Application of phosphorus fertilizer can lead to changes in soil test P and increase both labile and non-labile phosphorus pools. Sequential fractionation showed that the labile (H2O-P and NaHCO3-P) fractions significantly (P < 0.05) increased with the addition of phosphorus fertilizer across all sites. Significant increase was observed in the non-labile (NaOH-P, HCl-P and Residual-P) fractions during the accumulation phase. During the depletion phase, when no further P was added, the accumulated P in the labile P fractions declined but not to the original level. The rates of P application, soil properties, soil test P methods used and time effect all had significant effects on soil test P changes in the extraction experiment. Mehlich-3 extracted the greatest amount of P from the two depths and Olsen-P was intermediate while the smallest amount was extracted with water. The pattern of the rate of change in extractable P with P addition for the 0 – 7.5 cm depth was not site dependent as the results obtained at the different sites were similar. / October 2016

O fosfogesso, também denominado gesso agrícola, sub produto das industrias de fertilizantes fosfatados, pode ser utilizado como condicionador do solo devido a sua capacidade de proporcionar melhorias ao sistema solo-planta. No entanto, este resíduo concentra os radionuclídeos das séries do U e Th, presentes na rocha fosfatada usada como matéria prima, que podem impactar o meio ambiente. Com a finalidade de se verificar a concentração dos radionuclídeos biodisponíveis , foram analisadas amostras de fosfogesso e de fertilizantes fosfatados monoamônio fosfato e fertilizante superfosfato triplo, de duas procedências nacionais. A determinação da concentração de 226Ra, 228Ra e 210Pb se iniciou com a análise por espectrometria gama. Em seguida as amostras foram submetidas a um processo de extração branda com solução de EDTA-NH4 (0,05M) para que então o material lixiviado fosse analisado por meio de contagem alfa e beta total em detector proporcional de fluxo gasoso. Foram obtidos valores médios de extração de 1,6% - 1,7% para 210Pb, 0,5% - 1,4% para o 226Ra e 0,1% - 1,0% para o 228Ra nas amostras de fosfogesso. A baixa porcentagem de extração obtida para os radionuclídeos pode ser explicada tendo-se em vista que a solubilidade do fosfogesso variou de 7,7% a 16%. Para os fertilizantes fosfatados do tipo monoamônio fosfato os valores médios de extração foram inferiores a 26% para o 226Ra, inferiores a 10% para o 228Ra e inferiores a 10% para o 210Pb. Apesar da solubilidade da ordem de 77% dos fertilizantes fosfatados do tipo monoamônio fosfato, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. Para os fertilizantes fosfatados do tipo superfosfato triplo os valores médios de extração foram de 2,3% para o 226Ra, 1,2% para o 228Ra e 11,3% para o 210Pb. Mesmo com a solubilidade de 66% os fertilizantes fosfatados do tipo superfosfato triplo, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. / Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of 226Ra, 228Ra and 210Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA-NH4 (0,05M) solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for 210Pb, from 0.5% to 1.4% for 226Ra and from 0.1% to 1.0% for the 228Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for 226Ra, less than 10% for 228Ra and less than 10% for 210Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA-NH4 (0,05M) solution, low concentrations of radionuclides were observed in the extracted solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for 226Ra, 1.2% for 228Ra and 11.3% for 210Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA-NH4 solution, low concentrations of radionuclides were observed in the extracted solution.

