• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 85
  • 53
  • 26
  • 19
  • 16
  • 14
  • 12
  • 7
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 2
  • Tagged with
  • 262
  • 88
  • 50
  • 38
  • 30
  • 27
  • 23
  • 21
  • 18
  • 17
  • 15
  • 15
  • 14
  • 14
  • 14
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Uso de condicionador de solo a base de ácido húmico na cultura de cana-de-açúcar (Saccharum spp) / The use of a humic acid based soil conditioner in sugar cane crop (Saccharum spp)

Gullo, Marcelo José Mortati 02 August 2007 (has links)
Busca-se, no campo da fitotecnia, métodos que possam aumentar a produtividade dos canaviais atentando-se ao menor uso de adubos minerais, visando redução de custos e sustentabilidade da produção no setor sucroalcooleiro. Sob esse princípio, tem sido muito discutido o uso de condicionadores organominerais no solo, para promoção de alterações das propriedades físicas, químicas e biológicas, visando aumentar o teor de matéria orgânica, aumentar a diversidade e atividade da microbiota, incrementar a capacidade de troca catiônica e aniônica, desfavorecer a manutenção de íons metálicos na solução, ocasionando assim a diminuição da toxidez desses elementos. Assim, foi avaliado o uso do produto organomineral comercial a base de ácido húmico Agrolmin® na cultura da cana-de-açúcar, objetivando-se analisar sua influência na produtividade da cultura, a interação com a adubação mineral, adequar metodologia de aplicação, fixar diretriz quanto a doses de aplicação e resgatar a credibilidade dos condicionadores orgânicos como um fator de melhoria do ambiente de produção. Os experimentos foram instalados em área da Usina Santa Cândida, município Bocaina – SP, na variedade PO88-62, como cana-planta, e RB867515, como cana-soca. O delineamento experimental foi parcelas subdivididas, analisando-se as doses 0, 800, 1.600 e 2.400 kg/ha do adubo de formulação 2,5-10-10 (parcelas) com as doses 0 e 350 L/ha do produto comercial (sub-parcelas) para cana-planta, e as doses 0, 800, 1.600 e 2.400 kg/ha do adubo de formulação 09-00-09 (parcelas) com as doses 0, 300 e 600 L/ha do produto comercial (sub-parcelas) para cana-soca. Os resultados indicaram que o uso do produto comercial tem efeito significativo na produção da cultura, tanto para cana-planta como para cana-soca, equivalendo ao uso de aproximadamente 1.200 e 1.100 kg/ha de adubo mineral respectivamente, sendo que em cana-soca, a dose de 300 L/ha e 600 L/ha não mostraram diferença significativa. Em ambos os casos, nota-se que a resposta de produtividade da cultura ao uso do produto comercial é maior quanto menor a dose de adubo utilizada. Porém, tanto em cana-planta como em cana-soca, não foi observada estatisticamente interação significativa do produto comercial com a adubação mineral. Isso mostra que o uso de condicionadores de solo organominerais pode ser viável em se tratando de incremento de produção aliado a redução de adubação mineral. / Aims have been made to find ways to increase de productivity of sugar-cane crops using less mineral fertilizers, attending to a cost reduction and sustainability. Based on these principles, the use of organic-minerals products to promote physical, chemical and biological alterations in the soil system, seeking to increase the organic matter content, the biological diversity and activity, the cationic/anionic exchange capacity, disfavor the amount of metallic ions in the solution resulting in a decrease of the toxicity, caused when these metallic elements are present. The use of a commercial humic acid based soil conditioner product, named Agrolmin®, in a sugar cane crop was evaluated, in order to measure its influence in crop production, to check its interaction with the mineral fertilization, to adjust the application methodology, to define proportions procedures and to ransom the credibility of the organic conditioners as an environmental production improvement factor. The experiment was carried out on Santa Candida Sugarmill, located in Bocaina, São Paulo state, using the sugar cane varieties PO88-62 (plant cane), and RB867515 (ratoon). The experiment was laid out in split-plot, using 0, 800, 1.600 e 2.400 kg/ha of the mineral fertilizer 2,5-10-10 (plot) with 0 and 350 liters/ha of the commercial product (sub-plot) at the crop planting, and 0, 800, 1.600 e 2.400 kg/ha of the mineral fertilizer 09-00-09 (plot) with 0, 300 e 600 liters/ha of the commercial product (sub-plot), at first ratoon. Results shown that the use of the commercial product causes an significative increasing in the crop production, either in plant-cane and first ratoon, equivalent the use of 1.200 e 1.100 kg/ha of the mineral fertilizer. In both plant and ratoon, the response to productivity related to the use of the commercial product is greater as the mineral fertilizer's dose is smaller. However, either at planting or first ratoon, a significative interaction between Agrolmin® and the mineral fertilization was not observed. This shows that organic-mineral soil conditioners may be a good choice on a productivity improvement allied to a reducing mineral fertilization.
102

