Contrasting Precision Ag Technology Between Different Crop Species

By Dodi Wear

Objective or Purpose

To identify different types of precision agriculture technologies and how they are used in different crop species.

To be aware of what’s out there.

Three Basic Categories

Variable Rate Technology Various Sensing Devices Yield Monitors

Variable Rate Applicators

Variable Rate Applicators are mounted on planters to vary the seeding rate or on fertilizer applicators to vary the pounds applied on each small plot of land.

Variable Rate Applicators

VR fertilizer application was the first PA practice to reach the level that it could be used through the complete production cycle of gathering the data, developing a management plan based on information generated by the data, and implementing this plan through site-specific fertilizer application.

How Variable Rate Applicators Are Being Used Nitrate Leaching in Potato Cropping

It was demonstrated in a study done on 2 adjacent fields the effect of VRT in reducing the ground water contamination.

Rice & Soybeans in Arkansas It was found for phosphorus application that the

profitability of VRT was highly sensitive to both residual P and soil clay content when compared to URT

How Variable Rate Applicators Are Being Used VRT applications of lime has been proven

successful in the SE VRT was tested on corn hybrids and seeding

rates in CO Field test in MO to determine optimum

planting densities in different fields.

Sensing Devices

Soil Inductance Meter Measures soil electrical

conductivity (EC). Probably most common

form of continuous sensing. Soil EC has been observed in a number of cases to correlate highly with yield.

EC measured before planting can be related to plant-available-water-holding capacity.

Remotely Sensed Images Have Been Used To: Predict nitrogen need in corn Estimate cotton lint yield Assess insect damage in wheat Detect spider mites in cotton Assist in insecticide application Estimate clay concentration of surface soil Detect weeds Quantify hail or wind damage in crops Detect and Classify anomalies

Hyperspectral Sensing

New technology that is capable of providing info over a continuous spectrum in the visible, NIR, MIR wavebands.

Images acquired from hyperspectral sensors have been used for: Estimation of crop vigor and yield prediction Discrimination between crops, weeds, residue

and soil Quantitative measurements of crop water content

and leaf area index

Sensing Devices

Infrared thermometer was used to measure canopy temp to control irrigation events.

Infrared Spectrometer – used for determining plant water status.

Leaf Chlorophyll Meter – used for assessing plant nitrogen status. Chlorophyll Meter coupled with DGPS to map

nitrogen stress in corn.

Sensing Devices

Field spectral-imaging system with a liquid crystal tunable filter in peanuts and cotton.

Electromechanical sensor to count corn plants.

Cotton mass-flow and strength sensor was developed using a halogen lamp & NIR light.

Capacitance sensor, a sensor measuring power required at the PTO shaft, a microwave sensor & NIR sensors were tested to measure moisture content of forage.

Sensing Devices

Grain protein and oil content sensors are currently under development.

An infrared plant-temperature transducer was used to sense plant temperature changes caused by greenbug infestation.

Yield Monitoring

Most yield monitors measure the volume or mass-flow rate of harvested material and then integrate this flow rate to generate a time-periodic record of the amount of harvested material during that interval.

The most well developed yield monitoring technology is that for combine harvested crops, especially, small grains.

Yield Monitoring

Yield Monitoring

Development and commercialization of yield monitoring systems for other crops have just started.

Publications about yield monitors for other crops include cotton, forage, peanuts, potatoes, straw, sugarbeets, & tomatoes.

Companies are also working on developing sensors that can measure physical grain quality such as cracks, splits, color and such chemical properties as protein, carb and fiber content.

For forage crops, YM using a displacement sensor, a load cell, a capacitance-controlled oscillator and an optical sensor have been studied.

Yield Monitors

In large areas harvested by combines the monitors have shown themselves capable of accuracies of better than 5%.

In predicting the amount of grain in a combine hopper load, a truck load or the amount of grain harvested from a field of 10-40 or more acres, monitors often estimate with better than 2% accuracy.

References

Zhang, N., Wang, M., & Wang, N. Precision agriculture—a worldwide overview. Computers and Electronics in Agriculture. 36 (2002) 113-132.

Plant, R. Site-specific management: the application of information technology to crop production. Computers and Electronics in Agriculture. 30(1-3). Feb 2001. 9-29.