Kiara Nirghin, 16, holds her Google Science Fair trophy.

Cape Town - A 16-year-old schoolgirl from Joburg has won the grand prize at the Google Science Fair for inventing a cheap way to combat drought using orange peels.

Kiara Nirghin, a grade 11 pupil at St Martin’s High School, was inspired by the drought currently gripping South Africa. She designed a super-absorbent substance to retain water in soil so plants can make better use of the little rain they receive.

Instead of the expensive synthetic material farmers currently use, Kiara’s design uses orange and avocado peels to trap water.

Her submission, called “Fighting Drought with Fruit”, won her $50 000 (R697 000) in scholarship funding at the Google Science Fair awards in California on Tuesday.

Kiara couldn’t be contacted for comment on winning the prize, but shared a bit about herself on her competition submission.

“I absolutely love the captivating subjects of chemistry and physics in school,” she wrote.

“I have always had a great love for chemistry since I was young. I vividly remember at the age of seven experimenting with vinegar and baking soda solutions in plastic cups. My natural curiosity and questioning nature has sparked my everlasting love of science.”

Kiara conducted three experiments over 45 days that involved taking orange peels and avocado peels, putting them through various processes including boiling, sun drying, crushing and baking, and then carefully measuring their absorption properties.

“The results of the water retention test showed that the Orange peel mixture’ can absorb 76.1 percent of water,” Kiara wrote in the results of her experiment. “I was successful in creating a low-cost superabsorbent polymer (SAP).”

The orange peel mixture is made out of waste products from the fruit juice manufacturing industry, and may prove to be even better than the SAPs already in use in the agriculture industry.

“The only resources involved in the creation of the orange peel mixture’ were electricity and time, no special equipment nor materials were required,” Kiara reported.

The budding scientist said winning the Google Science Fair would be a great inspiration.

“With the prize I will hope to continue my studies in science, but also further the scientific development and application of my idea, and in addition extend scientific progress in elevating the problems that South Africa faces in food security and sustainable agricultural development.”

Cape Argus