Key points
- An irrigation trial (drip tape) with seven treatments ranging from no irrigation (rain fed) to 100% replacement of the soil water deficit was established in a commercial ‘Russet Burbank’ crop at Dorie, Mid Canterbury.
- Marketable yield was reduced from 79 t/ha to 40-60 t/ha when weekly irrigation fell below 66% of the soil water deficit.
- Irrigation reduced the amount of small (<60 mm) and medium (60-90 mm) sized tubers and increased the yield of large tubers (>90 mm).
- Replacing 66% of the soil water deficit weekly was the most water use efficient.
- Replacing only 50% of the soil water deficit after canopy closure gave a yield penalty of 10 t/ha.
- The treatment which applied only 50% of the deficit up until canopy closure, then 100% thereafter, had a similar size distribution and yield to the full irrigation treatments.
- Similarly, missing one week’s irrigation at canopy closure did not influence marketable yield.