Photos by Lena Chow and KC Tsang
Our affable guide Adrian with his rapt audience.
We had an unlikely combination of a butterfly and hydroponics adventure in our NSS Kids’ outing on 18 June 2011, to Oh Chin Huat Hydroponics Farm located near Yishun. The laid back vibe of the place was a natural balm to our frazzled city souls.
We started the day in an outdoor classroom where Oh’s Farm guide Adrian conducted a fascinating show and tell session on butterflies. He took us through the butterfly’s life cycle, from miniscule eggs deposited on host plants, to the caterpillars' metamorphism through various 'costume' or instar changes, their pupation and finally their eclosure as beautiful butterflies. A few brave kids even allowed the prickly-looking Mime and Autumn Leaf caterpillars to crawl all over their arms. However, mostly ‘spiky’ caterpillars have skin irritants and should not be handled.
Some girls have no fear of caterpillars, allowing them to crawl all over their arms.
Kids had an exciting time exploring the Butterfly Enclosure. Here, beauties such as Autumn Leaf, Lime, Plain Tiger, Tawny Coster and Jacinta Eggfly flit freely amongst their host and nectar plants. Some of us even caught the rare sight of an Autumn Leaf caterpillar transforming into a pupa, by doing a writhing ‘belly’ dance. A butterfly quiz had kids vying for plant prizes including some butterfly host plants. KC and Amy Tsang were great at promoting butterfly watching. They handed out information sheets, recommended various field guides, as well as sold copies of the pocket-sized “NSS Field Guide to the Butterflies of Singapore”.
We even saw a Tawny Coster Butterfly eclosing from its pupa case.
The adults particularly enjoyed the hydroponics tour. We learnt that Oh’s Farm grows six types of vegetables including Kang Kong, Chye Sim and Xiao Baicai, as well as 10 types of herbs such as Italian Basil, Sweet Basil and Stevia. We were astounded that the farm sells about 1,000 kg of produce daily, to supermarkets such as NTUC where it is marketed under the ‘Pasar’ brand. Our guide shared with us that the soil-free nutrient solution comprises 16 minerals. Minerals essential for vegetable growth, such as calcium, potassium, magnesium and phosphorous, are present in high concentrations. These are mixed together with trace elements such as copper, molybdenum, iron and manganese.
Vegetables are grown from seeds sown into sponges. These are placed in a dark, moist and warm Germination Room for two to three days, where 95% of them will sprout leaves. The seedlings are then transferred to a nursery where they are kept until they develop four leaves. These plantlets are then transplanted into greenhouses where cultivation occurs for another three to four weeks.
Vegetables and herbs are grown using the DRF (Dynamic Root Floating) hydroponics technique whereby a nutrient solution is circulated under the culture boards. This induces the plants to develop an air root system (numerous fine roots) in the humid space between the underside of the culture board and the surface of the nutrient solution. The plants are protected by black netting that covers the greenhouse, which negates the need for pesticides, lowers the amount of sunlight, as well as reduces the buildup of heat. These modified conditions are necessary as most vegetables and herbs consumed in Singapore originate from cooler climes such as South China. It takes about 28 days for Kang Kong to mature, which is a full week shorter than if it were grown in a regular farm. However, detractors claim that hydroponics-grown Kang Kong tastes more ‘watery’, less fibrous, and even less ‘delicious’ than the soil-grown variety.
We had fun sampling some of these produce. The Italian Basil had a numbing effect on our tongues, where purportedly only the healthy can detect. We enjoyed the taste of Stevia, a herb that is 250 times sweeter than cane sugar. It is sometimes used by diabetics as a sugar substitute. We were even allowed into the Cold Room (4°C to 8°C), which is essentially a walk-in misty refrigerator. Here, harvested vegetables are left for a day to rehydrate, so that their leaves do not tear as easily. Participants snapped up vegetable seeds, plantlets and fresh greens at the farm shop. Kids were encouraged to experiment with hydroponics at home, using a cut-up water bottle and some seeds. The tour aptly rounded off with each of us getting two free packets of leafy Xiao Baicai.