摘要：

Models are described which estimate the change in profit due to using different machinery on a horticultural enterprise. For irrigators, a soil moisture model predicts crop response over a number of years to different levels of irrigation, for any soil type and any weather region. Solutions to some typical problems in terms of cropping, labour and machinery to optomize profits are given. A low labour irrigator is very profitable. It is profitable to irrigate to the maximum on early potatoes, runner beans, leeks, onions and lettuce but not brussels sprouts, carrots, parsnips and cabbages. A sensitivity analysis shows that with a sprinkler system, a small reduction in the assumed onion and leek response would alter the conclusion, but for the other crops, a very large change in response would be needed. With the low labour irrigators, a large change in the response from early potatoes, runner beans, onions, leeks and lettuce would be needed to alter the conclusion. A wide range of transplanter rates are examined. For bare-rooted plants, increasing the rate from 2000 plants per operator hour with three operators, to 5000 plants per operator hour with two operators allows an extra capital expenditure on equipment of up to 330/ha before profit is reduced. Increasing the rate to 15,000 plants per operator hour with one operator using blocks or containers costing 10 per thousand only allows an extra capital expenditure on equipment of up to 40/ha.

展开