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.