A combustão do carvão para a produção de energia elétrica tem como consequência a geração de cinzas, que é um dos maiores resíduos gerados no Brasil, em termos de volume (4.109 dm³/ano). Visando a minimização do impacto ambiental causado pelo mau descarte das cinzas, este trabalho teve como objetivo sintetizar e caracterizar zeólitas obtidas a partir de cinza de carvão e aplicar na agricultura como fertilizante potássico. Para isso a cinza utilizada foi obtida no combustor piloto de leito fluidizado operando com carvão da Mina do Leão/RS e empregada para sintetizar material zeolítico a partir do tratamento hidrotérmico alcalino. Foram realizados ensaios experimentais utilizando razão solução/cinzas constante em 6 L mg-1, variando a concentração de hidróxido de potássio (KOH) entre 3 e 5 M, a temperatura entre 100 e 150 ºC e o tempo de reação entre 24 e 72 h. O material sintetizado e a cinza foram caracterizados quanto a sua composição química, mineralógica, morfologia, área superficial específica e capacidade de troca catiônica. Através da caracterização foi observada a formação de duas fases zeolíticas, a chabazita-K e a merlinoíta. A partir da caracterização do material, foi escolhido um dos produtos zeolíticos obtidos para aplicação em solo, como fertilizante de potássio para o cultivo de trigo (Triticum aestivum L.). A condição experimental escolhida foi de 5 M a concentração da solução de KOH, temperatura de 150 ºC e tempo de reação de 24 h. Nesta condição obteve-se apenas uma fase zeolítica identificada, a zeólita merlinoíta, com uma área superficial de 23,37 m² g e uma capacidade de troca catiônica (CTC) de 2,62 meq g 1. Para fins de comparação foi utilizado o fertilizante comercial, cloreto de potássio (KCl), que contém em torno de 60 % de K2O. Foram realizados 35 ensaios experimentais em casa de vegetação da EMBRAPA, utilizando 7 tratamentos (3 doses diferentes de KCl e zeólita 50, 100 e 150 % da dose máxima recomendada e o solo não tratado (testemunha)) em 5 blocos aleatórios. Os experimentos na casa de vegetação foram concluídos com 59 dias de cultivo de trigo e submetidos às análises como determinação da produção de matéria seca da parte aérea e raízes das plantas e análise química do solo e tecido foliar. Verificou-se que a zeólita merlinoíta obtida a partir da cinza de carvão pode ser utilizada como fertilizante, pois teve um desempenho similar ao KCl no crescimento do trigo, não inibindo seu crescimento. Utilizando o tratamento com zeólita 100 % a produção de matéria seca da parte aérea foi de 1,07 ± 0,09 g e raízes 1,6 ± 0,23 g e na análise do tecido foliar teve uma absorção de 3,39 ± 0,31. / Coal combustion for electricity production results in the generation of ash, which is one of the main waste generated in Brazil in terms of volume. Intending the minimization of the environmental impact caused by poor disposal of ashes, this study aimed to synthesize and characterize zeolites obtained from coal ash and apply in agriculture as potassium fertilizer. For this purpose, coal fly ash was obtained from a fluidized bed pilot combustor operating with coal from Mina do Leão/RS and used to synthesize zeolitic material through the alkaline hydrothermal treatment. Experimental tests were performed using the ratio volume of solution/mass of coal fly ash constant at 6 mL mg -1, varying the concentration of potassium hydroxide (KOH) between 3 and 5 M, temperature between 100 and 150 °C and reaction time between 24 and 72 h. The synthesized and coal fly ash material was characterized by their chemical composition, mineralogy, morphology, specific surface area and cation exchange capacity. With the characterization, it was observed the formation of two phases zeolite K-chabazite and merlinoite. By the characterization of the material, it was chosen one of the zeolitic products obtained for application to soil as a potassium fertilizer for the cultivation of wheat (Triticum aestivum L.). The chosen experimental condition was 5 M KOH solution, temperature of 150 °C and 24 h time of reaction. At this condition, only one zeolitic phase was identified, zeolite merlinoite, with a surface area of 23.37 m² g a cation exchange capacity (CEC) of 2.62 meq g-1. For purposes of comparison, the tests in the soil were performed using also a commercial fertilizer, potassium chloride (KCl), containing about 60 % of K2O. A total of 35 experimental trials were carried out in a greenhouse at EMBRAPA, using 7 treatments in 5 random blocks: 50, 100 and 150 % of the maximum recommended dose for KCl and for zeolite and untreated soil (witness). The experiments in the greenhouse were concluded with 59 days of wheat cultivation. The plants were submitted to analysis for dry matter in aerial parts and roots determination. Likewise, soil and foliar tissue were submitted to chemical analysis. It was found that the zeolite Merlinoite obtained from the coal fly ash can be used as a fertilizer because it had a similar performance to KCl in the wheat growth. The treatment with 100% zeolite presented a dry matter production of 1.07 ± 0.09 g for aerial parts and 1.6 ± 0.23 g for roots. Also, the leaf tissue analysis showed a potassium absorption of 3.39 ± 0.31 % m/m in this treatment.

