Reports show both the measured weight and the calculated water content of the substrate.

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1 With Priva Root Optimizer the plants get water when they need it After photosynthesis, crop transpiration is the most important plant process influencing production and quality. Priva Root Optimizer determines when to irrigate according to an transpiration calculation in combination with measurement of substrate weight and drain quantity. With these indicators, irrigation can be very precise. The system takes into account all external influences, such as extra evaporation by sun and wind, but also a sudden change of the weight because of plant handling. With an irrigation system that calculates the irrigation based on evaporation the plants always get the right amount of water. Generally it is assumed that evaporation would occur at a rate of 3 cc for each joule, but in practice, the rate is continuously changing. With the Root Optimizer the irrigation strategy is automatically adjusted based on the environmental conditions. It does not matter if the light intensity suddenly changes, or if the evaporation increases due to outside wind or due to increased heating pipe temperatures. During day time the desired drain is realised very precisely. In other systems the measured drain from the previous irrigation cycle is used to influence the time for the next start. With the Root Optimizer the desired drain is deciding the start frequency. The desired uptake is the amount of the water given minus the desired drain, when the plants have consumed the desired uptake, the next irrigation cycle is started. This will automatically give the right amount of drain after each irrigation cycle. The drain percentage can therefore be kept lower than with traditional methods, resulting in the greenhouse using less water and fertilizer. During night time it is common practise to slowly dry the substrate to desired minimum moisture content. The Root Optimizer program continually measures and monitors this process. Resulting in an additional irrigation start being given if the substrate dries out too quickly. The Priva Root Optimizer controls irrigation based on the actual water demand of the plants. This gives a very precise irrigation with the following advantages: Higher production because the plants always get enough water and at the right time. Savings in consumption of water and fertilizers because drain can be kept to a minimum. More stable EC in the substrate because nutrients are not washed out caused by too frequent irrigation starts. Optimal root growth by having the right water content in the substrate. Root problems are history. The system doesn t require extra interaction. On the contrary, it will adjust on its own. You only need to set up the system once and then you just let it do its job.

2 What do you need? The Root Optimizer is an advanced software module in the Priva Intégro process computer. The software uses the measurement of substrate weight and measurement of the drain quantity. The weight is measured with a Priva Groscale and the drain quantity with a Priva Drain Sensor. Priva Groscale The Priva Groscale system consists of either two or four weighing platforms or a weighing indicator. The weight of the water in the substrate slabs, which are placed in a stainless steel collection tray, is measured with the weighing platforms. The signals from the weighing platforms will be passed to the process computer after being combined and amplified by the weighing indicator. Reports show both the measured weight and the calculated water content of the substrate. Picture 1: Priva Groscale Priva Drain Sensor The drain water from the stainless steel tray is collected and measured with the Priva Drain Sensor. The measured drain quantity is recalculated to a drain in litres per m 2 based on the area the tray is representing. The irrigated water quantity during the last irrigation, which is measured with a flow sensor, is also recalculated to litres per m 2 based on the area covered by the irrigation valve. With this information the drain percentage can be calculated. In reports you can see the total accumulated drain quantity and drain percentage during today and the drain after the latest irrigation cycle. Picture 2: Priva Drain Sensor

3 Software configuration The measurements from the Groscale and the Drain sensor are collected and analyzed by a moisture measurement program. The program is internally linked to the irrigation valve that supplies water to the collection tray. An irrigation start program is linked to the moisture measurement program. This will activate all the Root Optimizer settings in the start program. Only one start program can be linked to a moisture program. The start program is linked to one or several valve groups, which in their turn are linked to irrigation valves. The start program is also linked to a climate compartment in order to get information about radiation and heating energy. From program version 726 the start program can also be linked to an inside radiation measurement. Groscale Drain sensor Root Optimizer Group Valves Valve Moisture Start Climate Table 1: Software configuration DESCRIPTION Software configuration Valve to moisture program Start program to moisture program Start program to valve group Start program to climate compartment Valves to valve group 1. Screen on dealer level SCREEN I I400.4R2 I400.4R1 I400.4R3 I401.4 For an accurate weight measurement both inputs for the Groscale should be used (I ).

