Strip Till for Precision Agriculture

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					          Precision Agriculture: Precision Resource Management                         44

7.2    Strip Till for Precision Agriculture:

Principal Investigators:

Agronomy                                                 Biosystems and Agricultural Engineering
Gregory Schwab, Ph.D.,                   Tim Stombaugh, Ph.D.,
                                                         Scott Shearer, Ph.D.,
Agricultural Economics
Carl Dillon, Ph.D.,

Clinton Hardy, Daviess County ANR Agent,


Historically, Kentucky has been a world leader in no-till crop production, but there are poorly

drained soils within the state where conventional tillage is still common. Tillage is used to speed

drying and warming in the spring and help assure timely planting. In the northern Corn Belt,

strip tillage (4-6 inches wide) in conjunction with deep placed (6-8 inches) P and K fertilizer has

been shown to improve corn yield while retaining residue cover similar to no tillage. Using

autosteering technology, farmers could simultaneously establish narrow fall tilled strips a

apply P and K fertilizer then plant within 3 cm of the center of the strip the following spring.

This system could reduce erosion potential, reduce the need for starter fertilizer, and increase

grain yield. The proposed study will investigate the agronomic and economic effects of using

precision steering, strip tillage, and deep placed fertilizer on corn grown on wet natured soils

currently under conventional tillage.


       Only a few short years ago, automatic steering systems and driverless tractors were

thought to be dreams for agriculture many, many years in the future. However, there has been a

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          Precision Agriculture: Precision Resource Management                       45
recent insurgence of automatic steering systems into the agricultural equipment industry.

Currently about 4 different companies offer some form of autosteer system for agricultural

equipment. Because of this recent insurgence and the claims made by manufacturers, many

Kentucky producers have been inquiring about the technology and wondering if it could be

economically viable for their operations.

       Autosteer systems are able to precisely control machine traffic in the field. Heidman et

al. (2002) demonstrated path deviations of less than +/- 2.5 cm using one commercially available

autosteer system. An immediate advantage is precise control of overlaps and skips for field

applications. This advantage alone may not be sufficient to justify the capital costs of the

equipment (Gan-Mor and Clark, 2001). Many producers who have claimed sufficient economic

returns on this significant capital investment have done so by altering their fundamental

management strategies or field operations to take advantage of autosteer capabilities. One

extreme example of this innovation is a vegetable producer in California who practiced pre-

emergent cultivation of his crops. Since he planted the crop using an autosteer system and

recorded the precise location of the crop rows, he was able to follow the planting operation with

an autosteer controlled cultivator and till between the rows when no crop was visible.

       For autosteer technology to be viable in Kentucky, appropriate practices must be

identified that would not be possible without the technology. One practice that could have

tremendous economic potential for Kentucky producers is fall strip tillage and banded deep

placement of fertilizer. Autosteer technology would be necessary to perform spring planting

directly in the narrowly tilled strips because they are often obscured by winter weeds or

windblown residue.     This precision placement would insure that the row would be planted
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          Precision Agriculture: Precision Resource Management                          46
directly over the fertilizer band. Strip tillage seems to be an excellent alternative to fall tillage

because the overall erosion control potential is similar to no-tillage while the in-row conditions

more closely resemble conventional tillage.          Strip tillage is more sustainable from a soils

standpoint, and it could likely increase economic returns to Kentucky farmers.


       The goal of this project is to determine the effectiveness of fall strip tillage and banded

deep fertilizer placement on poorly drained Kentucky soils that are currently conventionally

tilled. This goal will be accomplished through the following specific objectives:

       1. Equip an agricultural tractor with an autosteer system to perform precise field

       2. Evaluate the agronomic advantage of a strip tillage/banded deep fertilizer placement
       management system;

       3. Evaluate the economic viability of precision steering, strip tillage, and deep fertilizer
       placement, management system.


