This study examined the effects of seedbed and seedling environment on establishment of early and late seral dominant alpine species. Species studied included late seral dominant forbs (Geum rossii, Artemisia scopulorum, and Polemonium viscosum), early seral dominant forbs (Potentilla diversifolia and Sibbaldia procumbens), a late seral dominant grass (Festuca idahoensis), and early seral dominant grasses (Calamagrostis purpurascens and Deschampsia cespitosa). Germination responses of each species to wet vs. dry cold stratification and light vs. dark conditions were investigated. No statistical differences were observed in the seed germination of early and late seral dominant forbs or early and late seral dominant grasses, but significant differences were observed in the responses of grasses and forbs. Seed germination of forbs was greater under light than dark conditions and following wet cold storage. Effects of fertilization on growth responses and nutrient uptake of G. rossii and D. cespitosawere evaluated in a factorial greenhouse experiment in which seedlings of each species were grown at four levels of nitrogen (N) and phosphorous (P). The late seral dominant forb responded more like a species from a low-nutrient environment exhibiting lower relative growth rates, higher root:shoot ratios, and a smaller response to N than the early seral dominant. A field experiment on the Beartooth Plateau, Montana, examined the soil environment and seedling emergence, growth, and survival of seeded early and late seral dominants on loamy sand soils of a severe disturbance and on peat soils of an undisturbed area during two growing seasons. Effects of fertilizer and mulch were examined on the severely disturbed area. Differences between uncleared turf and turf cleared of vegetation (gap disturbance) were evaluated on the undisturbed area. The gap disturbance had higher levels of N and P and warmer soil than the severe disturbance or vegetated undisturbed area. Soil water potentials were never low enough to result in plant stress. Seedling growth was slow - .005 g to .04 g dry weight the first growing season and .02 g to .20 g the second growing season. Growth was greatest on the gap disturbance and on fertilized plots of the severely disturbed area. Early seral dominants had the largest seedlings and the smallest R/R+S ratios. Mortality was low - odds of .50 were rarely exceeded even after two years. Survival was higher on warm, nutrient rich soils of the gap disturbance. Mulch increased emergence and survival on the severe disturbance. Fertilization increased mortality, probably because an initial pulse of N was followed by a rapid decline. Higher mortality occurred in 1986 than 1985 as 1986 had a shorter growing season and cooler air and soil temperatures early in the growing season.

Conservation tillage programs have been successfully implemented for many agronomic cropping systems, but adoption of reduced tillage for vegetable crops has been slow. As many conventionally managed conservation tillage programs rely on synthetic herbicides for clean cultivation, alternative methods must be devised to suppress weed pressure and reduce reliance on mechanical cultivation to aid in the development of reduced tillage programs for organic cropping system. Strip tillage is a reduced tillage method that is well suited to vegetable crop production, and the utilization of cover crops and living mulches between rows provides a viable weed management option for organic systems. The adoption of reduced tillage and the inclusion of cover crops and living mulches have the potential to alter the agroecosystem in ways that impact plant development and crop yield, and augment weed, insect and disease pressure. The current study focuses on the use of strip tillage and the interplanting of spring-seeded living mulches and overwintered cover crops for early-season organic broccoli production. Data were collected on ground cover provided by cover crops and living mulches, crop physiological status (petiole sap nitrate, photosynthetic rate, plant growth and crop biomass) and pest pressure (weed relative abundance, insect density and disease incidence and severity). Living mulches provided the greatest ground coverage when cover crop establishment was poor; however, when cover crops produced a large amount of biomass, living mulch establishment was suppressed. Decreases in herbivorous pests and suppression of grassy and cool-season weed species were also observed, indicating that strip tillage and the use of spring-seeded living mulches and overwintered cover crops may provide beneficial pest management strategies. Decreases in crop growth and biomass, and decreases in petiole sap nitrate were observed, however, indicating reductions in crop vigor and yield may be expected with the implementation of strip tillage and living mulch crops. It is suggested that the utilization of strip tillage and living mulch crops may provide benefits to pest management which may outweigh declines in yield.

