Time Of Nitrogen Application Research Articles

Doses e épocas de aplicação de nitrogênio em cobertura na qualidade fisiológica de sementes de milho doce

A quantidade e a época de aplicação de nitrogênio em cobertura podem favorecer a qualidade fisiológica das sementes, com o aumento do teor de proteína, que são importantes no desenvolvimento do embrião. Neste trabalho objetivou-se avaliar a qualidade fisiológica de sementes de milho doce provenientes de plantas cultivadas sob diferentes doses e épocas de aplicação de nitrogênio em cobertura. Foram utilizadas sementes da variedade BR 400, provenientes de plantas submetidas às doses de 0, 40, 80, e 120 kg ha-1 de N aplicadas nos estádios vegetativo e reprodutivo. Foram determinadas a massa de 100 sementes, germinação, primeira contagem de germinação, a massa seca e o crescimento de plântulas, o vigor, pelos testes de frio, envelhecimento acelerado, emergência de plântulas no campo, tetrazólio, condutividade elétrica e índice de velocidade de emergência. Os dados foram submetidos à análise de variância pelo teste F a 5% e a estudo de regressão até 2° grau. As doses e épocas de aplicação de nitrogênio em cobertura não afetaram a massa de sementes e a germinação das sementes de milho doce. O aumento da dose de N em cobertura, com aplicação no estádio vegetativo, reduziu o comprimento da parte aérea, de raiz e total das plântulas.

Effect of Time and Methods of Nitrogen and Potassium Application at Different Growth Stages on Hybrid 1 and Giza 178 Rice Cultivare.

Effect of Time and Methods of Nitrogen and Potassium Application at Different Growth Stages on Hybrid 1 and Giza 178 Rice Cultivare.

多収性水稲品種「タカナリ」の効率的収量確保のための窒素施用時期

多収性水稲品種「タカナリ」の効率的収量確保のための窒素施用時期

Application times, sources and doses of nitrogen on wheat cultivars under no till in the Cerrado region

Proper management of nitrogen fertilization and using cultivars with high productive potential are essential to obtain high wheat yield. Thus, the objective of the present study was to assess the effects of different N doses and sources, one with a nitrification inhibitor, applied at sowing or as side dressing, on the production components and yield of two wheat cultivars irrigated, under no till, cultivated in a region of low altitude Cerrado (Selvíria - MS). A randomized block design was used in a 5x3x2x2 factorial arrangement, that is, five nitrogen doses (0, 50, 100, 150 and 200kg ha-1), three nitrogen sources (ammonium sulfonitrate with nitrification inhibitor (Entec®), ammonium sulfate and urea) and two nitrogen application times (at sowing or side dressing) on two wheat cultivars ('E 22' and 'E 42') with three replications. There was no difference for grain yield between the wheat cultivars and among the nitrogen sources. The application of nitrogen totally at sowing is feasible as well as the traditional application at sowing and side dressing. The nitrogen doses increased the leaf N content of the 'E 22' cultivar, resulting in a reduction in the hectolitric mass of the 'E 42' cultivar and increased grain yield of the 'E 22' and 'E 42' wheat yield cultivars, respectively, up to doses of 126 and 122kg ha-1 N, regardless of the application time and the nitrogen source.

FONTES E ÉPOCAS DE APLICAÇÃO DE NITROGÊNIO EM FEIJOEIRO DE INVERNO SOB SISTEMA PLANTIO DIRETO

The use of nitrogen by common bean is dependent on the source, dose and application time. This study aimed to evaluate the effect of N sources and application times on common bean under no-till system, in Selvíria, Mato Grosso do Sul State, Brazil, in 2006 and 2007. Treatments were disposed in a randomized blocks design, in a 3x6 factorial scheme, with four replications. Nitrogen sources (urea, entec, and ammonium sulfate) and application times (control - without N, at sowing, at the V3 development stage, at the V4-5 development stage, 1/3 at sowing + 2/3 at the V3 stage, and 1/3 at sowing + 2/3 at the V4-5 stage) were evaluated. The N sources had similar influence on common bean yield, affecting only the N leaf content, in 2006, and the use of entec provided leaf nutrient concentrations equivalent to the urea ones. The application of all available N at sowing affected the initial and final plant stands, in 2006, while the same was not observed in 2007. Application times did not influence on grains yield, for both years, however, in 2006, the nitrogen fertilization increased yield in more than 100%, on average, independently of the application time.

