A Study Into the Effects of Various Compost-Potting Soil Mixes in An Effort to Heighten Bio-Productivity and Lower Farm Expenses

Thursday, 17 December 2015
Poster Hall (Moscone South)
Adrienne Zhang1, Claire Valva1, Sonia Mahajan2, Krishna Ammini1, Johnny Ho1 and Darren Lo1, (1)Stanford University, Stanford, CA, United States, (2)Stanford University, Los Altos Hills, CA, United States
The Stanford farm is a small, sustainably run farm that prioritizes producing high-quality crops in an environmentally sustainable way. This experiment focuses on the soil used to germinate and cultivate crops in a controlled greenhouse environment. It was conducted with the objective of determining which ratio of compost to potting mix is most favorable in terms of both cost and biological productivity. The five ratios of compost to potting mix were created as follows: (1) 100% compost; (2) 75% compost and 25% potting mix; (3) 50% compost and 50% potting mix; (4) 25% compost and 75% potting mix; and (5) 100% potting mix. Three different crops with distinct needs were used in the experiment: an Indonesian cultivar of Cosmos flowers (Cosmos sp.), a heritage American Corn cultivar (Zea mays), and Ojo de Cabra beans (Phaseolus vulgaris). Ten pots of the corn, ten pots of the beans, and ten pots of the cosmos flowers were planted in each of the soil ratios mentioned above. The pots were placed in the greenhouse and watered regularly and equally by the greenhouse watering system. The experiment is ongoing and is not yet completed. However, thus far the results indicate that 75% compost and 25% potting mix is the most favorable ratio; the corn, bean, and cosmos plants grown using this ratio not only had the highest germination rate (90% of corn seeds, 90% of bean seeds, and 100% of cosmos seeds) but also had the highest average upward growth. According to data taken August 3, 2015, the corn plants grown using the 75:25 compost to potting mix ratio were the tallest by an average of 10.67cm, the beans grown in this ratio were tallest by an average of 3.96cm, and the cosmos were tallest by an average of 0.14 cm. As compost is a cheaper alternative to potting mix, using a compost-based soil would save the farm money while also maximizing plant growth.