RESEARCH & EVENTS
Irrigation key to getting value from almond trees planted at high density in the Riverland
Roberta De Bei 1 , Grant Thorp 2 , Ann
Smith 2 1
Plant and Food Research Australia
2
The New Zealand Institute for Plant and Food Research
30
PLANT Food Research Australia has established that higher kernel yields can be obtained from higherdensity almond tree plantings only by increasing irrigation rates . The work done at the Almond Centre of Excellence showed irrigation rates calculated per tree were more important than rates per hectare in terms of orchard yield for young , high-density blocks where trees were not light limited or crowded . The trial site was planted in July 2018 and includes Shasta ® and ‘ Vela ’ on Nemaguard rootstock , with planting densities of 513 ( 6.5 x3m ), 769 ( 6.5 x 2m ), 741 ( 4.5 x 3m ) and 1,111 ( 4.5 x 2m ) trees per hectare . For the first three years irrigation was set on a per hectare basis rather than a rate per tree ( 4.5 , 8.5 , and 9.7 ML / ha for 1st , 2nd , and 3rd-leaf trees , respectively ). This meant that in the lower density treatments each tree received more water and had higher yields per tree than trees in the higher density treatments , but the yields per hectare were similar because water per hectare was the same . In 2022 the irrigation design was modified by adding an extra irrigation lateral to the trees in the 4.5m rows to achieve the water application remaining questions it wants to reported in the table above right . answer : Increasing orchard productivity
• What are the longer-term and efficiency is of great benefit to economic and environmental growers . Planting density is a key benefits from planting more consideration and research projects trees per hectare ? on several tree crops have reported • How much water is too increased yields from planting more much , before an oversupply trees per hectare . With almond , of water causes root health early trials in California reported that problems ? ( This will be planting more trees per hectare gave particularly important for sites higher yields when trees were young , with heavier soils that have a but yields were not increased over great water-holding capacity the longer term . than the sandy soils in this
Irrigation is an important study ) consideration in an Australian
• Can fertiliser inputs be reduced ? In this trial , fertilisers environment with low rainfall and often on soils with high sand content were applied through the and low water-holding capacity , unlike irrigation lines , so rates were growing regions where irrigation proportionate to the amounts is used to supplement high natural of irrigation water applied . rainfall . The PFR team still has some
This article was adapted from the work In A Nutshell - Autumn 2024 Vol 25 Issue 1
Values in each column followed by different letters were significantly different ( p < 0.05 ).
Irrigation rates calculated per tree are more important than rates per hectare in terms of orchard yield for young , high-density blocks . presented at the VIII International Symposium on Almonds and Pistachios , California ( May 2023 ) and published in Acta Horticulturae . Thorp G ., Smith A ., Coates M and De Bei R . 2024 ( In Press ). Water use efficiency in high density planting trials with almond ( Prunus dulcis ( Mill .) D . A . Webb ).
Acknowledgements This research was funded by the Hort Frontiers Advanced Production Systems Fund , part of the Hort Frontiers strategic partnership initiative developed by Horticulture Innovation Australia Ltd , with co-investment from The New Zealand Institute for Plant and Food Research Ltd and contributions from the Almond Research and Development levy . We also acknowledge the support from Anthony Wachtel , Orchard Manager at the Almond Centre of Excellence .