Soil organic carbon sequestration as affected by tillage, crop residue, and nitrogen application in rice–wheat rotation system

Despite being a major domain of global food supply, rice–wheat cropping system is questioned for its contribution to carbon flux. Enhancing the organic carbon pool in this system is therefore necessary to reduce environmental degradation and maintain agricultural productivity. A field experiment (November 2002–March 2006) evaluated the effects of soil management practices such as tillage, crop residue, and timing of nitrogen (N) application on soil organic carbon (SOC) sequestration in the lowland of Chitwan Valley of Nepal. Rice (Oryza sativa L.) and wheat (Triticum aestivum L.) were grown in rotation adding 12 Mg ha−1 y−1 of field-dried residue. Mung-bean (Vigna radiata L.) was grown as a cover crop between the wheat and the rice. Timing of N application based on leaf color chart method was compared with recommended method of N application. At the end of the experiment SOC sequestration was quantified for five depths within 50 cm of soil profile. The difference in SOC sequestration between methods of N application was not apparent. However, soils sequestered significantly higher amount of SOC in the whole profile (0–50 cm soil depth) with more pronounced effect seen at 0–15 cm soil depth under no-tillage as compared with the SOC under conventional tillage. Crop residues added to no-tillage soils outperformed other treatment interactions. It is concluded that a rice–wheat system would serve as a greater sink of organic carbon with residue application under no-tillage system than with or without residue application when compared to the conventional tillage system in this condition.

Nitrogen Management Effect on the Production of Two Sweet Sorghum Cultivars under Arid Regions Conditions

A two years field study was conducted to evaluate the effect of response of two sweet sorghum cultivars to different sources and time of nitrogen application during 2009 and 2010 at experimental farm Faculty of Agriculture, South Valley University at Qena Governorate, Egypt. Two cultivars viz. Tracy and Honey and six combination of source and application time of nitrogen fertilizes viz. ammonium sulphate, 20.5% N in two equal doses (T1) and in three equal doses (T2), ammonium nitrate, 33.5% N in two equal doses (T3) and in three equal doses (T4), urea, 46.5% N in two equal doses (T5) and in three equal doses (T6) were tested in the study. The experiment was laid out in split plot design with cultivars in main plots and nitrogen fertilizers in sub-plots. Among sweet sorghum cultivars, cv Honey had the highest stalk height, stalk diameter, number of internodes per stalk, Brix value, sucrose content, apparent purity percentage and stalk and forage (leaves) yields and lowest reducing sugar content. Application of T4 gave the highest value of the above measurements and lowest reducing sugar content. Cultivar and nitrogen treatments interaction was significant on stalk and forage yields as well as reducing sugar content. The highest stalk and forage yields and lowest reducing sugar content were obtained by planting cv Honey and application of ammonium nitrate in three equal doses (at planting , 4 leaf stage and booting). Plant height, stalk diameter, forage yield, brix and sucrose were positively and strongly correlated with stalk yield.