       Traditionally, strip tillage has only been practiced in the northern Corn Belt. Minnesota

researchers have found that removing residue from the corn row improves no-till corn yields in

wet springs, but has little effect in dry springs (Vetsch and Randall, 2002). Research conducted

in northern Indiana has shown that strip tilled corn consistently yields as much as conventionally

tilled corn and consistently higher than no-till corn when planted on the same date (Griffith et al.,

1994). In Ohio, strip till corn yield was higher than to no-till but lower than fall deep tillage

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followed by spring secondary tillage (Kleinschmidt and Prill, 2002). Positive yield benefits of

strip tillage have been observed as far south as Alabama, where seed cotton yield was

significantly increased when compared to conventional tillage (Schwab et al., 2002). Regardless

of the crop or growing location, the yield advantage is generally attributed to warmer and dryer

soils at the time of planting.

         Even though soils in Kentucky are warmer than soils in the northern Corn Belt, Kentucky

corn growers often use fall conventional tillage on poorly drained soils to speed spring drying

and soil warming.         Approximately 30,000 acres in Daviess County alone has been

conventionally tilled this spring (Clint Hardy, Daviess Co. ANR Agent, personal

communications). Many of these growers use no-tillage on their well drained soils, but have been

forced to use tillage on their poorly drained soils to assure timely corn planting. Strip tillage

would allow these growers to preserve surface residue between the rows while maintaining the

advantages of tillage within the row. It would also reduce fuel usage because of lower draft

requirements of the strip tillage equipment, which is becoming more significant as fuel costs rise.

         An additional benefit of strip tillage is that producers can place fertilizer deeper in the

profile as the strips are being established. Using the autosteer technology, spring planted rows

can be placed close to fall applied fertilizer bands giving plant roots early season access to

fertilizer. Research has shown that this method can improve early season corn growth and yield

potential and potentially eliminate the need for starter fertilizer capabilities on the planter (Vyn,


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           Precision Agriculture: Precision Resource Management                          48
       Autosteer systems have been commercially available for several years. They generally

consist of a GPS receiver system, inertial attitude sensors, and steering hardware components

which must be installed in they hydraulic steering system on a tractor. There are a range of

systems available with varying degrees of accuracy. The lower cost autosteer systems ($10,000 -

$20,000), which are targeted toward larger chemical application and tillage equipment, will

provide steering accuracies to within three feet of the desired path. The systems of interest to

this project utilize Real Time Kinematic (RTK) GPS receivers, which can provide position

accuracy to less than 2 cm. These high accuracy systems can range in cost from $30,000 to

$50,000, and many of the hardware compone nts are not transportable from one machine to


       Several researchers have tested the guidance accuracy of RTK-based systems, and they

generally report steering accuracies within 5-10 cm of the desired path (Heidman et al., 2002;

Tucker et al., 2002). If care is taken when placing the RTK base station, machine patterns can be

repeated precisely from one field operation to the next. Therein lies the power of the autosteer

system for the strip till/banded deep placement of fertilizer operations described in this project.

       One concern regarding the accuracy of the autosteer systems is their performance on the

undulating terrain commonly found in KY fields.              Tucker et al. (2002) noted performance

degradations when a tractor was driven diagonally across terrace structures, but those conditions

are much more severe than an undulating terrain.                  More testing is needed to evaluate

performance on undulating terrain.

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Objective 1. Equip an agricultural tractor with an autosteer system to perform precise field

       All field operations will be performed with a John Deere 7220 tractor, which is already

owned by the investigators. This tractor is of sufficient size to pull the implements that will be

used in this study, and it is small enough to be easily hauled on a semi- trailer without special

freight permits. In addition to the tractor, the investigators also have the RTK GPS system;

therefore, the only components needed for the autosteer system are the tractor-specific hydraulic

components and electronic sensors.         This autosteer system will be installed by the system

supplier, and investigators will perform simple accuracy tests to verify system performance.

Position data will be logged throughout all tests, and evaluations will be made regarding

guidance performance on undulating terrain.

Objective 2. Evaluate the agronomic advantage of a strip tillage/banded deep fertilizer
placement management system.

