Comparing new, standard, and no fertilizer on vegetable yields

¶ … New Fertilizer Product for Vegetables

Identify the components

Fertilizer (New) (new fertilizer product)

Fertilizer (Std) (standard fertilizer product)

plots in community gardens across the city

Cucumber, green pepper, and broccoli plants

Gardening journal

Scale

What is the research question?

This research analyzes whether adding a new fertilizer product (Fertilizer (New)) to the soil will produce a higher total vegetable yield, in grams, when compared to: 1) vegetables grown in soil free of commercial fertilizers, or 2) vegetables grown in soil treated with the industry standard fertilizer product (Fertilizer (Std)).

What is your hypothesis?

Total vegetable yield will be significantly higher in soil treated with Fertilizer (New), compared to vegetable yields from soil treated with Fertilizer (Std) or from commercially untreated soil.

How would you select your subjects and assign them to a group?

Volunteers from 30 community gardens across the city will be recruited to plant vegetable gardens consisting of a fixed number of cucumber, green pepper, and broccoli plants. After recruitment of volunteers, each will be randomly assigned a soil treatment modality (Fertilizer (New), Fertilizer (Std), or no commercial fertilizer). Treatments will be equally assigned across groups (10 plots per treatment).

How would you conduct the experiment? Describe your procedures.

On day 1, each volunteer will receive an equal number of vegetable plants and the soil treatment assigned. Volunteers will then prepare their soil, plant the vegetables in their community plots, and be responsible for maintaining their gardens for a total of 20 weeks. Participants must keep a gardening journal outlining their observations and care schedule (watering, weeding, etc.), and submit weekly reports. When vegetables are ready to harvest, participants will weigh the vegetables right after picking (gram scales provided) and note totals in their weekly report.

At the end of the 20-week study period, total weights will be tabulated and compared across treatments (fertilizer type). Analysis will also consider whether type of vegetable impacts results. Journals will be examined for gardening care and experience, and results may be re-analyzed to exclude outliers or other unexpected events.

What are the ethical concerns with your study?

Volunteer gardeners must agree to a fairly onerous amount of physical labor (planting, caring for, and harvesting vegetables) and paperwork (reporting) to participate in this study. In return, they receive free vegetable plants and (perhaps) fertilizer. This could open the study to charges of exploitation, if volunteers are low-income and in need of free plants. However, by targeting current volunteers with existing community gardens (who presumably freely labor in the gardens already), ethical concerns are minimized. Further, while the study encourages participation throughout the 20-week study period, no penalty occurs if a volunteer decides to withdraw before the end of the study.