Hydroponics is a method of growing plants using a water based mineral nutrient solution, without soil. The culture of growing plants through hydroponics has recently seen significant growth. The controlled environment of hydroponics makes it easier to grow plants that are not traditionally grown in certain climates. Compared to soil-based growing, hydroponic systems require less water and space, allow greater control of nutrient levels, result in healthier plant growth, and are easier to keep pest and disease-free.

Hydroponics is only one form of soilless culture. It refers to technique in which plant roots are suspended in static, continuously aerated nutrient solution or a continuous or mist of nutrient solution. The growing of plants in an inorganic substance or in an inorganic material and periodically water with a nutrient solution should be referred to as soilless culture but not necessarily hydroponics. Conservation of water and nutrients is a feature of all the systems that can lead to a reduction in pollution of land and streams because valuable chemicals need not be lost.

Objectives

1) 80% Reduction in fertilizer cost from present reported VA costing Ref. VA July-August report.

2) Reduce Nitrogen input cost 80-90% with the help of MBBR.

3) To study the effect of control environment and ambient environment on spinach in the hydroponics system.

4) To study the effect of vermiwash on spinach in the hydroponics system.

Table: 1.1 Fertilizers used for hydroponics trails (July-August)

NutrientsQuantity (gm)Cost (Rs)
Ca(NO3)21500120
Urea150012
MgSO4100060
0:0:5050025
0:52:3450030
13:0:45100060
Jivamrit30 liters375

Total682
Cost/Kg of Spinach = 48.7

Table 1.1 shows results of hydroponics trials at polyhouse in July-August 2020.

Dec. 10.2020

We started with standard dosage of fertilizers as Solution A and B. Solution A is nitrogen fertilizer and B contents K, Mg and P.

Table: 2.1 (a) Standard dosage of fertilizers as Solution A and B.

Sr. NoName of fertilizerQuantity (g)Available Nutrients (g)

Solution – A
NPKCaMgS
1Calcium Nitrate Ca(No3)249.388.6912
2Urea CH4N2O171.4179.31

Solution – B






1Mono Ammonium Phosphate12:61:0(NH4)H2PO41001261
2Potassium Sulphate0:0:50K2SO489.28
4016.07
3Magnesium Sulphate MgSO43067.8

Table: 2.1 (b) Cost of Standard dosage of fertilizers as Solution A and B.

Sr. NoName of fertilizerQuantity (g)Cost (Rs)

Solution – A

1Calcium Nitrate Ca(No3)249.383.16
2Urea CH4N2O171.411.02

Solution – B

1Mono Ammonium Phosphate12:61:0(NH4)H2PO410014.2
2Potassium Sulphate0:0:50K2SO489.28
5.35
3Magnesium Sulphate MgSO4302.4

Total440.0726.13

Dec. 16. 2020

Table: 2.2 (a) Standard dosage of fertilizers as Solution A and B. (50% reduction in momo ammonium phosphate and potassium sulphate)

Sr. NoName of fertilizerQuantity (g)Available Nutrients (g)

Solution – A
NPKCaMgS
1Calcium Nitrate Ca(No3)249.388.6912
2Urea CH4N2O171.4179.31

Solution – B






1Mono Ammonium Phosphate12:61:0(NH4)H2PO450630.5
2Potassium Sulphate0:0:50K2SO444.64
208.035
3Magnesium Sulphate MgSO43067.8

Table 2.2 (b) Standard dosage of fertilizers as Solution A and B. (50% reduction in momo ammonium phosphate and potassium sulphate)

Sr. NoName of fertilizerQuantity (g)Cost (Rs)

Solution – A

1Calcium Nitrate Ca(No3)249.383.16
2Urea CH4N2O171.411.02

Solution – B

1Mono Ammonium Phosphate12:61:0(NH4)H2PO4507.1
2Potassium Sulphate0:0:50K2SO444.642.68
3Magnesium Sulphate MgSO4302.4

Total345.4316.36

Table 2.1 (a, b) and 2.2 (a, b) shows the initial doses and cost of fertilizers, these doses were excessive and costly so now we are providing 50% of mono ammonium phosphate and Potassium Sulphate doses. This shows positive results.

