Modern day macadamia irrigation and ridging

Drip irrigation

At the recent Ambermacs expo in White River producers came together to hear what experts had to say about research and technology in the industry. Michael Esmeraldo from Netafim South Africa was there to speak about irrigation in the orchards.

The topic of the day was modern day macadamia irrigation and ridging. According to Esmeraldo modern day farming is not always about new technology, high-tech machines and computers. The modern approach is also to be more efficient with the resources that is available to the producers.

“It is important that the entire irrigation industry, whether at producer, designer and supplier level, does its part to ensure that innovation breeds innovation to take the industry forward,” he said. “If we do not continue to find new ways to apply water and develop new technology that increases water use efficiencies, producers will not be able to keep up with the demand for food with the limited resources at their disposal. Irrigation innovation has come a long way and we have incredible irrigation technology and concepts to show for it. Let us never stop innovating in our pursuit of higher efficiency. “The agricultural industry has a definite responsibility to handle the water it has access to with care through more efficient irrigation. Agriculture is challenged to produce more with less - to feed the rapidly growing population with limited resources whilst protecting the environment for future generations. Efficient irrigation is not only about using water responsibly, but also about the vital task of ensuring food security and sustainability across the globe. Water use efficiency must always be the main focus of any irrigation system. To ensure optimal water use efMichael Esmeraldo, agro nomist ficiency, the choice of irrigation system is exand sales mana ger for Netafim tremely important with consideration to the South in the northern region. crop, conditions and circumstances.”

Micro-sprinkler irrigation

Although research and experience suggest that macadamia trees use water quite sparingly when compared to other tree crops, optimal irrigation remains crucial to efficient macadamia nut production. Irrigation of macadamia trees is particularly important during flowering, from the time of nut set, during nut filling and the vegetative growth period in mid-summer.

Efficient water use is about preventing water loss on the one hand and ensuring optimal water intake by the roots on the other. Water loss can occur through evaporation, deep percolation, subsurface outflow, run-off and transpiration.

The latter is the only positive water loss as water moves through the plant. The aim is, therefore, to maximise tree transpiration while minimising soil evaporation and water use by vegetation between tree rows. The main concern is evaporation and deep percolation. Limiting these two culprits is key, as they can then ensure highly efficient water use.

Various irrigation strategies exist and different methods of irrigation can be implemented. Prevailing climatic conditions in combination with factors such as soil depth and fertility, availability of water for irrigation and more will influence the irrigation strategy. Esmeraldo says that a tree does not know how it receives water. It only has a certain water requirement depending on the season, climate and crop stage.

Some of the main questions that needs to be asked is: • For how long should a producer irrigate to ensure that he

TO PAGE 14

Irrigation on ridges in the macadamia orchard.

Modern day macadamia irrigation and ridging

FROM PAGE 13

starts with a wet soil profile? • How should irrigation take place in the initial crop stages while roots are shallow? • How should irrigation take place in later stages when the root zone is well-established?

Drip irrigation So what is the advantages of drip irrigation? Drip irrigation is the most effective method with up to 30% of water saving. The water and fertilizer can be applied directly into the root zone, it is easy to work with and out of the way. Less labour is involved and less maintenance, which means more savings in the long run.

Some of the disadvantages includes the fact that the water cannot be seen while irrigation is on. According to Esmeraldo there are maintenance and management involved and some of the management is not yet well understood by everyone.

He continued by saying that most of the new drip developments in the last 5 years have been continuous low flow drip irrigation designs. These systems are designed to have three lines of 0,7 l/h to 1 l/h emitters every one meter apart to get to an application rate of 2,6 to 3,5 m3/ha/h. He suggested that producers start with one line and then add a second one from about 12 months onward and a third line when the tree is mature and in full production.

Micro-sprinkler irrigation When looking at the advantages of micro-sprinkler irrigation, it has a bigger wetted area, and less technical input is needed when it comes to scheduling and fertilizer. The producer can easily identify problems because irrigation is visible. Organic material decomposes quicker when using micro irrigation.

Disadvantages include that it promotes weed growth and the wind has a big impact on the water distribution. It is high on the maintenance side, which in return means that the labour cost involved is also high. Insects is prone to blocking the nozzles. This means that micro irrigation is more expensive in the long run.

According to Esmeraldo most of the micro design are between 30 to 50 l/h when there is one micro per tree. Most of the time the sprinkler will be placed between two trees if the spacing is between 8 m to 4 m the sprinkler will then be 2 m from the tree trunk. He suggested that the producer start with deflector/cone or concave spreader on the micro to keep the water close to the tree and not waste any water.

When using micro-sprinkler irrigation, the producer should

have two to three events per week depending on the water holding capacity of the soil and the system design. This system will be designed to apply about 4 mm/day in peak season. The trend with micro irrigation is also to go with lower flow and some of the new developments are 20 to 30 l/h.

Ridges Esmeraldo says it seems that most of the new macadamia developments are ridged regardless of the soils’ physical and chemical properties. Netafim did some research with Dr Phillip Myburgh from ARC to see if ridges really have such a big impact on root growth and tree health in general. The conclusion is that trees on ridges seem as if they are doing better and developing quicker than the trees on flat soil.

According to him the advantages of ridges include better drainage and more control of water and fertilizer. It also makes for warmer root zones and no compaction, quicker root development and less sub soil trouble.

Looking at some of the disadvantages, there is an initial financial investment and it takes time. In some cases it can be difficult to harvest because of the height and it can cause some management difficulties.

When asked which type of irrigation he would recommend, Esmeraldo said: “There is no one-size-fits-all solution in irrigation or perfect system. That is why proper planning is so crucial. You have to consider all of the advantages and disadvantages of a system and make a decision based on the circumstances of the farm, given all the variables. The final decision regarding the type of irrigation system will be determined by your experience and knowledge and prioritised irrigation goals.

“Various irrigation strategies exist and different methods of irrigation can be implemented. Prevailing climatic conditions in combination with factors such as soil depth and fertility, availability of water for irrigation and more, will influence the irrigation strategy. When we want to manage water optimally in orchards, it is important that we understand water balance in an orchard, soil-water interaction and factors that impact it.”

He concluded by saying that there is no silver bullet in any agricultural industry. It is about doing the necessary research and planning to find a solution for specific circumstances and continuously adapting to more efficient farming practices. The producer has to make smart decisions now to benefit later; farming is not a short-term activity.

“The industry must shift towards using fewer inputs more efficiently to grow more. If you take on the challenge with the right experts at your side, you can eliminate many inefficiencies and gain better control of your entire production system to finally grow your profit margin.”

reach for the top

Contains 2 active ingredients with contact and systemic properties for long lasting control of a wide range of diseases Better nut set and quality ensures optimal yields Both active ingredients are transported upward in the xylem to also protect new growth