Nitrogen fertiliser will burn away all your organic carbon in the soil so whenever you add nitrogen fertiliser in any form, you need to add a carbon source – either humic or fulvic acid, or compost at the same time – it helps to balance out – it doesn’t draw out nitrogen out of the soil. Nitrogen is a gas and you want to lock it up in the soil. Having a carbon source holds it into the soil. Just having pure ammonium or even pure fish fertiliser within a day or two, the nitrogen will just evaporate. I use foliar fertiliser in the main growing season when there’s new growth – it’s very weak – do it at regular fortnightly intervals. You’re building your brix levels up. You can feed the trees a lot more and by doing that and spraying small droplets over a leaf, it becomes rapidly absorbed into the tree within an hour or two and you can actually see changes in the plant within 4 hours. When they talk about flushing, it either means putting a lot of fertiliser and a lot of water to get that growth happening. If a tree is healthy it will ward off pests and diseases so keep fertilising small amounts which is better than large amounts as the plant can deal with it a lot better. Use stone mulch about 2½” thick white quartz $40.00 per tonne and paramagnetic basalt fines – $100.00 a tonne. Put the basalt fines down first and the quartz on top then compost around the outer ring of rocks – about 3-4 large shovels per tree and you can put it right up to the trunk. As the tree gets bigger, we can extend the ring of stone mulch. I set up a trial over about 20 different trees and I put a whole lot of different materials down as mulch: different rock sizes/particles, different wood mulches, straw, different types of sand then put the water on and let it sit for a day or two then came back and did the finger test and I was very surprised to see the difference – then when it rained, I did another finger test and its amazing how there’s such a big difference between the different types of mulches. The one that held the most amount of moisture was a combination of large 8ml quartz and very fine basalt rock. We expected other mulches to do a lot better but that one was the most effective for us. I’m an Arborist and can get wood mulch but found it broke down after a year and it had to be reapplied so putting down the stone, it didn’t break down. We found with a lot of other mulches in very dry conditions, it won’t allow penetration of a small shower of rain so if you have wood chips, it becomes a barrier so when the water rains on that spot, it will run off elsewhere. Straw mulch will soak up a lot of water but if you do the finger test, under the soil is still very dry. Some of the growth rates we’ve had by pushing the trees hard – we only had sticks when we started – no more than 300mm – and now after 3-4 months, they are up to chest height so we’re hoping that by the end of the season they will be pushing well over head height and fruiting 2-3kgs per tree so it really helps to do your fertigation through your lines and do foliar feeding. We use NTS products. An Indian scientist I talked to spoke about having a lot of plant vigour – they believe more in pruning so they push their plants with as much fertiliser and water as possible then they’ll go through and prune very heavily so the plant doesn’t lose any vigour but it will shock the tree and it will then fruit very heavily.
Fertiliser: With any crop it’s usually applied at the 1st major flush and there’s usually a window of opportunity from flushing to flowering so during that time, try and push them as much as possible.
Ben grows Jujube at Owen which is on the edge of the desert about an hour north of Adelaide. He imported a lot of varieties from Roger Meyer in California. He thinks a lot of our trees up here in Qld are lacking nitrogen so if your leaves are turning slightly yellow but still have a green vein, then you’ll know to put nitrogen on or if your tree is just sitting there and not doing anything, then push it along with some fertiliser.
Article compiled by Sheryl Backhouse