Clay Amended Soilless Substrates: Increasing Water and Nutrient Efficiency in Containerized Crop Production

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dc.contributor.advisor Ted E. Bilderback, Committee Co-Chair en_US
dc.contributor.advisor D. Keith Cassel, Committee Member en_US
dc.contributor.advisor Dean L. Hesterberg, Committee Member en_US
dc.contributor.advisor Stuart L. Warren, Committee Co-Chair en_US Owen, James Stetter Jr. en_US 2010-04-02T19:00:44Z 2010-04-02T19:00:44Z 2007-03-05 en_US
dc.identifier.other etd-02282006-183611 en_US
dc.description.abstract Current management practices in containerized crop production maximize plant growth by supplying adequate or excess nutrient and water inputs. In the United States, nursery production input use efficiency remains ≤ 50%, in part, because of the inert softwood bark used as a primary component of soilless substrate. One technique to increase input use efficiency would be to engineer a substrate that increases nutrient and water buffering capacity of the substrate. Clay may be such a component. Clay has been used in the past to generically describe an inorganic mineral aggregate to amend a peat- or bark-based soilless substrate that increased water and nutrient buffering capacity. Industrial mineral aggregates with various chemical composition, aggregate size, mineralogy, and temperature pretreatment have been used effectively as chemical absorbents, fertilizer carriers, or barrier clays to contain heavy metals. Experiments herein were conducted to determine which physical and chemical attributes of industrial mineral aggregate could increase input use efficiency in containerized crop production and at what amendment rate plant growth and water and nutrient use efficiency are maximized. Field experiments were conducted using Cotoneaster dammeri C.K. Schneid. "Skogholm" as an indicator plant for growth, net photosynthesis (P[subscript n]), stomatal conductance (g[subscript s]), and mineral nutrient content. Plant were potted into 14 L containers in a pine bark based (PB) substrate with known physical properties and grown for approximately 120 days in 2002, 2003, and 2004 on outdoor facilities in Raleigh, NC that allowed for collection of effluent and influent, which was used to calculate a water budget. In the laboratory, effluent NO₃-N, NH₄-N and dissolved reactive P (DRP) were quantified to determine effluent daily concentration and cumulative content which allowed for calculation of nutrient budgets. In 2002, a bentonite palygorskite industrial amendment with contrasting particle size and temperature pretreatment was evaluated for its effect on growth, and water and nutrient use efficiency. Substrate amended with a low volatile material (LVM) amended substrate leached 35% less dissolved reactive P (DRP) than the regular volatile aggregate amended substrate. In addition, a 0.25 to 0.85 mm aggregate amended substrate required 11 L less water applied per container when compared to 0.85 to 4.75 mm aggregate amended substrate. In 2003, 0% to 20% (by vol.) rate of the 0.25 to 0.85 mm LVM palygorskite bentonite mineral aggregate were compared. Plant growth and P[subscript n] increased curvilinearly and linearly with the maximum occurring at 12% and 11%, respectively. Container capacity and available water (AW) increased linearly with increasing amendment rate, whereas, unavailable water and air space decreased linearly with increasing rate of mineral aggregate. Water use efficiency of productivity and g[subscript s] was maximized at 11% clay amendment rate. Plant elemental nutrient content of P, K, Ca, and Mg increased when PB was amended with clay. In 2004, cotoneaster was grown in PB amended with 11% (by vol.) sand or 0.25 to 0.85 mm LVM palygorskite bentonite clay mineral aggregate. The PB amended with sand is representative of a typical industry substrate. Treatments included a leaching fraction (LF) of 0.1 or 0.2 and P fertilization rate of 1.0x or 0.5x. Pine bark amended with 11% (by vol.) clay increased AW 4% when compared to sand amendment. Water use efficiency and plant growth increased if PB was amended with clay rather than sand. Plant content of all macro-nutrients, with the exception of N, increased when PB was amended with clay versus sand. Reduction of LF from 0.2 to 0.1 decreased effluent DRP concentration and content 8% and 64%, respectively. A PB substrate amended with 11% (by vol.) 0.25 to 0.85 mm LVM palygorksite-bentonite clay mineral aggregate can grow an equivalent plant with half of the water and P inputs. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject stomatal conductance en_US
dc.subject substrate en_US
dc.subject irrigation en_US
dc.subject pine bark en_US
dc.subject XANES en_US
dc.subject photosynthesis en_US
dc.subject Clay en_US
dc.title Clay Amended Soilless Substrates: Increasing Water and Nutrient Efficiency in Containerized Crop Production en_US PhD en_US dissertation en_US Horticultural Science en_US

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