Unconventional way to test soil fertility using the principle of soil resistivity.It is done by using electrodes interfaced with raspberry pi.

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CHAPTER 1
INTRODUCTION
Plants require at least 16 elements for normal growth and for completion of their
life cycle. Those used in the largest amounts, carbon, hydrogen and oxygen, are non-
mineral elements supplied by air and water. The other 13 elements are taken up by
plants only in mineral form from the soil or must be added as fertilizers. Plants need
relatively large amounts of nitrogen, phosphorus, and potassium. These nutrients are
referred to asPrimary nutrients, and are the ones most frequently supplied to plants in
fertilizers. The three secondary elements, calcium, magnesium, and sulphur, are
required in smaller amounts than the primary nutrients. Calcium and magnesium are
usually supplied with liming materials, and sulphur with fertilizer materials.
Contaminants in rainfall also supply10 to 20 pounds of nitrogen and sulphur per acre
each year, depending on local air quality.
The micronutrients consist of seven essential elements: boron, copper, chlorine,
iron, manganese, molybdenum, and zinc. These elements occur in very small amounts
in both soils and plants, but their role is equally as important as the primary or
secondary nutrients. A deficiency of one or more of the micronutrients can lead to
severe do not contain sufficient amounts of these nutrients to meet the plant's
requirements for rapid growth and good production. In such cases, supplemental
micronutrient applications in the form of commercial fertilizers or foliar sprays must
be made. Thus the soil supplies 13 of the 15 elements required for nutrition of higher
plants. These elements must be available , continuously, and in balanced proportions
to support photosynthesis and other metabolic processes of plants.
If most of the essential elements is missing, plant productivity will be limited, or
the plant may cease to grow entirely. The principle of limiting factors, which states
that the level of production can be no greater than that allowed by the most limiting of
the essential plant growth factors, applies in both cropping systems and in natural
ecosystem.

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CHAPTER 2
SOIL FERTILITY
Essential elements can occur in one or more of three physical forms: solid, liquid or
gas. We tend to deal primarily with solid and liquid forms of the elements in soils, but
the non-mineral elements as well as nitrogen and sulphur can also occur in gaseous
forms underCertain soil conditions. The chemical form of an element strongly
influences how a nutrient reacts with other elements and compounds found in the soil.
The nutrient elements can each occur in several forms, but we need to consider those
which commonly occur in the soil .
Soil organic matter contains large amounts of carbon, which results in many complex
types of structures and chemical properties. But basically, organic matter reacts in the
soil like a tiny, spongy solid with a large amount of negative charge. Many of its
complexstructures also react strongly with smaller organic molecules, such as
pesticides and root exudates.
Soil nitrogen is the most difficult nutrient to characterize: it occurs in organic and
inorganic forms, in solution and as a gas, and as cation and an anion. Plant roots
absorb only the inorganic forms. Common forms of N contained in fertilizers and
fresh manuresinclude ammonia, urea, ammonium and nitrate.

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CHAPTER 3
EFFECTS ON CROPS
Nitrogen (N) is an essential nutrient used in relatively large amounts by all living
things. It is critically important to plants because it is a fundamental part of the
chlorophyll molecule and is essential in the formation of amino acids and proteins.
Plants obtain their N as inorganic nitrate and ammonium ions in the soil solution but
N is not a natural constituent of rocks or minerals.
Although phosphorus is required in lower amounts than other major nutrients, it is
critical in the early developmental stages of growth, and in energy transfer within the
plant throughout the growing season.. Typical phosphorus contents of plants range
between 0.1 to 0.46 percent P on a dry weight basis, approximately ten times less than
for nitrogen or potassium. Phosphorus apparently stimulates young root development
and earlier fruiting (earliness). It is essential in several biochemical that control
photosynthesis, respiration, cell division, and many other plant growth and
development processes. Phosphorus is concentrated in the seed and fruit, and strongly
affects seed formation.
Potassium is required by plants in approximately the same or slightly larger amounts
as nitrogen. Uptake of K occurs in the K+ form. Most of the functions of K in the
plant are indirect in that K is necessary for other chemical reactions to operate
properly. Some 60enzymes require the presence of K, with high concentrations of K
found in the active growing points and immature seeds. Potassium forms no organic
compounds within the plant, but remains in the ionic K+ form. The plant uses K in
photosynthesis, in carbohydrate transport, in water regulation, and in protein
synthesis. The benefits of proper K nutrition include improved disease resistance,
vigorous vegetative growth, increased drought tolerance, improved winter hardiness
of forages, and decreasedlodging. As a result, potassium fertilization is frequently
associated with improved crop quality as well as better handling and storage
properties.
Micronutrients are defined as those elements required in small quantities for higher
plant growth and reproduction. The exact quantity needed varies with plant species