The plastic mulch films, which are mostly made from LDPE, are used in order to increase the yields and to prevent the weed growth by covering the top of the soil by leaves or straw in nature. After a period, the mulch films turn into unmanageable quantities of soiled plastic films, which cause an environmental problem. Using degradable mulch films for agricultural purposes can be a solution for the environmental problems caused by the plastic mulch films. In this study, to introduce biodegradability to mulch films, a natural biopolymer starch was used. Before blending, starch was transformed into thermoplastic starch in order to make the starch processable. The need, to provide adhesion and interaction between thermoplastic starch and LDPE, citric and stearic acid were considered as compatibilizers. To accelerate the degradation of the LDPE matrix, three pro-oxidants cobalt(II) acetylacetonate, iron(III) stearate and manganase(II) stearate were used. The films prepared were characterized by FTIR spectroscopy / their thermal and mechanical properties were analyzed and buried under soil. The films recovered from soil after 76 days were characterized by FTIR spectroscopy, their weight loss were measured and their thermal and mechanical properties were analyzed. Studies showed that the use of cobalt(II) acetylacetonate gave improved results in terms of the mechanical properties and thermal stabilities of the films. Additionally, it is observed that the use of citric acid as a compatibilizer improved the thermal stabilities of starch in the films. Lastly, it is observed that the mechanical properties of the films were affected by the interactions between compatibilizers and pro-oxidants.

Reports from various institutions claim that garbage management in Rwanda has had diverse effects on both the natural environment and human society. Such claims prompted for an exploratory study to find out an optimal system to handle solid waste in Kigali City. The study considered a literature review and primary data from 400 randomly selected citizens. They were surveyed about their opinions on which system they perceived to be the optimal to handle garbage in Kigali City. The computer software Web-Hipre was used to analyze data on the three systems considered to handle solid waste in Rwanda: briquetting, composting, and incineration.The results indicate briquetting as the optimal alternative to handle solid waste from homesteads and workplaces of Kigali City. Briquetting considers production of solid fuels that may reduce destruction of forests for fuel. Other major reasons for briquetting, highlighted by respondents, include improved kitchen hygiene and sanitation and replacement of charcoal for a less dusty fuel. Economic factors governed surveyed participants to prioritise briquetting system to handle solid waste in Kigali. Composting may be considered for transforming organic materials into mulch to support farming activities in rural areas as well as gardening in the towns. However, a centralised incineration system is presently not suitable. The private sector has so far not fully been engaged in the transformation of solid waste into bioenergy in Rwanda.

Reports from various institutions claim that garbage management in Rwanda has had diverse effectson both the natural environment and human society. Such claims prompted for an exploratory study to find outan optimal system to handle solid waste in Kigali City.The study considered a literature review and primary data from 400 randomly selected citizens. They weresurveyed about their opinions on which system they perceived to be the optimal to handle garbage in KigaliCity. The computer software Web-Hipre was used to analyze data on the three systems considered to handlesolid waste in Rwanda: briquetting, composting, and incineration.The results indicate briquetting as the optimal alternative to handle solid waste from homesteads and workplacesof Kigali City. Briquetting considers production of solid fuels that may reduce destruction of forests for fuel.Other major reasons for briquetting, highlighted by respondents, include improved kitchen hygiene andsanitation and replacement of charcoal for a less dusty fuel.Economic factors governed surveyed participants to prioritise briquetting system to handle solid waste in Kigali.Composting may be considered for transforming organic materials into mulch to support farming activities inrural areas as well as gardening in the towns. However, a centralised incineration system is presently notsuitable. The private sector has so far not fully been engaged in the transformation of solid waste into bioenergyin Rwanda.

