Abstract:
An automated soil sampler is removably mounted on an agricultural tractor and collects soil samples in a farm field while the tractor is driven through the field. At a periodic interval, the soil sampler momentarily lowers a soil collection knife into the soil to collect a soil sample, raises the collection knife out of the soil, and transfers the collected soil sample into a bar-coded storage container. The GPS location of the soil sample is associated with the storage container&#39;s bar-code in a data file. The interval between successive periodic soil samples corresponds to a determined forward displacement of the tractor. Storage containers that have received soil samples are moved to a storage area until all of the soil samples for a given field have been collected.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/686,014, filed on Nov. 27, 2012, now U.S. Pat. No. 9,116,078. 
    
    
     TECHNICAL FIELD 
     This disclosure generally relates to soil sample collection and analysis, and more particularly to a soil sampler that automatically acquires and stores soil samples while being drawn through a farm field. 
     BACKGROUND OF THE INVENTION 
     Soil samples (usually the top 7 inches or so of the topsoil) are taken from farm fields and sent to a soil analysis lab to analyze the different soil nutrients contained in the samples. This analysis is used to determine the correct amount of nutrients to apply to farm fields. In the past, the process of collecting the soil samples was a slow tedious job done with a hand probe. Recently some automation has been added to soil sampler equipment to remove some of the hard work, but none have significantly increased the speed of sampling. 
     There is considerable variability of nutrient content in soil samples taken from different locations in a farm field. The only way to accurately measure this variability is to increase the number of samples taken within a field. But with conventional soil sampling techniques and mechanisms, this can become cost prohibitive due to the time required to collect the samples. Accordingly, what is needed is an improved and automated way of consistently and reliably acquiring soil samples for nutrient analysis. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an automated soil sampler that is removably mounted on an agricultural tractor, and that collects soil samples in a farm field while the tractor is driven through the field. The operator of the tractor manages the operation of the soil sampler from the cab of the tractor. At a periodic interval, the soil sampler lowers a soil collection knife into the soil for approximately 5 seconds to collect a soil sample, raises the collection knife out of the soil, and places the collected soil sample into a bar-coded storage container. When the soil sampler lowers the collection knife into the ground, it notes the GPS location of the soil sample and associates the noted GPS location with the storage container&#39;s bar-code in a data file. The interval between successive periodic soil samples corresponds to a determined forward displacement of the tractor (such as 150′). Storage containers that have received soil samples are moved to a storage area until all of the soil samples for a given field have been collected. 
     The soil sampler includes a soil breakdown assembly that leads the soil collection knife in preparation for soil sampling. The soil breakdown assembly includes an in-line rotating disk longitudinally aligned with the soil collection knife for cutting an initial furrow in the soil to be sampled, and an inwardly-toed slotted disk that shoves aside rocks, plant matter and other debris so that relatively clean soil is confronted by the soil collection knife. The collection knife has a series of sampling chambers that collect samples of topsoil at different soil depths, and a canted press wheel laterally offset from the collection knife urges soil into the sampling chambers as the collection knife is drawn through the soil by the forward movement of the tractor. 
     The soil sampler further includes a carrousel that carries empty storage cups, and a cup mover assembly that receives empty storage cups from the carousel and places one of them in a soil receiving station. A spout mechanism transfers a soil sample from the sampling chambers of the collection knife to the empty storage cup in the soil receiving station, and the filled storage cup is then transferred to a storage area. 
     With the disclosed soil sampler, the time required to collect soil samples has been greatly reduced, significantly increasing the number of samples that can be collected per hour. This greatly increases the precision and accuracy of nutrient maps developed from the soil sample lab results without significantly increasing the sample collection cost. And with accurate nutrient maps, farmers need only apply nutrients where needed, reducing environmental risk and improving profitability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a tractor and an automated soil sampler according to this invention, with the soil sampler in its transport position. 
         FIG. 2  is a side view of a tractor and an automated soil sampler according to this invention, with the soil sampler in its working position, and the soil collection knife lowered. 
         FIG. 3  is a close up view of soil sampler as depicted in  FIG. 1 , but sectioned to reveal critical soil sampling components. 
         FIG. 4  is a close up view of soil sampler as depicted in  FIG. 2 , but sectioned to reveal critical soil sampling components. 