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and the specific element. Seven elements are generally considered as plant
micronutrients, these include boron (B), Copper (Cu), chlorine (Cl), iron (Fe),
manganese (Mn), molybdenum(Mo), and zinc (Zn). To better understand the relative
amount of these elements needed by plants, we can look at the plant removal rate of a
crop like corn.
TYPES OF FERTILIZERS
Chemical Fertilizers
In dealing with soils low in nutrients, we must consider what the difference is
between organic and synthetic chemical fertilizers. The latter are used to feed the
plant directly; therefore the ingredients have to become available rapidly, which
means that a spring application has to produce a satisfactory crop during that growing
season. Except for phosphorous, any left-over nutrients will mostly have leached out
by the following spring and in doing so may pollute the
groundwater. Although certain bacteria are needed for the breakdown of some
chemical fertilizers, the balanced activity of soil organisms in releasing nutrients from
natural sources is not needed in the chemical program. It has been reported that
chemical fertilizers actually suppress microbial life in the soil.
Organic Fertilizers
Organic fertilizers, on the other hand, have low solubility; to release their nutrients
and for further decomposition they depend on micro-organisms and weak acids from
organic matter. They activate microbial life instead of suppressing it. Nutrients
become available when needed and there is little or no leaching. This means that
most organic fertilizers work more slowly, exceptblood meal and, to some extent bone
meal. It is a matter of long-term fertility rather than creating instant fertility. This
explains why it is good practice to mix these slow acting fertilizers in the compost
pile to start bacteria working on them. The bio-dynamic method stresses the
importance of a natural balance of soil life; if disturbed by chemicals, other
undesirable organisms may increase and fill the gap. It is claimed that this not only
pertains to bacteria but also to other important soil organisms like fungi, nematodes,
beetles, springtails and larvae. Organic matter, although so important in the life of the
soil, is not usually very rich in nutrients by itself unless organic fertilizers have been
added, and beginners in particular may need these to bring their soil to full fertility,

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which can then be maintained by compost and such organic amendments as are
necessary.
ADVANTAGES OF FERTILISERS
Descriptions and Uses of Available Organic Fertilizers
Note: Certified organic growers should check their certifying body guidelines before
usingorganic fertilizers.
Blood Meal - works rather quickly and is an excellent source of nitrogen for the
garden.
Bone Meal - releases its phosphorous faster than rock phosphate. It is relatively
expensive and more suited for garden use than for farm use.
Wood Ashes - hardwood preferably for most soils. Can not be purchased. Keep dry
before application to stop potash from leaching out.
Kelp - is derived from seaweed and, in addition to being rich in potash, has several
other beneficial properties. It promotes the release of locked-up minerals and it
contains hormones which enhance growth and have been reported to increase
resistance to insects, diseases and light frost.
Liquid Fish Fertilizers - are good for side dressing during the summer if plant
growth is not satisfactory and for container-grown plants. Dilute according to the
directions. They contain trace elements and work fairly fast.
Hard and Soft Rock Phosphates - do not move or dissolve in the soil, hence they
have to be worked in. The phosphorous becomes available after it has been acted
upon by micro-organisms; therefore, combine it with compost, manure or green
manure, especially clovers. Do not apply lime at the same time. If the soil is acid, soft
rock phosphate is preferred. Excess phosphate does not harm the plants or leach out. It
is stored in the soil until needed by plants in later years. Wear a dust mask or
respirator for handling rock phosphate.
Granite Dust and Greensand - are an excellent source of potash which becomes
available slowly. Greensand marl has a high moisture-holding capacity and is rich in

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trace elements due to its origin in the sea. It is difficult to find a source of supply.
Feed stores, garden centres, nurseries or even hardware stores may be able to get it for
you.
Worm Castings - boost the activity of soil life and improve structure.
Manure - from livestock and poultry varies widely in N, P and K content depending
on the kind of animal and its feed; also on the storage method, period of aging,
moisture content and the amount of incorporated bedding (straw, etc.). If improperly
handled, most of the ingredients may be lost by leaching and volatilization. Manure
contains high amounts of bacteria and organic matter and activates soil life. Dried
poultry and livestock manure (ideally from organic farms) is sold in bags with a
guaranteed analysis of N, P andK and is much easier to handle than raw manure.
Compost -made correctly by aerobic methods with good organic residues in sufficient
quantity, with the right carbon/nitrogen (C/N) proportions is valuable. It will break
down to an ideal C/N ratio with a high concentration of minerals. The effect of
compost is cumulative and too much should not be expected from it at once.
Various commercial granular organic fertilizer mixtures suitable for general use
are on the market. They can be applied with applicator equipment, such as lawn
spreaders.