O fosfogesso, também denominado gesso agrícola, sub produto das industrias de fertilizantes fosfatados, pode ser utilizado como condicionador do solo devido a sua capacidade de proporcionar melhorias ao sistema solo-planta. No entanto, este resíduo concentra os radionuclídeos das séries do U e Th, presentes na rocha fosfatada usada como matéria prima, que podem impactar o meio ambiente. Com a finalidade de se verificar a concentração dos radionuclídeos biodisponíveis , foram analisadas amostras de fosfogesso e de fertilizantes fosfatados monoamônio fosfato e fertilizante superfosfato triplo, de duas procedências nacionais. A determinação da concentração de 226Ra, 228Ra e 210Pb se iniciou com a análise por espectrometria gama. Em seguida as amostras foram submetidas a um processo de extração branda com solução de EDTA-NH4 (0,05M) para que então o material lixiviado fosse analisado por meio de contagem alfa e beta total em detector proporcional de fluxo gasoso. Foram obtidos valores médios de extração de 1,6% - 1,7% para 210Pb, 0,5% - 1,4% para o 226Ra e 0,1% - 1,0% para o 228Ra nas amostras de fosfogesso. A baixa porcentagem de extração obtida para os radionuclídeos pode ser explicada tendo-se em vista que a solubilidade do fosfogesso variou de 7,7% a 16%. Para os fertilizantes fosfatados do tipo monoamônio fosfato os valores médios de extração foram inferiores a 26% para o 226Ra, inferiores a 10% para o 228Ra e inferiores a 10% para o 210Pb. Apesar da solubilidade da ordem de 77% dos fertilizantes fosfatados do tipo monoamônio fosfato, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. Para os fertilizantes fosfatados do tipo superfosfato triplo os valores médios de extração foram de 2,3% para o 226Ra, 1,2% para o 228Ra e 11,3% para o 210Pb. Mesmo com a solubilidade de 66% os fertilizantes fosfatados do tipo superfosfato triplo, muito pouco dos radionuclídeos, presentes inicialmente, se concentraram na solução extraida. / Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of 226Ra, 228Ra and 210Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA-NH4 (0,05M) solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for 210Pb, from 0.5% to 1.4% for 226Ra and from 0.1% to 1.0% for the 228Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for 226Ra, less than 10% for 228Ra and less than 10% for 210Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA-NH4 (0,05M) solution, low concentrations of radionuclides were observed in the extracted solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for 226Ra, 1.2% for 228Ra and 11.3% for 210Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA-NH4 solution, low concentrations of radionuclides were observed in the extracted solution.

Digitized by Kansas Correctional Industries

Thesis (M. Sc. (Agricultural Management)) -- University of LImpopo, 2002 / Refer to document / NRF (National Research Foundation) and WRC (Water Research Commission)

Onion production in the United States is seriously affected by the tospovirus Iris Yellow Spot (IYSV), whose symptoms include lenticular-shaped lesions that reduce photosynthesis and bulb yield. Thrips tabacai Lindeman, onion thrips (OT), is the only known vector of the disease and a primary arthropod pest of onion. Frequent insecticide applications, increasing resistance in OT populations to insecticides, high nitrogen (N) fertilization rates and loss of yield to disease and insect pressure threaten sustainable onion production. The objectives of this study were to identify crop management strategies to enhance onion productivity while suppressing OT and IYSV. Three fertilizer rates and two crop rotations were assigned to replicated plots to assess effects on onion growth, yield, bulb storage quality, soil quality, thrips populations and IYSV incidence. Trap crops of carrot, buckwheat and lacey phacelia were established in commercial fields to evaluate impact on thrips populations and IYSV occurence. Reduced nitrogen (N) rates, one-third the standard grower rate (133.8 kg N ha-1), resulted in no yield loss as compared with the standard N rate, despite slower crop maturation. Onions treated with a standard N rate(401.8 kg N ha-1) had greater numbers of adult and immature OT than other treatments. Soil nitrate levels were lower and microbial activity measured as dehydrogenase and biomass were greater in reduced N treatments. Plots with buckwheat and phacelia had greater numbers of both adult and immature OT when trap crop apparancy was high (i.e. when onion plants were relatively smaller). There was no observed effect of trap crops on IYSV levels. Results suggest that reduced rate N applications lower numbers of OT while enhancing the microbial population, reducing potential for nitrate leaching while still maintaining yields. Potential for trap crops of buckwheat and lacey phacelia to attract onion thrips from onions exists with successive stands of highly apparent trap crops.

