SCIENTIFIC CONCEPTS

Scientific Concepts, Theories, & Inquiry

Scientific Concepts, Theories, & Inquiry

Problem statement

The sustainability of a production system can be greatly influence by the application of fertilizers. Conventional fertilizers are considered as unsustainable because of the energy utilized in their production. The use of nonrenewable resources for the formulation of production has a potential impact on the environment. For instance, 98% of the energy used in ammonia production is in the form of natural gas, a nonrenewable resource. Apart from organic fertilizers such as manure and compost, alternatives to conventional water-soluble fertilizers (WSFs) include controlled release fertilizers (CRFs).

Relevance of your testable question

The growth of a plant is highly effected by the form and concentration of fertilizer.

Literature review

Daniels Plant Food

The potential for runoff from conventional fertilizers can be potentially hazardous to the environment (Carpenter et al. 1998). Furthermore, phosphorus and potassium are mined from the earth's crust to be processed and included in conventional fertilizers. In response to these pressures, Daniels AgroSciences of Sherman, Texas has developed a special refining process that uses soapstock from oilseed refinement to produce a plant fertilizer, which naturally contains sufficient levels of phosphorus for plant production (Daniels 1995, 2002; Hodgson 1995). This product (Daniels Plant Food, 10-4-3) is a soy-based fertilizer used for ornamental production. It is marketed as a sustainable fertilizer, because the oilseed-extract used as the main nutrient source would otherwise be considered a waste product of cooking oil and animal feed production (Nelson et al. 2007). In addition, it is not necessary to mine additional phosphorus for its production. The formulation contains nitrogen in the following proportions of total nitrogen: 37% ammonium-N, 36.5% urea-N, 19% nitrate-N, and 7.5% organic-N. A more commonly used fertilizer, Peters Excel (15-5-15), is composed mostly of nitrate-N (78.7% of total N), urea-N (14%) and ammonium-N (7.3%).

Experimental design

Bedding plants were chosen for this study because they account for 45% of the wholesale value of floriculture sales (USDA 2008). In addition, their response to nitrogen levels and form is highly varied (Jeong and Lee 1992; Romero et al. 2006; van Iersel et al. 1998a, 1998b). Plant species that served as the focus of this study included geranium (Pelargonium× hortorum), marigold (Tagetes erecta), vinca (Catharanthus roseus), petunia (Petunia × hybrida hort. Vilm.-Andr.) and New Guinea impatiens (Impatiens hawkeri Bull.).

Bedding Plants

On 19 March 2010, rooted liners of geranium (Pelargonium × hortorum 'Allure Coral', 'Designer Peppermint Twist', 'Designer Scarlet' and 'Designer Violet'), marigold (Tagetes erecta 'Discovery Yellow'), vinca (Catharanthus roseus 'Titan Polka Dot'), petunia (Petunia × hybrida hort. Vilm.-Andr. 'Wave Purple') and New Guinea impatiens (Impatiens hawkeri Bull. 'Grape Crush', 'Celebrette Orange Crush', 'Celebrette Pink Hot' and 'Celebrette Rose Hot') were delivered from Dickman Farms and Greenhouses (Auburn, NY) and Tagawa Greenhouses, Inc. (Brighton, CO) to Purdue University (West Lafayette, IN, lat. 40°N). The plugs of genus were transplanted into 10cm (4.0 inch) round plastic (Myers Industries Lawn & Garden Group, Akron, OH) or rice hull pots (Circle of Life™; Ball Horticulture Company, West Chicago, IL) filled with a commercial soil ...