Soil and water management in vegetable brassica production
Soils need to be well structured and fertile to maximize growth and produce high yields.
Seedbed condition is important if crops are being grown from seed. A fine, consolidated seed zone encourages maximum germination and good establishment. Heavy soils are suitable for high yielding brassica crops, provided the soil is well structured.
Brassica crops are most productive when grown on soils with a neutral soil pH. The ideal being pH 6.5 for mineral soils and 5.5 on organic soils. When pH drops below 5.5, phosphorus, potassium, sulfur, calcium, magnesium and molybdenum availability drops, while undesired heavy metals, such as cadmium and aluminium can become more plant available.
Irrigation is also essential in many key production regions, but care is needed, especially approaching harvest, that water does not encourage disease on the florets or heads or create sudden growth flushes leading to nutrient imbalances and stem hollowing or cracking, particularly when high temperatures boost growth.
Water management – particularly in the 3-4 weeks prior to harvest - has to be carefully tailored to maximize head or curd production without risk of physical damage, disease and disorders. Brassicas are relatively tolerant of salinity. Moderately saline irrigation waters can be used, provided nutritional programs take into account any nutrient imbalances that may be created. Calcium availability must be maintained in order to reduce risks of disorders (e.g. tipburn) and ensure good quality produce.
