Spelling suggestions: "subject:"liminal""
131 |
Peut-on changer les trajectoires de croissance du chêne sessile et du sapin de Douglas suite à une sécheresse en modulant la fertilité du sol ? / Can we modify growth trajectories of sessile oak and Douglas fir following drought by changing the soil fertility?Bornot, Yoran 22 December 2017 (has links)
La fertilisation et les amendements sont des pratiques courantes en agronomie dont l’intérêt a été prospecté dans le domaine forestier. Des dispositifs expérimentaux de fertilisation ont été mis en place et étudiés par le passé. Le but de ces dispositifs était de déterminer si l’apport d’éléments nutritifs dans des milieux forestiers initialement pauvres ou acides pouvait augmenter la croissance voire restaurer l’état des cimes des arbres en situation de dépérissement. Par ailleurs, des études physiologiques ont montré l’implication de l’eau dans l’absorption des éléments nutritifs du sol et leur transport par la sève brute mais aussi via des effets combinés dans divers processus tels que la croissance cellulaire ou la régulation stomatique. Récemment, des épisodes de sécheresse extrême, responsables de vagues de dépérissement sur de nombreuses essences forestières, ont suscité l’inquiétude des gestionnaires. De plus, les modèles climatiques prédisent une augmentation de fréquence et d’intensité de l’aléa sécheresse dans un futur proche et la gestion forestière doit être adaptée pour y faire face. Dans ce contexte et grâce aux connaissances déjà acquises sur les interactions entre nutrition minérale et hydrique, nous cherchons à savoir si l’apport d’éléments nutritionnels pourrait atténuer les effets négatifs des déficits hydriques en agissant à la fois sur les capacités à supporter les sécheresses et à retrouver des niveaux de croissance optimale après l’aléa, c’est-à-dire améliorer la résilience des arbres. A l’inverse, la vulnérabilité des arbres aux déficits hydriques se trouverait-elle augmentée ? Pour répondre à cette problématique, nous avons exploité des dispositifs expérimentaux de fertilisation situés dans trois forêts en France sur deux essences forestières, le chêne sessile et le sapin de Douglas. Sur chacun de ces sites, des arbres sélectionnés ont été carottés à cœur afin de tracer les variations annuelles de croissance radiale à partir de mesures des largeurs de cernes. Ces courbes de croissance ont servi de base au calcul des indices de résistance, récupération et résilience de la croissance à des déficits hydriques du sol, calculés quant à eux à l'aide du modèle de bilan hydrique BILJOU©. Sur le site de Bercé, l’efficience d’utilisation de l’eau a de plus été appréhendée à partir du δ13C contenu dans le bois final des cernes. La croissance radiale des chênes de Bercé et de Tronçais a significativement été augmentée par la fertilisation et les variations interannuelles de croissance ont été modélisées par le climat et le déficit hydrique du sol. La croissance du sapin de Douglas quant à elle n’a que très peu été augmentée par l’apport en nutriments en forêt des Potées. Par ailleurs, cette analyse montre que la stimulation de croissance par la fertilisation est transitoire : moins de 10 ans après l’apport d’éléments nutritifs à Bercé et 20 ans à Tronçais, plus aucun effet sur la croissance ne subsiste. Malgré cet effet positif transitoire sur les croissances radiales du chêne, aucune différence entre les traitements sur les capacités des arbres à résister et récupérer après des épisodes de sécheresse. Les résistance et récupération de la croissance sont dépendantes de l’intensité et de la durée du déficit hydrique, donc de la sévérité de l’aléa et non de l’apport de nutriments. Ces résultats corroborent les analyses du δ13C dans les cernes des chênes qui, là encore, ne sont significativement corrélées qu’avec le climat et sont indépendantes du traitement. L’absence de modification de la résilience entre les traitements, quel que soit le site et l’essence étudiés, est discutée. Plus largement, ces travaux interrogent le concept de résilience et son utilisation en dendroécologie / Fertilization and liming are usual practices in agronomy but uncommon in forestry. Experimental liming or fertilization in forest were tested in the 1970’s. The initial aim of these experimentations was to determine if the addition of nutrients on poor or acidic forest soil could increase tree growth or even restore crown condition in case of decline. Physiological studies have established the implication of water availability in soil nutrients uptake and their transport in the sap and also via combined effects in various processes such as cell growth or stomatal control. Recently, extreme drought events responsible of many forest species diebacks have aroused the concern of forest managers. In addition, climate models predict an increase in the frequency and intensity of drought hazards in the future and forest management must be adapted to face them. In this context, and thanks to the current knowledge on the interactions between mineral and water alimentation, we investigate whether nutrient supply could mitigate the negative effects of water deficits by increasing the capacity 1/ to withstand droughts and 2/ to recover optimum growth after the drought induced crisis, i.e. to improve the resilience of trees. Conversely, would the vulnerability of trees to water deficits be increased? To answer this question, we investigated fertilization experiments located in three forests in France and applied on two species, sessile oak and Douglas fir. On each of these sites, selected trees were cored to the pith to determine the annual variations of radial growth from measurements of the tree-rings widths. These growth variations were used as a basis to the calculation of resistance, recovery and resilience indices to drought events, which were quantified using a soil water deficit index computed by the water balance model BILJOU©. On the site of Bercé, the water-use efficiency was estimated from the δ13C of the latewood. Retrospective analyses shown that the radial growth of oak trees in Bercé and Tronçais was significantly increased after the fertilization. Radial growth was then modelled from climate and soil water deficit. Douglas fir radial growth was slightly impacted by the nutrient supply in the Potées site. This analysis highlights the time-limited effect of this nutrient supply on the growth stimulation: no effect subsists more than 10 years after nutrient supply in Bercé and more than 20 years in Tronçais. Despite this transient effect on oak growth, no differences between treatments on the capacity of trees to resist and to recover after drought events was observed. The main factors influencing resistance and recovery of growth were the soil water deficit intensity and duration. These results corroborate δ13C analyzes in oak rings, which, again, were only significantly correlated with climate and were independent of treatment. The lack of modification of the resilience between the treatments, whatever the site and the species studied, is discussed. More broadly, the concept of resilience and its use in dendroecology are questioned