         FIG. 5  is a rear view of the soil sampler in its working position, and the soil collection knife lowered. 
         FIG. 6  is a rear view of the soil sampler in its working position, and the soil collection knife raised. 
         FIG. 7  is an opposite side view of the soil sampler with outer covering removed to reveal the cup carrousel. 
         FIG. 7 a    is a close up view of  FIG. 7 , sectioned to reveal a cup drop mechanism. 
         FIG. 8  is a rear view of soil sampler with outer covering removed to reveal the cup carrousel and sample storage apparatus. 
         FIG. 9  is a sectional view of the cup carrousel taken along line  9 - 9  of  FIG. 8 . 
         FIG. 10  is a sectional view taken along line  10 - 10  of  FIG. 8  to reveal the cup mover assembly. 
         FIG. 11  is a close up view of the soil collection knife. 
         FIG. 12  is a sectional view of the soil collection knife taken along line  12 - 12  of  FIG. 8 . 
         FIG. 12 a    is a sectional view of the soil collection knife as in  FIG. 12 , but with the armature retracted to expel a soil sample. 
         FIG. 13  is a sectional view of the soil collection knife taken along line  13 - 13  of  FIG. 12 . 
         FIG. 14  is a sectional view of the soil collection knife taken along line  14 - 14  of  FIG. 12 . 
         FIG. 14 a    is a sectional view of the soil collection knife as in  FIG. 14 , but with the armature retracted to expel a soil sample. 
         FIG. 15  is an isometric view of a collection cup revealing the bar code on its bottom surface. 
         FIGS. 15 a , 15 b , 15 c  and 15 d    depict a flow diagram representative of software code executed by the microcontroller of  FIG. 16  for controlling the operation of the disclosed soil sampler. 
         FIG. 16  is a block diagram of a microcontroller of the soil sampler. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-7  variously depict a soil sampler  12  according to this invention, as mounted on a conventional three-point hitch of a tractor  10 . As best seen in  FIG. 7 , the top link  11   a  of the three-point hitch is coupled to an upper frame element  21   a,  and the lift arms  11   b  of the three-point hitch are coupled to a lower frame element  21   b.    FIGS. 1 and 3  show the soil sampler  12  in a transport position with the lift arms  11   b  raised, while  FIGS. 2 and 4-7  show the soil sampler  12  in a working position with the lift arms  11   b  lowered. A hydraulic system including various solenoid valves and hydraulic valves necessary to the below-described operation of soil sampler  12  is generally designated in  FIGS. 5-7  by the reference numeral  28 . 
     The soil sampler  12  includes a soil breakdown assembly  13  that prepares the soil for sample collection and a soil collection knife  18  that is momentarily lowered into the soil rearward of the soil breakdown assembly  13  to collect soil at several different soil depths, and then raised to expel the collected soil for transfer to a soil storage mechanism  57 . The soil breakdown assembly  13  is located forward of the lowered soil collection knife  18 , and includes two rotary members that rotate with forward displacement of the tractor  10  when the soil sampler  12  is in the working position. The rotary members include a leading in-line disk  14 , and an inwardly-toed slotted disk  16  following the in-line disk  14 . The in-line disk  14  is longitudinally aligned with the soil collection knife  18 , and slices open the soil in advance of the soil collection knife  18 . The inwardly-toed slotted disk  16  is slightly offset from the initial furrow, and shoves aside rocks, plant matter and other debris so that relatively clean soil is confronted by the soil collection knife  18 . 
     As best seen in  FIGS. 3, 4 and 7 , the soil breakdown assembly  13  is mounted with respect to the lower frame member  21   b  on a swinging arm  24  such that in-line disk  14  and inwardly-toed disk  16  are raised above the ground when the soil sampler  12  is in its transport position ( FIG. 3 ) and lowered into contact with the ground when the soil sampler  12  is in its working position ( FIGS. 4 and 7 ). The inwardly-toed disk  16  is supported on an arm  16   a  that pivots about the axle of in-line disk  14 , and a spring  17  biases inwardly-toed slotted disk  16  against the soil. An air bag  15  disposed between upper frame member  21   a  and the swinging arm  24  is selectively inflated as described below to bias in-line disk  14  into the soil whenever the soil collection knife  18  is lowered. 
