3Phase program for growing cabbage on sandy soils

Three growth phases

Phase 1: crop establishment

Good growth in the first two to four weeks of crop life is critical to crop performance. Growth in this time has a major impact on final yield and the number of days from planting until harvest — one that cannot be made up in later growth phases.

To maximise crop nutrition and growth in the establishment phase, it is important to keep fertilisers in the zone of young roots.

Twice-weekly broadcast or boom spray fertiliser application — containing low rates of nitrogen — during establishment increase yield and reduce the time to harvest. Both methods place enough fertiliser within the reach of roots to maximise crop growth without excessive loss to the environment (see Figure 2).

Figure 2 Broadcast or spray applications of fertiliser during crop establishment place nutrients in the zone where young developing roots have access. These plants are shown 15 days after transplanting.

Applying granular NPK fertiliser to the soil surface on the day of planting is important for achieving maximum yields, regardless of later fertiliser delivery methods.

Phase 2: rapid growth

Once the root system is established, fertilisers are most effectively applied weekly by banding (see Figure 3).

Figure 3 banded fertiliser applications in the space between pairs of rows is an efficient way to achieve root uptake during the rapid growth phase. These plants are shown 43 days after transplanting.

Although both fertigation and broadcasting can be used in this phase, applying the required rates of fertiliser with these methods is difficult without unnecessary water use or the risk of leaf burn from lodged fertiliser granules.

Banding with compound granular fertilisers is most suitable as it minimises waste and allows the required rate to be applied in one pass.

Phase 3: maturation

Fertiliser is required after row closure as the demand for nitrogen continues to increase steadily. Continue weekly nitrogen fertigation until one week before harvest.