4 How to activate the Root Optimizer program The Root Optimizer program is called Dry-out start. In the Installation screen of the start program (I400.1) the Dry-out start has to be set on YES in all the periods in which the Root Optimizer should be active. In the Strategy screen (I400) new lines with settings will appear (see explanation later). It is also important to set the Transpiration sum setting on MONITOR (see explanation later). Dry-out or Drain Desired drain% Dry-out start YES increase drain% Transpirationn sum MONITOR Quantity increase drain% Dry-out limit How does it work? The Root Optimizer program determines when the next irrigation start should take place based on the water irrigated and the desired drain and the water uptake. Water irrigated The water irrigated is the amount of water in litres per m 2 given during one irrigation cycle. For each irrigation valve the nr of units (drippers) and area are set in the program. The irrigation quantity (ml) is set per unit (dripper). With this information the water irrigated in litres per m 2 can be calculated. With a flow sensor on the water supply the total irrigation quantity for the valve that is linked to the moisture program is measured. Based on the valve area the measured water irrigated in litres per m 2 is calculated. The measured water irrigated is normally equal to the calculated water irrigated. All the calculations are based on the measured water irrigated in litres per m 2. It is therefore importantt that all the valves that are started by the start program have the same irrigation quantity settings. For this purpose the valve group settings for time and quantity (I401) must be activated.

5 Example 1: Calculated and measured water irrigated DESCRIPTION Settings Nr of units per valve Area per valve Quantity per unit (dripper) Use group quantity and time Calculations Area per unit (dripper) SCREEN I411.1 I411.1 I401R3 I401R8 3150/5040 VALUE Yes 0,625 UNIT drippers m 2 ml/dripper m 2 Water irrigated per m 2 0,150/0,625 0,240 l/m 2 Measured water irrigated M400R16 0,240 l/m 2 Desired drain For each period in the start program the desired drain percentage can be set. The desired drain percentage can be increased based on the measured radiation. The influence is modulating between the start and end radiation values. If the actual accumulated drain quantity is lower than the desired drain quantity it is possible to increase the desired drain with a fixed percentage (Quantity increase drain). Actual Desired drain% Quantity increase drain% Desired drain% increase drain% Actual total drain quantity Desired total drain quantity start end

6 Example 2: Desired drain and radiation influence desired drain DESCRIPTION SCREEN VALUE UNIT Settings Desired drain I400R23 25 % increase drain I400R24 10 % Range radiation start I400.2R4 300 W/m 2 Range radiation end I400.2R4 600 W/m 2 Calculations Actual radiation increase drain 5 % Total desired drain % M4R6 450 W/m 2 Desired drain M400R12 30 % The desired drain percentage is set to 25%. The drain should be increased with 10% when the radiation level increases from 300 to 600 W/m 2. If the measured radiation is 450 W/m 2 the radiation influence will be 5%. The total desired drain will then be 30%. If both the start and end values for radiation influence drain (I400.2) are set on zero the setting for the radiation increase drain will disappear from the Strategy screen (I400). Do not forget to set the radiation increase to zero before resetting the radiation vales. Example 3: Quantity increase drain DESCRIPTION SCREEN VALUE UNIT Settings Quantity increase drain I400R25 5 % Calculations Quantity increase drain 0,840<1,504 5 % Desired drain M403 1,504 l/m 2 Actual drain M403 0,840 l/m 2 Quantity increase drain M400R12 5 % The total desired drain quantity in litres per m 2 so far today is calculated based on the water irrigated and desired drain (M403). With the drain sensor the total actual drain quantity is measured (M403). If the actual drain quantity is lower than the desired drain quantity the desired drain percentage will be increased with 5% (Quantity increase drain).

