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HomeFarmingPrecision irrigation boosts yield on Mpumalanga citrus farm

Precision irrigation boosts yield on Mpumalanga citrus farm


A double line of irrigation is put in in among the orchards. Right here, 0,7ℓ/h drippers are used to offer 2,3m3/ha/h of water. Photograph: Lindi Botha

“The times of beginning the pump in an orchard and assuming the timber will likely be watered are lengthy gone,” says Willem Kieviet, space supervisor of Indigo Fruit Farming on the outskirts of Mbombela, Mpumalanga.

As an alternative, he makes use of a meticulous technique wherein each resolution is backed up by information, and any water functions are checked and double-checked.

“You should take into consideration how a lot water you’re making use of and why. Ask your self what time of the day is greatest for irrigating and what the anticipated final result of the irrigation is, then measure whether or not it was achieved. Functions that depend on know-how have to be adopted up by folks, and vice versa.”

Indigo produces mandarins and seedless lemons, and has been utilizing drip irrigation since 1997. Kieviet prefers this technique to micro-irrigation, because it makes use of much less water.

“With micro-irrigation, there’s extra evaporation since you’re wetting a much bigger floor space. Additionally, the water penetration isn’t essentially as deep as with drip irrigation, so that you lose a portion of the water you apply. Drip irrigation is extra targeted on a particular space.”

Because the farms have largely sandy loam soil, drip irrigation offers an additional profit: the drippers present an appropriate circulate of water to prime up the moisture ranges with out run-off.

The irrigation system differs considerably from orchard to orchard, as new techniques have been launched on the farms since 1997. Whereas some orchards are planted to a single row of timber with double dripper strains, others have double rows of timber with double dripper strains.

The water circulate additionally varies, starting from 0,7ℓ/h to 2,3ℓ/h. The latter is used for single-row strains and offers water at a charge of 4,6m³/ha/h. The 0,7ℓ/h drippers are positioned in double rows and supply 2,3m³/ha/h of water.

Slowing the circulate
Kieviet says Indigo is transferring in the direction of reduced- circulate irrigation. The timber nonetheless obtain the identical quantity of water total, however their uptake is much better with decrease circulate over an extended interval.

Every block has a devoted important irrigation line in order that the system will be managed from the pumphouse, fairly than the orchard. There are additionally circulate and stress meters on every line to detect issues and precisely measure what’s being utilized.

All the system is automated, which permits Kieviet to view all of the irrigation functions at a look, with downside areas displaying up in several colors on his pc display.

Controlling the irrigation from the pumphouse on every farm simplifies administration, as valves don’t should be turned on and off within the orchards, which may very well be affected by human error.

The timber obtain between 3 500m³ and 4 500m³/ ha/yr of irrigation water. Citrus timber require about 6 500m³/ha/yr. Rainfall within the space is about 820mm yearly, which enhances the scheduled irrigation, however Kieviet factors out that not all rain offers efficient irrigation.

“For instance, it would rain softly for a while. Though this may depend in the direction of annual rainfall, it doesn’t actually add a lot water for the timber. Conversely, storms deliver quite a lot of water, however most of it flows away. We estimate that about 50% of the rain we obtain is definitely efficient irrigation.”

The automated irrigation is scheduled for early mornings earlier than it turns into too sizzling, as timber cease functioning and absorbing water when the temperature exceeds 35°C. The early-morning irrigation additionally provides the timber the water they want for photosynthesis and transpiration.

Water availability
Irrigation water is obtained via a canal system from the Primkop Dam. Kieviet says that the water high quality is nice, usually sustaining a pH of seven.

At sure instances of the yr, nevertheless, corresponding to in the direction of the tip of winter, there are extra micro-organisms within the water and it’s then essential to handle the filtration techniques to stop clogging of the pipes. Indigo makes use of spin clear filters for the water filtration.

Kiewiet and his group present a steady dose of hydrogen peroxide all-year spherical to maintain the drippers clear. Yearly, nevertheless, simply earlier than the fertigation programme begins, they apply a booster remedy of the compound. Regular dosing continues thereafter.

Indigo has a complete of 200 000m3 of water storage capability. Preserving the dams full has been a problem, nevertheless, particularly through the drought over the previous few years.

“As a result of our dams should not very huge, and there aren’t many within the space, it’s necessary to get a daily circulate of water into them. This implies managing the canal techniques correctly in order that we get the allotted quantity of water on time.”

Checking and double-checking
Indigo takes water utilization so severely that checks and balances are in place for each system on the farms to make sure that nothing is wasted. The timber are irrigated optimally on the time they want it most, and the system is managed meticulously to stop any system failures.

Initially of every season in July, Kieviet works out an irrigation plan primarily based on a set method.

“I have a look at the maturity of the timber, cover protection, and the assumed evapotranspiration each month of the yr. For the final of those, we use the 10-year common as offered by climate stations on the farms. We then add the crop issue to bear in mind the totally different necessities of the fruit at totally different instances of the yr. After this, we plan precisely how a lot water must be utilized in a yr. That is the theoretical determine we work in the direction of. As quickly as we begin implementing the irrigation schedule, we document how a lot was utilized, the place we stand when it comes to the requirement, and the place we’re forward or behind.”

