca and Tanzania grasses. There was a high positive correlation among DM, LDM and SDM and the Mombaca grass MTW. The dry matter production and morphogenic characteristics were influenced by the nitrogen fertilization as a result of the substantial increase in the flow of tissues stimulated by fertilization, proving the importance of N for forage biomass accumulation.

Physiological performances of two populations of Compsopogon caeruleus (Rhodophyta) to inorganic nitrogen and phosphorus impoverishment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Seed quality, chlorophyll content index and leaf nitrogen levels in maize inoculated with Azospirillum brasilense

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Morphogenic parameters and productivity of grass-Pioneer subjected to nitrogen

Objective of this work by evaluating the effect of nitrogen on forage yield and morphogenesis of elephant grass cv. Pioneer. The experimental design was randomized blocks with five replications, totaling 20 experimental units. Treatments consisted of four nitrogen levels (100, 200, 300 and 400 kg ha(-1) yr(-1)). The experiment was conducted under irrigated conditions. Evaluative cuts were made at 50 cm soil with values of light interception (95%) without pre-defined intervals. It was observed that N fertilization increased significantly (P<0.05) the production of dry matter per hectare, leaf appearance rate (leaves days(-1)tiller(-1)), leaf elongation rate (cm tiller(-1) day(-1)) and stem elongation rate (cm day(-1)). The process of this forage senescence is accelerated with increasing doses of nitrogen and leaf appearance rate, thereby reducing the phyllochron. It required a study on the economic viability of higher doses of nitrogen in grazed elephant grass cv. Pioneer.

Maize leaf phytotoxicity and grain yield are affected by nitrogen source and application method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efficiency of nitrogen sources and rates on growth and dry matter yield of tifton 85

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Kinetic and thermodynamic investigation of Arthrospira (Spirulina) platensis fed-batch cultivation in a tubular photobioreactor using urea as nitrogen source

BACKGROUND: Fed-batch culture allows the cultivation of Arthrospira platensis using urea as nitrogen source. Tubular photobioreactors substantially increase cell growth, but the successful use of this cheap nitrogen source requires a knowledge of the kinetic and thermodynamic parameters of the process. This work aims at identifying the effect of two independent variables, temperature (T) and urea daily molar flow-rate (U), on cell growth, biomass composition and thermodynamic parameters involved in this photosynthetic cultivation. RESULTS: The optimal values obtained were T = 32 degrees C and U = 1.16 mmol L-1 d-1, under which the maximum cell concentration was 4186 +/- 39 mg L-1, cell productivity 541 +/- 5 mg L-1 d-1 and yield of biomass on nitrogen 14.3 +/- 0.1 mg mg-1. Applying an Arrhenius-type approach, the thermodynamic parameters of growth (?H* = 98.2 kJ mol-1; ?S* = - 0.020 kJ mol-1 K-1; ?G* = 104.1 kJ mol-1) and its thermal inactivation (Delta H-D(0) =168.9 kJ mol-1; Delta S-D(0) = 0.459 kJ mol-1 K-1; Delta G(D)(0) =31.98 kJ mol-1) were estimated. CONCLUSIONS: To maximize cell growth T and U were simultaneously optimized. Biomass lipid content was not influenced by the experimental conditions, while protein content was dependent on both independent variables. Using urea as nitrogen source prevented the inhibitory effect already observed with ammonium salts. Copyright (c) 2012 Society of Chemical Industry

Arthrospira platensis biomass with high protein content cultivated in continuous process using urea as nitrogen source

Aims: Arthrospira platensis has been studied for single-cell protein production because of its biomass composition and its ability of growing in alternative media. This work evaluated the effects of different dilution rates (D) and urea concentrations (N0) on A.similar to platensis continuous culture, in terms of growth, kinetic parameters, biomass composition and nitrogen removal. Methods and results: Arthrospira platensis was continuously cultivated in a glass-made vertical column photobioreactor agitated with Rushton turbines. There were used different dilution rates (0.040.44 day-1) and urea concentrations (0.5 and 5 mmol l-1). With N0 = 5 mmol l-1, the maximum steady-state biomass concentration was1415 mg l-1, achieved with D = 0.04 day-1, but the highest protein content (71.9%) was obtained by applying D = 0.12 day-1, attaining a protein productivity of 106.41 mg l-1 day-1. Nitrogen removal reached 99% on steady-state conditions. Conclusions: The best results were achieved by applying N0 = 5 mmol l-1; however, urea led to inhibitory conditions at D = 0.16 day-1, inducing the system wash-out. The agitation afforded satisfactory mixture and did not harm the trichomes structure. Significance and Impact of the Study: These results can enhance the basis for the continuous removal of nitrogenous wastewater pollutants using cyanobacteria, with an easily assembled photobioreactor.