|
132 |
Correção do solo e sistemas de rotação de culturas sobre a absorção de nutrientes e produção de soja / Soil correction and crop rotation systems on nutrient uptake and yield of soybeanCAETANO, Jeander Oliveira 25 February 2011 (has links)
Made available in DSpace on 2014-07-29T14:52:06Z (GMT). No. of bitstreams: 1
Tese Jeander Oliveira Caetano.pdf: 1156626 bytes, checksum: c57accce2f7f7f942e8b9d04e2aba986 (MD5)
Previous issue date: 2011-02-25 / Crop rotation and the increase in straw on the soil are among the main requirements for the implementation and maintenance of no-tillage in the Cerrado. The use of integrated crop and livestock production, coupled with the introduction of Brachiaria in agricultural areas has helped to maintain this coverage and increased amounts of plant species as alternatives to rotation. Thus, there is a need to evaluate these cover crops and forms of fertility management which are widely used by farmers in Brazil. The aim was to evaluate the effect of two forms of soil correction, four types of soil cover and four levels of KCl on production and nutrient content of aerial part dry biomass of soil cover types, the yield and content soybean leaf nutrient and chemical attributes of an Oxisol. The experimental was arranged in a randomized block design, with four replications, the field was laid out in 2x4x4 and arranged in strip-split plot design. Was evaluated the forms of soil correction initial total and annual installment (main plot), the types of soil cover Brachiaria brizantha, B. ruziziensis, sorghum crop residues and spontaneous vegetation (subplots) and the levels of KCl correspondents to 0 kg ha-1, 20 kg ha-1, 40 kg ha-1 e 60 kg ha-1 of K2O (subsubplots). On the soil, for the depths 0-20 cm and 20-40 cm analyzed the pH CaCl2, organic matter, exchangeable Ca, Mg, K and Al, H+Al and the contents of available P, Fe, Mn, Cu and Zn. In the leaves were determined N, P, K, Ca, Mg, Fe, Mn, Cu and Zn. Was collected dry biomass of soil cover and estimated soybean yield. The forms of soil correction initial total and annual installment not influence soybean yield. B. brizantha produces highest biomass, which occurs in the highest soybean yield. Potassium is the nutrient of greatest accumulation in leaf of B. brizantha and B. ruziziensis. The increasing levels of KCl do not affect the soybean yield. The soybean yield is more affected by the kind of cover crops than by the form of correction and levels of potassium. / A rotação de culturas, aliada à elevação de palhada sobre o solo, estão entre os principais requisitos para a implantação e manutenção do sistema plantio direto no Cerrado. O uso da integração lavoura-pecuária, aliada à introdução das braquiárias em áreas agrícolas, tem auxiliado a manutenção dessa cobertura e o aumento da quantidade de espécies de plantas como alternativas para rotação. Assim, ocorre a necessidade da avaliação dessas plantas de cobertura e das formas de manejo da fertilidade que são amplamente utilizadas pelos agricultores no Brasil. O objetivo foi avaliar o efeito de duas formas de correções de solo, quatro tipos de cobertura vegetal e quatro doses de KCl sobre a produção e teor de nutrientes da parte aérea da biomassa seca dos tipos de cobertura vegetal, a produtividade de grãos e teor de nutrientes foliares da soja e os atributos químicos de um Latossolo Vermelho. O delineamento foi em blocos ao acaso, com quatro repetições, em parcelas subsubdivididas 2x4x4. Foi avaliada as formas de correção de solo total inicial e parcelada anual (parcela), os tipos de cobertura vegetal do solo Brachiaria brizantha, B. ruziziensis, restos culturais de sorgo e vegetação espontânea (subparcela) e as doses de KCl correspondentes a 0 kg ha-1, 20 kg ha-1, 40 kg ha-1 e 60 kg ha-1 de K2O (subsubparcela). No solo, para as camadas de 0-20 cm e de 20-40 cm, analisaram-se o pH CaCl2; a matéria orgânica; os teores de Ca, Mg, K e Al trocáveis; o H+Al e os teores disponíveis de P, Fe, Mn, Cu e Zn. Nas folhas analisaram-se N, P, K, Ca, Mg, Fe, Mn, Cu e Zn. Realizou-se a coleta da biomassa seca das coberturas e dos grãos da soja. As formas de correção total inicial e parcelada anual não influenciam o rendimento da soja. A B. brizantha produz a maior biomassa seca, sob a qual ocorre o maior rendimento de soja. O potássio é o nutriente de maior acúmulo foliar na B. brizantha e B. ruziziensis. A elevação das doses de KCl não tem influência sobre o rendimento da soja. O rendimento de grãos de soja é mais afetado pelo tipo de cobertura do solo do que pela forma de correção e dose de potássio.
|
133 |
Adubação de mudas de baru (Dipteryx alata Vog.), em viveiro / Fertilization of baru seedlings (Dipteryx alata vog.), in nurseryPACHECO, Abílio Rodrigues 08 August 2008 (has links)
Made available in DSpace on 2014-07-29T14:52:10Z (GMT). No. of bitstreams: 1
TESE ABilio pacheco.pdf: 3158421 bytes, checksum: 3e5f4883d7c4592062690f37f06f4935 (MD5)
Previous issue date: 2008-08-08 / Producing seedlings of good quality is an important step in the process
of planting forest species. Addition of lime and fertilizers contribute in obtaining
good quality seedlings, however, information is limited on fertilization and nutrition
of native species of savannah. The objective of this study was to evaluate growth
response of baru seedlings (Dipteryx alata Vog.) to organic and mineral fertilizers.
Seedlings were produced in plastic bags with a diameter of 20 cm x 30 cm and
capacity of four liters of substrate. Clay Dark Red Latosol collected from subsoil
(20 cm depth) from Federal District of Planaltina, DF was used. The first experiment
was conducted in complete randomized blocks, with eleven treatments in a
factorial arrangement (4X2), with three replications (composed of seedlings coming
from different matrix) and plots consisted of three seedlings. The treatments tested
were E0+D0, E10+D0, E20+D0, E30+D0, E0+D1, E0+D2, E0+ALL, E10+D1,
E10+D2, E10+ALL and E20+D1, where: E0, E10, E20 and E30 are doses of cattle
manure varied from 0 to 30% in relation to final volume of mixed subsoil; D1 and
D2 are traditional rates of chemical fertilizers, and D2 is double of D1 and D1
equivalent to dolomitic lime incorporated in the subsoil (0,5 g L-1) + P (150 mg L-1)
+ K (200 mg L-1) + Zn (5 mg L-1) + Cu (5 mg L-1) + Mn (5 mg L-1) + B (1 mg L-1) +
Mo (0,5 mg L-1) + N (50 mg recipient-1 month-1, diluted in water); P and K were
applied in the form of triple superphosphate and potassium chloride, respectively,
Zn, Cu and Mn in the form of sulfates, B and Mo in the forms of borax and sodium
molibidate, respectively.; ALL is symbol of slow release fertilizer in six months (2.4
g recipient-1 after emergence of seedlings and five months of age), contain N
(15%), P2O5 (10%), K2O (10%), Ca (3,5), Mg (1,5%), S (3%), B (0,02%), Cu
(0,05%), Fe (0,5%), Mn (0,1%), Zn (0,05%) and Mo (0,004%). In others experiments
(1, 2, 3, and 4) baru seedlings were submitted to four rates of dolomitic lime (0.0,
0.5, 1.0 and 2.0 g L-1 of substrate), P (0, 150, 300 and 600 mg L-1), K (0,100, 200