The growth of spinach in this system was satisfactory with some yellow spots on few plants might be due to Mg deficiency. It is known from literature that heavy dose of calcium leads to high Ca/Mg ratio resulting into Mg deficiency. The other reason could be precipitation of Mg with Mono Ammonium Phosphate as Ammonium Magnesium phosphate i.e. Struvite

Other than MAP, cost of calcium nitrate INR 64 per kg with 17 % nitrogen is major cost contributor. Hence we were trying to find out the exact requirement of fertilizers typically NPK and Ca, Mg, as well as S. One of the way to match it with the minerals and nitrogen present in spinach. Hence we decided to look at mineral content of spinach for nitrogen we looked at the proteins and amino acids present in 100 gm of spinach. Rest oxygen, carbon and hydrogen is extracted from water and air.

Below table i.e. table 3.1 describes nutrients present in 100gm spinach Table no. 3.1 (a) Nutrient present / 100g of Spinach

Sr. No.Ingredientsquantity/100g
1.Moisture 95.1g
2.Energy14 Kcal
3.Protein3.2 g
4.Fat0.3 g
5.Ash1.72 g
6.Fiber2.7 g
7.Carbohydrates3.50 g
8.Calcium99 mg
9.Iron2.71 mg
10.Magnesium79 mg
11.Phosphorus49 mg
12.Potassium558 mg
13.Sodium79 mg
14.Zinc 0.53 mg
15.Copper0.130 mg
16.Manganese0.897 mg
17.Celium1.00 mg
18.Nitrogen0.22 g

3.1 (b)Vitamins

Sr. No.Vitaminsquantity/100g
1.Vit. C28.1 mg
2.Thiamine (vit. B1)0.078 mg
3.Riboflavin (vit. B2)0.189 mg
4.Niacin ( vit. B3)0.724 mg
5.Pantothenic acid (vit. B5)0.065 mg
6.Vit. B60.195 mg
7.Folate (vit. B)194 μg
8.Vit. A672 μg
9.Vit. E1.89 mg

Table 3.1 (c) is the list of amino acid with its weight in 100g of spinach, below this table 3.1 snapshots of note book pages illustrates structure and nitrogen calculations for 100g spinach.

Dec. 18. 2020

3.1 (c) Amino Acids

Sr. No.Amino acidsquantity/100g
1Arginine5.6 mg
2Histidine2.2 mg
3Isoleucine4.8 mg
4Leucine8.5 mg
5Lycine6.4 mg
6Methionine1.8 mg
7Phenylalanine5.3 mg
8Threonine4.6 mg
9Tryptophan1.6 mg
10Valine5.6 mg

Dec. 19.2020

From table 3.1 (a & c) as well as calculation described on snapshot it is clear that 100g of spinach contents 0.2246 gm of nitrogen. The metabolic activity of spinach might need some nitrogen and rest of the minerals hence we decided to use three time higher dosage of all the minerals and nitrogen Table 4.1 and 4.2 describes the fertilizers based on above calculations. Two sets spinach hydrophobics were running parable and details are mention in Table 4.1 (a, b) and 4.2 (a, b).

Table: 4.1 (a) Spinach needs Following Fertilizer Kitchen Hydroponic System Ambient environment.

Name of FertilizerQuantity (g)NPKMgCaSFeZnmncu
0:52:349.95.133.42
Chilmix6.07





0.3040.2120.1520.0607
MgSO42


0.40
0.52



Table: 4.1 (b) Cost of fertilizers used for Kitchen Hydroponic System Ambient environment.

Name of FertilizerQuantity (g)Cost (Rs)
Potassium Phosphate 9.91.5
Micro-Nutrients  6.077.34
MgSO420.08
Ammonia700.7
Ca(OH)2600.24
Total147.979.86
Cost/Kg = 9.86

Table: 4.2 (a) Spinach needs Following Fertilizers Polyhouse Hydroponic System controlled environment.

Name of FertilizersQuantity (g)NPKMgCaSFeZnmncu
0:52:3437.819.613.09
Chilmix23.2      1.160.8120.580.232
MgSO4 2   0.4 0.52    

Table: 4.3 (b) Cost of fertilizers used for Polyhouse Hydroponic System controlled environment.