7 By increasing the desired drain percentage the remaining quantity available for the plants will decrease. This means the start will be performed earlier and the drain quantity will increase. This quantity increase will continue until the actual total drain quantity is equal to or higher than the desired drain quantity. Calculated dry-out limit (drain) From the measured water irrigated the total desired drain quantity is deducted. The remaining water quantity available for the water uptake of the plants is called the Dry-out limit. When the drywill automatically out of the substrate equals this quantity the next irrigation cycle is started. This give the right amount of drain after each irrigation cycle. Dry-out limit Water gift Desired drain quantity Actual Desired drain% Quantity increase drain% Desired drain% increase drain% Actual total drain quantity Desired total drain quantity start end Example 4: Calculated drain quantity and dry-out limit DESCRIPTION Calculations Total desired drain Measured water irrigated Desired drain quantity Dry-out limit Desired drain Quantity increase drain Dry-out limit Measured water irrigated Desired drain SCREEN 30+5 M400R16 35% of 0,240 0,240-0,084 M400R12 M400R12 M400R13 M400R16 M400R17 VALUE 35 0,240 0,084 0, ,156 0,240 0,084 UNIT % l/m 2 l/m 2 l/m 2 % % l/m 2 l/m 2 l/m 2 The measured water dose from the last irrigation cycle is 0,240 l/m 2. The total desired drain percentage is 35% (25% desired drain + 5% radiation increase + 5% quantity increase). The desired drain quantity will then be 35% of 0,240 l/m 2, which equals 0,084 l/m 2 drain.

8 The dry-out limit (the remaining quantity available for the plants) will then be 0,156 l/m 2. When the substrate has dried out with 0,156 l/m 2 the next irrigation cycle will be started. The water irrigated will be the same as before 0,2400 l/m 2. The substrate will then first be filled up (saturated) with 0,156 l/m 2 and the remaining quantity 0,084 l/m 2 will give the desired drain of 35%. Set dry-out limit (no drain) In day time you want to keep a high water content in the substrate and you want to have a certain amount of drain. During the night time no drain is wanted and the water content should decrease in a controlled manner. The dry-out is describing the water uptake of the plants. It is the opposite of the water content. In periods when drain is desired the dry-out limit is calculated automatically based on the water irrigated and the desired drain percentage, as described before. In periods when no drain is desired (night period) the desired drain percentage should be set to zero. The dry-out limit then becomes a setting for how much the substrate is allowed to dry out in that period. This is indicated by the Drain or dry-out status field in the Strategy screen (I400). In periods with desired drain the status will be DRAIN and in periods with no drain the status will be DRY-OUT. Calculated Dry-out limit Set Dry-out limit

9 Example 5: Desired dry-out in period with no drain DESCRIPTION SCREEN VALUE UNIT Settings Nr of units slab weigher I drippers Nr of units per valve I drippers Area per valve I m 2 Drain or dry-out I400R23 DRY-OUT Desired drain% I400R23 0 % Dry-out limit I400R27 0,800 l/m 2 Calculations Area per unit (dripper) 3150/5040 0,625 m 2 Area slab weigher 8x0,625 5,0 m 2 Desired weight loss 4,0 kg (litres) Desired dry-out 4,0/5,0 0,800 l/m 2 The measuring area of the slab weigher (Groscale) is calculated based on the number of drippers in the collection tray, the total number of drippers and the area covered by the valve. If the desired weight loss during the night period is 4,0 kg the desired dry-out can be calculated (0,800 l/m 2 ). This value should be set as the wanted dry-out limit for that period. Modulating or switching dry-out limit change The attribute set next to the Dry-out limit setting is used to select whether the strategy between two periods changes over to this value as modulating or switching. The sign means that the dry-out limit will be activated immediately with no delay (switching function). The sign / indicates that the dry-out limit is reached at the end of the period (modulating function).

10 Measured dry-out When the measured dry-out has reached the calculated dry-out limit the next irrigation cycle is started. Consequently the actual dry-out has to be measured. During irrigation cycle the measured weight of the substrate increases. At the end of the irrigation cycle drain is measured by the drain sensor. After finished irrigation cycle drain is still measured and the weight of the substrate decreases due to the after drain. Finally the drain sensor detects that drain has almost stopped. From that point the measured weight loss is equal to the water uptake of the plants. By measuring the change in weight the actual dry-out can be calculated. During irrigation and during drain it is not possible to measure the dry-out by weight. Instead a transpiration model is used to calculate the dry-out in this period. The measured dry-out (water uptake) is therefore a combination of a really measured water uptake based on weight measurement and a calculated water uptake based on a transpiration model.