and 400 mg L-1) and N (0, 50, 100 and 200 mg seedling-1 month-1), in combination
with two rates of cattle manure (10% and 20% in relation to final volume of mixture
with subsoil). These experiments were conducted in complete randomized blocks
in a factorial arrangement (4x2), with three replications (composed of seedlings
coming from different matrix) and plots consisted of three seedlings. Source of N
was urea (45% N), P triple superphosphate (45% P2O5), and K potassium chloride
(60% K2O), respectively. After eight month of seedlings age following observations
were made: Stem diameter of 5 cm height, plant height, top dry matter, soil and
leaves chemical analysis for each treatment combination. In the first experiment,
baru seedlings presented positive response to addition of traditional chemical
fertilizers (rates D1 and D2) and slow release (ALL). Organic manure improved
growth of seedlings with the addition of 20% and 30% cattle manure, however
there was no difference between two rates. All treatments tested permitted
production of seedlings of good quality for commercial sale and planting in the
field, except of control treatment without fertilization (E0%+D0) and which received only 10% cattle manure with addition of subsoil (E10%+D0). Organic manure
(20% cattle manure) and mineral fertilizers (D1, D2 and ALL) increased fertility of
the substrate and leaf concentrations of N, P, K, S and Zn. In the experiments 1
and 4, seedlings presented positive growth to cattle manure incorporated in the
subsoil, rate 20% better than rate 10%. Incorporation of cattle manure in the
subsoil in the dose of 20%, supplied adequate fertilization in the substrate and
foliar nutrition for growth and mineral nutrition of baru seedlings. In the presence of
cattle manure incorporated in the subsoil in the 10 and 20% rates, seedling growth
response was negative with the addition of potassium and there was no response
with the addition of lime and phosphorus. Nitrogen topdressing monthly gave
positive response to growth and height, stem diameter, top dry weight, when
applied after incorporation of cattle manure in the subsoil in the dose of 10%, but
response was positive in relation to height with rate of 20% cattle manure. / A produção de mudas de boa qualidade constitui uma importante etapa
do processo de implantação de espécies florestais. A adequação do substrato por
meio da adição de corretivos e fertilizantes contribui para a obtenção de mudas de
melhor qualidade, mas ainda são escassas as informações relativas à adubação e
à nutrição de espécies nativas do cerrado. Assim, este trabalho foi conduzido com
o objetivo de avaliar as respostas de crescimento de mudas de baru (Dipteryx
alata Vog.) às adubações orgânica e mineral, em cinco experimentos. As mudas
foram produzidas em sacos plásticos com dimensões de 20 cm x 30 cm e
capacidade para quatro litros de substrato, sendo este constituído pelo subsolo
(abaixo de 20 cm de profundidade) de um Latossolo Vermelho da região de
Planaltina, DF, com teor de 50 g de argila K-1 de solo. O primeiro experimento foi
conduzido no delineamento de blocos completos ao acaso, com onze
tratamentos, três repetições (compostas por mudas oriundas de sementes de
diferentes plantas matrizes) e parcelas constituídas por três mudas cada. Os
tratamentos testados foram E0+ D0, E10+D0, E20+D0, E30+D0, E0+D1, E0+D2,
E0+ALL, E10+D1, E10+D2, E10+ALL e E20+D1, sendo: E0, E10, E20 e E30 as
doses de esterco bovino variando de 0 a 30% em relação ao volume final da
mistura com o subsolo; D1 e D2 as doses de adubos menerais tradicionais, onde
D2 é o dobro da dose D1 e D1 equivale à incorporação ao subsolo de calcário
dolomítico (0,5 g L-1) + P (150 mg L-1) + K (200 mg L-1) + Zn (5 mg L-1) + Cu (5 mg
L-1) + Mn (5 mg L-1) + B (1 mg L-1) + Mo (0,5 mg L-1) + N (50 mg recipiente-1 mês-1,
diluído em água); P e K foram aplicados na forma de superfosfato triplo e cloreto
de potássio, respectivamente, Zn, Cu e Mn na forma de sulfatos, B e Mo na forma
de bórax e molibidato de sódio, respectivamente; ALL simboliza a adição de
adubo de liberação lenta em seis meses (2,4 g recipiente-1 após a emergência
das plântulas e aos cinco meses de idade), contendo N (15%), P2O5 (10%), K2O
(10%), Ca (3,5%), Mg (1,5%), S (3%), B (0,02%), Cu (0,05%), Fe (0,5%), Mn
(0,1%), Zn (0,05%) e Mo (0,004%). Nos outros quatro experimentos (1, 2, 3 e 4)
as mudas de baru foram submetidas a quatro doses de calcário dolomítico (0,0;
0,5; 1,0 e 2,0 g L-1 de substrato), P (0, 150, 300 e 600 mg L-1), K (0, 100, 200 e
400 mg L-1) e N (0, 50, 100 e 200 mg muda-1 mês-1), respectivamente, em
combinação com duas doses de esterco bovino (10% e 20% em relação ao volume
final da mistura com o subsolo). Os experimentos foram conduzidos no delineamento
de blocos completos ao acaso, em esquema fatorial (4x2), com três repetições
(compostas por mudas oriundas de sementes de diferentes plantas matrizes) e
parcelas constituídas por três mudas cada. As fontes de N, P e K foram a uréia
(45% de N), o superfosfato triplo (45% de P2O5) e o cloreto de potássio (60% de
K2O), respectivamente. Aos oito meses de idade todos os experimentos foram avaliados quanto as seguintes variáveis: diâmetro do caule a 5 cm do coleto, altura
da planta, matéria seca da parte aérea e teores de nutrientes do solo e das folhas
para cada combinação de doses. No primeiro experimento observou-se que o
crescimento das mudas foi incrementado pela adição de adubos minerais
tradicionais (nas doses D1 e D2) e de liberação lenta (ALL). A adubação orgânica
promoveu o crescimento das mudas nas doses de 20% e 30% de esterco bovino,
não havendo diferença entre estas. Com a adição de 10% e 20% de esterco
bovino ao subsolo ainda houve resposta positiva de crescimento das mudas à
adição de adubos minerais tradicionais (D1) e de liberação lenta (ALL), não
havendo efeito diferenciado destes. Todos os tratamentos testados permitiram a
produção de mudas de boa qualidade, passíveis de comercialização e plantio
no campo, exceto o controle sem adubação (E0%+D0) e aquele com apenas 10%
de esterco adicionado ao subsolo (E10%+D0). As adubações orgânica (20%
de esterco) e mineral (D1, D2 e ALL) elevaram a fertilidade do substrato e os
teores foliares de N, P, K, S e Zn. Nos demais experimentos (1, 2, 3 e 4)
constatou-se que as mudas apresentaram resposta positiva de crescimento às doses
de esterco bovino incorporadas ao subsolo, sendo a dose de 20% superior à de
10%. A incorporação de esterco bovino ao subsolo na dose de 20% promoveu a
adequação da fertilidade do substrato e dos teores foliares dos nutrientes para o
crescimento e a nutrição mineral das mudas. Na presença de esterco bovino
incorporado ao subsolo nas doses de 10% e 20% há resposta negativa de
crescimento das mudas à adição de potássio e ausência de resposta à adição de
calcário dolomítico e fósforo. A adubação nitrogenada em coberturas mensais
promoveu resposta positiva no crescimento em altura, diâmetro do caule e matéria
seca da parte aérea, quando aplicada após a incorporação de esterco bovino ao
subsolo na dose de 10%, mas apenas na altura da muda com a dose de 20% de
esterco.
