FarmCorder - Crop Nutrition Deficiency Sensor

Farming remains to be backbone of developing countries like India and Africa and it is the principal source of livelihood for majority of the population in the countries. Farmers however, use antiquated techniques which lead to overuse or under usage of fertilizer,water which leads to disastrous yields. Our solution to this problem is “FarmCorder” system. We propose a new simple and intuitive sensor based system which consists of base hand held module. The leaf nutrients are measured by leaf probe which works by multi-spectral spectroscopy. The soil moisture probe which works by capacitive moisture sensing. The data logging is performed by a low power micro-controller and data is sent to a remote server with GPS coordinates via a GSM module where the data is processed and appropriate fertilizer advice is provided.

It was late summer in my hometown and I visited my dad's village farm during my university break, I found my dad to be perplexed in the field jotting down something on his notebook. Upon inquiry I learned that it was time for fertilizer application in his rice crop and that he was finding it difficult to find out how much fertilizer to apply for his crop. I had heard of the recent surge in fertilizer cost but I was surprised to hear that it was causing him quite a bit of capital investment and that the amount had to spot on. I found the problem to be a bit odd and I wondered if anyone had come up with a solution to solve this rather giant problem. A visit to a nearby Agriculture research facility made me realize the magnitude of the problem and the wide array of farmers whose very livelihood was affected by the same.This sort of inspired me to come up with a solution to make not only my dad's job easy but also aid all small farmers in developing nations.

Step 1: Problem:

•The Farmers in developing nations currently needs to manually assess crop quality which may or may not lead to the right assessment

• Small Farmers are disconnected with use of technology

• Over-usage or under-usage of nitrogen fertilizer can result in financial and economical damage to farmer

• Existing systems are either too expensive and complex or are too narrow and limited to certain crop variety

• Data collection and sharing is nearly unavailable for farm sensing data

Step 2: Existing Solutions:

Konica Miltona SPAD-502 meter:

It is a handheld device with a clip like apparatus which could be used to identify the signs of nutrient deficiency by non destructively sensing the leaf's chlorophyll concentration.
Pro's: Rugged build quality & Accuracy

Con's: Very expensive (1000$+)Hard to interpret by normal farmers & No network functionality

Upon using the SPAD meter myself I was able to realize the fundamental flaw with it, The SPAD meter was exclusively designed for use by researchers and scientists. It did not need to be used by a farmer, The SPAD meter outputted the SPAD value which needed to be interpreted for the particular crop variety to identify and quantify nutrient deficiency and a regular farmer would lack those tools.

Leaf Color Chart:

In the other end of the spectrum was the humble Leaf Color Chart The leaf color chart was made by the International Rice Research Institute to help farmers make smarter decisions during fertilizer application, It however was hurdled by it's flaws leading to it's absense from farmers toolkit.

Pro's: Easy interpretation &Validated by research institutions also Extremely inexpensive

Con's: Only for select variety's of rice & Difficult to read under strong sunlight also Narrow perspective provided on status of crop.

My goal was now set, I wanted FarmCorder to be a device that would be accurate like the SPAD meter while being inexpensive and provide farmers with actionable data about their crop while being easy to interpret.

Step 3: Solution:

This is the basic design of our project,The system has to be easy to use even by an uneducated farmer.A crop expresses it’s nutrient requirements through it’s leaves. Thus it is possible to evaluate the nutrient content of a crop through it’s leaves. The above block diagram illustrates the various components and sensing elements. The spectroscopy sensor consists of a multispectral light source consisting of LED’s of wavelength 650nm(Deep Red), 605nm (Orange),940nm (Infrared), 810nm(Near-IR) a 1330nm(Mid-IR) laser diode. The LED and laser diode intensity is adjusted by pulse width modulation using MSP430G2553 microcontroller. The Soil moisture based on the HDC1000 is attached to the soil piercing probe and the sensor itself is hermitically sealed to avoid damage, The sensor’s sensitivity is unaffected nonetheless thanks to the capacitive sensing method. FarmCorder prototype 1.0 would use only 650nm and 940nm LED for SPAD sensing the other features will be added soon in future versions,

The light sensor I originally wanted to use was the TI OPT101 sensor but to my dismay it was not sensitive to the infrared spectrum. I eventually decided to use the AMS's TSL2561 i2c light sensor as it had inbuilt amplification filtering and ADC conversion. I picked up the Sparkfun's TSL2561 sensor and designed my own custom variant including custom LED's and drivers.

I sent the PCB's off to get fabricated by OSHPARK.
I got my clip sensor done at last and tested using a simple clip with a strip of 3M double tape

Step 4: Components :

Texas Instruments CC3200 Dev board
TSL2561 Chlorophyll Light sensor
TI HDC1080 Humidity Sensor
3.7V LiPo Battery with Charger circuit
Solar Panel - Optional power source
OLED Display 128x64 0.96"

Step 5: Leaf Spectroscopy :

Nitrogen is an essential element for plant growth and development. It is a major component of chlorophyll in plant leaves. Chlorophyll levels affect leaf area, leaf weight, plant size, and transpiration rate. Too little nitrogen can cause nitrogen deficiency symptoms affecting plant quality, pro- ductivity, and salability. Too much nitrogen is not good either, as nitrogen toxicity can occur in overfertilized plants, leading to stunted growth and a poor quality plant. Overfertilizing can be a source of unnecessary extra costs as well as an environmental hazard in the case of nutrient runoff.

The SPAD meter works by emitting two frequencies of light, one at a wavelength of 650 nm (red) and one at 940 nm (infrared). Leaf chlorophyll absorbs red light but not infrared, the difference in absorption is measured by the meter and termed SPAD. Therefore, the unit of measurement is SPAD, a ratio that is provided by the meter. The value does not give an actual chlorophyll or nitrate count Rather than saying, “there is this number of chlorophyll,” the meter value can be interpreted as, “this is a ratio of reflection vs. absorption.” The infrared absorbance is used to account for the leaf thickness.

Additionally, plants cease to create chlorophyll once a certain threshold has been reached. Consequently, the meter cannot indicate an abundance of nitrate, only a possible deficiency. In terms of estimating nitrate content, the measured value is most useful when compared to a well fertilized control group.