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Marci Spaw and Kimberly A. Williams

This decision case presents the issues a grower would face when deciding where to place and how to orient a high tunnel structure on a specific farm site. It provides a tool to teach site planning concepts on a small scale that are easily transferable to issues addressed when planning for construction of all sizes and types of protected-environment structures. In this case, the owner of Full Moon Farm must decide the placement of her high tunnels on a given farm site. Factors to consider include wind, snow, and ice loads as well as structural integrity, labor efficiency, and optimizing light levels. Ultimately, no one solution meets all recommended criteria, so the grower must prioritize the importance of various factors to come to a decision. This case study is intended for use in upper-level undergraduate horticulture courses, and although the principles are broadly applicable to site planning across geographic regions, it is most appropriate for climates above lat. 35°N. In particular, it may prove useful in courses such as greenhouse management and production courses for vegetables, cut flowers, and small fruits, where students assume the role of grower/farmer in the site planning process. This case study is supported by a website version with digital images, digital video, and maps that can be used both inside and outside of the classroom; all are downloadable from the website http://www.hightunnels.org/planningcasestudy.htm. The teaching notes present an unorthodox solution to the Full Moon Farm site planning dilemma.

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Kimberly A. Williams and Paul V. Nelson

Seven organic materials including 1) the bacterium Brevibacterium lactofermentum (Okumura et al.) in a nonviable state, 2) a mixture of two bacteria, Bacillus licheniformis (Weigmann) and Bacillus subtilis (Ehrenberg), plus the fungus Aspergillus niger (van Tieghem) in a nonviable state, 3) an activated microbial sludge from waste-water treatment, 4) sludge from a poultry manure methane generator, 5) unsteamed bonemeal, 6) aged pine needles, and 7) poultry feathers were evaluated to determine their pattern and term of N release and the possibility of using them as an integral part of root media releasing N at a steady, low rate over 10 to 12 weeks for production of Dendranthema × grandiflorum (Ramat.) Kitamura `Sunny Mandalay'. These were compared to the inorganic slow-release fertilizer micro Osmocote (17N-3.9P-10.8K) and a weekly liquid fertilizer control. All organic sources released N most rapidly during the first 2 weeks, followed by a decline, which ended at 6 to 7 weeks. Brevibacterium lactofermentum, bonemeal, and micro Osmocote treatments resulted in about equal growth, which was similar to growth of a weekly liquid fertilizer control for 9 weeks in the first and for 12 weeks in the second experiment. The period of N release could not be extended through increased application rate of source due to the high initial release rate. It was not possible to lower source application rates to achieve an effective, low soil solution concentration due to the large variation in release rate over time. Efficiency of N use varied among plants grown in media treated with various microorganismal sources and was highest in those treated with B. lactofermentum. Nitrogen release from ground poultry feathers was inadequate, and additions of the viable hydrolyzing bacterium B. licheniformis to feathers failed to increase soil solution N levels. Attempts to retard mineralization of B. lactofermentum by cross-linking proteins contained within the bacterium by means of heat treatment at 116C vs. 82C failed. While anaerobic poultry manure sludge proved to be an inefficient source of N, it provided large amounts of P. Organic sources released primarily ammoniacal N, which raised the medium pH by as much as one unit, necessitating the use of less limestone in the medium formulation.

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Kimberly A. Williams and Paul V. Nelson

Nutrient solution with a molar ratio of 10 N: 1 P: 3 K was applied in scheduled intervals at rates of 0.5, 1, 4, or 20 mm N (NO3 + NH4) to Dendranthema ×grandiflorum (Ramat.) Kitamura `Sunny Mandalay' plants seven (7/day) or 14 times/day (14/day). These plants were compared to a 20 mm N control in which nutrient solution was applied when the soil moisture tension reached 30 kPa. Plants with 7/day had significant quadratic relationships for height, width, and dry weight, with the lowest responses at the low nutrient concentration. With 14/day, height and dry weight did not differ, although width did increase linearly with nutrient solution concentration. However, linear regression slopes for all three variables were much lower with 1Vday than with 7/day. At midcrop in both experiments, significant regression curves indicated that the lower concentrations of nutrient solution resulted in lower tissue N and K levels; however, slopes of the linear regressions were lower with 14/day than with 7/day. With 7/day, the water content (percentage) of plants in the schedule-fertilized treatments was higher in plants receiving higher nutrient concentrations, as indicated by the significant linear and quadratic regression curves. With 14/day, the water content was linearly related to solution nutrient concentration, but with a lower slope than with 7/day. These three trends indicate that steady-state nutrition was more closely achieved in a commercial-style substrate with 14/day applications of nutrient solution. These results suggest that plant growth that meets commercial expectations can be achieved at lower soil solution nutrient concentrations than currently applied.