PRODUTIVIDADE DO ARROZ DE TERRAS ALTAS EM FUNÇÃO DO MANEJO DO SOLO E DA ÉPOCA DE APLICAÇÃO DE NITROGÊNIO

Proper soil management and N application time can significantly increase upland rice yield. Thus, the objective of this study was to evaluate the interaction between soil management and nitrogen application time on upland rice development and yield. The experimental design was randomized blocks, in a 5x2 factorial scheme, consisting of five soil management systems (moldboard plow and leveling disc harrow; harrow plow and leveling disc harrow; “matabroto”-type scarifier; no-tillage; and “Aeromix” - superficial scarification equipment) and two N application times (all N in the base, being 45 kg ha -1 of N applied with the aid of a mechanical traction fertilizer machine, 1 day before rice sowing, + 45 kg ha -1 of N at sowing; and 45 kg ha -1 of N at sowing + 45 kg ha -1 at the beginning of plant tillering), with 4 repetitions. There was no interaction among factors, concerning final plants stand. For treatments where the soil was plowed by using moldboard plow and disk harrow, yield was higher when the nitrogen was parceled out. When nitrogen was all applied during the planting time, the treatment with the “matabroto”-type scarifier presented the highest yield, differing statistically from all the other treatments. Conventional tillage yield (moldboard plow or disk harrow) was similar to no-tillage, when all N was applied during the planting time. KEY-WORDS: Oryza sativa ; no-tillage; conventional tillage; scarification.

DOSES E ÉPOCAS DE APLICAÇÃO DE NITROGÊNIO EM ARROZ DE VÁRZEA

The most outstanding crop, concerning agribusiness in the Roraima State, is lowland rice. Therefore, the recommendation of new cultivars, as well as the study of correct handling for nitrogen fertilizing, are important to maximize grain yield and reduce production costs and environmental impacts. Thus, the objective of this study was to identify the nitrogen doses and application times most adjusted to the rice cultivar BRS Jacana, in Roraima lowlands. The experiment took place at the Santa Cecilia Farm, a lowland area of the Rio Branco river, in Canta, Roraima State, Brazil, from December (2007) to March (2008), on a tb distrophic haplic gleissol. The experiments were conducted under a split-plot scheme, with plots displayed under a randomized blocks design with four replicates. Treatments consisted of four N doses (50 kg ha -1 , 100 kg ha -1 , 150 kg ha -1 , and 200 kg ha -1 ), combined with four application times: E1 - half dose at sowing and half 45 days after emergence (dae); E2 - half dose 15 days after emergence (dae) and half 45 days after emergence (dae); E3 - one application 15 days after emergence (dae); and E4 - one application 45 days after emergence (dae), totalizing 16 treatments and 64 experimental units. Concerning the BRS Jacana lowland rice cultivar, the best combination was the application of 118 kg ha -1 of nitrogen, half at sowing and half 45 days after emergence. KEY-WORDS: Oryza sativa L.; lowland rice; maximum economic yield.

Chlorophyll meter-based nitrogen management of rice grown under alternate wetting and drying irrigation

Farmers have adopted alternate wetting and drying (AWD) irrigation to cope with water scarcity in rice production. This practice shifts rice land away from being continuously anaerobic to being partly aerobic, thus affecting nutrient availability to the rice plant, and requiring some adjustment in nutrient management. The use of a chlorophyll meter (also known as a SPAD meter) has been proven effective in increasing nitrogen-use efficiency (NUE) in continuously flooded (CF) rice, but its use has not been investigated under AWD irrigation. This study aimed at testing the hypotheses that (i) SPAD-based N management can be applied to AWD in the same way it is used in CF rice, and (ii) combining chlorophyll meter-based nitrogen management and AWD can enhance NUE, save water, and maintain high rice yield. Experiments were conducted in a split-plot design with four replications in the 2004 and 2005 dry seasons (DS) at IRRI. The main plots were three water treatments: CF, AWD that involved irrigation application when the soil dried to soil water potential at 15-cm depth of −20 kPa (AWD −20) and −80 kPa (AWD −80) in 2004, and AWD −10 and AWD −50 were used in 2005. The subplots were five N management treatments: zero N (N 0), 180 kg N ha −1 in four splits (N 180), and three SPAD-based N-management treatments in which N was applied when the SPAD reading of the youngest fully extended leaf was less than or equaled 35 (N SPAD35), 38 (N SPAD38), and 41 (N SPAD41). In 2005, N SPAD32 was tested instead of N SPAD41. A good correlation between leaf N content per unit leaf area and the SPAD reading was observed for all water treatments, suggesting that the SPAD reading can be used to estimate leaf N of rice grown under AWD in a way similar to that under CF. SPAD readings and leaf color chart (LCC) values also showed a good correlation. There were no water × nitrogen interactive effects on rice yield, water input, water productivity, and N-use efficiency. Rice yield in AWD −10 was similar to those of CF; yields of other AWD treatments were significantly lower than those of CF. AWD −10 reduced irrigation water input by 20% and significantly increased water productivity compared with CF. The apparent nitrogen recovery and agronomic N-use efficiency (ANUE) of AWD −10 and AWD −20 were similar to those of CF. The ANUE of N SPAD38 and N SPAD35 was consistently higher than that of N 180 in all water treatments. N SPAD38 consistently gave yield similar to that of N 180 in all water treatments, while yield of N SPAD35 about 90% of that of CF. We conclude that a combination of AWD −10 and SPAD-based N management, using critical value 38, can save irrigation water and N fertilizer while maintaining high yield as in CF conditions with fixed time and rate of nitrogen application of 180 kg ha −1. Treatments AWD −20 and N SPAD35 may be accepted by farmers when water and N fertilizer are scarce and costly. The findings also suggested LCC can also be a practical tool for N-fertilizer management of rice grown under AWD, but this needs further field validation.