     As best seen in  FIGS. 11-13 , the soil collection knife  18  has a metal housing  83  that terminates in a knife blade  70  which cuts through the soil in the furrow opened by in-line disk  14 . A longitudinal cavity  83   a  spans the length of housing  83 , and knife blade  70  is open on one side to expose the cavity  83   a , as best seen in  FIGS. 12 and 12   a . A metal plate  89  fastened to housing  83  partially covers the knife blade opening to form a soil capture slot  90  that spans the height of the knife blade  70 , as best seen in  FIGS. 11 and 13 . The leading edge of the plate  89  is inwardly beveled as shown in  FIG. 13  to form a cutting edge  89   a  that shears off a thin sliver of soil as the soil collection knife blade  70  is drawn through the soil, and directs the sheared-off soil through the soil capture slot  90  and into the cavity  83   a . Advantageously, the plate  89  is adjustably fastened to the housing  83  so that the width of the soil capture slot  90  can be increased or decreased to suit the condition of the soil being sampled. As explained below, the housing  83  of soil collection knife  18  additionally includes a soil release opening  86  above the knife blade  70  through which a collected soil sample is expelled once the soil collection knife  18  has been raised. 
     As best seen in  FIGS. 3-4 , the soil collection knife  18  is part of a collection knife assembly  19 , and the assembly  19  is mounted on a tubular member  21   c  that is pivotably supported by the soil sampler frame. A hydraulic cylinder  22  mounted on the soil sampler frame is selectively extended to rotate the collection knife assembly  19  toward tractor  10  and thereby raise the soil collection knife  18 , or retracted to rotate the collection knife assembly  19  away from tractor  10  and thereby lower the soil collection knife  18  into the soil to be sampled.  FIGS. 2 and 4-5  illustrate the soil collection knife  18  in the lowered position, and  FIGS. 1, 3 and 6-7  illustrate the soil collection knife  18  in the raised position. In use, the soil collection knife  18  is only lowered when the soil sampler  12  is in its working position. 
     As best seen in  FIGS. 5-6 , a resilient wiper  23  is clamped in a support bracket  23   a , and the support bracket  23   a  is mounted on the soil sampler frame in proximity to the collection knife assembly  19  such that the knife blade  70  brushes against the wiper  23  each time the hydraulic cylinder  22  is extended and retracted to raise and lower the soil collection knife  18 . Specifically, the wiper  23  brushes across the soil capture slot  90  of the knife blade  70  to scrub off soil or debris clinging thereto. 
     As best seen in  FIG. 5 , the soil sampler  12  additionally includes a toothed canted press wheel  20  that is laterally offset from the soil capture slot  90  of knife blade  70 . The press wheel  20  is supported on an arm  20   a  that is pivotally mounted on the frame of soil sampler  12  such that the press wheel  20  is lifted in the air when the soil sampler  12  is in its transport position ( FIGS. 1 and 3 ), and resting on the soil when the soil sampler  12  in its working position ( FIGS. 2 and 4-7 ). With the soil sampler  12  in its working position, the press wheel  20  rolls along the soil surface, and the peripheral teeth of the press wheel  20  prevent it from skidding when it encounters field debris. Due to its canted orientation, press wheel  20  biases the surface soil laterally towards the soil capture slot  90  of knife blade  70  to ensure consistent and reliable sampling of soil lying near the ground surface. 
