Introduction
There is little readily available information (at least in English) for the rates of fertiliser applied to jujubes. There are documents that describe the fertiliser practices of subsistence farmers in India and China and the rates of fertiliser used. These farmers mainly used manures. The rate of nutrients supplied by these organic fertilisers is difficult to calculate as the composition of the manures is not given.
For mature trees the amount of nutrient removed from the orchard in the fruit (crop removal figures) provides a guide of what to apply. Table 1 below shows how much nitrogen (N), phosphorus (P) and potassium (K) is removed in various amounts of fruit. However, not all the fertiliser applied to the soil is available to the plant.
Nitrogen is readily leached past the trees roots by rainfall and irrigation (especially on sandy soils), and can be lost to the atmosphere by volatilization. Phosphorus is fixed (tied up) by most soils and only a percentage is available to the plant. Potassium is also held by particles of clay or leached in sandy soils.
Consequently, higher rates of nutrients than those listed in Table 1 will generally need to be applied in the fertiliser program (unless the soil has a high fertility).
| N | P | K | |
| kg in 1 tonne crop | 3 | 0.3 | 4 |
| kg in 5 tonne crop | 15 | 1.5 | 20 |
| kg in 10 tonne crop | 30 | 3 | 40 |
| kg in 20 tonne crop | 60 | 6 | 80 |
Studies in China have found that 0.75 kg of nitrogen, 0.44 kg of phosphorus and 1.1 kg of potassium was needed to produce 100 kg of high quality fruit. Using these recommendations Table 2 shows how much nutrient would be required for four yields.
| N | P | K | |
| kg in 1 tonne crop | 7.5 | 4.4 | 11 |
| kg in 5 tonne crop | 37.5 | 22 | 55 |
| kg in 10 tonne crop | 75 | 44 | 110 |
| kg in 20 tonne crop | 150 | 88 | 220 |
More recent research from western China found that for maximum yield and fruit quality of twelve year old, drip irrigated jujube trees, they required 209 kg N/ha/year, 171 kg P/ha/year and 217 kg K/ha/year. These rates are higher than most fertiliser recommendations for other deciduous crops such as apples and stone fruit. These jujube trees were planted on a 2 metre by 5 metre spacing and yielded 23 tonnes per hectare.
The rate of nutrient required will depend on the soil type, fertiliser history, tree size and yield.
The tables below give some general fertiliser recommendations for jujubes and are based on what has been traditionally applied to deciduous fruit crops in Western Australia.
These figures should be modified taking into account leaf analysis results, soil analysis results, tree size, tree growth in the last year, yield and fruit quality.
Pre-plant recommendations
Inorganic fertilisers
For new orchard sites apply phosphorus and trace elements prior to planting and cultivate into the soil. The following fertiliser blend is recommended for apple crops on new orchard sites in the south west of WA.
| Fertiliser | Kg/ha of fertiliser | Kg/ha of each element |
| Superphosphate | 1500 | 136 kg of P |
| Magnesium sulphate# | 250 | 25 kg of Mg |
| Manganese sulphate | 100 | 25 kg of Mn |
| Copper sulphate | 50 | 12.5 kg of Cu |
| Zinc oxide* | 100 | 70 kg of Zn |
# Magnesium may also be applied separately as dolomite lime (about 10-12% Mg). Magnesium sulphate may be deleted from the initial blend and applied through the irrigation, if required, after planting.
* Zinc sulphate may be substituted for zinc oxide, with approximately 350kg of zinc sulphate required to supply the equivalent amount of zinc.
This blend should be top dressed along the proposed tree rows in a 2 metre wide strip, followed by deep cultivation, four to five weeks before planting.
Conduct a pre plant soil test. If the soil pHwater is less than 5.5 apply lime to bring the pHwater up to at least 6.5. Cultivate the lime into the soil. If the site for the proposed jujube orchard is old horticultural land the soil test results may show high levels of some of the nutrients listed in Table 3. In this case the pre plant fertiliser applications may be able to be reduced.
Organic fertilisers
Organic fertilisers such as manures and composts can be applied instead of the inorganic fertilisers listed above, or in combination with inorganic fertilisers. It is important to have the nutrient analysis of any organic amendments to be able to calculate how much to apply. The rate at which organic products break down and release nutrients is very variable. For example, fresh manures can release large amounts of nitrogen within the first three weeks following application while composts are more stable and will release much smaller amounts of nutrients over many years. Apply organic amendments to the ground surface either along the tree line (for wide spaced tree rows) or over the whole orchard and cultivate into the soil.
Do not plant jujube trees into soil within three weeks of applying fresh manure as the large amounts of nitrogen being released can kill the trees. Organic materials can contain weed seeds, glass and other impurities.
Table 4 gives the nutrient concentrations of deep litter poultry manure and commercially available compost. The application of raw poultry manure is banned in areas from Harvey to Gingin and in the Perth Hills. Manure that has been treated in a manner to control stable fly can be used in these areas (often partially composted).
| Product | Moisture content | Bulk density (tonnes/m3) | Average Nitrogen | Average Phosphorus | Average Potassium |
| Poultry manure | 25% (Summer) | 0.4 | 3% | 1% | 1.25% |
| Compost | low | 0.9 | 1% | 0.3% | 0.4% |
Table 5 shows the amount of nitrogen, phosphorus and potassium contained in 10 tonnes of poultry manure and a commercially available compost. These products also contain many of the other macro and trace elements required by plants.
| Product | Rate (t/ha) | Kg N/ha | Kg P/ha | Kg K/ha |
| Poultry manure* | 10 | 270 | 90 | 112 |
| Compost | 10 | 103 | 33 | 41 |
*10 t/ha is equivalent to about 30 m3/ha (bulk density =0.4 and 75 % dry matter)
In order to supply the same amount of phosphorus as the pre plant inorganic program listed in Table 3 you would need to apply 15 tonnes/ha (45 m3/ha) of poultry manure or 40 tonnes per hectare of compost (assuming the same composition as listed in Table 4). In addition to the fertiliser value of composts and manures there may be other benefits to the soil such as increasing its ability to hold nutrients. As mentioned above composts and to a lesser extent manures release nutrients over a longer period time than inorganic fertilisers.
