A sustainable supply of fresh water for the human population is a global concern. Intriguingly, about 70% of the total fresh water consumed in the world annually is claimed by agriculture alone; this fraction is even higher in the Middle East and North Africa (MENA) region, where natural regeneration of groundwater is the slowest. Thus, there is a serious need for innovative materials and technologies to enhance the efficiency water usage in agriculture. To this end, plastic mulches have been employed across the developed world to minimize evaporative loss of water from top-soils. While plastic mulches are inexpensive, they do require specialized farm machinery for installation and long processing times. On one hand, plastic mulches have proven to increase crop yields, but on the other their non-biodegradability poses serious environmental concerns. In response, development of low-cost bio-/photo-degradable artificial mulches remains an area of intense research. In this thesis, we report on a novel superhydrophobic material exploiting inexpensive simple components to reduce the amount of water required for irrigation in agriculture by suppressing evaporative losses from the top-soil. Our material consists of ordinary beach sand coated with < 20 nm thick layer of paraffin wax. We synthesized and extensively characterized our material and applied them as mulches for tomato and barley plants at the KAUST greenhouse. We found that when a ~5 mm thick layer of superhydrophobic sand was placed onto the top-soil in pots, it dramatically suppressed evaporative losses and significantly enhanced the yields. Our preliminary field-scale experiments with tomatoes and barley crops at the Hada Al Sham site corroborate these results. Our approach might find applications in desert agriculture and other fields and alleviate water stress in the MENA region.

The effects of black polyethylene (PE) mulch alone and in combination with plastic film tunnels (Agronet, Reemay, whiteperforated, clear, and clear-slitted) were studied on morphology and yield of sweet corn in North Logan, Utah. Yields of "Miracle" sweet corn (Zea mays L.) were increased significantly by using black PE mulch and with a combination of various types of plastic row covers, as compared to unmulched soil. Standard-growth analysis procedures were conducted to verify responses among treatments. Treatment effects were determined by measuring days to first flowering, ear weight, number of side tillers, cob length, cob circumference, cob fill length, number of rows, and number of kernels missing per cob. Leaf area, plant height, and total shoot dry mass were significantly larger for mulched than for unmulched plants.

Weeds and soil-borne diseases can cause large yield losses in field-grown tomato (Solanum lycopersicum) production. Techniques have been developed to reduce soil-based problems. In this study, we evaluated the impacts of cover crops, soil steaming, and plastic mulch to reduce weed and disease pressure in field-grown tomatoes. Four cover crop treatments were grown in the fall and winter before spring planting. Soils were steamed to a target temperature of 71.1 °C for 0, 5, or 20 minutes. Plastic mulch was also used on half of the rows. Yield, weed densities, and disease incidence were recorded. Reduced flowering time and stringent flowering requirements may reduce the ability to conduct crosses in many plants. Many factors control flowering. Terminal Flowering Locus 1 (TFL1) inhibits flower development. In this study, we attempted to transiently downregulate TFL1 via virus-induced gene silencing (VIGS) in Antirrhinum, Penstemon, Petunia, Rosa, and Rudbeckia.

No description available.

Strawberry cultivar performance affected by various cultural practices was investigated in two production systems. The first study investigated strawberry yield, fruit quality, and production timing of eight cultivars when using black and red plastic mulches in a high tunnel production system. The high tunnel increased air temperatures and advanced strawberry fruiting by four to six weeks compared to local openield production. The second study investigated plant growth, yield, and fruit quality of 10 cultivars fertilized with organic or conventional fertilizer and irrigated once or twice daily with the same total irrigation volume in a container system. Strawberry cultivars varied in their yield and quality variables including soluble solids contents, firmness, and titratible acidity in the two production systems. Mulch color, fertilizer type, and irrigation frequency had varying effects on the growth microenvironment, fruit yield, and certain quality variables.