Adubação nitrogenada na cultura do milho safrinha irrigado em plantio direto

A cultura do milho safrinha é uma importante alternativa econômica para a entressafra. Contudo, esta cultura remove grandes quantidades de nitrogênio (N) e necessita de manejo adequado da adubação nitrogenada para obtenção de elevadas produtividades. O objetivo deste trabalho foi avaliar o efeito de fontes, doses e épocas de aplicação de N nas características agronômicas e na produtividade de grãos de milho safrinha irrigado. O experimento foi realizado em Selvíria (MS), em Latossolo Vermelho Distroférrico, irrigado por aspersão e sob plantio direto, em 2007 e 2008. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições, dispostos em um esquema fatorial 5 x 3 x 2, sendo: cinco doses de N (0, 50, 100, 150 e 200 kg ha-1), três fontes de N (sulfonitrato de amônio com inibidor de nitrificação, sulfato de amônio e uréia) aplicadas na semeadura ou em cobertura, no estádio de seis folhas. As fontes de N proporcionaram semelhantes produtividades de grãos de milho safrinha irrigado e com efeito similar quanto às características agronômicas estudadas. A antecipação da adubação nitrogenada foi viável, assim como a tradicional aplicação de N em cobertura. O incremento das doses de N aumentou o teor de N foliar, os números de grãos por fileira e por espiga, e consequentemente, a produtividade de grãos de milho safrinha irrigado. O incremento das doses de nitrogênio aumentou a produtividade de grãos de milho safrinha cultivado após milho até a dose de 150 kg ha-1 de N, em média, independentemente da época de aplicação e da fonte de N.

Corn (<i>Zea Mays</i> L.) Plant Characteristics and Grain Yield Response to N Fertilization Programs in No-Tillage System

Problem statement: Nitrogen application timing and Nitrogen (N) rate are two important factors to influence corn production in No-Tillage (NT) system, but N recommendations may need to be revised due to insufficient rainfall in dryland rain-fed environment. Approach: This study was to determine the effects of two N application timing (planting and split application at planting and V6 corn growth stage) and five N rates (0, 45, 90, 135 and 180 kg N ha−1) on corn plant characteristics and grain yield under rain-fed and low corn yield environment. Plant characteristics included the measurement of plant height, ear height, relative chlorophyll content (SPAD) and normalized Difference Vegetation Index (NDVI). Results: Plant height and ear height at R1 stage, SPAD at R1 and NDVI at V8 and R1 increased significantly with increasing N rates, while N application timing had no effect on measured canopy characteristics. Grain yield increased from 2.2-3.8 Mg ha−1 as N rate changed from 0-180 kg ha−1. However, applying more than 90 kg N ha−1 did not significantly increase grain yields. The N application timing did not influence yield. Strong correlations were observed among corn plant characteristics and between plant NDVI at V8 and R1 stages and grain yields. Conclusion: These results indicate that N application timing was not important factor to affect corn plant characteristics and grain yield under rain-fed and low corn yield dryland conditions and we may not expect a significant grain yield increase with application exceeding 90 kg N ha-1 under these conditions. Plant NDVI at V8 and R1 stage could be a good indicator to predict corn grain yield.

