Nuts : Almond, Pecan, Walnut, Macadamia, Hazelnut, Cashew

Cultivation of nuts

Most nut plantations around the world are planted and cultivated in a similar manner and typically, the trees are widely spaced in stands reaching up to 12 x 12 meters. Pruning, spraying, weed control and harvesting are all highly mechanized. To optimize use of the land area, some plantations begin with more dense spacing and after the trees have developed, they are thinned to reach the stand required and avoid excessive mutual shading. Around the world it is accepted practice to plant relatively dense stands of hazelnuts, which are thinned out after 10 years, when mutual shading is intense.

This method enables optimal use of the land area and resources during the initial growing stages. It is also accepted practice to intercrop nut plantations, to exploit the available areas between the lines of trees. Recently, the trend has been to plan and adapt the plantation (the stand and how the trees are planted; the selection of the irrigation and fertilization equipment), for agricultural mechanization, which will save manpower. For example: the planting of long lines of trees closer together, but with wider paths between the lines to allow more convenient passage of machinery through the plantation.

Irrigation and fertilization systems are designed to provide optimal solutions for plant needs and they constitute an important tool, leading the plantation towards good, high quality yields. With careful planning and design, in addition to irrigation and fertilization, the systems already extant in the plantation can be used to improve agro-technical methodologies.

For example: Where irrigation equipment is at risk of damage by indigenous fauna, drip

systems can be buried in the soil.

Sprinklers / micro sprinklers can be used to wet heavy soil and prevent the cracking and rutting, which make movement difficult for nut harvesting machinery.

Sprinklers / micro sprinklers can be used to protect against frost in susceptible areas, which will prevent significant damage to the trees and lower final yields.

Pruning and shaping the trees  

There are several different types of pruning methods for nut plantations:

• Technical pruning, including pruning the sides of the trees along the planted line and topping.
• Vista or window pruning to allow light to enter the tree canopy. In most varieties, window pruning is executed to allow light into the center of the canopy and prevent excessive shading. Contrastingly, in almond plantations, shade in the canopy area helps increase yields and therefore, window pruning is avoided.
• Trunk cleaning – In plantations using mechanical trunk shakers to harvest the crop, there must be no branches on the trunk up to a height of 60cm to 90cm, because that is where the shaker arms grip the tree trunk. Clearing away any branches there also helps with other mechanized

activities in the plantation.

Sanitation

To keep trees healthy and avoid the dissemination of diseases and/or the weakening of the trees, sanitation techniques must be applied to the entire plantation area. That includes the removal of damaged trees and neglected adjacent plantations; the removal of stumps, suckers and roots. Make sure that all the woody material is burned close to where it is cut or uprooted.

Try to avoid disturbing the soil or undertaking any other activity, which might cause stress and weakening of the trees.

Pollination

Some nut trees are self-sterile and they must receive foreign pollen from pollinating trees specially planted in the plantation area. Usually, pollinating trees are not the same variety as the yielding trees (the principal variety in the plantation). In pecan and hazelnut plantations, 5% to 15% of the total number of trees must be pollinators. If we take pecan as an example –

Flowering is timed so that the male flowers blossom first, but spread their pollen only in the spring with the blossoming of the female flowers (when the climatic conditions are optimal). Certain varieties of walnut are self-fertile, but larger, better quality yields are reached through reciprocal pollination by a pollinating variety.

The contribution made by irrigation to vegetative growth and yield:

In the past, nut plantations were planted and grew in an area suitable for the needs of each individual variety, in terms of climate, rainfall and soil type.

Over the years, with the introduction of advanced irrigation systems, nut plantation areas have expanded into locations not ideal in those terms, because irrigation and fertilization systems can adapt to the differing conditions and a larger range of areas.

A great deal of research has shown that there is a direct link between water quantity, quality, availability and how it is applied and the strength of trees’ vegetative growth, resistance to disease and climatic damage and the quantity and quality of the crop achieved.

For example:

• Irrigation and fertilization of cashew trees during the dry season (when growing cashews in very hot tropical and sub-tropical regions) prevents weakening of the trees caused by drought stress conditions. They also help maintain continuous growth, improve resistance to disease and they shorten the time it takes for the tree to reach maturity and begin yielding a crop.
• Maintaining irrigation continuity throughout the dry season and after harvesting an almond tree crop encourages leaf growth and improves crop quantity and quality in the following season. Furthermore, there is a direct link between the tree irrigation and fertilization regime and the effective number of flowers during the flowering season. Deficit irrigation and drought stress result in the dropping of flowers, inadequate filling of the pit and lower yields.

