Packaged commercial grower mixes routinely contain wetting agents. Studies report that dry components such as pine bark can be more thoroughly moistened if wetting agents are used. Under frequent leaching irrigations, wetting agents have been reported to enhance nutrient loss. Effective longevity is expected to be only 3 to 4 weeks. New products claim greater longevity and advertise that less water volume is required for optimum plant growth. One such product is Saturaid (Debco Pty, Victoria, Australia). The objective of this study was to evaluate the effect of Saturaid on physical properties, nutrient levels, and growth under decreasing irrigation volume. The granular wetting agent was incorporated at 0, 1.0, and 2.0 g·liter–1 substrate volume. Cotoneaster dammeri `Skogholm' plants were potted into 2.8-liter pots and irrigated with 500 ml of water for 22 days, after which one-third of the containers received 425 ml (–15%) and one-third were irrigated with 350 ml (–30%) daily. Saturaid had little effect on moisture and air characteristics, and no effect on foliar nutrients or on leachates collected at 43, 64, or 84 days. When irrigation volume was decreased 15%, top dry weight was greatest at 2 g, followed by 1 g of Saturaid. When irrigation volume was decreased 30%, the same results occurred for top and root growth.
Increasing environmental concerns and legislation in many states and in other countries require that we take a more comprehensive sustainable “best management” approach to production techniques in nursery and greenhouse operations. This is particularly important because these production facilities are typically intense users of resources that are applied to relatively small land areas. We have developed an online knowledge center to facilitate the implementation of more sustainable practices within the nursery and greenhouse industry. A web-based knowledge center provides the most cost-effective mechanism for information delivery, as our potential audiences are extremely diverse and widespread. We currently have a registered user database of over 450 educators, growers, and industry professionals, and undergraduate and graduate students. A gateway website provides an overview of the issues and the goals of the project. The associated knowledge center currently has 25 in-depth learning modules, designed in a Moodle learning management framework. These learning modules are designed to actively engage learners in topics on substrate, irrigation, surface water, and nutrient and crop health management, which are integral to formulating farm-specific strategies for more sustainable water and nutrient management practices. Additional modules provide assessment and implementation tools for irrigation audits, irrigation methods and technologies, and water and nutrient management planning. The instructional design of the learning modules was paramount because there can be multiple strategies to improve site-specific production practices, which often require an integration of knowledge from engineering, plant science, and plant pathology disciplines. The assessment and review of current practices, and the decision to change a practice, are often not linear, nor simple. All modules were designed with this process in mind, and include numerous resources [pictures, diagrams, case studies, and assessment tools (e.g., spreadsheets and example calculations)] to enable the learner to fully understand all of the options available and to think critically about his/her decisions. Sixteen of the modules were used to teach an intensive 400-level “Principles of Water and Nutrient Management” course at the University of Maryland during Spring 2008 and 2009. The water and nutrient management planning module also supports the nursery and greenhouse Farmer Training Certification program in Maryland. The Maryland Department of Agriculture provides continuing education credits for all consultants and growers who register and complete any module in the knowledge center. Although these learning resources were developed by faculty in the eastern region of the United States, much of the information is applicable to more widespread audiences.