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Kimberly A. Williams and Paul V. Nelson

Most soilless container root media have limited ability to retain nutrients. Zeolites are minerals of substantial cation exchange capacity that can be precharged with K, and possibly PO4, and used as a component of soilless media as a slow-release nutrient source. A zeolite clinoptilolite (Cp) was charged with K and PO4 at two concentrations and combined at 20% of the mix with sphagnum peat (60%) and perlite (20%) to evaluate its use as the sole source of these nutrients during production of Dendranthema ×grandiflorum (Ramat.) Kitamura `Sunny Mandalay.' Phosphate, K, Na, and pH were determined on unaltered bulk root medium solutions collected over the course of production, and foliar analyses were determined on tissue collected at the middle and end of the crop. All leachate was collected and analyzed to allow for the creation of K and PO4 budgets. Plants that relied on precharged Cp at the low and high rates to meet their K needs and received a N/P/-K fertilizer had similar dry mass and tissue K concentrations as the control plants that received a complete fertilizer. The use of precharged Cp at the low rate reduced K losses through leaching to 23% of the amount lost from control plants receiving water-soluble fertilizer (WSF). Plants that relied on precharged Cp for their PO4 had a lower dry mass and tissue P levels than those of the complete control treatment. However, PO4 concentrations in the root medium solution were above acceptable levels during the first month of production and should be considered when developing a fertilizer application strategy using Cp precharged with PO4.

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Kimberly A. Williams and Paul V. Nelson

Soilless container medium components such as peatmoss and perlite have almost no capacity to retain PO4-P, and preplant amendments of triple superphosphate (TSP) are readily leached. Al amendments were tested to reduce P losses from these media. Al2(SO4)3 solutions at rates of 320 and 960 μg Al/cc were applied to a 70 peat: 30 perlite medium and dried at 70C. Adsorption isotherms were created at 25C for the Al2(SO4)3-amended media and an unamended control using solutions of Ca(H2PO4)2 at concentrations of P ranging from 0 to 500 μg·ml–1. Isotherms showed that P retention increased as Al concentration increased. In a greenhouse study, Dendranthema ×grandiflorum `Sunny Mandalay' was grown in these media with 100 g P/m3 from TSP incorporated into the mixes before planting. PO4-P, soluble Al, and pH were determined on unaltered medium solutions collected throughout the cropping cycle and foliar analyses were determined on tissue collected at mid- and end-crop. The highest rate of Al was excessive and resulted in low pH and soluble Al levels in the medium solution early and in the cropping cycle, which were detrimental to plant growth. When Al was applied at 320 μg/cc, soluble Al levels in medium solution were not significantly higher than in the unamended control, PO4-P leached from TSP was reduced, and sufficient PO4-P was released throughout the cropping cycle to result in optimal plant growth.

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Ellen T. Paparozzi and Kimberly A. Williams

Chat rooms and their use in everyday life are becoming increasingly common, and the technology may be a useful tool to link students with experts of a given subject material and each other. In our shared course Plant Nutrition and Nutrient Management, we experimented with using a chat room to link students with experts in the field of plant nutrition. Our main goal was to enhance the learning experience of the students by providing them with access to national and international plant nutrition researchers. Web CT was used to create and conduct the chat rooms and a chat etiquette evolved to prevent crosstalk and control the flow of the discussions. Positive outcomes of the chat room use included exposure of students to the technology and beneficial interaction between students and experts. Negative aspects of chat room use included the time involved to coordinate the overall effort and train experts to use the technology; the slow pace of some chats; effective grading; and the superficial coverage of some topics. We are developing modifications for future sessions to allow subjects to be explored in more depth and to improve networking between students and experts.

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Joshua K. Craver and Kimberly A. Williams

Student learning from producing crops in recirculating culture for a 6-week module in the Fall 2013 course HORT 570 Greenhouse Operations Management at Kansas State University was assessed. The module design followed Kolb’s experiential learning model, with teams of students responsible for production of lettuce (Lactuca sativa ‘Green Oak Leaf’) or basil (Ocimum basilicum ‘Italian Large Leaf’) and chives (Allium schoenoprasum ‘Purly’) crops in either a nutrient film technique (NFT) or in-pot recirculating culture system. Goals were to discern if this class experience would 1) improve student confidence and understanding of not only recirculating solution culture systems, but also general crop nutrient management; and 2) improve higher-order learning (HOL) skills of applying, analyzing, and evaluating information. Student learning was evaluated by administering the same survey, which included questions to evaluate student perception, lower-order learning (LOL), and HOL, at four separate times during the semester: 1) before mentioning plant nutrition, hydroponics, or recirculating solution culture; 2) after plant nutrition lectures but before the experiential module; 3) immediately upon completion of the experiential module; and 4) at the end of the semester. An increase in student confidence related to managing crop production in recirculating solution culture and nutrient management was perceived by students upon completion of the module. A significant increase in LOL occurred after the material was presented during the course lectures with an increase also occurring upon completion of the experiential module. In contrast, HOL did not significantly increase after the lecture material was presented, but significantly increased upon completion of the module. Both LOL and HOL was retained at the end of the semester. This evidence supports the role of experiential learning in improving student understanding and fostering HOL.