Spikelet sterility of rice observed in the record hot summer of 2007 and the factors associated with its variation

Heat-induced spikelet sterility is one of the major threats to rice production from global warming. Previous chamber experiments have shown that even a short exposure to heat can induce spikelet sterility, but actual damage to a crop in the open field has rarely been reported. In the mid-summer of 2007, the Kanto and Tokai regions in Japan experienced record high temperatures above 40°C. We examined whether this extreme heat event induced sterility in open fields. We collected panicle samples from 132 fields in 5 prefectures in the Kanto and Tokai regions. Maximum air temperature averaged over a 5-day period around the heading stage exceeded the threshold for sterility (35°C) in more than 40% of the crops surveyed. Spikelet sterility ranged from 2% to 23%, and was more than 10% in 20% of the crops studied. Spikelet sterility in 2007 was apparently higher than that in the normal summer of 2008 and peaked with the heat wave, which confirms for the first time that extreme heat in midsummer induced sterility under open field conditions in Japan, but to a lesser extent than what was predicted from previous chamber experiments. The lesson from this survey is that air temperature per se is not sufficient to predict the occurrence of heat-induced sterility and that factors influencing the heat budget of the panicles are needed to account for the crop damage. Crop management practices such as selection of tolerant cultivars and optimizing the timing and amount of nitrogen application could moderate the occurrence of heat induced spikelet sterility which can help to develop adaptation measures to climate change.

Nitrogen Rate and Application Timing Affect the Yield and Risk Associated with Stockpiling Tall Fescue for Winter Grazing

Nitrogen Rate and Application Timing Affect the Yield and Risk Associated with Stockpiling Tall Fescue for Winter Grazing

Comparison of Liquid Swine Manure and Aqua-Ammonia Nitrogen Application Timing on Subsurface Drainage Water Quality in Iowa

In Iowa and many other Midwestern states, excess water is removed artificially through subsurface drainage systems. While these drainage systems are vital for crop production, nitrogen (N), added as manure or commercial fertilizer, or derived from soil organic matter, can be carried as nitrate-nitrogen (NO3-N) to downstream water bodies. A five-year, five-replication, field study was initiated in the fall of 1999 in Pocahontas County, Iowa, on 0.05 ha plots that are predominantly Nicollet, Webster, and Canisteo clay loams with 3% to 5% organic matter located on glacial till within the Des Moines Lobe. The objective was to determine the influence of seasonal N application as ammonia or liquid swine manure on flow-weighted NO3-N concentrations and losses in subsurface drainage water and crop yields in a corn-soybean rotation. Four aqua-ammonia N treatments (168 or 252 kg N ha-1 applied for corn in late fall or as an early season side-dress) and three manure treatments (218 kg N ha-1 for corn in late fall or spring or 168 kg N ha-1 in the fall for both corn and soybean) were imposed on subsurface-drained, continuous flow-monitored plots. Precipitation during the drainage season (March to November) was slightly below the long-term norm (722 mm) for all four years in the study period and ranged from 615 mm in 2001 (85% of normal) to 707 mm (98% of normal) in 2004. Monthly rainfall was highly variable, and subsurface drainage, or the lack thereof, usually mimicked the precipitation patterns. On average, 69% of subsurface drainage occurred in May and June of each year, with lower amounts in April and July. Four-year average flow-weighted NO3-N concentrations measured in drainage water were ranked: spring aqua-ammonia 252 (23 mg L-1) = fall manure 168 every year (23 mg L-1) > fall aqua-ammonia 252 (19 mg L-1) = spring manure 218 (18 mg L-1) = fall manure 218 (17 mg L-1) > spring aqua-ammonia 168 (15 mg L-1) = fall aqua-ammonia 168 (14 mg L-1). Corn yields were significantly greater (p = 0.05) for the spring and fall manure 218 rates than for non-manure treatments. Soybean yields were significantly greater (p = 0.05) for the treatments with a spring nitrogen application to the previous corn crop. Overall, under the slightly dry to normal precipitation conditions of this study, corn yields and NO3-N concentrations in subsurface drainage were not significantly different (p = 0.05) between fall and spring treatments at the 168 aqua-ammonia or 218 kg ha-1 N manure N rates.