Post plant recommendations
The tables below give recommendations for fertiliser rates to apply to jujubes post planting. These recommendations have been modified from general recommendations for deciduous fruit orchards.
Table 6 gives suggested rates in grams of element per tree. The user can then decide which fertilisers they wish to use to supply that amount of each element and work out the rate required based on the percentage of each element in that fertiliser.
The rates are for an orchard with a tree spacing of 4 m x 2 m or similar. For higher density orchards (e.g. 3 m x 1.5 m) the fertiliser rates (g/tree) listed below will need to be reduced for mature trees due to the smaller tree size.
Using proprietary NPK plus trace element fertilisers provides an easy approach to fertilising. They are generally formulated in ratios that are suitable for most horticultural crops. Table 7 gives recommendations for fertilising jujubes when using NPK plus trace element fertilisers.
| Tree age | Rate and time of application |
| Years 1 to 3 | Conduct leaf and soil analysis and use the results to modify the general recommendations listed in this table.
Apply: 20 g nitrogen per year of tree age (e.g. in Year 2 apply 40 g of N/tree) 10 g of phosphorus per year of tree age 20 g of potassium per year of tree age 5 g of magnesium per year of tree age
Apply nitrogen, potassium and magnesium via fertigation in 7 equal monthly applications from September to March (e.g. in Year 1 apply 7 applications of 3 g of N/tree).
Phosphorus can be applied in one application in winter or throughout the season. However, on white sands apply in more than one application as phosphorus can leach on these soils.
|
| Year 4 onwards | 60 - 120 g of nitrogen annually per tree (depending on tree size)
30 g of phosphorus annually per tree Phosphorus can be applied in one application in winter or throughout the season. However, on white sands apply in more than one application as phosphorus can leach on these soils.
80 - 150 g of potassium annually per tree Apply from September to April or at the same time as the nitrogen.
30 g of magnesium annually per tree Apply the magnesium from September to April or at the same time as the nitrogen.
If leaf analysis results show low calcium or sulphur levels apply gypsum in one Spring application. Alternatively, use fertilisers which contain these elements such as calcium nitrate, potassium sulphate and magnesium sulphate.
If leaf analysis results show low trace element levels apply the deficient element to the soil and/or as a foliar application. |
| Tree age | Rate and time of application |
|
Years 1 to 3 | Conduct leaf and soil analysis and use the results to modify the general recommendations listed in this table.
150 g per year of tree age of a NPK plus trace element fertiliser (12-4-15 or similar mix). For example, in Year 2 apply 300 g of fertiliser/tree/year.
Apply a soluble mixed fertiliser via fertigation in 7 monthly applications from September to March (e.g. in Year 1 apply 7 applications of 22 g of fertiliser/tree).
For sprinkler irrigated orchards without fertigation equipment a non-fertigation grade NPK fertiliser can be applied by hand to the wetting pattern at the monthly intervals suggested above. Spread the fertiliser over the whole root zone. |
| Year 4 onwards | Conduct leaf and soil analysis and use the results to modify the general recommendations listed in this table.
500 - 1000 g per tree of a NPK plus trace element fertiliser, depending on tree size (12-4-15 or similar mix).
Apply a soluble mixed fertiliser via fertigation in 5 monthly applications (September, October, November, December, and then one application immediately following harvest). For example, apply 5 applications over the year each of 200 g of fertiliser/tree. Don’t apply nitrogen in the 8 weeks before harvest as it may cause fruit quality issues.
For sprinkler irrigated orchards without fertigation equipment a non-fertigation grade NPK fertiliser can be applied by hand to the wetting pattern at the monthly intervals suggested above. Spread the fertiliser over the whole root zone.
If leaf analysis results show low calcium or sulphur levels apply gypsum in one Spring application.
If leaf analysis results show low trace element levels apply the deficient element to the soil and/or as a foliar application. |
Acknowledgements
This work was carried out by independant agronomist Neil Lantzke through the Perth NRM Healthy Soils Healthy Rivers program and supported by AgriFutures Australia.
References
Mengjun Liu (2006) ‘Chinese Jujube: Botany and horticulture.’ Horticultural Reviews Vol 32, Edited by Jules Janick. John Wiley and Sons.
San B., Yildirim, A.N., Polat, M. and Yildirim, F. (2009). ‘Mineral composition of leaves and fruits of some promising Jujube (Zizyphus jujube MiIlar) Genotypes’. Asian Journal of chemistry Vol 21, No 4 2898 – 2902.
Wang. Z., Li. N. and Quan. L (2014). ‘Effects of water and fertiliser coupling on the yield and quality of drip irrigated Chinese jujube in an extreme arid region.’ Advanced Journal of Food Science and Technology 6 (5) 634- 637.