Name of FertilizerQuantity (g)Cost (Rs)
Potassium Phosphate 37.85.67
Micro-Nutrients  23.227.84
MgSO4100*648
Ammonia4404.4
Total68385.91
Cost/Kg = 10.47

dosing mention in table 4.1 and 4.2 for 2 kg of spinach and 8 kg of spinach resulted in satisfactory growth. we could harvest total 8 kg of spinach in 15 days. further exact calculation indicate that 97% of potassium requirement is fulfilled by 0:52:34. the amount of phosphorus coming from 151 gms of 0:52:34 resulted in to excess of phosphorus (8.79 times higher).

Epsom salt 2% solution total 30 lit. was used to compensate magnesium requirement. that means 600 gms of magnesium sulphate was used which is 19.04 times more than calculated value.

500 lits of fresh water was used for above mentioned polyhouse system supplying 30000 mg of calcium based on 150 ppm hardness. this is 3.78 times more than calculated value.

For iron, Sodium, zinc and manganese similar calculations were not perform.

Calcium Nitrate’s  cost is higher than ammonia so we had decided to give ammonia to the system and also added BARC culture which has nitrifying bacteria which convert ammonia into nitrates. Bacteria need surface area to grow so we provided MBBR (Moving Bed Bio-Reactor) and shade-net to grow their colonies and also for aeration bubbles were added.

Observation

The results of both the systems are satisfactory i.e. the ammonia is getting converted into nitrates and the plants are also growing well. pH is also maintained.

Both systems showed positive results at the initial stage, but as nitrifying bacteria started converting ammonia into nitrate,  due to which nitric acid formed in the systems started changing pH from slightly basic to acidic.

Dec. 29.2020

Acidic pH gives stroke to plants. So we used Ca(HO)2 to increase pH which reacts with nitrate to form Ca(No3)2 and H2 get released. 

After the addition of Ca(HO)2, magnesium got precipitated. Hence plants started showing magnesium deficiency so to recover that deficiency we started spraying magnesium which shows better results.

To maintain pH we had separated the MBBR system and provided nitrates from that separated system to plants. As a result the pH was maintained and the plant shows better growth.

Jan. 14. 2021

Nutrients and its Cost for Kitchen Hydroponics System

Tab. 5.1 a For 14.6 Kg Spinach                                                

NutrientsQuantity (gm)Cost (Rs)
Ca(NO3)21500120
Urea150012
MgSO4100060
0:0:5050025
0:52:3450030
13:0:45100060
Jivamrit30 liters375

Total682
Cost/Kg of spinach= 48.7

5.1 b Cost For 1 kg of Spinach

Name of FertilizerQuantity (g)Cost (Rs)
Potassium Phosphate 9.91.5
Micro-Nutrients  6.077.34
MgSO420.08
Ammonia700.7
Ca(OH)2600.24
Total147.979.86
Cost/Kg of spinach= 9.86

Tab. 5.2 a Cost For 14.6 Kg Spinach

NutrientsQuantity (gm)Cost (Rs)
Ca(NO3)21500120
Urea150012
MgSO4100060
0:0:5050025
0:52:3450030
13:0:45100060
Jivamrit30 liters375

Total682
Cost/Kg = 48.7

Tab. 5.2 b Cost For 8.2 Kg of Spinach

Name of FertilizerQuantity (g)Cost (Rs)
Potassium Phosphate 37.85.67
Micro-Nutrients  23.227.84
MgSO4100*648
Ammonia4404.4
Total68385.91
Cost/Kg = 10.47

Observation table google sheet link: https://docs.google.com/spreadsheets/d/1G_FWIqOQJchAuf8ySRBH3ukuIjtgEjJdoN0344w418A/edit#gid=0

Feb. 16. 2021

Conclusion note for Cost Effective  Hydroponics System for Spinach

There was usage of Jeevamrutha and calcium nitrate in July-August hydroponics system trail which was costly, then we calculated fertilizer requirement of spinach from that we got to know, spinach required less amount of fertilizers which are provided from potassium phosphate, magnesium sulphate, nitrogen and some amount of micronutrients. Because of these changes, 80 % cost of fertilizers was reduced from the present report VA costing.

