SOILESS CULTURE OF HORTICULTURE CROPS LABORATORY REPORT
Nutrient Solution Preparation
Arghya Narendra Dianastya
FACULTY OF AGRICULTURE DEPARTEMENT OF AGRONOMY KASETSART UNIVERSITY
I. INTRODUCTION
The word "hydroponics" was coined many years ago to describe plant culture in inert soils where nutrients and water are supplied from storage tanks, saved, and recirculated as needed. The start of the "classical system" is attributed to W. C. Gericke in the 1930's, although the idea of using solution culture and gravel preceded Geri cke by many years. Hydroponic also means nutrient solution culture with no supporting medium. Current hydroponics systems of cultivation can be classified according to the techniques employed. A hydroponic technique refers to the method of applying nutrient solution to the plant roots. In hydroponic or in soil culture, plants require 16 elements for growth and these nutrients can be supplied from air, water, and fertilizers. The 16 elements are carbon (C), hydrogen (H), oxygen (O), phosphorus (P), potassium (K), nitrogen (N), sulfur (S), calcium (Ca), iron (Fe), magnesium (Mg), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), and chlorine (Cl). The key to successful management of a fertilizer program is to ensure adequate concentrations of all nutrients throughout the life l ife cycle c ycle of the crop. Inadequate or excessive amounts of any nutrient result in poor crop performance. Excessive amounts can be especially troublesome since they can damage the crop, waste money and fertilizer resources, and pollute the environment when fertilizer is released during flushing of the nutrient delivery system. Hydroponic requires nutrient solution to grow. Nutrient solution refers to the solution that contains all of essential plant minerals in the relative proportion that suitable for optimum growth. Understanding of the plant nutrients, as management of plant nutrition through management of nutrient solution is the key to success in hydroponic gardening. The hydroponic methods enable growers to control the availability of essential elements by adjusting or changing the nutrient solution to suit the plant growth stage and to provide them in balanced amounts. However, incorrect management of the nutrient solution can damage the plants and lead to complete failure. The success or failure of a hydroponic garden therefore, depends primarily on the strict nutrient management ma nagement programme. Carefully manipulating the nutrient solution pH level, temperature and electrical conductivity and replacing the solution whenever necessary, will lead to a successful hydroponic garden. Every plant has different need for pH level and EC.
The optimum pH range for hydroponic nutrient solution is between 5.8 and 6.5. beside the pH range, the other thing that should be considered is The Electrical Conductivity or EC. The electrical conductivity indicates the strength of nutrient solution, as measured by an Ec meter. The unit for measuring Ec is dS/ m. A limitation of Ec is that it indicates only the total concentration of the solution and not the individual nutrient components. The ideal EC range for hydroponics is between 1.5 and 2.5 dS/m . Higher EC will prevent nutrient absorption due to osmotic pressure and lower Ec severely affect plant health and yield due to not many nutrient existed in the solution for plant growth.
(Tabel: pH range and nutrient solution availability)
(the EC range of some hydroponic vegetables)
At the beginning, soilless-culture farmer should understand how to prepare nutrient solution that can be used for longtime and using the right pH and EC. Traditionally, the stock nutrient solution with 50 to 200 times of normal concentration will be prepared for long term use. One of the advanteges of preparing the stock nutrient solution is that it makes the work easier in term of fertilizer weight. In this stage, we use 2 separate place to make a stock nutrient, which actually makes separation between Ca(NO3)2.4H2O from MgSO4.7H2O and NH2H2PO4 to avoid the preticipation of minerals in the tank. This is because only in high concentration condition, without tank separation, the CaSO4 and Ca3(PO4)2 can be generated form, so we must separate Ca(NO3)2 from the fertilizer tat contain SO4-2 and PO4-3 In this exercise, it will be conducted how to make nutrient solution with concentration 15 times higher than normal and also measure the right EC and pH for each solution.
II. OBJECTIVES
1. To Familiar students with how to calculate the amount of fertilizers to be used to prepare the stock nutrient solution. 2. To Familiar student with how to dissolve the fertili zer in the stock solution tanks. 3. To familiar students with how to calculate volume of the stock nutrient solution to be used to prepare the nutrient solution in the growing system. 4. To familiar students with how to dilute the A and B stock solution in the growing system.
III. METHODE
Exercise I : 1. Preparing 15 liters of the stock nutrient solution of Enshi’s solution with 50 times concentration of normal concentration. Show the full calculation in the table 3.
Exercise II : 1. Preparation of 5 Liters of Enshi’s Enshi’s nutrient solution with with 0.5 time concentration and calculate to find the amount of stock solution A and B needed to be used for preparation of 5 Liters of Enshi’s nutrient solution with 0.5 times concentration. 2. Use the result from the calculation to prepare the 5 ;iters Enshi nutrient solution by using the RO water dilution. 3. Measure the EC and pH of the preparednutrient solution. 4. Write the report, show hte calculation in a) and report the EC and and pH in number number 3 with the discussion whether the measured EC is equal to 0.5 mS cm -1 as needed or not. If not, what should be the reason.
RESULTS AND DISCUSSION
-1
The Reason Why the EC in Stock Nutrient Solution is not Equal to 0.5 mS cm :
Good and consistent water quality is essential for hydroponics. Fresh water free from pesticide runoff, microbial contamination, algae, or high levels of salts must be available throughout the year. Water pH levels above the desirable range (5.0 to 7.0) may hinder absorption of some plant nutrients; pH levels below this range permit excessive absorption of some nutrients, which which may lead to toxic levels of those elements. Beside the pH, the EC range of water to dilute the solution of hydroponic culture is also improtant.The electrical conductivity of good quality raw water should be below 0.5 mS/cm or mmhos/cm. By the definition, we can understand that electrical conductivity is a measure of how well a material accommodates the movement of an electric charge. Because of in the practicum we add more nutrient solution, it means the content of salt or dissolve ion in the solution also increase. Because the electrical current is transported by the ions in solution, the conductivity increases as the concentration of ions increases. And bacause of that reason the EC that come up in measurment is 1.3 mS/cm or mmhos/cm instead of 0.5 mS/cm or mmhos/cm. Eventhough the EC of nutrient solution is 1.3 mS/cm or mmhos/cm, this EC level is still preferable by hydroponic plant. This is because The ideal EC range for hydroponics is between 1.5 and 2.5 dS/m . Higher EC will prevent nutrient absorption due to osmotic pressure and lower Ec severely affect plant health and yield due to not many nutrient existed exist ed in the solution for plant growth. growth. Most of hydroponic plants need EC that have range level from 1.00 to 2.8 depend on the variety of plant. But it also has to be understood that different growth stage of plant require different EC range. The function of measuring the electrical conductivity is the farmer can understand what wether the solution has lost nutrients or water due to evaporation, if measurements are done at the exact same pH value. The EC should be measured when the solution is prepared and three times each day after then. If your solution’s EC becomes too high, the farmer can add water to lower it to the original value. If EC becomes too low (70% of original value), the should not add nutrients. Instead of add a nutrient, the farmer should dispose off the old nutrient and prepare a fresh-new solution.
(table of EC range for hydroponic crops)
