Reduced pass harvesting of cauliflower and broccoli

Page last updated: Tuesday, 18 October 2016 - 8:22am

Please note: This content may be out of date and is currently under review.

Cauliflower and broccoli crops generally require multiple harvests to remove all marketable curds or heads. By improving the uniformity of plant maturation, crops can be harvested in a single pass.

This saves costs and also provides opportunity for crops to be harvested mechanically. Crop uniformity can be improved with appropriate irrigation and fertiliser management.

A key to uniform crop maturity is even plant growth from transplanting through to harvest. Crop maturation uniformity can be improved by  changes to fertiliser and irrigation management but it is also influenced by factors which cannot be easily controlled such as plant genetics and environmental conditions. Due to these other factors it is not possible to get all of a crop maturing at the same time. Trials have shown that about 80% of a crop can be uniformly mature for one harvest if fertiliser and irrigation are carefully managed.

The following management system is particularly suited to crops grown in summer months on soils that have some clay content and adequate water-holding capacity. The irrigation techniques are not suitable for sandy soils due to their low water-holding capacity which necessitates more frequent watering.

These crop management techniques were developed and tested on karri loam soils in the Manjimup region, about 300km south-west of Perth. Due to the high degree of variability of soils across vegetable growing regions and the impact of soil type on crop development, the reduced pass harvest system should be tested on-farm before implementing on a large scale.

Fertiliser

The strategies for fertiliser management to improve crop uniformity include changes to application methods, timings and rates:

  • Apply basal fertiliser in an incorporated strip, rather than banded beneath the plant. Incorporation leads to a slight increase in yield, reduced growing time and fewer harvests.
  • Apply nitrogen-based fertiliser regularly and in small amounts throughout the life of the crop. Applying large amounts occasionally may lead to fluctuations in growth rates and uneven growth across a crop. The first application of nitrogen fertiliser after transplanting should be within one week and thereafter applied ‘little and often’.  See table 1 for an example fertiliser application schedule used for reduced pass harvest demonstration crops.
  • Apply post-transplant fertiliser in a liquid form. If possible, dissolve granular fertiliser and apply through a boom spray rather than in a granular form through a spreader. This method is more accurate as each plant receives a similar amount of fertiliser. It can also save money as fertiliser application is more targeted and not wasted on non-cropped areas. Ensure irrigation is going when nitrogen-based liquid fertilisers are applied to prevent damage to plants.
Table 1. Example of fertiliser application rates, timings and methods for broccoli and cauliflower reduced pass harvest demonstration crops grown over summer on karri loam soil in Manjimup.
Fertiliser Rate
(kg/ha)

Days after

transplanting

Application method

NPK blend +

micronutrients

  • nitrogen
  • phosphorus
  • potassium

 

 

135

125

95

At planting Strip incorporation
Urea 37 3

Boom spray under irrigation

Potassium nitrate

100 10

Boom spray under irrigation

Boron 10 14

Boom spray

Zinc sulphate 14 14

Boom spray

Sodium molybdate 1 14

Boom spray

Urea 75 21

Boom spray under irrigation

Calcium chelate 1 28

Boom spray

Urea 75 31

Boom spray under irrigation

Urea 75 42

Boom spray under irrigation

Potassium nitrate 100 42

Boom spray under irrigation

Boron 10 45

Boom spray

Zinc sulphate 14 45

Boom spray

Urea 75 50

Boom spray under irrigation

Calcium nitrate 150 57

Boom spray under irrigation

Calcium nitrate

100 64

Boom spray under irrigation

Calcium nitrate

50 71

Boom spray under irrigation

The last three applications of calcium nitrate may not be required, depending on harvest date.

Contact information

Rachel Lancaster
+61 (0)8 9780 6210

Author

Alison Mathews

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