Soil in Containers | Vegetable gardening | Hydroponics farming in India

The same soil can be used every year but it has to be enriched by adding fertilizers such as compost or manure. Ideally compost / manure should be added every month or so depending on the plants you grow. Between crops you should add compost as well. Neem oil cake can be mixed but it has to be well decomposed. Raw neem cake mixed in soil can cause temp build up due to decomposition. hope this helps