Fertlizers

Durian trees are perennials and they use all the food reserves in the trunk, branches and twigs for fruit production. After each fruiting season, all these food reserves are used up and need to be replaced. If the replacement is insufficient, the trees will not bear a good crop in the following season, or it may not fruit at all. And they have about five months to prepare enough food reserves for the next season.

Durian trees take up nutrients year after year from the soil around them. Fertilizers are needed to maintain the health and productivity of the the trees.

More nutrients are needed as the trees grow older and bigger. Less vigorous trees require more nutrients to help them recover. The higher the yield in the previous season, the more nutrients is required to help the trees recover faster for the next season. Durian requires different proportions of N, P, and K as the tree reaches different developmental stages.

Durian orchard management follows closely that of the durian growth stages. These stages are very dynamic and there is no clear-cut cross-over from one stage to the next. There is always some overlaps. The development stages are greatly affected by the environment, the durian clones or cultivars and vigor of the trees. Even individual tree exhibits different stages of crop development on different parts of the trees.

Fertilizer article from
International Tropical Fruits Network

Nutrient Deficiency
Newly planted durian seedlings are more sensitive to macro and micro nutrient deficiencies compared to mature trees. The main effects of nutrient deficiencies are dwarfing, longer juvenile periods, late flowering, late fruiting, low yield and fruit drop before reaches maturity. The more serious effect is seedling mortality. The main symptoms due to deficiency in some elements are given in Table 1. Table 1: Symptoms due to nutrient deficiency Nutrient Deficiency Symptoms Nitrogen (N) Yellowing of older leaves and chlorosis Phosphorus (P) Reduction in leaf sizes Calcium (K) Yellowing of older leaf tips, then spread to leaf margin, followed by necrosis Magnesium (Mg) Yellowing of older leaves beginning at the veins spreading towards leaf tips. The leaf veins remain green. This is followed by leaf drop Sulfur (S) Yellowing of young leaves and the surface of the effected leaves turn uneven. The veins remain green Iron (Fe) Yellowing of young leaves and the surface of the effected leaves turn uneven. The veins remain green Manganese (Mn) Dwarfing of the seedlings, yellowing and chlorosis in the older leaves although the veins remain green Copper (Cu) The young shoots wrinkle with yellowing at leaf margin. This usually results in stunted growth of shoots. Proliferation also spread to the older leaves which also result in stunted growth
Fertiliser types
At an early development stage, a high N and P fertilisation is necessary. The rates are given in the table on Fertiliser Application. Most compound fertilisers such as Nitrophoska green, blue or red containing the recommended combinations are suitable. Organic fertilisers such as chicken dung or cow dung at the rate of 15 to 30 kg/ plant is given annually. At maturity, durian requires high K fertilisation for fruit development.
Fertiliser application
Under normal conditions fertiliser is broadcasted around the canopy, slightly further away from the canopy radius. Under steep terrain fertiliser is applied in holes dug around the canopy radius (pocket application). After applying the fertiliser the holes are covered. Fertilisation should be carried out during the wetter months. Recommended fertilisers given at different rates according to the different ages of the plants is given in Table 2 . The fertiliser types are interchangeable. Table 2: Fertilisation time table Age of plants (years) Kg/plant/year Frequency Combination of elements Fertilizer types 1 0.6 6 14 : 13 : 9 : 2 1/2 14 : 13 : 9 : 2 1/2 2 1.0 4 15 : 15 : 15 vegetative 3 2.0 4 15 : 15 : 6 : 4 vegetative 4 3.6 4 11 : 16 : 9 : 2 1/2 vegetative 5* 4.5 4 12 : 12 : 17: 2 +TE Fruit development 6 6.0 4 12 : 12 : 17:2 + TE Fruit development 7 7.5 3 13 : 13 : 20 Fruit development 8 9.0 3 12 : 6 : 22 : 3 Fruit development 9 10 3 15 : 7 :18 :2 Fruit development 10 or more 10 3 ` Fruit development *Change to fertiliser combination for fruit development although the plants are still vegetative