Plants need water and fertilizer to grow . In the hi - tech nursery industry , growers apply both at the same time . A fertilizer injection organization provides the plant food , and the drip irrigation system distribute the H2O equally to the flora . How severely can it be ? When Godfrey Dol , he is write the series below about irrigation , was a educatee studying chemistry , he was never interested in agriculture . You plant a seed , add urine , fertiliser , sunshine , and a little while later , you harvest . How hard can this be ? A lot grueling than he could have ever envisage .
OverwateringSo it is with irrigation , Godfrey continues . When I was about 18 , my sister always asked me to look after her firm plants when she went on vacation . She commented that the plants always look goodish after I looked after them . Little did she know that I would leave to irrigate them . By not water them , I inadvertently strengthened the root organisation , whereas my baby ' love for her plant made her water them almost every day .
My sister is not the only one overwatering plants . Most multitude who love plants finger like they want to do something for them . The obvious affair is to give them water . In our instinctive minds , we like solid food , and we want to spoil our plants by give them pot of what we would care ourselves . We give them water , more and more , not make that give too much water is uncollectible for plant . Farmers also like to be on the safe side — the first thing they do when works wilt is to trigger another irrigation .
In a glasshouse , wilt is usually not from a want of H2O , but from a poor origin system . How can we optimize the rootage system to have the plants execute optimally ? How can we keep them sizeable with minimal use of chemical ?
The theme of a plant are like the muscular tissue in a marathon runner . There are time when we need to stress them , and time that we need to bring up them — pick out what to do when is a far greater challenge than looking after my sisters ' house plant . What do we measure?To irrigate the right way , we need to have sex what information we can use to improve our strategy . The first affair we want to know is the EC and pH of the drip mold and drain . For Lycopersicon esculentum , the drip EC should be 3.0 . Since the plant use more water than fertilizer , the salt content in the growing sensitive must be about 1.5 times mellow than the drip EC , in this cause , 4.5 . A lower EC reduce the quality of the fruit ( softness and low-toned brix ) , while a eminent EC results in less ontogeny and small fruit . The pH is important because , at broken and high pH , some chemicals are not water - soluble and thus become unavailable to the works . The optimum chain in the growing medium is pH=5.5 - 6.0 . Due to ascendent bodily function , the pH in the growing mass medium can well rise above 6.0 . In that case , the dripping result can be align to as down as 5.0 . humbled is not advisable , especially when Rockwool is used as low pH can dissolve the fibers . valuate the drain percentage is also important , but not critical , as we will find out later .
So far , it is pretty straightforward . But how do we keep plant lovers from over - water their greenhouse harvest ? Or mass like me , underwatering my babe ' plants . get in the teetotal - down . The drydown is the remainder in the moisture content of the farm sensitive between the maximal and lower limit of a 24 - hr period . The height is usually attain mid - good afternoon , while the minimum is achieved just before the first irrigation in the morning . Using this information , we can produce some irrigation road map . How do we know when to originate and stop the irrigation , and how much urine do we give in aggregate .
How do we measure everything ?
The tools we needThere are some canonical tools that we demand to collect the veracious information . A ordered series or moisture message sensor is a very useful puppet . If they are not uncommitted , a manual drainage station such as project below is a must . Even if a ordered series or moisture sensor is available , a manual drain station is still commend . habituate at least one slab and collect all the days debilitate weewee in a bottle or bucket . A pH and EC meter are used to measure out EC and pH , while a measure flask can measure volume to 100 ml accuracy . Be sure also to value the bulk irrigate per dripper . It is a good assay to do it if the volume of irrigation water calculated by the climate computer is the same as the measured dripper volume . It also allows for the calculation of the drain percentage , by separate the drain loudness by the dripper volume .
Figure 1 ; Manual Drain Station
The key components we want to quantify are the % dry - down , the EC in the drain , and the timing of the first drain . These three variables separate us most of what we need to sleep together to make the right-hand irrigation scheme . The pct dry - down narrate us if we are steering the plant life into a vegetal or reproductive centering . The EC of the drainpipe indicates whether we give the right amount of pee . The timing of the first drain differentiate us if we have the maturate culture medium hydrated enough so the plant can transpire at a maximal rate .
Is the measure representative?In the glasshouse industry we increasingly make use of sensors . These sensors must be representative of the rest of the irrigation geographical zone . In the example of irrigation , one can question whether measuring one slab can comprise 10,000 other slabs .
Statistically speaking the answer is no . It ’s like picking a risque colour marble out of a travelling bag with 10,000 otherwise dyed marble , the chances are downcast . But if the irrigation geographical zone is planted with the same variety and the dispersion of temperature , humidness , lightness and CO2 is even , then it is like pee-pee all the other marbles light blue or dark blue and all of a sudden your luck of displume out a blue marble is far greater .
It is surprising how a little sample can still be representative of the greenhouse . But only if the above parameters are even . More measurements are always good and therefore I favour to back up a moisture sensing element or scale of measurement with a manual drain station . If the two evaluate scheme show a difference , the grower can execute manual EC measurements of the surrounding growing spiritualist to verify that the single points of measurement are valid representations of the irrigation zona .
It is also important to verify that the growing media contain a representative number of works . When the planting density is changed , it can happen that the metric slab does not have the right amount of plants .
Equally important is that any equipment that is used is defend to a proper criterion . It let in the EC and pH metre .
This miniskirt - serial of three parts about irrigation - strategy in semi - unopen glasshouses will extend with talk about how to manage the irrigation and what strategies to use for unlike stage of the crop .
While the irrigation scheme in a semi - unopen glasshouse does n’t differ from a established glasshouse , Godfrey hopes that this series clarifies in comparative elementary term what is important in determining the right irrigation strategy . The strategy described in this series was the strategy used by the Automatoes Team , who wonthe Autonomous Glasshouse Challengethis twelvemonth with the lowest water and fertiliser use .
For more entropy : Glasshouse Consultancywww.glasshouse-consultancy.com
Godfrey DolLinkedIn[email protected]+81 80 700 94 006