|
134 |
HIGIENIZAÇÃO DE LODO ANAERÓBIO DE ESGOTO POR MEIO ALCALINO ESTUDO DE CASO DA ETE LAGES APARECIDA DE GOIÂNIA - GO / Anaerobic sewage sludge treatment by limingROCHA, Ana Lúcia Colares Lopes 25 August 2009 (has links)
Made available in DSpace on 2014-07-29T15:01:51Z (GMT). No. of bitstreams: 1
dissertacao ana lucia.pdf: 3901601 bytes, checksum: 03ec33115672e8cb73a4e8e1ddeb239f (MD5)
Previous issue date: 2009-08-25 / The aim of the present study was to evaluate the efficiency of the alkaline treatment of
sanitary sewage sludge produced in the upflow anaerobic sludge blanket (UASB) of the Lages
Sewage Treatment Plant, located in Aparecida de Goiânia, GO, Brazil and operated by
Saneamento de Goiás, S.A. Saneago. The sludge, which was dewatered into drying beds
until a mean moisture of 47.55%, was mixed in a cement mixer with hydrated lime and
quicklime in two experiments. The limes were mixed with sewage sludge and four treatments
were established, one of them without lime and the others with concentrations of, 12.6%, 21%
and 29.4% for each experiment, with three repetitions. Samples of the treated sludge in each
treatment were collected 0, 15, 30, 60, 90 and 120 days after mixing. Thermotolerant
coliforms, total helminth eggs, viable helminth eggs, volatile solids, total solids (TS), pH and
moisture were evaluated. All treatments in the two experiments met the condition of
reduction in vector attractiveness cited in appendix one of Conama resolution no.375 except
the hydrated lime treatment, whose lime dosage was 12.6%. Although growth of
thermotolerant coliforms occurred in association with the drop in pH in some treatments
during the storage period, in all the results of both experiments the values were below the
limit established in Conama resolution no.375 for type A sludge: 1,000 NMP.g.MS-1. Among
the species of viable helminth eggs identified, Ascaris sp. was predominated. All the
treatments with quicklime reached concentrations of viable helminth eggs below 0.25
egg.g.MS-1, the limit for type A sludge, immediately after mixing, except for the treatment
with 12.6% of quicklime. For the hydrated lime treatments, this condition was met within 15
days except for the treatment whose lime dosage was 12.6%. Both, hydrated lime and
quicklime, were efficient in meeting the requirements of Conama resolution no.375 for type A
sludges in regard to the parameters for thermotolerant coliforms and viable helminth eggs. In
terms of dosages applied and storage time, the quicklime treatments stood out because of their
greater potential for raising and maintaining pH and because of their greater efficiency in
removing thermotolerant coliforms and viable helminth eggs / O presente trabalho objetivou avaliar a eficiência da higienização alcalina do lodo de esgoto
sanitário, produzido no reator anaeróbio de fluxo ascendente e manta de lodo (UASB), da
Estação de Tratamento de Esgotos ETE Lages, localizada em Aparecida de Goiânia GO e
operada pela Saneamento de Goiás S.A. Saneago. O lodo desaguado em leitos de secagem,
com umidade média de 47,55%, foi misturado em betoneira com cal hidratada e com cal
virgem, caracterizando 2 experimentos. As cales foram misturadas ao lodo de esgoto e
estabelecidos quatro tratamentos, um testemunha, sem adição de cal, e os demais nas
concentrações de 12,6%, 21% e 29,4%, para cada experimento, com três repetições. Foram
coletadas amostras do lodo higienizado de cada tratamento logo após a mistura a 0, 15, 30, 60,
90 e 120 dias após a mistura. Avaliaram-se os coliformes termotolerantes, ovos totais e ovos
viáveis de helmintos, sólidos voláteis, sólidos totais, pH e umidade. Todos os tratamentos dos
dois experimentos atenderam à condição de redução de atratividade de vetores, citada no
anexo I da resolução Conama no375, exceto o tratamento com cal hidratada na dosagem de
12,6% de cal. Embora tenha ocorrido o crescimento de coliformes termotolerantes, associado
à queda do pH, em alguns tratamentos durante o período de estocagem, em todos os
resultados de ambos os experimentos, os valores estiveram abaixo do limite estabelecido pela
resolução Conama no375 para lodos tipo A, de 1.000 NMP.g.MS-1. Dentre as espécies de ovos
viáveis de helmintos identificadas, Ascaris sp. foi predominante. Todos os tratamentos com
cal virgem atingiram concentrações de ovos viáveis de helmintos abaixo de 0,25 ovo.g.MS-1,
limite para lodos tipo A, logo após a higienização, exceto para o tratamento com 12,6% de
cal. Nos tratamentos com a cal hidratada, essa condição foi atendida aos 15 dias, exceto para o
tratamento cuja dosagem foi 12,6% de cal. Considerando o atendimento à resolução Conama
no375 para lodos tipo A, com relação aos parâmetros de coliformes termotolerantes e ovos
viáveis de helmintos, ambas as cales, virgem e hidratada, foram eficientes. Em função das
dosagens aplicadas e do tempo de estocagem, os tratamentos com a cal virgem se destacaram
pelo maior potencial de elevação e manutenção do pH e pela maior eficiência na remoção de
coliformes termotolerantes e ovos viáveis de helmintos
|
135 |
Ruokohelpiviljelyn optimointi suopohjilla:turvetuotantoalueiden geologisen ympäristön, pohjaturpeen sekä kierrätyslannoitteiden käytön vaikutus ruokohelpin käyttämiin alkuaineisiin ja satoonParviainen, T. (Timo) 15 May 2007 (has links)
Abstract
There are various after-use options on the cut-away peatlands, depending on the characteristics of the soil. If the soil is devoid of rock, cultivation of reed canary grass is a profitable after-use option. The aim of this study was to determine how characteristics of peat, peatland surroundings and fertilizers influence the element uptake of reed canary grass.
In the present investigation the peat production areas of Luesuo, Piipsanneva and Jouttenisenneva were selected as study areas. A comprehensive sampling programme was carried out in each of the study areas. In addition, two experimental areas for cultivation of reed canary grass were established in Luesuo and Hankilanneva between 2004 and 2005.
The results obtained indicate that all study areas were suitable for cultivating reed canary grass, but fertilizers must be added to make up nutrient deficiencies. The study areas were very clean from heavy metals. The results also suggest that the characteristics of peat or surroundings of peatland do not influence the nutrient level of peat significantly, considering the cultivation of reed canary grass. The large geochemical provinces have a smaller impact on nutrient and heavy metal levels in the peat on the peat cut-away areas compared to smaller geochemical units. Heavy metal content in the peat and in the mineral soil under the peat seems to correlate. Reed canary grass does not uptake heavy metals from the cultivation media effectively.
Liming slag was better for liming in cultivation of reed canary grass than ash. Although ash has large amounts usable nutrients, especially potassium, it did not raise the heavy metal content in peat to harmful levels, it can therefore be used in the cultivation of reed canary grass.
Stock fertilized fur animal manure compost produced almost as much biomass as optimized artificial fertilizers. After the correction of nutrient deficiencies, compost is suitable for the cultivation of reed canary grass in peatlands. Because the total nutrient levels are high in compost, its fertilizer effect lasts longer than in artificial fertilizers, where nutrients are all in a dissolved form.