       The strip tillage/banded deep fertilizer placement system will be established using a 6

row DMI 5310 strip tiller which is on 3-yr a loan to the investigators. Conventional tillage will

be established according to farmer practice while weed control and other cultural practices will

be the same as the cooperator’s current methods.                  Two sites will be established in

Daviess/Mclean Counties and one site in Nelson County on farmer/cooperator sites that are

currently conventionally tilled.      A detailed digital elevation model of each site will be

constructed using the RTK GPS system, and soil samples will be collected on a 0.25 acre grid

spacing and analyzed for pH, P, K, Ca, Mg, and Zn.

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         The experiment will be conducted using a strip plot design, with plots being established

for the length of the field – ideally at least 800 feet. The treatments will include strip till with

and without deep-placed fertilizer, and conventional till with and without broadcast fertilizer for

a total of four treatments. Each treatment will be replicated four times in a randomized complete

block design. Additional treatments that include partial fertilizer rates according to banded

application recommendations will be added if field space is available and if the cooperator is

interested. A modification will be made to the fertilizer drop components on the strip tillage tool

to allow either banded deep placement or broadcast application of fertilizer so that all treatments

can be applied with the same equipment.

         The plots will be planted using an investigator-owned 4-row planter.               Autosteer

technology will allow use of the 4-row planter with the 6-row tillage implement since guess row

errors will be only a few centimeters. The minimum test area size will be 4.5 acres. Plots will

be harvested using a combine with a yield monitor, and individual plots will be weighed using a

weigh-wagon. Orthogonal contrast will be used to statistically compare yield in the conventional

and strip till plots without fertilizer, and strip till plots with and without deep placement of

fertilizer.    Grid soil analysis will be used to determine spatial correlation of yield to soil


Objective 3. Evaluate the economic viability of a strip tillage/deep fertilizer placement
management system.

         The economic analysis calls for a combination of enterprise budgeting and partial

budgeting. The enterprise budgeting technique is mechanism for conducting detailed analysis of

production costs associated with a given commodity. Budgets for traditional and precision

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agriculture production will be developed.             Computerized enterprise budgeting software

(Mississippi State Budget Generator) will be used. Operating and ownership costs will be

estimated using standards for production economics defined by the American Society of

Agricultural Engineers. Data required for these enterprise budgets include machinery prices,

input prices and input requirements as well as the data generated through this research project.

Published data regarding current Kentucky machinery and input prices (Kentucky Agricultural

Statistics and UK Agricultural Economics) will be used when possible and supplemented with

agribusiness supplier information and contact with farmers and other expert advisors. Expert

opinion will also be utilized in revising existing traditional enterprise budgets regarding input


        Partial bud geting will be used to provide comparisons for producers considering the

adoption of precision agriculture. Partial budgeting deals only with the changes in costs of

production or changes in income resulting from the adoption of precision agriculture. It also

permits one to determine whether or not a change in the whole farm operation can be expected to

increase profitability.


The proposed research project will enable farmers to make informed agronomic and economic

decisions regarding the effectiveness of strip tillage, precision steering and deep placement of

fertilizer in corn production. Currently, many Kentucky farmers are considering these options

for wet natured soils. A shift from fall/spring conventional tillage to fall strip tillage will have

numerous benefits from a soils perspective. By maintaining residue between the tilled strips, soil

erosion potential will be dramatically reduced. The added residue will also conserve moisture
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during period of drought, improve soil struc ture, and increase the long-term sustainability of row

crop production on these poorly drained soils. By placing P fertilizer deeper in the soil profile,

the potential for P loss will also be dramatically reduced.

       Farmers will reduce their input cost us ing strip tillage by: 1) reducing the number of

tillage passes, 2) improving fertilizer use efficiency via banding, 3) reducing fertilizer cost by

purchasing in the fall at lower prices, and 4) reduce labor requirements at planting. In addition to

reducing cost, past research has shown that strip till yields are comparable or higher than

conventional tillage, further increasing the value of the practice.

                                 Kentucky Agricultural Experiment Station