Vertical farming (VF) allows for a higher number of plants to be grown in a limited land area, maximizing agricultural land use. VF employs multiple vertical shelves. Each shelf consists of several levels. This paper aims to develop a computer simulation model. The computer model could predict the sunlight availability received at each level of the shelves. The model was developed using RHINO (RHINOCEROS) software with Grasshopper plug-in. The VF shelf was constructed for the experiment in Chiang Mai, Thailand. The experiment data is used to validate the computer model. The validated computer simulation model is then used to predict the daily averaged Photosynthetic Photon Flux Density (PPFD) received by each level of vertical shelves. Year-round daily averaged PPFD provides insights into the seasonal variations of sunlight availability. For the VF shelf constructed for experiment in Chiang Mai, it was found that the top level of the shelf would receive a yearly average of 1275.17 PPFD. The middle and bottom would receive 781.29 and 617.67 PPFD, respectively. The month with the lowest amount of sunlight is in January. This computer simulation model will help predict solar radiation received by each vertical farming shelf. The farmers could identify suitable shelf designs to provide enough PPFD for specific crops to be grown.

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Soil erosion is a severe risk on the sloping agricultural land due to improper managements. This study aimed to evaluate and compare the dynamics of soil loss and runoff under different land use types in order to fi nd the best soil erosion control for sustainable land use planning. A fi eld trial was conducted in Bor Krai village, Mea Hong Son Province, North-Western Thai Highlands during 2008-2009. Four land use types were selected for comparative measurement, including i) 4-year-fallow land (FaL), ii) mixed orchard (MixO), iii) maize (M) and iv) upland rice (UR). Surface runoff (SR) and soil loss (SL) were monitored after each effective rainstorm using modifi ed Gerlach troughs (GT). The GT was made of a bamboo and linked to a 50-litre container by a rubber hose. The size of GTs was 0.5-0.7 m long and 0.1-0.2 m diameter. The GTs were installed perpendicular to the contour line at the lower part of each land use. The results showed that, during the 2-yr, monoculture with inappropriate soil water conservation caused the fi rst average highest values of SR and SL (SR=299 m 3 ha -1 ) and (SL=3.4 t ha -1 ) while FaL yielded the lowest SR (41 m 3 ha -1 ) and SL (0.01 t ha -1 ) amounts. Moreover, further study is required for long-term prediction to estimate annual soil loss under different land use types.