 The nitrogen source in the first system was calcium nitrate (392.48 Rs/kg of nitrogen) which is expensive. So we started converting ammonia (48.57 Rs/Kg)  into nitrates with the help of nitrifying bacteria in microbial culture. For the growth of these bacteria’s they need surface area which is fulfilled by MBBR.  Because of it nitrogen input cost was reduced by 88% with the help of the moving bed bio reactor (MBBR) system.

Table 6 : Nitrogen sources and its costs.

Sr. No.Fertilizers“N” content (%) Cost (Rs)
1Calcium Nitrate17392.48
2Urea4613.04
3Ammonia1748.57
4Nitric Acid1478.57
  1. As nitrifying bacteria started converting ammonia into nitrates at that stage we observed that the pH of water started reducing from slightly basic to acidic, to increasing pH we added calcium hydroxide. Due to excess of calcium hydroxide dosing there was magnesium deficiency so we sprayed magnesium sulphate which worked effectively.
  2. As we mentioned above the system of ammonia conversion to nitrates is an elaborate system and was also time consuming. Hence we want to try nitric acid as an alternative. 
  3. From the kitchen system we are getting 50.31 g spinach / sq ft in 36 days and in a controlled environment we got 123 g spinach/ sq. ft. which means In the ambient environment we got 1200 g spinach from 60 plants and in the controlled environment we got 2857.14 g spinach from 60 plants in 36 days.

Feb. 19.2020

MBBR Based Hydroponics System with Positives and Highlighted Problems

  • The Major change of hydroponics system was installation of MBBR system with nitrifying bacterias and conversion of Ammonia into nitrates, which reduces 88% nitrogen cost than reported in July-August-2020 VA report.
  • A minimum Incubation time of 5 days should be given to the Nitrifying bacterial culture, these are very slow growing or slow adapting organisms and they need time to consume oxygen and ammonia and convert it into nitrate so this process is delayed.
  • When the system is incubated the nitrates start to form in a huge amount and you need to check if the amount of nitrates are suitable for the growth of the crop.
  • Proper aeration should be provided through air pumps with proper flow rates and proper diffusers should be provided so that there is efficient mass transfer in the system. 
  •  DO(Dissolved oxygen) should be maintained over 2 mg/L.
  • As nitrifying bacteria started converting ammonia into nitrates at that stage we observed that the pH of water started reducing from slightly basic to acidic, to increase pH we have added calcium hydroxide. Due to excess of calcium hydroxide dosing there was magnesium deficiency so we sprayed magnesium sulphate which worked effectively.
  • In the MBBR based hydroponics system it is difficult to maintain pH and Electrical Conductivity (EC) due to that, plants had root injury and shock (due to acidic pH) which directly affects on its growth.
  • So we needed to develop an alternative nitrates producing system, produced nitrates were transferred to the main hydroponics system. Which increased capital cost investment.
  • Hence we want to try nitric acid as an alternative. This system reduces major capital investment as we exclude MBBR, Culture and also an alternative systems investment.
  •  The culture used in this system is also useful for aquaponics because fish produced excreta (ammonia) is converted into nitrates using above mentioned culture.

March 07. 2021

As we mentioned in conclusion, we started trails of nitric acid as an alternative for MBBR based Hydroponic systems. This system reduces major capital investment as we exclude MBBR, Culture, and also alternative systems investment.

Tab. 6.1 a Cost of Fertilizers For Nitric Acid Treatment for Polyhouse hydroponics system.

Name of FertilizerQuantityRate (Rs)
KNO3 115.59 gm 5.75
HNO391.76 ml 1.20
NH318.65 ml 0.18
MgSO431.69 gm 0.62
KH2PO40.17 gm 0.020
Total7.77

Tab. 6.1 b Cost of Fertilizers For Nitric Acid Treatment for Kitchen hydroponics system.

Name of FertilizerQuantityRate
KNO3 14.44 gm 0.72
HNO311.47 ml 0.15
NH32.33 ml 0.022
MgSO43.96 gm 0.077
KH2PO40.0212 gm 0.0024
Total0.97

Two sets of spinach hydrophobics were running parable and details for the nitric acid trail are mention in Table 6.1 (a and b).

March 12. 2021

Because of the life span of spinach was over we remove all the plants from the system and start growing new plants.

March 13. 2021

New experimental setup for Nitric acid trail.