     As illustrated in  FIGS. 11-14 , the knife blade  70  of soil collection knife  18  incorporates a series of four sampling chambers  72 ,  74 ,  75 ,  76  inboard of the soil capture slot  90 . The sampling chambers  72 ,  74 ,  75 ,  76  are disposed at different soil depths to collect samples of topsoil at different soil depths, and the canted press wheel  20  urges soil into the sampling chambers  72 ,  74 ,  75 ,  76  as the knife blade  70  is drawn through the soil by the forward movement of the tractor  10 . The sampling chambers  72 ,  74 ,  75 ,  76  are physically defined by the housing  83  of soil collection knife  18  and the teeth  85   a ,  85   b ,  85   c ,  85   d  of a linear armature  84  slidably received within the housing cavity  83   a . The teeth  85   a  - 85   d  are disposed at the outboard end of armature  84 , and the position of armature  84  within the housing  83  is controlled by a hydraulic cylinder  77 , as best seen in  FIG. 5 and 14-14   a .  FIGS. 12, 14 and 12   a ,  14   a  respectively depict extended and retracted positions of the armature  84 . When the hydraulic cylinder  77  is retracted as shown in  FIGS. 12 and 14 , the armature  84  is fully extended into the knife blade  70 , and the teeth  85   a  - 85   d  of armature  84  are aligned with the soil capture slot  90  to collect soil samples. When the hydraulic cylinder  77  is extended as shown in  FIGS. 12 a  and 14 a   , the armature  84  is retracted from knife blade  70  so that the collected soil samples in sampling chambers  72 ,  74 ,  75 ,  76  can be expelled through the soil release opening  86  of housing  83 . A swinging panel or trap door  87  covers the soil release opening  86  when the soil collection knife  18  is lowered (as illustrated in  FIG. 11 ) to prevent soil from entering the soil release opening  86 , and uncovers the opening  86  when the soil collection knife  18  is raised (as illustrated in  FIGS. 12 and 12   a ) to allow the collected soil sample to be expelled. As shown in  FIGS. 12 and 12   a , the trap door  87  pivots about a pin  87   a  and a cable  88  coupling the trap door  87  to a frame member of soil sampler  12  affirmatively opens the trap door  87  when the soil collection knife  18  is raised. 
     The armature  84  can be advantageously equipped with a slot clean-out attachment  84   a , as best seen in  FIGS. 12 and 12   a . In the illustrated embodiment, the clean-out attachment  84   a  is removably fastened the outboard end of armature  84 , and includes a tab  84   b  that protrudes through the soil capture slot  90  just beyond the outermost armature tooth  85   a . Each time the armature  84  is extended and retracted, the tab  84   b  of clean-out attachment  84   a  correspondingly moves within the soil capture slot  90  to remove any soil, mud or debris lodged in the soil capture slot  90 . This action, along with the wiping action of wiper  23 , ensures that the soil capture slot  90  will be fully open and unblocked when the soil collection knife  18  is subsequently lowered to collect the next soil sample. 
     After the soil collection knife  18  has been drawn through the soil for a predetermined distance (or time), the hydraulic cylinder  22  is extended to raise the soil collection knife  18  out of the soil as illustrated in  FIG. 6 . As the soil collection knife  18  is being raised, the trap door  87  swings open to uncover soil release opening  86 , and once the soil collection knife  18  is fully raised, a movable spout  27   a  is positioned under the soil release opening  86 , as illustrated in  FIGS. 6 and 8 . The hydraulic cylinder  77  is then extended to bring the teeth  85   a  - 85   d  of armature  84  into registry with the soil release opening  86  to expel the soil sample. In practice, the hydraulic cylinder  77  is cycled several times to produce repeated fore and aft movement of the armature  84  within the collection knife housing  83  to dislodge the soil samples from the sampling chambers  72 ,  74 ,  75 ,  76 . Additionally, an air nozzle  91  blows high-pressure air into the sampling chambers  72 ,  74 ,  75 ,  76  as they come into registry with the soil release opening  86  to help expel the soil sample, as illustrated in  FIG. 12 a   . Compressed air for this and other purposes mentioned herein is obtained from an on-board air compressor  25  and pressure tank  25   a , depicted in  FIGS. 1-2 . 
     The soil expelled through the soil release opening  86  drops into the movable spout  27   a , which together with a fixed spout  27   b , transfers the soil to a storage cup  50  positioned by a cup mover assembly  30  of the soil storage mechanism  57 , as seen in  FIGS. 6 and 8 . Once the soil sample has been dislodged and transferred to the storage cup  50 , the movable spout  27   a  is retracted, allowing the soil collection knife  18  to be lowered to collect the next soil sample. 
     While all of the sampling chambers  72 ,  74 ,  75 ,  76  can be combined for producing a composite of the soil profile as described above, it is alternatively possible to individually expel and collect the soil collected in sampling chambers  72 ,  74 ,  75 ,  76  if desired. That would provide separate soil samples at various depths in the location where the samples are collected. 