Already in the first growing season the cultivation of reed canary grass changed the cut-away peatland from a carbon source to a carbon sink. In this respect, the reed canary grass cultivation can be used to produce bioenergy to replace fossil fuels in accordance with the goals of Kyoto Protocol. / Tiivistelmä
Turvetuotannosta vapautuneella suopohjalla toteutetaan erilaisia jälkikäyttötapoja riippuen suopohjan ominaisuuksista. Jos suopohja on kohtuullisen kivetöntä, ruokohelpiviljely on kannattavaa. Viljelty ruokohelpi poltetaan turpeen tai hakkeen seassa. Tämän tutkimuksen tarkoitus oli selvittää miten pohjaturpeen ja suopohjan ympäristöalueiden ominaisuudet sekä viljelyyn käytetyt lannoite- ja kalkitusaineet vaikuttavat ruokohelpin käyttämiin ravinteisiin.
Ruokohelpiviljelyn lannoituskustannukset ovat suuret, joten suopohjan luontainen ravinnetila kannattaa huomioida lannoitusta suunniteltaessa. Suopohjan ravinnetila saadaan selville laatimalla alueelle viljavuusanalyysi. Kyseisen analyysin yhteydessä on hyödyllistä tehdä myös raskasmetallianalyysit, jotta viljelykäyttöön tulevan suopohjan puhtaudesta voidaan varmistua.
Tutkimuksen kohdealueiksi valittiin Luesuon, Piipsannevan ja Jouttenisennevan turvetuotantoalueet. Lisäksi tutkimusta varten perustettiin ruokohelpin viljelykoealueet Luesuolle ja Hankilannevalle vuosina 2004 ja 2005. Tutkimusalueilla suoritettiin kattava näytteenotto. Näytteistä analysoitiin tärkeimmät kasviravinteet sekä joukko raskasmetalleja. Tulosten perusteella tutkimusalueille laadittiin viljavuusluokittelu. Tutkimusalueet soveltuvat hyvin ruokohelpiviljelyyn, mutta ravinnepuutokset tulee korjata lannoituksella käytettäen suopohjille suositeltua lannoitusta. Tutkimusalueet osoittautuivat puhtaiksi raskasmetalleista.
Tutkimuksen kohteina olleiden suopohjien liukoisen kaliumin ja fosforin pitoisuudet olivat hyvin alhaisia, eivätkä turpeen tai ympäristön ominaisuudet vaikuttaneet niiden pitoisuuksiin ruokohelpiviljelyn kannalta merkittävästi. Liukoisen magnesiumin ja kalsiumin pitoisuudet sen sijaan vaihtelivat tutkituilla suopohjilla kohtuullisen paljon riippuen turpeen ominaisuuksista. Geokemiallisella provinssilla ei todettu olevan niin suurta merkitystä suopohjien lopputurpeiden alkuainepitoisuuksiin kuin pienemmillä geokemiallisilla yksiköillä. Tutkittujen suopohjien turpeen ja sen alla olevan kivennäismaan raskasmetallipitoisuudet korreloivat keskenään.
Tutkimustulosten mukaan kasvualustan raskasmetallit eivät siirry tehokkaasti ruokohelpiin. Poikkeuksena olivat sinkin ja molybdeenin pitoisuudet, joita ruokohelpissä esiintyi korkeampina pitoisuuksina kuin kasvualustassa. Haitallisten raskasmetallien pitoisuudet olivat huomattavasti alhaisempia ruokohelpissä kuin kasvualustassa. Ruokohelpi sisälsi raskasmetalleja erittäin pieninä pitoisuuksina, joten viimeisen kasvukuukauden muutokset olivat vaikeasti tulkittavissa. Näyttää kuitenkin siltä, että ruokohelpi siirtää ainakin osan kuparista, sinkistä ja molybdeenistä juuristoonsa talven ajaksi.
Suoritettujen lannoituskokeiden perusteella teräskuona soveltuu voimalaitostuhkaa paremmin turvekentän kalkitukseen ruokohelpiviljelyssä. Voimalaitostuhka sisältää kuitenkin huomattavia määriä hyödynnettäviä ravinteita, etenkin kaliumia. Tutkimuksessa havaittiin, ettei voimalaitostuhka lisännyt edes ylisuurina annoksina kasvualustan raskasmetallipitoisuuksia haitallisesti, joten sitä voidaan käyttää ruokohelpiviljelyssä.
Varastolannoitetulla kompostilla saavutettiin lähes yhtä hyvä ruokohelpisato kuin optimoidulla mineraalilannoitteella. Näin ollen turkislantakompostia voidaan ravinnekorjausten jälkeen käyttää mainiosti ruokohelpiviljelyyn. Kompostin ravinnevaikutus on myös suurten kokonaisravinnepitoisuuksien vuoksi pidempi kuin mineraalilannoitteilla. Fosforin varastolannoitus turkislantakompostilla onnistui ensimmäisen kasvukauden perusteella hyvin.
Tutkimuksessa todettiin, että jo ensimmäisenä kasvukautena ruokohelpiviljelyllä saadaan muutettua hiililähteenä toimiva entinen turvetuotantoalue hiilinieluksi. Ruokohelpiviljelyllä tuotetulla bioenergialla voidaan lisäksi korvata fossiilisia polttoaineita Kioton ympäristösopimuksen tavoitteiden mukaisesti.
|
136 |
Treatment of acid mine lakes: lab and field studiesSchipek, Mandy 22 November 2011 (has links)
Mining of lignite in Lusatia has a long history of over 100 years. The extracted brown coal is utilized to generate electricity in three large power plants: Jänschwalde, Boxberg, and Schwarze Pumpe. With an annual carbon dioxide (CO2) output of approximately 50 million tons, these power plants are among Germany’s large-scale CO2 emitters.
The environmental impact from open-pit mining is of a considerable degree and currently poses a challenging problem. The groundwater deficit in 1990 was 7 billion m3 over a surface area of approximately 2100 km2 (Luckner, 2006a) and was bisected in value until today. Due to the decline of mining activity and the termination of mine drainage at most open pits in the Lusatian region, the groundwater table has recovered forming 28 pit lakes (Zschiedrich, 2011). The majority of the post mining lakes do not meet the quality standards for pH, iron or sulfate parameters; because of pyrite oxidation that produces acid mine drainage (Luckner, 2006b, Klapper and Schultze, 1995, Schultze et al., 2010). The post mining lakes in Lusatia have low pH values (3 – 4), high sulfate contents (up to 2800 ppm) as well as high iron concentrations (100 – 150 ppm).
Lakes are flooded by groundwater and using surface water from Spree and Neisse River to achieve fast filling and dilution; however, due to the limited availability of surface water, further rehabilitation strategies for the region had to be investigated.
Between 1970 and 1990, approximately 26 million m3 of suspended fly ash were deposited in the lake Burghammer and settled as an ash body at its base; where it may be used for rehabilitation. In a first experiment conducted in 2001 material from the ash body was picked up and redistributed throughout the lake. By this treatment the pH of the lake was raised temporarily; however, a sustainable remediation was not achieved.