Towards a taxonomic classification of humus forms : third approximation

Klinka, Karel, Krestov, Pavel, Fons, Jaume, Chourmouzis, Christine January 1997 (has links)
The importance of humus form or forest floor as a principal component of terrestrial forest ecosystems has led to the development of a taxonomic classification of humus forms for BC (first approximation: Klinka et al. 1981; second approximation: Green et al. 1993). This classification, as all others, is based on the field-observable (morphological) features because we expect that they reflect differences in the nature and development of humus forms. However, there is a continuing need to test (1) whether humus forms that appear different are in fact different in their physical, chemical, and biotic properties, and (2) the portability of the classification outside the area in which it was developed. As a result of recent studies of the biotic component of humus forms and recent testing of the classification outside British Columbia (Scandinavia, southeastern Russia, and northeastern China), we have recognized several new diagnostic horizons, and hence new taxa. In this pamphlet, we present synopsis of the third approximation of the classification for review and testing. For more detailed information on the background, methodology, and classification of humus forms, the readers should consult Green et al. (1993). Each humus form is represented by the sequence of organic and mineral horizons that constitute the humus form profile. Identification of a humus form, i.e., giving it a name, requires description of the humus form profile – the identification of master and subordinate horizons. For this reason we have included a description of the horizon designations as well as a synopsis of the classification and a key to the identification of humus forms.
103

Effects of ammonium lignosulphonate and diammonium phosphate on soil organic matter, phosphorous fractions and corn (Zea mays L.) yield in two eastern Canadian soils

Xie, Xinghua January 1993 (has links)
Phosphorous fertilizer has an efficiency of about 10 percent, and this efficiency must be improved, in order to avoid excessive loss of a non-renewable resource. Ammonium lignosulphonate (ALS), a by-product of the pulp and paper industry, is expected to improve efficiency of fertilizer phosphate (P) for corn (Zea mays L.) production. Field experiments were conducted to investigate effects of added ALS and P on soil organic matter and P fractions, as well as corn yields and nutrient uptake in a Ste. Rosalie clay soil and an Ormstown silty clay loam soil in 1990 and 1991. Incubation studies showed that added ALS increased organic matter but added P as diammonium phosphate (DAP) decreased organic matter in the fertilizer band location in both soils. Applied ALS with P increased Mehlich-III (M$ sb3$P) extractable P and bicarbonate extractable P in the fertilizer band location in both soils during early incubation periods. Soil Ca-P was decreased with increased ALS. However, soil Al-P and Fe-P compounds were increased with increased ALS. Applied P increased corn shoot P concentration at the six leaf stage, and increased grain yields, total dry matter (TDM) and N and P uptake in both soils. Applied ALS at up to 608 kg ha$ sp{-1}$ with P increased corn shoot P concentration at the six leaf stage in the Ste. Rosalie soil in 1991. Applied ALS at up to 304 kg ha$ sp{-1}$ with P increased grain yield, N and P uptake. However, applied ALS without P decreased stover N concentration. Thus, ALS may improve efficiency of fertilizer P for corn production depending on soil and application methods.
104

Effects of management practices on soil organic matter content, soil microbial activity and diversity in the KwaZulu-Natal midlands.