NaanDanJain offers a large reange of irrigation solutions for nuts:

Micro Sprinklers

The use of micro sprinklers to irrigate nut plantations has grown considerably over recent years, because micro sprinklers provide many advantages:

• Irrigation adapted specifically for the plantation; the foliage does not get wet, while at the same time, the wetting zone and irrigation volume can be matched optimally to the tree growth stage. Increasing wetting zone radius as the tree grows is easy and rapid, requiring only another sprinkler between the trees.
• Matching the wetting radius and the area beneath the trees to the growth of tree root surface area, with the aim of increasing water and fertilizer take up efficiency and to help establish and stabilize the tree in the soil.
• Irrigation using a wide range of flow rates, including very low rates (2002 Aqua Smart – Up to 20 liters / hour; 15 liters / hour for the Jet family).
• See table below.
• Irrigation using micro sprinkles overhead for cooling and frost protection up to about -3º C. Wetting the area helps prevent freezing, which can often cause irreversible damage to the trees.
• In heavy soils, irrigation using micro sprinklers prevents soil cracking and the formation of deep ruts, which interfere with nut harvesting and other mechanized agricultural activities.
• The application of herbicides and sprouting retardants through the micro
• sprinkler system is effective, more uniform and saves manpower.

There are a number of ways to install micro sprinklers in nut

plantations:

1. Single micro sprinkler – Position a single sprinkler between trees in the line. This sprinkler should have a wide wetting radius in order to maintain a large wetting volume, without wetting the tree trunk (when the tree is sensitive), which also means it helps prevent the development of disease and rotting.
2. Two low volume sprinklers positioned one on each side of the tree at a distance of 1m – 1.5 meters (depending on the planting stand) from the trunk. This setup ensures that the wetting strip is broad and continuous along the row.
3. Hang the sprinkler upside down – Achieved using a weighting system from the blind distribution line laid out at a height of 1 – 1.5meters above the soil, between the trees in the row. This system has a number of advantages:
4. Wider wetting radius
5. It prevents harm to the water carrying pipes by indigenous fauna.
6. Workers and machines benefit from a clear passageway.
7. Easy, efficient monitoring of system functioning.

NDJ offers a wide selection of micro sprinklers for use in nut plantations:

2002 AquaSmart

2005 AquaMaster

Smart Jet

Sprinklers Systems

It is standard practice to use sprinkler systems in nut plantations with free draining soil, when the trees have been planted on raised banks; when the ground is stony and it is necessary to enlarge the trees’ root system and establish the trees more firmly; in areas requiring supplementary irrigation during dry seasons and in adult plantations to avoid wetting the young trees’ foliage.

Sprinklers continue to work well in difficult climatic conditions such as strong winds and they can be installed in a very wide range of ground conditions.

Sprinkler systems have low filtering requirements, which means they can also be used for plantations with a poor quality water supply.

Using sprinklers on heavy soils enables flushing salts to soil depth. Selecting the correct type of sprinkler and sprinkler layout is primarily a function of the planting stand, plantation age and tree canopy configuration. Usually, the use of low angle sprinklers (which do not wet the tree foliage), with a broad wetting radius is the best way to irrigate nut plantations.

NaanDanJain recommends the use of 4º to 12º, low wetting angle sprinklers and using this unique irrigation equipment, it is possible to irrigate at high flow rates with larger distances between sprinklers and thereby, to achieve very high levels of irrigation uniformity.

NaanDanJain offers a wide selection of sprinklers of use un nuts plantation:

Magic Drive LA

5024 SD

6024 SD

6004 SD

OPAL

Drip Irrigation

Drip irrigation is an irrigation method widely used in plantations all over the world. While a plantation is still young, a single dripper line is laid close to the tree trunk. As the tree grows, another line is added and sometimes, even a third and fourth line are added (as appropriate to the type of soil and the tree root volume). Dripper lines can be very long.

Drip irrigation has many advantages:

• The ability to work at low flow rates.
• Dripping saves water (a solution for countries where water is scarce, but drip irrigation does have relatively high filtering requirements).
• Maintains a continuous wetted strip along the line of trees
• Optimal method for fertilizing the trees
• Avoids wetting the tree trunk and helps reduce humidity, which prevents rotting, disease and weed growth.