     As best seen in  FIGS. 5-6 and 8 , the movable and fixed spouts  27   a  ,  27   b  cooperate to transfer a collected soil sample from the soil release opening  86  of soil collection knife  18  to a storage cup  50  positioned by cup mover assembly  30 . The fixed spout  27   b  is mounted above the storage cup  50  at an angle defined by the relative locations of the storage cup  50  and the soil release opening  86 . Both ends of the fixed spout  27   b  are open, and the lower end is positioned just above the collection cup  50 . The movable spout  27   a  is mounted on one end of a slide plate  92 , at an angle defined by the relative locations of the soil release opening  86  and the upper end of fixed spout  27   b . The slide plate  92  is slidably supported in a set of mounting brackets  94 ,  95  on the underside of a platform  47  above the cup mover assembly  30 , and a hydraulic cylinder  36  mounted on the underside of platform  47  is coupled to the plate  92  for controlling the lateral position of plate  92 , and hence, movable spout  27   a . When the hydraulic cylinder  36  is fully retracted, as shown in  FIG. 5 , the movable spout  27   a  is in a home position, allowing the soil collection knife  18  to be lowered and then raised as described above. When the hydraulic cylinder  36  is fully extended, as shown in  FIGS. 6 and 8 , the movable spout  27   a  is in a soil transfer position in which its lower end is aligned with the upper end of fixed spout  27   b , and its upper end is positioned under the soil release opening  86  of soil collection knife  18 . In this soil transfer position, a soil sample expelled from the soil release opening  86  is routed to the collection cup  50  through the combination of movable spout  27   a  and fixed spout  27   b.    
     As shown in  FIG. 8 , the cup mover assembly  30  is mounted on a metal platform  52  disposed below the platform  47 , and a cup dispensing chute  48  extends downward from the platform  47  toward the cup mover assembly  30  for delivering empty storage cups  50  to the cup mover assembly  30 . And as best seen in  FIG. 10 , the cup mover assembly  30  includes a cup translating member  30   a  mounted for rotation within a frame  30   b . A servomotor  44  is coupled to a central hub of cup translating member  30   a  via speed reduction gearing  32  and drive shaft  44   a  for controlling the rotation of cup translating member  30   a  within the frame  30   b , and an encoder  44   b  senses its rotary orientation. The cup translating member  30   a  has two oppositely disposed peripheral recesses  31   a ,  31   b , each sized to accommodate a storage cup  50 , so that a storage cup  50  placed in a given peripheral recess  31   a ,  31   b  rests on the platform  52 , and is laterally trapped between the given recess  31   a ,  31   b  and the fame  30   b.    
     As best seen in  FIG. 8 , the cup mover assembly  30  is configured so that when one of the recesses  31   a ,  31   b  is vertically aligned with the cup dispensing chute  48  (referred to herein as the cup drop station), the oppositely disposed recess  31   b ,  31   a  will be vertically aligned with the lower end of the fixed spout  27   b  (referred to herein as the soil receiving station). In operation then, the servo motor  44  rotates the cup translating member  30   a  so that a given peripheral recess  31   a ,  31   b  stops in the cup drop station, and after an empty storage cup  50  is dispensed from the chute  48 , rotates the cup translating member  30   a  by 180 degrees so that the empty storage cup  50  is translated to the soil receiving station. At such point, another empty storage cup  50  may be dispensed into the recess  31   a ,  31   b  that is in the cup drop station, and a new soil sample from soil collection knife  18  may be routed via the movable and fixed spouts  27   a ,  27   b  into the storage cup  50  in the soil receiving station. Thereafter, the servomotor  44  can be activated to rotate the cup translating member  30   a  by another 180 degrees so that the empty storage cup  50  the in cup drop station is translated to the soil receiving station, and the just-filled storage cup  50  is ejected from the cup mover assembly  30  through an opening  30   c  in the frame  30   b , as illustrated in  FIG. 10 . The filled storage cups  50  ejected from the cup mover assembly  30  continue to rest on the platform  52  and are pushed rearward of the cup mover assembly  30  onto a storage area portion of the platform  52  where all filled storage cups  50  are temporarily stored. As best seen in  FIG. 7 , the platform  52  extends well rearward of the cup mover assembly  30 , and in the illustrated embodiment encompasses an area sufficient to hold about 200 storage cups  50 . 