Based on these experiments it was investigated whether the ash reacts more sufficiently through additional CO2 injection or not. Aim was to combine the rehabilitation of acid mine lakes with the utilization of atmospheric carbon dioxide emissions from coal-fired power plants. The CO2 sequestration is achieved through the generation and accumulation of carbonates in the lake. The following equations describe the precipitation of carbonate by using CO2 and alkaline earth cations M:
CO2 + MO → MCO3 (s)
CO2 + M(OH)2 → MCO3 (s) + H2O
Therefore, neutral pH conditions are necessary for the long-term accumulation of carbonates in the lakes.
In laboratory investigations it was shown, that the 20 to 30 years old fly ash deposits of lake Burghammer can be used for carbonate sequestration and lake water treatment. Bivalent ions (Ca2+, Mg2+) are eluable and available for carbonate precipitation; on average we assumed 1 wt.-% of reactive calcium to be contained in the settled ash sediments. Settled fly ash sediments are less reactive than fresh fly ash from a power plant (e.g. Schwarze Pumpe). During batch experiments, we increased the buffering capacity to maximum values of 7 mmol/L. Beforehand no buffering capacity exists due to the low pH of 2.9 in the lake. Batch investigations provided a sequestration potential of 17 g CO2/kg ash sediment; in comparison fresh fly ash results in a sequestration potential of 33 g CO2/kg ash (Schipek and Merkel, 2008b, Schipek and Merkel, 2008a, Schipek, 2009).
Based on the laboratory results a field experiment was conducted. In this field experiment gas injection lances were installed to a sediment depth of 12 m. Gaseous CO2 was applied with a pressure of 2.2 bar and 2.2 m³/h for 3 months and lake water was monitored during injection. Variations in total inorganic carbon due to diffusion processes of CO2 saturated pore waters could be observed. As the pilot experiment comprised only a small area of lake Burghammer no initial neutralisition (e.g. by a suction excavator) was possible. Thus, no further changes in water chemistry were observed.
Drilling cores in the vicinity of the injection area provided mineralogical and geochemical conditions before and after CO2 treatment. No trace metal mobilization was found during CO2 injection. Most elements showed decreasing trends or didn’t change significantly. Calculated saturation indices for calcite indicated equilibrium conditions or slightly oversaturated conditions (SICalcite,average +0.12; SICalcite,median +0.31). Geochemical and mineralogical investigations proved that CO2 sequestration is possible with an average precipitation rate of 0.5 wt.-% (2.2 g CO2/kg). The maximum rate for carbonate precipitation was determined with 7.4 wt.-% Calcite, according to 32.6 g CO2 per kilogram treated ash.
Besides the use of the settled fly ash as neutralizing agent in acidic mining lakes, laboratory and field investigations were conducted in order to improve in-lake liming. In batch and columns experiments, different liming agents (synthetic marble powder and industrial products) were tested and investigated. Significant differences in reactivity were obvious at pCO2 > 3.8 • 10-4 atm. Ions typical for acid mine drainage (e.g. Mn2+, Cd2+, SO42-) do have different effects on the kinetic of carbonate dissolution. Manganese concentrations typical for acidic mining lakes inhibit calcite dissolution. Cadmium has as well a significant influence on dissolution and kinetics. Only circa 50 % of the calcium concentration was reached with cadmium as inhibitor compared to the dissolution in pure water. Increased CO2 partial pressure might be used to compensate inhibtion by material impurities and/or water constituents.
Column experiments showed that a multi-stage application of liming agent increases the efficiency of a lake treatment. The combination of a first application of calcite (up to pH 4.5) and further application of Ca(OH)2 seemed to be the most promising method. This treatment sheme was successfully applied in lake Burghammer from March 2009 – December 2010 (initial neutralisation and 6 follow-up treatments).
Finally, it can be concluded, that in lignite mining districts in-lake treatment of acidic mining lakes is a seminal method to handle water quality problems. Using gaseous CO2 in combination with industrial by-products can be accounted as sustainable method for CO2 sequestration and for treatment of AMD. The advantage for mining areas lays in the prevention during treatment of acid mine lakes. Nevertheless, this method presents only a niche solution due to the dependence on alkaline materials, e.g. fly ash.
The development of further strategies and optimization during lake water treatment by in-lake liming might improve the effectiveness of the method. Using calcite instead of NaOH or CaO as liming agent will provide advantages in being more economic and ecological (CO2 bilance). In order to enhance efficiency the use of calcite in combination with CO2 can be a worth considering suggesting. If meteorological parameters (wind) and lake specific characteristics (morphology, currents, etc.) will be considered efforts and costs for in-lake liming will be minimized. / Der Abbau von Braunkohle im Lausitzer Bergbaurevier hat seit über 100 Jahren Tradition. Die abgebaute Braunkohle wird dabei hauptsächliche zur Energieerzeugung in den drei großen Kraftwerken Jänschwalde, Boxberg und Schwarze Pumpe genutzt. Mit einem jährlichen Kohlenstoffdioxid (CO2) – Ausstoß von circa 50 Millionen Tonnen gehören diese Kraftwerke zu Deutschlands größten CO2-Emittenten.
Der Einfluss auf die Umwelt durch Tagebau-Betrieb ist von beträchtlichem Ausmaß und bringt große Probleme mit sich. Im Jahr 1990 betrug das Grundwasser-Defizit im Lausitzer Bergbaurevier 7 Milliarden m³ auf einer Fläche von circa 2100 km² (Luckner, 2006a). Dieses Defizit hat sich bis zum heutigen Zeitpunkt halbiert. Durch den Rückgang der Bergbauaktivitäten und die Beendigung der Wasserhaltungsmaßnahmen in den meisten Tagebauen, hat der ansteigende Grundwasserspiegel 28 Tagebaufolgeseen geschaffen (Zschiedrich, 2011). Der überwiegende Teil der Tagebaufolgeseen ist aufgrund der Pyritoxidation, welche AMD (acid mine drainage) produziert, hinsichtlich der Wasserqualitätsparameter stark beeinflusst (Luckner, 2006b, Klapper and Schultze, 1995, Schultze et al., 2010). Die Tagebaufolgeseen im Lausitzer Bergbaurevier sind durch niedrige pH-Werte (3 – 4), hoche Sulfat-Konzentrationen (bis zu 2800 ppm) und hohe Eisengehalte (100 – 150 ppm) gekennzeichnet.
Die entstehenden Seen sind hauptsächlich durch aufsteigendes Grundwasser und Oberflächenwasser aus den Flüssen Spree und Neisse geflutet. Aufgrund der geringen Verfügbarkeit von Oberflächenwasser mussten weitere Sanierungsmaßnahmen für die Region untersucht werden.
Zwischen 1970 und 1990 wurden im Tagebaufolgesee Burghammer circa 26 Millionen m³ Flugasche-Suspension als Aschekörper abgelagert, wobei eine Nutzung zu Sanierungszwecken angedacht war. Im Rahmen einer Aschesedimentumlagerung im Jahr 2001 wurde der pH-Wert des Seewassers kurzzeitig angehoben, eine nachhaltige Sanierung fand jedoch nicht statt.
