CONSIDERATIONS FOR HIGH-DENSITY MANGO ORCHARDS
Planting density is an important aspect of orchard designs. It is a contributing factor to an orchard’s yield potential and the rate at which it can return investment. Planting too many trees can be costly and counterproductive. On the other hand, too few trees can lead to a waste of space and resources.
The planting density of mango trees depends on several factors such as the variety of mango, soil type, climate, irrigation, and management practices. Generally, the recommended planting density for mango trees is around 312 trees per hectare (8m x 4m spacing).
A very safe spacing in a high-density mango orchard is 6m x 2m which equates to 833 trees per hectare. It is important to determine what works with your management setup and in your climate.
The greater the adversity in climate and conditions, the greater the management effort required. It is advisable to opt for high planting densities in suitable conditions as this reduces the management effort needed to ensure profitability.
Owing to their to their monsoonal background, mango trees are adaptable and can grow in a variety of soils and climates. They can withstand a wide range of weather conditions from hot and humid to chilly and dry.
As a result, mango trees can be grown across a large region in South Africa. Mangoes can be cultivated successfully in temperatures ranging from 5 °C to 45 °C, with optimal day temperatures falling between 27 °C and 36 °C. Mango trees thrive on well-draining, organic-rich soils with a pH range of 5.5 to 7.5. They prefer sandy loam or loamy soils with sufficient drainage and aeration for the roots – which can grow up to 6m deep – so they require soil at least 1m deep.
Management is the key factor in high planting density orchards. Cultivars with different seasonalities need to be treated differently regarding pruning and other practices. This is particularly important in the early years after planting. With correct pruning and tree training, yields exceeding 30 tonnes per hectare could be expected.
Figure 1: Density difference Tommy Atkins 1995-2001 (22.8 ha) (Du Preez, 2023)
Light
The amount of light intercepted by a tree and its distribution within the canopy is critical in optimising tree photosynthesis efficiency, carbon partitioning and overall productivity. Manging light distribution within the canopy can be particularly challenging and dependent on the tree’s growth habit. It is important to keep this in mind when shaping the canopy.
Research has shown that a central leader and a pyramidal hedgerow shape, with a working space of 1.8 – 2 m between the hedges, gives the best long-term results (DuPreez, 2023).
Figure 2: Well-shaped tree and between-row opening, to optimise sunlight interception and leaf area per ha, as well as ease of spraying and harvesting.
Spacing
Spacing of either 6m x 4m or 6m x 2m typically produces a 4m-high pyramidal-shaped hedgerow with the ideal 1.8 – 2m working space and good leaf canopy area per ha efficiency. It is important to note that other spacing options are viable and that it depends on the cultivar growth habit, climate (heat units), and amount of pruning you are willing to do.
As seen in Figure 1, the Tommy Atkins 6m x m2 spacing had a higher initial yield but eventually both 6m x 2m and 6m x 4m plantings had similar yields of about 25 tonnes per hectare.
Once the hedgerow is formed, yields are mostly determined by genetics and climate. In cases where the tree spacing and pruning are optimised for light interception and distribution, high-density orchards produce remarkably well. It has been shown that trees trained as single leader or espalier, have more evenly distributed light in the inner canopy compared to conventionally closed vase-trained trees. In a recent study, 5-year-old high-density, espalier trained trees with approximately 5000 m3/ha canopy volume yielded close to close to 50 t/ha at 40% light interception.
Figure 3: Density difference Kent 1995-2021 (47.8 ha)
Sometimes changes in how one fertilises and prunes will help to obtain more constantly good yields rather than the big yield differences. The variability is however not permanent (as shown in Figure 3) (DuPreez, 2023).
Water and nutrients
It is important to ensure the availability of water and nutrients in a high-density orchard to complement the pruning work for optimal photosynthesis. Irrigation that is timed according to growth stages affects yield more than timed fertilisation. The critical stages for adequate water are at flowering, fruit set and fruit development. Fertiliser and irrigation during the critical stages are important for water use efficiency (WUE), partial fertiliser productivity (PFP) and fruit quality.
Applying fertiliser at the fruit expansion stage has a greater effect on fruit yield and WUE whereas applying fertiliser at the fruit ripening stage improves the contents of total sugar, vitamin C, carotenoids, fruit water and soluble solids. Nutrient management and the use of balanced fertiliser are important to manage as an overdose of fertiliser is a major cause of saline soils.
In today’s economic climate, it is important to speed up productivity and increase return on investment.
Although high-density plantings are more capital intensive, it speeds up the development of leaf canopy, which results in higher yields.
Traditional planting spacings will catch up to the yields of high-density plantings as soon as the leaf canopy per area equals that of high-density planting.
Keep sustainability in mind and farm with a long-term plan.
References
DuPreez, 2023. MANGO PIPS.13.. Mango Pips, February.
Guangzhao, S. et al., 2022. Optimizing irrigation and fertilization at various growth stages to improve mango yield, fruit quality and water-fertilizer use efficiency in xerothermic regions. Agricultural Water Management, 260(https://doi.org/10.1016/j.agwat.2021.107296).
Khan, M. & Ahmed, N., 2021. Sustainable management of mango nutrient for better yield and quality. Cercetari Agronomice in Moldova (Agronomic Research in Moldova), 184(4), pp. 473-501. DOI: 10.46909/cerce-2020-040
Mahmud, K. et al., 2020. Light Relation in Intensive Mango Orchards. Brisbane, Australia, the third International Tropical Agriculture Conference (TROPAG 2019).
Oosthuyse, S., 1993. Tree Spacing Trends and Options for Yield Improvement in Mango. S.A. Mango Growers' Assoc. Yearbook, Volume 13, pp. 34-39.