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Nutrient Solutions |
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Solution Management |
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Laboratory Analysis Fertiliser Quality |
Optimising hydroponic crop nutrient uptake. Regular analyses of recirculating hydroponic solutions and adjustments of the stock solution recipes allows crop nutrient uptake to be optimised for both yield and product quality. Estimating crop nutrient uptake rates provides a better control than adjusting recipes according to set target concentrations in the solution. Adjusting Stock solution recipes according to analysis results Target method. The common method of adjustment following a recirculating solution analysis is to compare the nutrient concentrations in the recirculating solution with some set of standards, and then increase or decrease the amount of each nutrient in the stock solution recipe according to whether the concentration is above or below the target. The nutrient concentration shown in the analysis does not give a very good idea of how much change should be made in the recipe, this is a guessing game and even the most experienced users of this method find it takes several successive analysis with over and shoot in the adjustments before the proper balance is reached. This process is far from ideal for crops whose uptake demands change with growth and development or according to seasonal changes in the environment. Nutrient uptake method. Two successive analyses of the recirculating nutrient solution with proper records can be used to estimate a crops nutrient uptake rate. This method allows the crop to provide feedback on how much nutrient is being taken and allows a logical adjustment to the stock solution recipe to be made. The uptake rates can be compared with some past history of uptake rates and adjustments can be which recognise both current crop demands and expected future demands due to growth stage or environment. The uptake method is not only more logical than the target method but it also helps to avoid the overshoot undershoot approach to the central target. Some other advantages of nutrient uptake based solutions. The calculated uptake is feedback from the crop on what nutrients are actually be taken up and can provide valuable guidelines for crops where target values are not known. Target values for tomatoes for example are for ordinary round and beef tomatoes, they are not as reliable for acid free, Roma or cherry tomatoes. New Hydroponic Crops Calculating nutrient uptake rates is basically an accounting operation but with amounts of nutrients instead of amounts of money. Two solution analyses are like two bank statements, when nutrient concentrations multiplied by the solution volume equals the amount of each nutrient in the system at the times of the first and second solution analysis. Records of water use, A & B stock solution and acid or alkali added show how much of each nutrient has put into the system (how much has been paid into the bank) in the time between the two analyses. The difference between the amount of each nutrient in the first analysis plus the amount of all the additions and minus the amount at the final analysis must equal the withdrawls from the system. In a well run recirculating nutrient solution, the only withdrawls will be the uptake of nutrients by the crop. Leaky systems have uncontrolled withdrawls, but it is sometimes possible to estimate the volume of solution leaked and hence the loss of nutrients. Making Uptake Calculations
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