Active crop sensor to detect variability of nitrogen supply and biomass on sugarcane fields

Nitrogen management has been intensively studied on several crops and recently associated with variable rate on-the-go application based on crop sensors. Such studies are scarce for sugarcane and as a biofuel crop the energy input matters, seeking high positive energy balance production and low carbon emission on the whole production system. This article presents the procedure and shows the first results obtained using a nitrogen and biomass sensor (N-Sensor (TM) ALS, Yara International ASA) to indicate the nitrogen application demands of commercial sugarcane fields. Eight commercial fields from one sugar mill in the state of Sao Paulo, Brazil, varying from 15 to 25 ha in size, were monitored. Conditions varied from sandy to heavy soils and the previous harvesting occurred in May and October 2009, including first, second, and third ratoon stages. Each field was scanned with the sensor three times during the season (at 0.2, 0.4, and 0.6 m stem height), followed by tissue sampling for biomass and nitrogen uptake at ten spots inside the area, guided by the different values shown by the sensor. The results showed a high correlation between sensor values and sugarcane biomass and nitrogen uptake, thereby supporting the potential use of this technology to develop algorithms to manage variable rate application of nitrogen for sugarcane.

Photosynthetic efficiency and rate of CO2 assimilation by Arthrospira (Spirulina) platensis continuously cultivated in a tubular photobioreactor

Similar to other photosynthetic microorganisms, the cyanobacterium Arthrospira platensis can be used to produce pigments, single cell proteins, fatty acids (which can be used for bioenergy), food and feed supplements, and biofixation of CO2. Cultivation in a specifically designed tubular photobioreactor is suitable for photosynthetic biomass production, because the cultivation area can be reduced by distributing the microbial cells vertically, thus avoiding loss of ammonia and CO2. The aim of this study was to investigate the influence of light intensity and dilution rate on the photosynthetic efficiency and CO2 assimilation efficiency of A. platensis cultured in a tubular photobioreactor in a continuous process. Urea was used as a nitrogen source and CO2 as carbon source and for pH control. Steady-state conditions were achieved in most of the runs, indicating that continuous cultivation of this cyanobacterium in a tubular photobioreactor could be an interesting alternative for the large-scale fixation of CO2 to mitigate the greenhouse effect while producing high protein content biomass.

Introducing Acacia mangium trees in Eucalyptus grandis plantations: consequences for soil organic matter stocks and nitrogen mineralization

Background and aims Eucalyptus plantations cover 20 million hectares on highly weathered soils. Large amounts of nitrogen (N) exported during harvesting lead to concerns about their sustainability. Our goal was to assess the potential of introducing A. mangium trees in highly productive Eucalyptus plantations to enhance soil organic matter stocks and N availability. Methods A randomized block design was set up in a Brazilian Ferralsol soil to assess the effects of mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and mixed plantations (50A:50E)on soil organic matter stocks and net N mineralization. Results A 6-year rotation of mono-specific A. mangium plantations led to carbon (C) and N stocks in the forest floor that were 44% lower and 86% higher than in pure E. grandis stands, respectively. Carbon and N stocks were not significantly different between the three treatments in the 0-15 cm soil layer. Field incubations conducted every 4 weeks for the two last years of the rotation estimated net soil N mineralization in 100A and 100E at 124 and 64 kg ha(-1) yr(-1), respectively. Nitrogen inputs to soil with litterfall were of the same order as net N mineralization. Conclusions Acacia mangium trees largely increased the turnover rate of N in the topsoil. Introducing A. mangium trees might improve mineral N availability in soils where commercial Eucalyptus plantations have been managed for a long time.