Crops grown in sandy soils require frequent irrigation. As a result, nitrogen (N) fertilizers. such as ammonium sulfate((NH4)2SO4), are leached from the rooting zone of crops. This loss of N increases N fertilizer use and the potential for nitrate (NO3-) contamination of water. Ammonium-loaded clinoptilolite (NH4+-Cp) may reduce this N leaching, increase N fertilizer use-efficiency, and prevent NO3- contamination of water while sustaining normal crop growth. The potential of NH4+-Cp as a N fertilizer was assessed in three leaching experiments without plants and two leaching experiments with plants. Pots containing rounded quartz sand were amended with (NH4)2SO4 and one of three NH4+-Cp size fractions: small ( Finally, in two leaching studies, pots containing the sandy soil were planted with sweet corn and grown for 35 d and 42 d, respectively. No differences were found among N sources in corn relative growth rates, leaf area ratios, and net assimilation rates, even though the corn plants that were fertilized with NH4+-Cp assimilated significantly more N than the (NH4)2SO4-fertilized plants. The pots fertilized with NH5+-Cp leached In the greenhouse, NH4+-Cp is a slow-release fertilizer that will reduce N leaching while maintaining normal plant growth. However, field studies are needed to confirm the suitability of NH4+-Cp as a slow-release fertilizer under field conditions.

It is generally recognized that one of the most important factors limiting crop production is soil nitrogen. Farmers today are using more nitrogen fertilizers than ever before. All indications show that this usage will probably continue to increase. With the expanded use of nitrogen, it has become desirable to increase the efficiency from nitrogen fertilizers. One factor which will affect the efficiency is the position of the nitrogen in the soil in relation to the plant roots.

The increasing input costs for traditional agriculture has led land owners and producers in search of alternative opportunities to increase on-farm income. Replacing agricultural crops with short rotation woody species such as hybrid poplar trees is a form of agroforestry. The objectives of this project were to evaluate: 1) a suitable planting stock for hybrid poplar, 2) the effect of nitrogen (N) fertilizer application and pruning on hybrid poplar growth and, 3) the response of four hybrid poplar clones to fertilizer application and their suitability in the boreal transition ecoregion of Saskatchewan. <p>Two trials were established near Meadow Lake, Saskatchewan where three stock types (cuttings, root cuttings and rooted plugs) of Walker poplar were planted into former alfalfa and pasture fields. Trees were pruned each spring to remove multiple leaders and fertilized in year 2 with 100 kg N ha-1. The presence of roots on rooted cutting and plug stock types was beneficial in terms of hybrid poplar growth and survival. Trees grown from planting stock without roots had survival rates between 32-37% whereas, the survival of trees with roots at the time of planting ranged from 62-81% after two years of growth. Trees that were planted as a rooted stock were 3.5 to 4.2 times greater in height and 4.0 to 5.6 times greater in root collar diameter than trees planted as an un-rooted stock type. The application of fertilizer N decreased tree volumes by 31% at the Alfalfa site and had no effect on tree growth at the Pasture site. The total amount of fertilizer N recovered by the hybrid poplar trees ranged from 1-3% at the Alfalfa site and 3-5% at the Pasture site. <p>The second study involved planting four clones of hybrid poplar (Hill, Katepwa, Walker and WP-69) at the same two sites and applying fertilizer at rates of 0, 150 and 300 kg N ha-1 the first two years. Following the second growing season, Katepwa and WP-69 clones had the highest tree volumes of 750 and 1147 cm3 of the four clones evaluated. The Walker clone had the poorest survival rates (52-56%) compared to the other three clones (> 90% survival). Foliar N levels were not correlated with tree height at the Alfalfa (p=0.1326) or the Pasture (p=0.1063) sites. The relationship between foliar P concentration and tree height was more pronounced during July at the Alfalfa site with an r2 value of 0.7102. The N:P ratios for foliar tissue decreased with increasing fertilizer N application during August at the Alfalfa site. Foliar N:P ratios were the same among fertilizer and clone treatments at the Pasture site in August. <p>Results from this study suggest that rooted stock types increase the successful establishment of hybrid poplar plantations. However, application of N fertilizer may not increase growth of trees if soil N is adequate. Other soil nutrients need to be measured prior to fertilization to determine what nutrients may be limiting plant growth.