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Kimberly A. Williams and Ellen T. Paparozzi

A model for the creation of shared synchronous courses between universities has been developed based on our experiences during the development and delivery of an upper-level undergraduate/graduate course in Plant Nutrition and Nutrient Management offered by Kansas State Univ. and the Univ. of Nebraska–Lincoln. The course was conducted during the Spring 1999 semester using two-way compressed video so that instructors and students at both sites could see and hear each other in live time. Our model is set up as a flow-chart and currently has 10 steps that include areas such as “Identifying the Need,” “University Must-Do's,” “Distance Class Technology Requirements,” and “Advertising the Course.” Each step details procedures to follow, offers ideas and suggestions, and includes examples taken from our course. Also included is information about web site development and chat room use. The model is easily adapted for use with distance technologies similar to two-way compressed video such as Internet 2. An electronic version of the model can be accessed at http://www.oznet.ksu.edu/dp_hfrr/Floriculture.

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Valerie M. Jonas and Kimberly A. Williams

A series of experiments were conducted to determine the ranges of irrigation frequency and N and P fertilization regimes that produce ivy geranium (Pelargonium peltatum L.) plants of optimum commercial quality. Two cultivars, `Sybil Holmes' and `Amethyst', were grown. Data collected included fresh and dry weights, ratings, leaf area, height, width, ratings, and nutrient tissue content. Individual pots were weighed daily and irrigated when weight of pots dropped by 15%, 30%, 45%, or 60% of container capacity (CC). Leaf water potential was measured using a pressure chamber. At both mid and end of crop, plants irrigated when pot weight dropped by 30% of CC were under least water stress (e.g., water potential of –7.0 to –4.7 MPa). Irrigation frequencies at 15%, 45%, or 60% of CC had similar water potentials (e.g., –9.9 to –9.1 MPa). At 15%, a plausible explanation of the stress is that oxygen was limiting in the root zone due to water-logging; at 45% and 60%, water was the limiting factor. Single factor experiments with N at five concentrations ranging from 2 to 32 mm and P at five concentrations ranging from 0.08 to 2.56 mm were conducted. Quadratic equations were fit to curves of growth responses plotted against concentration of N or P applied. As an example of results, N fertilizer rates of 16 and 32 mm for `Amethyst' resulted in similar, commercially acceptable dry weights (37g), but different N tissue concentrations of 3.4% and 3.9% respectively. For `Sybil Holmes', N fertilizer rates of 10 and 26 mm resulted in similar dry weights (21g) but different tissue concentrations of 2.8% and 3.4%, respectively.

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Kimberly A. Williams and Paul V. Nelson

Soilless container media have almost no capacity to retain PO4 or K. The nutrient retention of two calcined clays, attapulgite and arcillite, and brick chips, precharged with PO4 and K, was investigated. These could serve as an alternative slow-release fertilizer when incorporated into a soilless medium as a component of the mix. Sorption curves were developed at 25 °C for attapulgite of two particle sizes (0.8 to 1.6 mm and 1.6 to 3.2 mm), arcillite (1.1 to 3.2 mm), screened pieces of brick (1.0 to 3.6 mm), and a medium of 7 sphagnum peat: 3 perlite (v/v) using solutions of KH2PO4 (P at 0 to 20,000 mg.L-1). Curves indicated that PO4 and K sorption were similar for both particle sizes of attapulgite, so only the larger size [1.6 to 3.2 mm (8 to 16 mesh)] was used in greenhouse studies. Materials were evaluated in greenhouse studies by growing 'Sunny Mandalay' chrysanthemum [Dendranthema ×grandiflora Kitam. (syn. Chrysanthemum morifolium Ramat.)]. The precharged materials were tested at 10%, 20%, and 30% by volume of a peat: perlite root medium. Phosphate, K, and pH were determined on unaltered medium solutions collected throughout the cropping cycle and foliar analyses were determined on tissue collected at midcrop and end of the crop. Data indicated that precharged calcined clays retained and released PO4, and to some degree K, over time. Precharged clays did not provide K at levels which met plant needs during the latter half of the cropping cycle, but it was released and used at appreciable levels during the first month of crop production. Growth of plants receiving PO4 solely from precharged attapulgite and arcillite at 20% of the medium volume was not significantly different from that of a commercial control when the leaching fraction was maintained at 0.2. However, release of PO4 from the brick chips was not enough to match plant demand. Phosphate lost through leaching from the precharged clays was reduced by about two-thirds compared to control plants fertilized with P at 46.5 mg.L-1 from water-soluble fertilizer at each watering.