Effect of management, climate and soil conditions on N 2O and NO emissions from an arable crop rotation using high temporal resolution measurements

Quantifying the nitrous oxide (N 2O) and nitric oxide (NO) fluxes emitted from croplands remains a major challenge. Field measurements in different climates, soil and agricultural conditions are still scarce and emissions are generally assessed from a small number of measurements. In this study, we report continuously measured N 2O and NO fluxes with a high temporal resolution over a 2-year crop sequence of barley and maize in northern France. Measurements were carried out using 6 automatic chambers at a rate of 16 mean flux measurements per day. Additional laboratory measurements on soil cores were conducted to study the response of NO and N 2O emissions to environmental conditions. The detection limit of the chamber setup was found to be 3 ng N m −2 s −1 for N 2O and 0.1 ng N m −2 s −1 for NO. Nitrous oxide fluxes were higher than the threshold 37% of the time, while they were 72% of the time for NO fluxes. The cumulated annual NO and N 2O emissions were 1.7 kg N 2O-N ha −1 and 0.5 kg NO-N ha −1 in 2007, but 2.9 kg N 2O-N ha −1 and 0.7 kg NO-N ha −1 in 2008. These inter-annual differences were largely related to crop types and to their respective management practices. The forms, amounts and timing of nitrogen applications and the mineralization of organic matter by incorporation of crop residues were found to be the main factor controlling the emissions peaks. The inter-annual variability was also due to different weather conditions encountered in 2007 and 2008. In 2007, the fractioned N inputs applied on barley (54 kg ha −1 in March and in April) did not generate N 2O emissions peaks because of the low rainfall during the spring. However, the significant rainfall observed in the summer and fall of 2007, promoted rapid decomposition of barley residues which caused high levels of N 2O emissions. In 2008, the application of dairy cattle slurry and mineral fertilizer before the emergence of maize (107 kg N min ha −1 or 130 kg N tot ha −1 in all) coincided with large rainfalls promoting both NO and N 2O emissions, which remained high until early summer. Laboratory measurements corroborated the field observations: NO fluxes were maximum at a water-filled pore space (WFPS) of around 27% while N 2O fluxes were optimal at 68% WFPS, with a maximum potentially 14 times larger than for NO.

Evaluation of plant components of maize on different times of Nitrogen application in succession to different cover crops

O milho ( Zea mays L.) vem sendo implantado em lavouras no sistema de plantio direto, onde seu uso tem trazido melhores resultados na producao devido ao menor revolvimento do solo, reduzindo assim o risco de erosoes, mantendo as caracteristicas naturais e melhora na retencao de agua. O experimento foi semeado em area de lavoura comercial, caracterizado por Latossolo Vermelho Distrofico, no municipio de Capitao Leonidas Marques-PR, no ano agricola 2008/2009. O objetivo deste trabalho foi avaliar o desenvolvimento da cultura do milho, segundo os diferentes periodos de aplicacao de nitrogenio, fornecido em forma de ureia, em sucessao a quatro diferentes coberturas de solo: a aveia preta ( Avena strigosa ), nabo forrageiro ( Raphanus sativus ), trigo ( Triticum spp.) e a vegetacao espontânea natural (pousio), juntamente com diferentes aplicacoes de N, dispostas da seguinte maneira (1/3 sulco + 2/3 com 8 folhas e 1/3 sulco + 1/3 com 4 folhas + 1/3 com 8 folhas). O delineamento experimental utilizado foi o de blocos casualizados, onde foram avaliados a altura de planta e da insercao da espiga, espessura de colmo e espiga e comprimento de espiga. Os resultados demonstram que as diferentes epocas de aplicacao e as diferentes coberturas de solo nao diferiram significativamente nos resultados obtidos.