Les mécanismes qui contrôlent le stockage du carbone dans le sol ne sont pas tous clairement identifiés et il reste une grande incertitude concernant leur quantification. L'usage et la gestion des sols sont les facteurs principaux qui influencent les transformations de la matière organique, déterminant la minéralisation du carbone et de l'azote ou leur rétention dans le sol<br />L'objectif principal de cette thèse est l'identification des processus physiques et biologiques qui sont influencés par la localisation des résidus dans le sol, en interaction avec la qualité de ces résidus. La localisation initiale des résidus modifie des propriétés physiques du sol : les dynamiques d'eau, le transport des solutés ou la température du sol. La qualité biochimique des résidus influence les processus (micro-)biologiques : les biotransformations du carbone et de l'azote, l'activité et la composition des populations microbiennes dans le sol. Ces changements physiques et biologiques interagissent, peuvent modifier la structure du sol (par l'agrégation) et, en retour, influencer la décomposition de la matière organique. <br />La première partie de ce travail traite de l'influence de la qualité des résidus végétaux et du type de sol sur la minéralisation du C et N en contact 'optimal' avec le sol (incorporation homogène des résidus finement coupés). Il est montré que sous conditions contrôlées et d'azote non limitant, la qualité des résidus est le facteur principal déterminant la vitesse de décomposition. Le type de sol a un effet négligeable sur les dynamiques de décomposition à court terme. Par contre, la minéralisation du carbone à plus long terme dépend du type de sol, ce qui est probablement lié aux différences dans la capacité du sol à stabiliser du carbone soluble ou d'origine microbienne.<br />La deuxième partie traite de l'effet de la localisation des résidus sur la minéralisation du C et N pour des résidus de colza dans un sol limoneux. Des colonnes de sol sont construites avec des résidus soit incorporés soit laissés à la surface du sol. Les colonnes sont placées périodiquement sous un simulateur de pluie pour simuler des conditions hydriques relativement similaires au champ. L'évaporation du sol est fortement réduite avec le mulch, ce qui conduit à une humidité du sol plus grande que lorsque les résidus sont incorporés. Simultanément, on observe un dessèchement rapide du mulch de résidus. Le C et N issu des résidus est distribué différemment dans le sol selon que ceux-ci sont à la surface ou incorporés. Les différences dans la disponibilité d'eau et des nutriments conduisent à une vitesse de décomposition plus lente pour des résidus à la surface que pour des résidus incorporés dans le sol. Cependant, la minéralisation nette de l'azote est plus grande dans le sol sous mulch qu'avec incorporation des résidus en raison de l'humidité plus grande qui favorise la minéralisation et d'une moindre organisation d'azote.<br />L'influence de la localisation des résidus sur le devenir du C et N dans le sol et dans les agrégats est examinée afin d'évaluer les mécanismes qui contrôlent le stockage du carbone dans le sol. A court terme, une grande partie de la matière organique particulaire (MOP) est retenue à la surface du sol avec le traitement mulch alors que toute la MOP a disparu quand les résidus sont incorporés. La présence des résidus augmente la taille moyenne des agrégats comparé au sol témoin et des agrégats plus larges sont trouvés dans la couche de sol 0-5 cm sous le mulch que dans la couche ou les résidus sont incorporés. La quantité totale du C des résidus récupérée dans les agrégats est similaire avec les résidus laissés à la surface et les résidus incorporés, mais elle est distribuée différemment dans le profil du sol. Malgré les différences dans la façon dont le C 'nouveau' entre dans le sol, la distribution relative du C des résidus dans les micro et macro agrégats est la même pour les deux localisations, probablement parce que dans les deux cas le C des résidus entre dans les agrégats sous forme soluble.<br />Finalement, l'interaction entre la localisation des résidus et leur qualité est étudiée. Un mulch réduit fortement l'évaporation du sol et l'importance de cette réduction dépend de la qualité physique du mulch. Des changements dans l'humidité du mulch, identifié comme facteur principal qui détermine la décomposition du mulch, dépend aussi de la qualité (physique) des résidus. Avec l'incorporation des résidus, la vitesse de minéralisation de C est principalement influencée par la qualité biochimique des résidus. L'interaction la plus forte entre localisation et qualité des résidus est observée sur les dynamiques de l'azote : la minéralisation nette de l'azote est déterminée par l'interaction entre l'humidité du sol (effet localisation) et la disponibilité de l'azote (effet qualité). Ces résultats permettent de développer et de calibrer un module du modèle PASTIS (Garnier et al., 2003), conçu pour simuler la décomposition d'un mulch. La modélisation avec PASTISmulch a permis d'avoir accès au flux brut d'azote, d'estimer le transport des nitrates et le lessivage potentiel dans le profil du sol, et de quantifier l'impact de la localisation et qualité des résidus sur la minéralisation du C et N dans le sol.