<p> Measurements of soil temperature and soil moisture values beneath and in close proximity to circular mulches of hay and straw were made. The experiments were conducted to determine whether sub-surface effects vary with mulch diameter, and to acquire information concerning the seasonal changes in such effects produced by a mulch of most favourable diameter. The modification of soil climate increased with a greater mulch size. A circular mulch with a diameter of 60 cms or less was considered to be of no practical value for winter protection of roots. The mulch with a 240 cms. diameter, provided some winter protection, preventing freezing of the soil, and, in summer caused considerable modification of the sub-surface climate. In the summer, soil temperatures were lowered by values of up to 5°C and 2.5°C at 5 and 100 cms. depth respectively. After a two-month period of dry weather, moisture values at 0-10 cms. depth beneath the mulch were 20% by volume, whereas, outside the mulch they were 5%. These differences decreased with increasing depth but were over 10% at 100 ems. </p> / Thesis / Master of Science (MSc)

No description available.

Sustainable agriculture is a crucial factor to be considered in order to meet the growing demand for food production. The need for low cost and highly functional materials to provide the most efficient cultivation process has led the agriculture industry to consume petrochemical and mineral based material in an enormous amount. Thus, disposal of the used mulch materials has become a serious environmental issue. In this work, the possibility of using wood pulp fibre in two distinct applications in agriculture is investigated. First, agricultural mulching is the subject of the study and second, we focus on using wood pulp fibre as growing medium in greenhouses. Mulching in agriculture is an essential practice in order to have high crop yield, healthy products, and more efficient cultivation process. Over the years, agricultural mulch has been made out of a variety of materials. The most common of all is plastic mulch due to its low price and high functionality. However, the problems associated with applying and removing the enormous load of plastic and their disposal have made it an option far from ideal. Therefore, there is a need to develop mulches based on biodegradable materials. Paper-based mulch is one of the candidates, In the first chapter of this work, with a review of previous works in this area, we attempt to develop a new spray-able mulch based on wood pulp fibre. A novel foam forming method is utilised to deposit wood pulp fibres in combination with other chemicals as an evenly distributed fibre network on a porous bed. Currently available paper based-mulch is of a very high basis weight. In first part of this work, application of a foam formed low basis weight paper-based mulch is investigated. Whereas, in the second chapter, the use of wood pulp fibres in a similar function as “rockwool” in soilless greenhouse farming is investigated. Rockwool is named after fibres made of melted minerals at temperatures as high as 2000°C. Rockwool is used as blocks for seeds growth and propagation and as an alternative for soil in greenhouses. The feasibility of microenvironment control of the rockwool blocks in crop production plus its low cost have made is popular. However, their disposal has always been an environmental issue. The biodegradability of wood pulp fibres is a great advantage over mineral fibres used in rockwool. In the second chapter of current work, we study the possibility of using wood pulp fibres as carriers for agriculturally beneficial chemicals. Specifically, we focus on binding and release properties of small organic molecules from wood pulp fibres. The goal is to achieve an understanding of the capability of wood pulp fibres to be used in building biodegradable growing medium blocks in greenhouses. / Thesis / Master of Applied Science (MASc)

As urban land expands across the globe and impervious surfaces continue to be used for constructing urban infrastructure, stormwater treatment costs and environmental damage from untreated stormwater will rise. Well designed urban landscapes can employ trees and soils to reduce stormwater runoff flowing to streams and treatment facilities. Typical urban soil, however, is compacted and restricts tree growth via high soil strength and inadequate gas exchange. A site preparation method that deeply incorporates compost and includes trees for long term carbon input and pore development was evaluated in the urban setting of Arlington, Virginia. Three species were used in that study of 25 streetside plantings. The site preparation affected soil at 15 30 cm by lowering soil bulk density by 13.3%, and increasing macro-aggregate-associated carbon by 151% compared to control plots, and resulted in 77% greater tree growth during the first year after transplant. In a second experiment, rainfall simulations were used to evaluate common landscape mulch materials for their ability to prevent compaction from traffic as well their affect on surface runoff before and after traffic. When plots were subjected to heavy rainfall, (>97 mm/h) mulches were found to reduce sediment loss 82% and 73% before and after traffic, respectively. Runoff rates from wood chips were only 0.19 ml/s faster after traffic while rates from bare soil and marble gravel with geotextile increased 2.28 and 2.56 ml/s, respectively. Management of soils, trees and landscapes for stormwater benefit could reduce cost of wastewater treatment for municipalities and can prevent environmental degradation. / Master of Science

No description available.