A circulate meter fitted to each important irrigation line measures the precise water that the timber obtain and permits Kiewiet and his group to observe the water used per block.

“All the irrigation system is automated and set to observe the theoretical values versus the precise values, so it’s that a lot simpler to handle and measure,” he explains. “An alarm goes off on my pc if there are any giant discrepancies between theoretical and precise figures, so we are able to react rapidly if there are leaks or different issues.

“In the end, we goal to keep away from any extra or deficiencies. We use soil moisture probes to see how a lot water the tree extracts, and the way a lot must be given to make sure there’s no deficit.”

The human issue
Expertise is backed up by onsite commentary, with one employee assigned to every 10ha block. It’s these workers’ accountability to stroll via the orchards each day to examine for any issues.

Soil observations are carried out as soon as per week and in contrast with the info on the pc system’s graphs. Samples are taken at totally different depths after which scored from one to 5, in line with the extent of moisture within the soil. Kieviet goals for a rating of three to 4, with 5 being very moist and one being very dry.

“If I see a correlation between this bodily evaluation and that of the probes, I can assume all the pieces is working because it ought to with the irrigation. The following step is to stroll via the orchard to see whether or not the situation of the timber correlates with all the pieces else.

“For instance, the method we have now for irrigation, as decided originally of the season, might prescribe that we want 17 hours of irrigation to get the specified development. However after we add the outcomes from the soil moisture probes, it might present that there’s [plenty of] moisture within the soil already. We then replace the irrigation cycle accordingly to stop the timber from being overwatered.”

Kieviet additionally pays consideration to {the electrical} conductivity (EC), taking each day measurements within the orchards to confirm the figures offered by measurements within the pumphouse.

“We have now a container beneath a dripper within the orchard and measure how a lot water has been utilized by that dripper, and the EC and pH of the water. We wish an EC of between 1,6 and a pair of. So we have now the theoretical info from the pumps, and what’s truly being utilized.”

The stress offered by the system is a crucial think about making certain a good circulate of water all through the orchards. At the least one bar of stress is required within the dripper strains, and water ought to attain all of the pipes inside 5 minutes of the irrigation beginning. If it takes any longer, the farthest finish of the road will at all times obtain much less water, because the water takes longest to succeed in that space, and the water circulate there will even cease first when the system is turned off.

Stress within the orchards is measured utilizing a hand-held meter, and there may be additionally a meter within the pumphouse. Once more, what’s proven within the pumphouse is verified within the orchards.

The gradient of the orchards can be an element that have to be thought-about when designing an irrigation system. Kieviet stresses that the design is the start line of an efficient
system; it should be certain that the proper floor space will be irrigated with out fluctuations in water provide.

“Dripper strains should not be over 200m in size, in any other case you wrestle to get sufficient water circulate via all the pipe.”

Key irrigation intervals
Kieviet pays particular consideration to sure intervals all year long to make sure that every tree performs optimally.

“The interval between harvest completion and fruit set for the subsequent season happens at
a essential time, and the irrigation have to be managed rigorously throughout this era.

“The humidity is low at the moment of the yr and the summer time rain has but to reach. So we have to irrigate in line with the phenological wants of the timber; this may guarantee good flowering and fruit set.

“The following interval that’s necessary to handle is February to March, when inside fruit high quality must be prioritised and water is then lowered.

“An excessive amount of water originally of the yr can cut back the Brix figures [the levels of sugars and other compounds in fruit].

“Throughout [harvesting], it’s necessary to proceed irrigating in order that the fruit doesn’t get too comfortable.

“However you may’t have too little water both, or the fruit will develop rind breakdown because of the lack of moisture. Might is flower- initiation time, and the tree must have sufficient water to see this course of via.”

It’s essential at these levels to observe the probes and evaluate the deliberate irrigation in opposition to what the timber are receiving and absorbing.

“After we have a look at the soil moisture content material on a graph, we need to see ups and downs; there should be wetter instances and drier instances. That is in order that the soil and roots have time to aerate and take up oxygen.”

Whereas utilizing the least quantity of water to acquire yield, the administration of Indigo is observing the water it takes to provide a kilogram of fruit and hoping to make modifications in future.

“We’ve seen that because the cultivars differ in yield from yr to yr, whereas the quantity of irrigation would stay the identical, we’re successfully utilizing extra water to provide a smaller yield within the off yr. We’ve began measuring the quantity of water used yearly per kilogram of fruit obtained, so we are able to [ultimately] remove huge variations within the litres of water used to provide a kilogram of fruit. We need to acquire a set yield, with a set high quality, utilizing a set quantity of water. With water sources more and more beneath stress, we have to guarantee our long-term sustainability. And meaning watching each drop and managing it appropriately.”

Electronic mail Charlene Nieuwoudt at [email protected].



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