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CHAPTER 4
RASPBERRY PI MICROCONTROLLER
INTRODUCTION AND FEATURES
The Raspberry Pi is a series of credit card- sized single board computers developed in
the United Kingdom by the Raspberry Pi Foundation with the intent to promote the
teaching of basic computer science in schools and developing countries. The original
Pi and Pi 2 are manufactured in several board configurations through licensed
manufacturing agreements with Newark Element 14, RS Components and Ego man.
The hardware is same across all manufacturers.
Several generations of Pi has been released. All models feature a Broadcom system on
chip which include an ARM compatible CPU and an on chip graphic processor unit
GPU. CPU speed range is from 700 Mhz to 1.2 Ghz for pi 3 and on board memory
range from 256 MB to 1 GB RAM secure digital SD cards are used to store the
operating system and program memory in either the SDHC or Micro SDHC sizes.
Most boards have between one and four USB slots, HDMI and composite video
output, and a 3.5 mm phono jack for audio. Lower level output is provided by a
number of GPIO pins which support common protocols like I2C. Some models have
an RJ45 Ethernet port and the Pi 3 has on board Wi-Fi 802.11n and Bluetooth.
The Foundation provides Debian and Arch Linux ARM distributions for download,
and promotes Python as the main programming language, with support for BBC
BASIC C,C++, Java, Perl, Ruby, Squeak Smalltalk and more also available.
The system on a chip (SoC) used in the first generation Raspberry Pi is somewhat
equivalent to the chip used in older smartphones. The Raspberry Pi is based on the
Broadcom BCM2835 SoC, which includes an 700 MHz ARM1176JZF-S processor,
Video Core IV graphics processing unit (GPU), and RAM. It has a Level 1 cache of
16 KB and a Level 2 cache of 128 KB. The Level 2 cache is used primarily by the
GPU. The SoC is stacked underneath the RAM chip, so only its edge is visible.

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ARCHITECTURE AND PIN DIAGRAM
● Two Models A& B, priced at $25 and $35Respectively
● Model A/B:
○ Broadcom BCM2835 (CPU & GPU)
○ 256/512MB SDRAM
○ 1/2 USB 2.0 Ports
○ None/Ethernet Port
○ HDMI
○ Audio
○ SD Card Slot
○ Micro USB for power
● ARM11J6JZF-S (ARM11 Family)
● ARMv6 Architecture
● Single Core
● 32-Bit RISC
● 700 MHz Clock Rate
● 8 Pipeline Stages
● Branch Prediction

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BLOCK DIAGRAM
Fig 4.1-ARMv6 Architecture

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PIPELINE STAGES USED BY RASPBERRYPI
Fig 4.2-Pipelie stages used by Raspberry Pi

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PIN DIAGRAM
Fig 4.3-Pin Diagram Raspberry Pi
● Core
● Load Store Unit
● Pre fetch Unit
● Memory System
● Level On
● Interrupt Handling
● System Control
● AMBA Interface
● Coprocessor Interface
● Debug
● Instruction cycle summary and interlocks
● Vector Floating-Pointe Mem. System

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APPLICATIONS AND USES
● Robotics
● Game emulation
● Media Servers
● Education (Python is the primary language used)
● Powerful enough to be used as a personal computer
● Thousands of other projects (Often used in Senior Design)

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CHAPTER 5
SOIL TEMPERATURE MEASUREMENT USING
TEMPERATURE SENSOR
Base Station Options
1. Raspberry Pi
- System-on-a-chip device that functions as an open source computing device
- Inexpensive and flexible
2. Existing Computer Station
-Pre-existing computer station located at elementary school
- No additional cost, but increased risk due to not having access to station during
design phase.
3. Temperature sensor
- Easily measures the temperature of soil and notes the rate of soil fertility loss due to
increased temperature.
Structure/Enclosure Options
1. Waterproof Enclosure with Modular Components
- Provide safe housing for electrical components
- Most flexible
2. Waterproof Enclosure with Hard-Wired Components

