Request for advice/ experience of growing tomatoes in CEA conditions in Central Africa.

Malawi Fruits (Scottish Charity 042777, and institutional member of the TAA) is asking for advice, preferably based on experience, on issues that might arise when growing tomatoes in in north-central Malawi under Controlled Environment Agriculture (CEA) conditions under polythene tunnels .  With our Malawian partners we have a project and funding for groups of women (3-4) and disabled people to raise around 400 plants in grow-bags on 13.0 m by 9.0 m poly-tunnels. There is a severe shortage/lack of tomatoes in the rainy season.  Processors, supermarkets and hotels who buy imported stock will buy in-country if the quality is right and supply is year-round. The project aims to enter this niche market, with women growing tomatoes year round in polythene sacks in poly-tunnels, other vegetables may follow.

The project is deliberately ‘low tech’, but it still raises a number of issues. Here is one cluster of questions: readers’ experiences may answer them and also reach beyond these to other experiences. Answers please by email to Charles.

Question cluster: soil quality, nematodes and leaf miner. We know that the soil needs replacing after one crop, hence the bags to make this easier; bags needb to be washed and sterilized after each crop. The initial two replacements will be with more ‘virgin’ soil, but we are considering consolidating used soil outside the tunnels and then growing two non-Solanaceous crops in succession, such as carrots, onions and beans, before reusing the first soil for the next/fourth crop of tomatoes.  Would this procedure be likely to work?