Irrigation management in cocopeat.pdf

Irrigation management in cocopeat Important Definitions for this Presentation 1)STEERING the crop= Growers technique / tools to control crop production and growth in a desired direction 2)VEGETATIVE growth= Crop growth with thick stems, upright flowers truss, strong growth, poor fruit se...

Irrigation management in cocopeat Important Definitions for this Presentation 1)STEERING the crop= Growers technique / tools to control crop production and growth in a desired direction 2)VEGETATIVE growth= Crop growth with thick stems, upright flowers truss, strong growth, poor fruit set as all crops energy going into leaf growth 3)GENERATIVE growth= Thin stems, flower truss at 90 degrees to stem, long thin leaves, high fruit set, small fruit size and slow speed of plant growth 4)BALANCED crop= Plant growth is strong while fruit growth and size is also performing well 1 2  Irrigation Management Cocopeat Vegetative Crop 3  Irrigation Management Cocopeat Generative Crop 4  Irrigation Management Cocopeat What is the purpose Irrigation ? 1) Water for growth of the plant / crop 2) Water for Transpiration to cool the plant 3) Water to allow excess salts to be drained from the root zone Simple Formula for Greenhouse Crop Irrigation Requirements 100 joules light = 300 mls Irrigation per m 2 Approximate requirements broken into -100 mls for plant growth -100 mls for Transpiration -100 mls for Drain runoff / EC regulation 5  Irrigation Management Cocopeat Irrigate Tomatoes effectively irrigation application should be LINKED to accumulated light levels Irrigation based on TIME alone will not accurately meet the crops demands for irrigation Exception is on low light / cloudy days where accumulated light will not trigger sufficient irrigation for EC control of the growing slab hence override timed irrigation applications should be applied 6 7  Irrigation Management Cocopeat Volume of Irrigation to apply per DRIPPER or per SQUARE METRE is critical -Cocopeat growbags have a threshold of water infiltration which if exceed does not allow irrigation to pass through the slab rather it moves around the sides of the bag -This is referred to as FALSE DRAIN 8  Irrigation Management Cocopeat False Drain does not allow for the regulation of EC in the slab and hence crops can be pushed into a highly GENERATIVE mode which may decrease crop yields CRITICAL THAT IRRIGATION DOES NOT SUPPLY MORE THAN 300-450 mls per square metre per application to avoid FALSE DRAIN occurring This is equivalent to 2 L / hr drippers @ 3 per square metre applying no more than 2-3 minutes of irrigation at any one time 9  Irrigation Management Cocopeat Shorter more frequent irrigations are much better than longer intervals of larger volumes Irrigation VOLUME should be FIXED through the day and irrigation TIMINGS should be changed to suit light levels. 10 11  Irrigation Management Cocopeat - Irrigation period through the day is critical to be able to STEER crop in the desired direction and to keep fruit production in balance Ideal COCOPEAT volume to allow STEERING of the crop is approximately 8 -10 Litres Cocopeat per square metre of greenhouse Ideal GROWBAG size for modern greenhouses - 1 metre long x 15 cm wide x 10 cm high Less than 8 L is insufficient in periods of hot weather hence crop will STEER to GENERATIVE actions Greater than 10 L is too much available water volume and crop will STEER towards VEGETATIVE actions 12  Irrigation Management Cocopeat To allow for maximal crop production Cocopeat requires drying during the night period to allow the oxygenation of the root zone. Drying of the root zone also has the effective of producing plant hormones in the crop to STEER the growth in the growers desired direction. COCOPEAT Drying 8-10 % at night STEERS GENERATIVE Drying Less than 6 % at night STEERS VEGATIVELY Knowing the moisture content of the growbag is critical to STEER the crop and knowing when to start and stop irrigation each day. Moisture Content can measured Automatically or Manually using either 1)Scales to measure the weight of the water changes in the growbag 2)Electronic meters to measure water content directly 13 14  Irrigation Management Cocopeat Irrigation start time should be approximately 1-2 hours after sunrise to allow the crop to WAKEUP and start to absorb water from the growbag Measuring water content allows the grower to see when the crop is ACTIVE and the first irrigation should be applied If irrigation is applied to early excessive ROOT PRESSURE may force water into the fruit and SPLIT fruit may result The LAST irrigation of the DAY should be timed to allow sufficient drying time of the COCOPEAT overnight. This last irrigation may occur 2-3 hours before SUNSET to give the active crop time to reduce the Water Content in the growbag. 15 16  Irrigation Management Cocopeat DRAIN (Runoff) is essential in Hydroponic media to regulate the EC of the growbag. EC has the effect of OSMOTIC PRESSURE on the plant and determines the volume of water the plant can absorb. HIGH EC reduces water uptake and is a GENERATIVE action LOW EC increases water uptake and is a VEGETATIVE action In general COCOPEAT requires approximate 30-40 % DRAIN each day to keep the root zone at a set EC level by the grower 17  Irrigation Management Cocopeat IMPORTANT that is an AVERAGE figure for the day and must be varied at different times of the day to keep the EC of the root zone constant Maximum DRAIN should occur at the peak of light through the day as this is when the plant is absorbing large volumes of water and reduce nutrient uptake occurs. This is the critical time than DRAIN must be around 50 % to keep the EC in balance in the growbag The first 1 or 2 irrigations at the start of the day should not cause DRAIN as the growbag will have dried down at night 18 19 20  Irrigation Management Cocopeat To keep the rootzone at the IDEAL EC level for desired STEERING of growth the EC must be monitored regularly The DRAIN EC is critical to be known so effective irrigation cycles can be scheduled. If the DRAIN EC is HIGH more frequent irrigations should be given to slowly bring it back into range If the DRAIN EC is LOW less irrigations should be given to bring it back into range THE APPLICATION OF LOW EC or WATER ALONE through the irrigation should never be given to reduce the EC and this will cause the plant to take up large volume of water and fruit quality will be greatly reduced with symptoms of SOFT fruit. If the EC in the DRAIN needs to be altered more than 0.5 dsm it should be gradually done over a period 1-2 days so the plant is not shocked by the changes in the root zone. 21  Irrigation Management Cocopeat The greenhouse computer should be used to automatically adjust the EC of the irrigation based on light intensity as this helps keep the ROOTZONE of the growbag at a constant EC level- However the difference between HIGH light and LOW light EC setpoints should not be more than 0.5 dsm as a change through the day greater than this will cause unstable root zone and loss of yield and quality During intense summer periods where night temperatures do not drop below 25 degrees night applications of Irrigation may be require to stop the slab drying down to far and causing the EC to rise. In summer growbags starting off below desired WC can be hard to bring to saturation when heat / light levels are high. Checking WC graphs during hot night periods is critical to ensure growbags do not dry down too far. 22 23 Cocopeat Nutrition Management -For Tomatoes it is NOT necessary to have growbags pre buffer treated provide a reputable company with good quality cocopeat is being sourced -Complete nutrient solution at Hydration is acceptable to buffer the bags -Trace elements should be in CHELATE form i.e. EDTA where possible top ensure full availability in the root zone -This is particularly important for COPPER which is degraded when Copper Sulfate in used both in the Nutrient Tanks and in the Growing Media -Nutrient Tanks should be kept at a pH level of less than 5.5 to ensure full nutrient availability when used. -If runoff water coming from the growbags is greater than 5.8 pH units then Iron DPTA should be used in preference to Iron EDTA -If pH is fluctuating then a combination of the two Iron Chelate forms should be used -If EC raised NEVER flush with WATER as this will decrease crop yield. Use greater irrigation frequency to lower the EC of the rootzone 24