2 pp. / Describes how to select the appropriate lawn mower to properly mow the species of grass at the correct height for high, medium, or low maintenance levels.

Magistrantūros studijų baigiamajame darbe pateikiami dirvožemio temperatūros, drėgnumo, kietumo, pH, humusingumo, azotingumo, fosforingumo, kalingumo įvairių organinių mulčių ir skirtingo storio sluoksnio liekamojo poveikio tyrimų duomenys. Darbo objektas – raudonojo burokėlio (Beta vulgaris var. vulgaris) pasėlis, kuris nuo 2010 m. nebuvo pakartotinai mulčiuotas. Darbo metodai: dirvožemio temperatūra buvo matuojama kas 10 dienų nuo gegužės 20 iki rugsėjo 30 dienos elektroniniu termometru dviejose laukelio vietose 0–10 cm dirvožemio sluoksnyje. Dirvožemio drėgnumas nustatytas taip pat kas 10 dienų, imant dirvožemio ėminius agrocheminiu grąžtu 0–20 cm dirvožemio sluoksnyje. Dirvožemio kietumas nustatytas pavasarį dirvai pasiekus fizinę brandą 0–25 cm sluoksnyje elektroniniu kietmačiu. Dirvožemio agrocheminės savybės nustatytos po burokėlių derliaus nuėmimo, imant ėminius 0–20 cm dirvožemio sluoksnyje. Dirvožemio analizės atliktos maisto žaliavų, agronominių ir zootechninių tyrimų laboratorijoje taikomais metodais. Dirvožemio pH nustatytas potenciometriniu metodu 1 N KCl ištraukoje, suminio azoto kiekis – Kjeldalio metodu, judriojo fosforo kiekis – CAL metodu, naudojant spektrofotometrą, judriojo kalio kiekis CAL metodu, naudojant liepsnos fotometrą. Humuso kiekis nustatytas – Tiurino metodu. Darbo rezultatai. Anksčiau įterpti organiniai mulčiai mažino dirvožemio temperatūrą, drėgmės išgaravimą ir kietumą. Dirvožemio temperatūra buvo esmingai (0,2–0,6 °C) mažesnė, o drėgnumas... [toliau žr. visą tekstą] / Master degree research paper provides research data of soil temperature, humidity, bulk density, pH, humusness, nitrogen, phosphorus and potassium contents, residual effect of various organic mulches and different mulch thickness layers. Object of the work – red beet culture (Beta vulgaris var. vulgaris), which has not been repeatedly mulched since 2010. Method of the work: soil temperature was measured every 10 days from May 20 till August 30 by an electronic thermometer in two places of a field at 0-10 cm soil layer. Soil humidity was as well measured every 10 days taking soil samples with agrochemical drill at 0-20 cm soil layer. Soil bulk density was determined in spring, when the soil reached physical maturity at 0-25 cm layer by an electronic hardness meter. Agrochemical properties of the soil were established after beetroot reaping taking samples at 0-20 cm soil layer. Soil analysis was conducted using methods applied in food raw materials, agronomical and zootechnics research laboratory. Soil pH was established by potentiometer in 1 N KCl extract, total nitrogen amount – by means of Kjeldal method, labile phosphorus amount – by means of CAL method using spectrophotometer, labile potassium amount – by means of CAL method using flame photometer. Humus amount was established by means of Tiurin‘s method. The results of work. Earlier introduced organic mulches have decreased soil temperature, humidity evaporation and bulk density. Soil temperature was considerably lower (0... [to full text]