     As illustrated in  FIG. 15 , an identification label is affixed to the bottom of each storage cup  50  so that the soil sampler  12  can scan the identification labels as the storage cups  50  are filled with soil samples and store the identification codes along with the corresponding GPS location markers. In the preferred embodiment of this invention, the identification code of a given storage cup  50  is scanned when the storage cup  50  is in the soil receiving station of cup mover assembly  30 . To this end, a small opening is formed in platform  52  so that a scanner  54  mounted below the platform  52  can scan the identification code of a storage cup  50  in the soil receiving station of cup mover assembly  30 , as best seen in  FIG. 8 . An air nozzle  60  blows air across the scanner  54  to remove extraneous dirt or other debris that could interfere with the scanning. Other air nozzles may also be directed toward the cup mover assembly  30  to blow away loose dirt that might otherwise interfere with the operation of the moving components. 
     Empty storage cups  50  that will eventually be dispensed into the cup mover assembly  30  as described above are stored in a carousel  25  that is rotatably mounted on the upper surface of platform  47 , as best seen in  FIG. 8 . The empty storage cups  50  are stacked in a number of vertically disposed plastic tubes  25   a  supported about the periphery of carousel  25 , as illustrated in  FIGS. 8-9 . A servomotor  40  is coupled to carousel  25  via reduction gearing  25   b  for controllably rotating the carousel  25 , and as the carousel  25  is rotated, each of the plastic tubes  25   a  is successively brought into vertical alignment with the cup dispensing chute  48 , as best seen in  FIG. 9 . The platform  47  has an opening  47   a  directly above the cup dispensing chute  48 , and a slide gate  49  disposed between the carousel  25  and the top of platform  47  can be extended upon activation of an electric motor  49   a  to cover the opening  47   a . In use, the slide gate  49  is extended to cover the opening  47   a  when the servomotor  40  is activated to rotate the carousel  25 , and retracted to uncover the opening  47   a  once the carousel  25  has been positioned so that one of the plastic tubes  25   a  is vertically aligned with the cup dispensing chute  48 . Once the slide gate  49  has been retracted to uncover the opening  47   a  (as shown in  FIG. 9 ), the empty soil collection cups  50  stacked in the vertically aligned tube  25   a  are free to drop into the chute  48 . A sensor  25   d  mounted adjacent the periphery of carousel  25  in vertical alignment with the chute  48  detects when the respective plastic tube  25   a  is empty of cups  50 , signaling that it is time to extend the slide gate  49  and activate servomotor  40  to advance the carousel  25  and bring a different plastic tube  25   a  into alignment with the chute  48 . 
     Once a stack of empty storage cups  50  have been dropped into the cup dispensing chute  48 , a cup drop mechanism  45  is selectively activated to separate out one storage cup  50  and deliver it to the cup drop station of cup mover assembly  30  as described above. As seen in  FIGS. 7, 7   a  and  8 , the cup drop mechanism  45  includes two gripper wheels  46   a  and  46   b  oppositely disposed about the chute  48  that slightly protrude into the chute  48  through oppositely disposed openings  48   a  and  48   b  formed in the sidewall of chute  48 . When a stack of storage cups  50  is dropped into the chute  48 , the bottom-most storage cup  50  comes into contact with the periphery of wheels  46   a  and  46   b  , and cannot move lower in the chute  48  until the wheels  46   a ,  46   b  rotate in a direction to produce downward movement. In the illustrated embodiment, the wheel  46   a  is a driven wheel, while the wheel  46   b  is an idler wheel, biased toward the chute by a spring  46   c . A servomotor  46   d  coupled to the axle of wheel  46   a  is selectively activated to rotate the wheel  46   a , and a sensor  46 e mounted on platform  52  adjacent cup mover assembly  30  detects the presence or absence of a storage cup  50  in the cup drop station of cup mover assembly  30 . In operation, a storage cup  50  is dispensed by activating the servomotor  46   d  until the sensor  46 e detects that a storage cup  50  has been dropped into the cup drop station of cup mover assembly  30 , and then deactivating the servomotor  46   d.    
     It should be understood that various limit switches and position encoders are employed to control or confirm completion of the required movements described above, even though such switches and encoders have not been illustrated in order to not overly complicate the drawings. 