Sub Surface Drip Irrigation

Nut plantations usually cover a large area with lots of movement of animals, including rodents, birds, small reptiles and sometimes even large wild pigs, which can damage equipment and systems laid out on the ground surface, such as surface drip lines, distribution pipes and often, sprinklers as well. That damage can add up to very large sums. Moreover, in many plantations, there is ever increasing use of agricultural machines at every growing stage, including surface nut harvesting. Burying the dripper lines in the ground makes life easier because the surface is clear for the easy passage of machinery and ongoing work. During planting, two to four dripper lines are buried to a depth of 10cm to 30cm below the soil surface as appropriate for the soil conditions and the risks at large in the plantation. Those dripper lines wait to be used, beginning in the plantation’s third year.

During the first two years, the plantation is irrigated using a surface dripper system. After two years (or three according to tree development), the plantation moves over to irrigation using the buried system. If the variety of trees in the plantation has high water demands, such as pecans, which have a very large spread of roots and high water demands; two to four dripper lines are buried on each side of the row of trees in order to reach full wetting of the soil and to reach irrigation volumes sufficient to achieve optimum tree growth (Texas, USA). Dripper systems, including SDI systems, require a high standard of filtration, collection pipes, line flushing systems and vacuum valves. High standards of regular maintenance, good quality filtering and system monitoring will extend the system’s proper functioning and length of working life.

When laying very long lines in a plantation (500 to 700 meters), the grower must ensure that the minimum pressure reaches 3 bar at the beginning of the line and that line must be a 20mm pipe with one meter spacing between drippers, working at a flow rate of 1 to 1.1 l/h.

SDI drippers have many advantages:

• Optimal irrigation and fertilization into the root ball area.
• Less weed development in the plantation area.
• The irrigation equipment is protected against pests and climatic damage.

NaanDanJain offers a wide selection of Subsurface Drippers:

AmnonDrip PC & PC AS

TopDrip HD PC & PC AS

Fertilization with irrigation

Nut plantations are fertilized according to the type of soil, water quality, plantation age and according to the testing of the local soil. Usually, fertilization for a young plantation is based primarily on nitrogen fertilizer, which encourages the vegetative growth necessary for optimal establishment of the young trees. Later on, fertilizer composition changes to provide support for flower development, budding and pit filling.

It is well known that nut trees are sensitive to a lack of zinc, which is vital at the flowering stage and during pit filling. Normally, the recommendation is to apply nutrition bands or a foliar spray of zinc (pecans, cashew and macadamia).

Optimal irrigation and fertilization make significant contributions to crop yield and quality. Accelerated growth when the tree is young will mean that it will take less time to reach maturity and yield its first crop. Nitrogen fertilizer supports vegetative growth and a larger number of branches to carry the fruit in the coming years. Nitrogen also helps maintain trunk strength and strengthens the tree’s ability to deal with diseases and natural forces.

Irrigation solutions for Nurseries

Most nurseries adopt two principal working methods. For both those methods, NDJ offers the very best in irrigation equipment for young trees:

Grafting

A specific variety is grafted onto a suitable local rootstock: The grafted plant is moved into a climate controlled greenhouse in which high humidity is maintained for two to three weeks while the tissues in the graft and the rootstock fuse together.

To maintain the high humidity and low temperatures suitable for this stage, it is a good idea to install NDJ’S Supper Fogger  with a flow rate of 13 to 24 liters an hour, producing 50 to 70 micron droplets. This type of fogger can also be found as low pressure equipment.

After fusing, the grafted plants are moved to a shade house, where they can harden off (how

to irrigate grafted plants from the hardening stage is explained below).

Sowing

Nuts are sown directly into growing pots. Immediately after sowing, the pots must receive a heavy watering, followed by regulated volumes of water, adjusted to suit the plant’s rate and stage of growth.

Micro sprinklers are recommended for watering seeds and grafted plants during the hardening stage in a shade house. The small droplets produced by micro sprinklers do not harm buds and delicate plants and they do not damage soil texture. This system provides an even distribution of water covering all the growing pots and ensures uniform irrigation.

Using micro sprinklers, it is also easy to change application rates as the plants grow.

Moreover, micro sprinklers can be installed hanging upside down, which provides a number of additional, significant advantages:

convenient work setup; wide, comfortable growing areas unimpeded by pipes and equipment. Those advantages make it easier for the workers, for mechanization and when moving the plants around. At this early development stage, accurate irrigation and droplet size must be accurate in order to prevent damage to the delicate plants, while maintaining high humidity and low temperatures.

Therefore, the recommendation is to use micro sprinklers spaced out as appropriate for plant and building size.