Magistrantūros studijų baigiamajame darbe pateikiami įsėtų įsėlių įtakos pasėlio piktžolėtumui, morfometriniams ir produktyvumo rodikliams tyrimo duomenys. Darbo objektas – kukurūzų (Zea mays) monopasėlis, tarpiniai įsėliniai augalai, piktžolės. Darbo metodai: Eksperimentas vykdytas 2009-2011 m. Aleksandro Stulginskio universiteto (buvęs LŽŪU) Bandymų stotyje sekliai glėjiško karbonatingo išplautžemio (Calc(ar)i-Epihypogleyic Luvisol, LVg-p-w-cc(sc)) dulkiško priemolio sąlygomis. Eksperimento variantai: 1. ravėjimas 1-2 kartus (kontrolinis variantas) (R2K); 2. vasarinių rapsų (Brassica napus L.) tarpinis pasėlis (VRTP); 3. baltųjų garstyčių (Sinapis alba L.) tarpinis pasėlis (BGTP); 4.vasarinių miežių (Hordeum vulgare L.) tarpinis pasėlis (VMTP); 5. gausiažiedžių (vienamečių) svidrių (Lolium multiflorum Lamk.) tarpinis pasėlis (GSTP); 6. apyninių liucernų (Medicago lupulina L.) tarpinis pasėlis (ALTP); 7. persikinių dobilų (Trifolium resupinatum L.) tarpinis pasėlis (PDTP); 8. raudonųjų dobilų (Trifolium pratense L.) tarpinis pasėlis (ADTP). Darbo rezultatai. Piktžolių bendroji sausoji masė priklausė nuo tarpinių įsėlinių augalų masės. Nustatytas priklausomumas tarp tarpinių įsėlinių augalų sausosios masės ir visų piktžolių sausosios masės (r=-0,444). Labiausiai piktžolės išplito tarpiniuose pasėliuose, anksti šienavimo metu eliminuotuose iš kukurūzų tarpueilių: baltųjų garstyčių, vasarinių miežių bei vasarinių rapsų. Mažiausia sausoji piktžolių masė nustatyta... [toliau žr. visą tekstą] / In the final work of master degree studies there is given data of investigation of influence of living mulch on crop weediness, morphometric and productivity indicators. The object of the work – maize (Zea mays) monoculture, living mulch plants, weeds. The methods of work: The experiment was performed in 2009-2011 in the Experimental station of Aleksandras Stulginskis under the conditions of silty loam Luvisol ((Calc(ar)i-Epihypogleyic Luvisol, LVg-p-w-cc(sc)). The treatments of experiment: 1. Hand weeding (control variation) (R2K); 2. Spring rape (Brassica napus L.) living mulch (VRTP);3. White mustard (Sinapis alba L.) living mulch (BGTP); 4. Spring barley (Hordeum vulgare L.) living mulch (VMTP); 5. Italian ryegrass (Lolium multiflorum Lamk.) living mulch (GSTP); 6. Black medic (Medicago lupulina l.) living mulch (ALTP); 7.Persian clover (Trifolium resupinatum L.) living mulch (PDTP); 8. Red clover (Trifolium pratense L.) living mulch (ADTP). The results of the work: The total dry mass of the weeds was dependant upon the mass of mulch plants. The dependence indicated between the dry mass of mulch plants and the dry mass of all weeds (r=-0,444). Mostly weeds expanded in the intermediate crops which were moved from the interrows of maize: white mustard, spring barley and spring rape. The lowest dry mass of weeds was indicated in the mulch of ryegrass, Persian and red clover. These mulches produced essentially highest biomass. In the field experiment the most of... [to full text]

A field study evaluating the sustainability of four organic vegetable production systems was conducted in Lexington, Kentucky in 2006 and 2007. The four systems included no-till, raised beds covered with biodegradable black mulch, bare ground with shallow cultivation, and bare ground with shallow cultivation and wood chip mulch. The two-year study compared yield, weed control, labor, and costs associated with each system, as well as physical, chemical, and microbiological soil characteristics. In 2006, tomatoes (Lycopersicon esculentum Mill.) were grown in the four systems, with no significant difference in yield. Summer squash (Cucurbita pepo L.) was grown in the four systems in 2007. The no-till system had significantly lower yields than other systems. The bare ground with cultivation and mulch system had the best weed control in both years.