Auf Grundlage dieser Ergebnisse wurde im Rahmen dieser Dissertation untersucht, ob die abgelagerten Aschesedimente nachhaltiger durch Einsatz von CO2 reagieren. Ziel war es die Sanierung von Tagebaufolgeseen mit der Reduktion von CO2-Emissionen aus Kohlekraftwerken zu kombinieren. Diese CO2-Sequestrierung sollte durch die Bildung und Ablagerung von Carbonaten im Seesediment erfolgen. Die Gleichungen (1) und (2) beschreiben dabei die Fällungsreaktion von Carbonaten aus CO2 mit dem Alkalimetall M (aus Oxiden bzw. Hydroxiden):
CO2 + MO → MCO3 (s)
CO2 + M(OH)2 → MCO3 (s) + H2O
Zur Carbonatfällung und nachhaltigen Ablagerung sind neutrale pH-Bedingungen notwendig.
In Laboruntersuchungen konnte gezeigt werden, dass die 20 bis 30 Jahre alten Flugaschesedimente zur CO2-Sequestrierung in Kombination mit Seewasserbehandlung genutzt werden können. Zweiwertige Ionen (Ca2+, Mg2+) sind aus den Aschesedimenten eluierbar und stehen für die Fällungsreaktion zur Verfügung. Durchschnittlich 1 Masse-% reaktives Calcium befindet sich in den Sedimenten. Die abgelagerten Aschesedimente sind dabei weniger reaktiv als frische Flugaschen aus Kohlekraftwerken (z.B. Schwarze Pumpe). In Batch-Versuchen mit Tagebaufolgesee-Wasser konnte die Säure-Pufferkapazität auf maximal 7 mmol/L erhöht werden. Sequestrierungs-Raten von 17 g CO2/kg Aschesediment wurden im Rahmen der Versuche erreicht. Im Vergleich dazu betrugen die Sequestrierungs-Raten in Versuchen mit frischen Flugaschen bis 33 g CO2/kg Asche (Schipek and Merkel, 2008b, Schipek and Merkel, 2008a, Schipek, 2009).
Auf Grundlage dieser Laborergebnisse wurde ein Feldversuch im Tagebaufolgesee Burghammer geplant. Während diesem wurden Gasinjektionslanzen bis in eine Sedimenttiefe von 12 m im abgelagerten Aschesediment installiert. Gasförmiges CO2 wurde mit einem durchschnittlichen Druck von 2.2 bar und 2.2 m³/h für eine Dauer von 3 Monaten injiziert. Während dieser Zeit fand ein kontinuierliches Monitoring des Seewassers im Bereich der Injektion statt. Veränderungen des Gehaltes an TIC (total inorganic carbon) aufgrund von Diffusionprozessen von CO2-gesättigtem Porenwasser aus dem Aschekörper waren beobachtbar. Da der Feldversuch nur in einem begrenzten Bereich des Tagebaufolgesees Burghammer stattfand und keine Initialneutralisierung vorsah, konnten keine weiteren, großmaßstäblichen Veränderungen im Wasserkörper festgestellt werden.
Bohrkernentnahmen im Umfeld des Behandlungsgebietes lieferten Aussagen bezüglich der mineralogischen und geochemischen Beschaffenheit vor und nach CO2-Injektion. Im Porenwasser wurde keine Spurenmetall-(re)-mobilisierung durch die Behandlung mit CO2 festgestellt. Nahezu alle Elemente zeigten einen abnehmenden Trend durch die Behandlung mit CO2, bzw. keine signifikanten Veränderungen. Modellierte Sättigungsindizes für Calcit wiesen auf Gleichgewichtsbedingungen oder leichte Übersättigung bzgl. Calcit hin (SICalcit, Mittelwert +0.12; SICalcit, Median +0.31). Geochemische und mineralogische Untersuchungen zeigten, daß CO2-Sequestrierung mit einer durchschnittlichen Fällungsrate von 0.5 Masse-% (2.2 g CO2/kg Aschesediment) erreicht wurde. Die maximale Fällungsrate wurde mit 7.4 Masse-% Calcit bestimmt, dies entspricht einer Festlegung von 32.6 g CO2/ kg Aschesediment.
Neben der Nutzung der abgelagerten Aschesedimente zur Behandlung des Tagebaufolgeseewassers wurden desweiteren Labor- und Feldversuche durchgeführt um In-Lake-Behandlungen mit industriellen Kalkprodukten zu optimieren. In Batch- und Säulenversuchen wurden verschiedene Kalkprodukte (synthetisches Marmorpulver und industrielle Produkte) getestet und untersucht. Signifikante Unterschiede auf die Reaktivität wurde bei erhöhten CO2-Partialdrücken (pCO2 > 3.8 • 10-4 bar) beobachtet. Wasserinhaltsstoffe, die typisch für AMD sind (z.B.. Mn2+, Cd2+, SO42-) zeigten einen signifikanten Einfluss auf die Calcit-Lösungskinetik. Mangankonzentrationen, wie sie in Lausitzer Tagebaufolgeseen vorkommen, zeigten – ebenso wie Cadmium - eine inhibitierende Wirkung auf die Kinetik. Im Vergleich zu Versuchen mit destilliertem Wasser wurden nur ungefähr 50 % der Calcium-Gleichgewichtskonzentration mit Cadmium als Inhibitor erreicht. Erhöhte CO2-Partialdrücke könnten genutzt werden, um die inhibitierende Wirkung von vorhanden Materialverunreinigungen und/oder Wasserinhaltsstoffen zu kompensieren.
Säulenversuche zeigten, dass der mehrstufige Einsatz von Kalkprodukten die Effizienz während einer Seewasserbehandlung erhöht. Die Kombination einer Erstbehandlung mit Kalksteinmehl (bis pH 4.5), und einer Behandlungsfortsetzung mit Ca(OH)2 erwies sich als wirkungsvollste Methode. Dieses Behandlungsschema (Initialneutralisation, 6 Nachfolgebehandlungen) wurde im Tagebaufolgesee Burghammer von März 2009 – Dezember 2010 erfolgreich angewandt.
Zusammenfassend lässt sich sagen, dass in ehemaligen Bergbaurevieren die In-Lake-Behandlung von Tagebaufolgeseen eine zukunftsträchtige Methode zur Behandlung von Wasserqualitätsproblemen darstellt. Die Nutzung von gasförmigen CO2 in Kombination mit industriellen „Abfall-Produkten“ kann als nachhaltige Methode zur CO2-Sequestrierung und zur Behandlung von AMD bezeichnet werden. Der Vorteil in Bergbaurevieren liegt dabei in der Vorbeugung der Entstehung von Wasserqualitätsproblemen. Dennoch stellt diese Methode nur eine Nischenlösung aufgrund der Verfügbarkeit der alkalischen Materialien (Flugasche) dar.