Nsabimana, Donat. January 2002 (has links)
The objective of this study was to investigate the effects of land use and management practice on the soil organic matter content and the size, activity and diversity of the microbial biomass. These effects were investigated using samples taken from the top (0-10 cm) layer of the soils from long-term agricultural managements including natural grassland, maize under conventional (maize CT), maize under zero tillage (maize ZT), annual ryegrass, Eucalyptus, Pinus, and permanent kikuyu pasture. The natural grassland was used as a control since records indicated that no agricultural activity had ever been exerted on the soil. The measurements used to investigate these effects included soil organic C, total N, soil pH, microbial biomass C, basal respiration rate, microbial quotient, metabolic quotient, dehydrogenase activity, fluorescein diacetate (FDA) hydrolysis, arginine ammonification rate, arylsulphatase activity and acid and alkaline phosphatase activities. The microbial functional diversity was measured using the Biolog Ecoplate and catabolic response profiles methods. Soil organic Cand total Nwere lowest under maize CT, followed by maize ZT and annual ryegrass and were higher under natural grassland, Eucalyptus and Pinus plantations while permanent kikuyu pasture had the highest values. The other analyses, namely microbial biomass C, basal respiration rate, FDA hydrolysis, arginine ammonification rate and arylsulphatase activity also followed the same pattern. Annual cultivation was responsible for a decrease in microbial biomass C, basal respiration rate and enzyme activity, principally because there was an appreciable decrease in soil organic matter content. Conversely, permanent pasture, Eucalyptus and Pinus plantations increased appreciably the amount of organic C and consequently, promoted the size and activity of the microbial biomass in the soils. The principle component scores showed that management practices affected the microbial functional diversity because different treatments were found in separate zones of the principle component spaces. The regression analysis showed that the variation in the PC1 and PC2 scores was correlated with the variation in soil organic C, exchangeable acidity, extractable P and exchangeable K and Mg. In addition, richness, evenness, Shannon, and Simpson diversity indices showed that any management practice affects the dynamics of soil microbial diversity. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.
105

Anoxic conditions in a Douglas fir litter layer implications for denitrification /

Lee, Guurtruida Elisabeth Maria van der, January 2000 (has links)
Proefschrift Universiteit van Amsterdam. / Auteursnaam op omslag: Guda van der Lee. Met lit. opg. - Met samenvatting in het Nederlands.
106

The influence of inorganic matrices on the decomposition of organic materials /

Skene, Trudi Marie. January 1997 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1997? / Includes bibliographical references (leaves 134-148).
107

Estimation de la matière organique des sols agricoles au Sud du Québec par l'utilisation de réflectances spectrales

Richard, Pierrot, January 1900 (has links)
Thèses (M.Sc.)--Université de Sherbrooke (Canada), 2007. / Titre de l'écran-titre (visionné le 20 juin 2008). In ProQuest dissertations and theses. Publié aussi en version papier.
108

Composition and cycling of natural organic matter: Insights from NMR spectroscopy

Sannigrahi, Poulomi. January 2005 (has links)
Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006. / Taillefert, Martial, Committee Member ; Weber, Rodney, Committee Member ; Stack, Andrew, Committee Member ; Benner, Ronald, Committee Member ; Ingall, Ellery, Committee Chair. Includes bibliographical references.
109

Změny obsahu humusu a půdní reakce na vybraných lokalitách Moravského krasu

Boráková, Iveta January 2014 (has links)
This thesis deals with the content of soil organic matter and soil reaction to selected locations in protected landscape area Moravian karst. 30 lokalities was compared (10 arable land, 10 permanent grassland, 10 forest). Samples were taken from surface mineral horizon in 2011 and 2013. In the theoretical part is discussed the issue of soil organic matter and soil reaction. There is characterized area Moravian Karst. The practical part includes processing methods, results, evaluation, statistical and graphical processing. Average content of humus increases in the order: arable land < permanent grassland < forest. The values in 2013 were lower than in 2011. Soil reaction was in 2011 for arable land, permanent grassland and forest vegetation very similar. Soil reaction was in 2013 similar only with arable land and grassland, the forests were lower. The values in 2013 were lower than in 2011 In 2013, the soil reaction is similar only with cropland and grassland, the forests were lower. Based on analysis of variance (ANOVA: one factor) was shown influence the type of vegetation on humus content. Influence the type of vegetation on soil reaction wasn't shown. A statistically significant difference was demonstrated between the measured values of cnotent humus and soil reaction in 2011 and 2013.
110

Palynologický výskum pokryvného humusu a vrchných minerálnych vrstiev lesných pód :kritická štúdia o možnostiach využitia na príklade Jihlavských vrchov /

Križo, Milan January 1964 (has links)
No description available.

Page generated in 0.0382 seconds