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- Also provides safe housing for electrical components
- More stability, but less flexibility
PROPOSEDDESIGN SOLUTION
Fig 5.1-Crop Sensor Network Diagram(a)
Fig 5.1-Crop Sensor Network Diagram(b)

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COORDINATING THE TESTER USING WIRELESS
COMMUNICATION DEVICES LIKE ZIGBEE.
Fig 5.2-Coordination Setup Using Zigbee

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Fig 5.3-Raspberry Pi Micro

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CHAPTER 6
SOIL NITROGEN TESTING USING ELECTRODES
The nitrogen content is very essential in determining the soil fertility content. This is
measured by two electrodes namely anode and cathode which measures the current
flowing through the soil. The two electrodes carries the charged ions which develops
the electric current.
This current is measured and depending upon the rate of flow the intensity of the LED
bulb is gradually changed. The LED glows with highest efficiency when the the
current flowing though the circuit is above the buffer value and it glows at the lowest
intensity when no or very few amperes of current flow through the electrodes.
A potentiometer is also provided to change the values of the current passing through
the electrodes and thus on varying the resistance the voltage also chabges which
further affects the intensity of the LED.
The elctrodes measuring the current thus measures the negative ions or anions of the
nitrogen present in the soil and thus determines the reduced or the increased content
of nitrogen in the soil thus verifying that nitrogen content in the soil affects the soil
fertility.
It uses the principle of ohm law as:- voltage is current times resistance.

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ALGORITHM AND CALCULATIONS
The device uses the python programming language to access the function. It uses a
simple subtraction program with one fixed value and the other value is a variable
which is a measured temperature value of the soil using the temperature sensor.
The basic steps are as follows:-
1 Initiate the program with two variables
2 Give the appropriate string operand for measuring value from a temperature
sensor.
3 Define one value as a constant room temperature.
4 Define the other variable as the measured temperature.
5 Perform a subtraction among these values.
6 Give a checking condition such that if the output of difference operation is
greater than 5 degree Celsius the LED glows indicating loss of soil fertility.
7 If not the LED doesn’t glow indicating the soil fertility is intact apt for the
crops in mind, in this case its corn.

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The sample program is given as
import time
importRPi.GPIO as GPIO ## Import GPIO library
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.OUT) ## GPIO Pin 11 is output
float senseout,roomout
float n=abs(roomout-senseout)
if(n>=5)
GPIO.output(11,True) ##led on
time.sleep(5)
GPIO.output(11,False) #led off after 5 seconds
else
print("something will happen")

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CONCLUSION
Thus we have successfully developed the soil fertility tester using a raspberry pi
which reduces physical hassles and also reduces cost. Thus making this device cheap,
affordable and scientifically potent for further research projects and advancements.

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REFERENCES
[1].National Bureau of Statistics of China, China Statistical Yearbook 2006, Beijing
China, 2006.
[2]. Minzan Li. "Soil Parameters Sensing for Precision Farming": [Ph.D.
Dissertation].Tokyo: Tokyo University of Agriculture and Technology, 2000.
[3]. Missouri Agricultural Experimental Station, Recommended chemical soil test
procedures, Columbia, US: North Central Regional Research Publication, University
of Missouri, 1998.
[4]. J. Ruzicka, E.H Hansen. and E.A. Zagatto, "Flow injection analysis. Part II: use
of ion-selective electrodes for rapid analysis of soil extracts and blood serum.
Determination of potassium sodium and nitrate", Analytica Chimica Acta, Vol. 88,
no. 1, pp. 1-16, 1977.
[CrossRef]
[5] C. Hongbo, E.H. Hansen and J. Ruzicka, "Evaluation of critical parameters for
measurement of pH by flow injection analysis", Analytica Chimica Acta, Vol. 169,
pp. 209-220, 1985.
[CrossRef]
[6]. F. AMR, L. JLC, and R. AOSS, "Potentiometric determination of total nitrogen in
soils by flow injection analysis with a gas-diffusion unit", Australian Journal of Soil
Research, Vol. 34, pp. 503, 1996.
[CrossRef]
[7].H.J. Kim, J.W. Hummel, and S.J. Birrell, "Evaluation of ion-selective membranes
for realtime soil nutrient sensing", Transactions of the ASAE, Vol. 46, no. 3, pp.
1075-1086, 2003.

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