11 Measured dry-out based on weight measurement In the time period between the last drain and the next irrigation start and during the night period the measured dry-out is based on weight measurement. Example 6: Measured dry-out based on weight measurement DESCRIPTION SCREEN VALUE UNIT Settings Nr of units slab weigher I drippers Nr of units per valve I drippers Area per valve I m 2 Calculations Area per unit (dripper) 3150/5040 0,625 m 2 Area slab weigher 8x0,625 5,0 m 2 Weight loss Time ,75-27,50 0,25 kg (litres) Measured dry-out 0,25/5,0 0,05 l/m 2 Substrate weight Time 1 M405 27,750 kg Substrate weight Time 2 M405 27,500 kg The measuring area of the slab weigher (Groscale) is calculated based on the number of drippers in the collection tray, the total number of drippers and the area covered by the valve. By measuring the weight loss over time the dry-out quantity in litres per m 2 can be calculated. It is important that the number of units (drippers) for the valve and slab weigher and the valve area is correctly filled in. Measured dry-out based on transpiration model During irrigation and during drain the measured dry-out is calculated based on the transpiration model. The transpiration model calculates, on the basis of the measured or calculated radiation in the greenhouse and the heat discharge of the heating network, the quantity of water which the plants should transpire. above the crop is accumulated over time (in J/cm 2 ). Outside radiation is corrected with the translucency of the roof and the radiation limitation of the curtains (M100). from assimilation light is included in the calculation (M100). Energy coming from the heating pipes is accumulated over time (in J/cm 2 ). This is the sum of the capacities of all pipes of the compartment and the capacity of any autonomous heating pipes (M104), scaled according to area. The quantity of transpiration by the plant also depends on the surface area of the leaf. The more leaf there is the more transpiration. The plant size factor (I400.1) is used when calculating the measured transpiration sum. In a mature plant canopy where the entire roof area is covered with leafs the factor is 100%. In a younger plant canopy the factor is lower.

12 Transpiration sum Plant size factor Transpiration sum radiation Transpiration sum heating factor Heating factor Measured radiation Calculated radiation Energy usage heating pipes limitation curtain Assimilation light Translucency roof Outside radiation To get a correct transpiration calculation it is important that the start program is linked to the correct climate compartment (I400.4). is often confused with light. Many computers are equipped with a light meter (a lux meter). This is simply because light meters are cheap. Solar contains light and also long-wave radiation (heat). Light drives the photosynthesis, which makes plants grow. Transpiration and temperature are mainly driven by the long-wave radiation. Irrigation control should be based on a measurement of solar radiation that includes both light and long-wave radiation (solarimeter). Using a light meter leads to inaccurate irrigation control.

13 Table 2: Settings and measurements for the transpiration model DESCRIPTION SCREEN UNIT Settings Compartment area I m 2 Area with heating area I m 2 Area with curtain I m 2 Area with assimilation light I m 2 Translucency roof I101R1 % limitation curtain I168.1R3 % factor I400.5R4 % Heating factor I400.5R3 % Plant size factor I400.1R19 % Transpiration sum radiation M400R14 l/m 2 Transpiration sum heating M400R15 l/m 2 Transpiration sum total M400R19 l/m 2 1. Screen on dealer level Adjustment of the transpiration model The transpiration model also calculates the accumulated transpiration sum over the day in litres per m 2. The moisture measurement program measures the accumulated water irrigated and drain quantity in litres per m 2 over the day. The difference is the total water uptake of the plants. By comparing the calculated transpiration sum with the measured water uptake over one day it is possible to judge the accuracy of the transpiration model. The values should not differ too much from each other. Example 7: Calculated and measured water uptake DESCRIPTION SCREEN VALUE UNIT Transpiration sum yesterday M ,325 l/m 2 Water uptake yesterday M ,895 l/m 2 In this example the measured water uptake is higher than the calculated. By increasing the Plant size factor (I400.1) the transpiration model can be adjusted and the calculated transpiration will increase.