Effects of outreach on the awareness and adoption of conservation practices by farmers in two agricultural watersheds of the Mackinaw River, Illinois

Increased awareness of the contributions of nonpoint source runoff to the degra- dation of water quality in the Mississippi River and Gulf of Mexico emphasizes the need to increase conservation practices that reduce nutrient export from agricultural lands. To achieve long-term conservation goals in agricultural landscapes, it is important to understand farmers' perspectives on what practices are effective, practical, and economically attainable. We con- ducted a series of surveys, interspersed with focused outreach, of farmers in two agricultural watersheds in central Illinois in an attempt to better understand how outreach influenced their views on and adoption of conservation practices. Programs differed between the two water- sheds in terms of the levels of intensity at which outreach efforts were conducted. Survey results suggest that more intensive outreach efforts, such as one-on-one landowner visits, localized workshops, and tours, can increase adoption of conservation practices associated with cost-share programs. Technical and financial assistance provided in a timely manner that did not interfere with planting and harvesting were major incentives among farmers in both watersheds to participate in cost-share conservation programs. Primary disincentives among farmers to enroll in cost-share programs were associated with multiple programmatic changes and complex application processes. Results indicate that there remains a need for outreach that increases awareness and implementation of conservation and best management practices specific to reducing agricultural runoff from tile-drained sources. Mitigation of nonpoint runoff will also require more effective management of nitrogen application rates and timing in order to conserve freshwater resources in Midwest agricultural landscapes and downstream waters. Integrated outreach teams comprised of stakeholders and local conservation agencies may lead to successful outreach efforts and reduce demands on limited conservation agency staff time.

VARIABILITY OF GRAIN AND OIL YIELD IN SPRING SAFFLOWER AS AFFECTED BY NITROGEN APPLICATION

This research was carried out to determine the effects of rate and time of nitrogen (N) application on safflower in a calcareous soil. The nitrogen rates were 50, 75, 100, 125, and 150 kg ha−1 and three split application methods were used. Experimental treatments were conducted as a factorial in a randomized complete block design (RCBD) with three replications. Duncan's Multiple Range Test (DMRT) indicated that the three split application of 100 kg ha−1 of nitrogen in stages of sowing date, early stem elongation, and early flowering had higher grain yield (2627 kg ha−1) than other treatments. This result was forecasted by results of increases in number of heads per square meter (heads m−2), number of grains per head (grains/head), and thousand grain weight (TGW). The highest oil yield was 755 kg ha−1 with the 100 kg ha−1 nitrogen application and was 727 kg ha−1 in treatment of three split application.

Análise econômica da adubação nitrogenada em trigo irrigado sob plantio direto no cerrado

O nitrogênio é o nutriente acumulado em maior quantidade e de mais alto custo na produção do trigo. Sendo assim, este trabalho foi realizado com o objetivo de determinar a viabilidade econômica (em 2007 e 2008) da utilização de diferentes fontes, doses e épocas de aplicação de nitrogênio na produtividade de grãos de dois cultivares de trigo irrigados, em Selvíria-MS. Para tal, um único experimento foi desenvolvido em 2007, na área experimental pertencente à Faculdade de Engenharia - UNESP, em um Latossolo Vermelho Distrófico. Para análise econômica foram considerados os custos (2007 e 2008) e os acréscimos de produção dos diferentes manejos da adubação nitrogenada, correspondentes a cada tratamento do fatorial. Ou seja, cinco doses de N (0, 50, 100, 150 e 200 kg ha-1), três fontes de N (Entec®, sulfato de amônio e uréia) e duas épocas de aplicação (totalmente na semeadura, ao lado das linhas ou em cobertura), em dois cultivares de trigo (E 21 e IAC 370), com quatro repetições. Concluiu-se que: o acréscimo no valor de produção para o produtor foi maior em junho de 2008. A aplicação da dose de 50 kg ha-1 de N apresentou sempre maior vantagem econômica, independentemente da fonte e época de aplicação. A ureia aplicada em cobertura, independentemente da dose de N, proporcionou benefícios líquidos positivos para o cultivar E 21 e IAC 370 em 2008. Recomenda-se para obtenção da maior margem de ganho a aplicação de 50 kg ha-1 de N, de sulfato de amônio, em cobertura, para ambos os cultivares.