After each harvest is carried out, the weight of tubers are measured and converted to units of food energy. Thus, an indication is obtained of energy input and output. This helps to ascertain just how marginal kumara horticulture is in the Cook Strait region, at least in today's climatic conditions. An essential component of this study, of course, is to use traditional varieties of kumara.
This project, is largely under the joint direction of Graham Harris and Mike Burtenshaw, two Senior Lecturers in the School of Natural Resources at the Open Polytechnic of New Zealand.
Although the primary objective of this experimental garden was the issue of efficacy of gardening in Cook Strait, a number of other research questions were added along the way. For example, during the first season we grew two plants on each mound, one on the north side and one on the south side, to see if there is a difference in yield between the two plants. Soil exhaustion is also monitored over time by carrying out soil analysis regularly.
We were also interested to know whether the two experimental gardens had the same thermal energy input from the sun, and if not, whether the kumara yield was related to this difference. With this in mind, special thermal cells, designed by Wal Ambrose in Australian National University, were planted in some of the mounds in both gardens. The results of this study have been most interesting.
We have been pleasantly surprised at the yield results at both these experimental gardens, given the marginal climatic conditions in Cook Strait.
Another aspect of this project has been proximate analysis of kumara tubers. That is, the analysis of how much starch, sugar, fibre, etc. is present in these traditional kumara tubers.
During the growing season, special note was taken of weeds in the garden, and we found that only European introduced weeds took hold.
So far, these experiments have only been underway for two years, the summer of 1999-2000, and the summer of 2000-2001. We intend to keep growing the kumara in these plots for several years still. The latest growing season of 2000-2001 has been a severe drought, certainly the worst for 100 years. The yield for this season is therefore of special interest. The results show no decline in yield, despite almost no rain over the entire period, and certainly no human watering.