Die Entwicklung und Optimierung weiterführender Strategien zur In-Lake-Behandlung durch Kalkung wird zur Effizienzerhöhung beitragen. Die Nutzung von Kalksteinmehl anstelle von NaOH bzw. CaO als Neutralisationsprodukt wird Vorteile hinsichtlich ökonomischer und ökologischer Sicht (CO2-Bilanz) mit sich führen. Um die Effizienz beim Einsatz von Kalksteinmehl zu steigern, kann der Einsatz von CO2 in Betracht gezogen werden. Sobald meteorologische Parameter (Wind) und see-spezifische Merkmale (Morphologie, Strömungen, etc.) berücksichtigt werden, kann der Aufwand und die Kosten für In-Lake-Behandlungen minimiert werden.
|
137 |
Influence de différentes pratiques agricoles sur la qualité et la santé des sols : étude de cas sur des vergers slovènes irrigués ou en agriculture biologique / Agricultural practices impact on soil quality and health : case study of slovenian irrigated or organic orchardsMursec, Mateja 15 September 2011 (has links)
Une mauvaise connaissance des propriétés des sols et de leur fonctionnement peut avoir de nombreuses conséquences néfastes sur le rendement et la qualité des récoltes, sur la dégradation des sols et sur une pollution de l’environnement. En raison de l’importance des pratiques agricoles, notre étude s’est focalisée sur leur impact sur la qualité et la santé des sols. La recherche s’est effectuée de novembre 2003 à octobre 2007 sur des vergers de pommiers implantés sur des collines dans le nord-est de la Slovénie. Deux pratiques agricoles fréquentes dans cette région ont été suivies : (i) une irrigation localisée au goutte à goutte sur des Calcaric Cambisol (CALCOSOL) développés sur marnes, et ses effets sur la stabilité structurale des sols et leur biomasse microbienne à la Station expérimentale de Gačnik et (ii) la combinaison d’un engrais organique (Compo guano) et d’un amendement calcaire dans un verger conduit en agriculture biologique à Pohorski dvor sur un District Cambisol (ALOCRISOL) développé sur schistes. La présence de microbes pathogènes fécaux dans le sol, dus à l’irrigation ou à l’apport d’engrais organiques animaux a aussi été recherchée sur les deux sites. Le régime hydrique du sol a été suivi durant deux étés par des relevés tensiométriques hebdomadaires sur les deux sites. A la station expérimentale de Gačnik, un rang irrigué a été comparé à un rang non irrigué. La teneur en matière organique totale, son fractionnement granulométrique et la signature isotopique des différentes fractions permettant de discuter de leur origine et leur turn over ont été mesurés. La biomasse microbienne et son activité ont été caractérisées au printemps et à l’automne en 2004 et 2005. La stabilité structurale a été mesurée selon la méthode de Bartoli à l’automne 2004 et au printemps 2005. Sur le verger conduit en agriculture biologique à Pohorski dvor seul le pH et les paramètres microbiologiques ont été suivis selon la même périodicité en comparant les différents traitements dans une expérimentation par blocs. Enfin, sur les deux sites, une quantification des champignons, des bactéries (aérobies, anaérobies, coliformes fécaux) et des virus présents dans le sol a été réalisée. Incidence de l’irrigation par goutte à goutte sur la qualité du sol sur le site de Gačnik sur la qualité physique du sol- Les sols de ce verger, argilo-limoneux et carbonatés, varient fortement de l’amont à l’aval de la parcelle située sur une pente de 15%. le sol est peu épais à l’amont, la marne altérée apparaissant dès 60 cm tandis qu’à mi-pente et à l’aval le sol est épais >1 m et la marne plus fortement altérée. L’observation des profils pédologiques et l’historique de la parcelle montrent que le sol a été fortement remanié sur les 60 premiers centimètres préalablement à la plantation du verger. Le passage d’une plantation en terrasses à une plantation dans le sens de la pente a conduit à l’effacement des terrasses suivi d’un labour profond dont en voit encore la trace à 60 cm de profondeur à l’aval de la parcelle (Fig. 3.3 & Tab. 3.9). Un échantillonnage systématique de la teneur en carbone organique de l’horizon de surface, selon un pas de 6 m, montre un accroissement selon la pente suivant une forme en zig-zag reflétant la trace des anciennes terrasses (Fig. 3.19). Dans les 30 premiers centimètres la teneur en matières organiques, le rapport C/N et la capacité d’échange cationique augmentent de l’amont vers l’aval tandis la teneur en carbonates de calcium décroît (Fig. 3.15). Le pH reste stable entre 8 et 8, 4. A la surface du sol dans les rangs de plantation traités par désherbage chimique, une croûte alguaire se forme sur le côté ombragé du rang... / Underestimation of soil properties and poor understanding of soil conditions can have many negative consequences, which results in quality or quantity of yield, soil degradation or even environmental pollution. According to importance of agricultural practices, our study focused on their impact on soil quality and health. The research took place from November 2003 to October 2007 in apple orchards in north-eastern Slovenia where two frequent agricultural practices were investigated: (i) drip irrigation on Calcaric Cambisol and its effects on structural stability and microbial biomass at Gačnik experimental station and (ii) combination of organic fertiliser (Campo guano) and liming in organic farming to enhance microbial biomass and nitrogen nutrition at Pohorshi dvor on Dystric Cambisol. The presence of faecal pathogens in the soil due to irrigation or organic fertilizer was also investigated. Water potential was measured during two seasons in both locations. Structural stability according Bartoli method, organic mater characteristics (including grain size organic matter fractionation and isotopic signature of organic carbon origin), and microbiological parameters were analysed as potential indicators of soil quality in irrigation practice comparing an irrigated (IR) to a non-irrigated (NIR) row. In organic farming, mainly pH and microbiological parameters were followed according treatments on an experimental blocks comparison. According to hilly terrain and land levelling in Gačnik, we were dealing with two groups of soil differing in thickness, organic matter, and calcium carbonate contents: one at upslope and another at mid and downslope. Considering soil characteristics, slope effect was more expressed than irrigation effect. According to slope, water gravimetric content (W), organic matter (OM), microbial biomass (MB), and respiration (R) increased towards downslope while total carbonates (Ca) and structural stability (SS) decreased. According to irrigation, W, OM, and SS contents decreased, while MB and R increased from NIR to IR rows. No difference was observed for Ca between treatments. According to slope, higher carbonate content was as an important factor for higher structural stability as organic matter pool. According to irrigation, lower W in IRR row could be explained by modification in root distribution due to drip irrigation. Irrigation leads to an increase of soil microbial biomass and its activity (as a short-time effect) and decrease of OM (as a long-term effect); moreover, a decrease of OM originating from the marl bedrock was observed in IRR row and attributed to microbial mineralization. Lower SS of IRR row is related to the OM reduction. Seasonal variations of structural stability show complex trends resulting from the combination of climatic conditions and biological activity. In organic fertilising study, the interaction of Compo guano and lime together was not clear, but in long term this is probably the best solution because it had positive consequences on both soil pH and available nitrogen, while preserving fair levels of MB and labile organic matter (LOM). Irrigation water and Compo guano were considered as eventual sources of faecal coliforms which remains in soils. From our study it was concluded that OM, MB, R and faecal coliforms can be treated as general useful indicators in assessing soil quality. According to agricultural practice, SS should be emphasized as an important quality indicator in irrigation practice and pH in organic farming.
|
Page generated in 0.0467 seconds