     In order to operate the soil sampler  12 , a microprocessor-based controller  112  such as a Renu Model FT4057T-E Controller may be mounted in the cab of tractor  10 . The Renu controller, for example, has a number of slots for receiving digital and analog I/O modules, and executes a software program such as generally described by the flow diagram of  FIGS. 15 a -15 d    for regulating the operation of soil sampler  12 . It will be appreciated that other controllers could alternatively be used. The controller  112  and other electrical system components of the soil sampler  12  are generally depicted in the block diagram of  FIG. 16 . As indicated, the controller  112  has communication ports for receiving inputs from various devices including the tractor&#39;s GPS unit  114 , barcode reader  54 , motor encoder  44   b , and the various other sensors and encoders. Controller  112  also has a USB port for a portable memory device  118  for recordation of the data collected during a soil sampling run, a touchscreen display/interface, and a power supply  120 . Power supply  120  has an emergency stop  122 , receives power from tractor  10  and outputs both a 12V signal and a 24V signal. 
       FIGS. 15 a -15 d    are flow diagrams representative of software routines executed by the controller  112  of  FIG. 16  for controlling the operation of the soil sampler  12 . Referring initially to  FIG. 15 a   , soil sampling operation is initialized at block  200  once the operator has moved the tractor  10  into the field to be sampled and lowered the soil sampler  12  into the working position, as depicted in  FIG. 2 . As indicated at block  200 , the initialization process includes initializing/resetting the system controller  112  and the various flags and counters/timers, initializing/homing the carousel  25  and cup mover assembly  30 , and turning on an on-board air compressor  25  to build up a supply of compressed air for the various air nozzles. 
     Following initialization, block  202  is executed to activate the servomotor  46   d  of cup drop mechanism  45  until an empty storage cup  50  has been dispensed into the cup drop station of cup mover assembly  30 , and block  204  is executed to activate servomotor  44  to rotate the cup translating member  30   a  of cup mover assembly  30  by 180 degrees to move the dispensed storage cup  50  into the soil receiving station. The blocks  206 - 208  are then executed to re-activate the servomotor  46   d  until another empty storage cup  50  has been dispensed into the cup drop station, and to activate the scanner  54  to read the identification code of the storage cup  50  resting in the soil receiving station. The air nozzle  60  is also activated at this time to clear the scanner  54  of any soil or debris. If the identification code is not successfully read, as determined at block  210 , it is assumed either that there is no storage cup in the soil receiving station, or that the cup&#39;s identification code has been damaged or obscured for some reason; in this case, the blocks  204 - 208  are re-executed to advance the cup translating member  30   a  of cup mover  30  by 180 degrees, to dispense another empty storage cup  50  into the cup drop station, and to scan the identification code of the storage cup  50  now resting in the soil receiving station. 
     When block  210  confirms that the identification code of the storage cup  50  in the soil receiving station has been successfully scanned, the remaining blocks  212 - 226  of  FIG. 15 a    are executed as indicated to determine the sampling mode (i.e., automatic or manual), and if the soil sampler  12  is ready to initiate sampling. If the operator has requested initiation of automatic sampling (AUTO-SAMPLE), block  212  is answered in the affirmative, and block  214  determines if the conditions for the auto-sample mode have been met. These conditions may include, for example, soil sampler  12  in working position, tractor  10  moving forward at the specified speed, movable spout  27   a  retracted, etc. If one or more of the conditions are not met, block  216  is executed to notify the operator so that the required change(s) can be made—for example, the display of controller  112  may be used to advise the operator to lower the soil sampler  12  to the working position. Once the conditions have been met, block  218  directs the controller  112  to execute the auto-sample routine, which is represented by the flow diagram of  FIG. 15   b.    
     In a similar way, block  220  determines if the operator has requested initiation of manual sampling (MANUAL-SAMPLE). The manual sampling mode differs from automatic sampling in that the operator manually initiates the collection of each soil sample as the tractor  10  is driven though the field. If block  220  is answered in the affirmative, block  222  determines if the conditions for the manual-sample mode have been met. These conditions may be the same or similar to the conditions for automatic sampling mentioned above in reference to block  214 . If one or more of the conditions are not met, block  224  is executed to notify the operator so that the required change(s) can be made; and once the conditions have been met, block  226  directs the controller  112  to execute the manual-sample routine, which is represented by the flow diagram of  FIG. 15   c.    
     Referring now to the auto-sample routine of  FIG. 15 b   , the block  230  is first executed to determine if the soil collection knife  18  is already lowered. Initially of course, block  230  will be answered in the negative, and blocks  232 - 240  are executed to initiate sample collection at the proper time. A timer value (Sample_Interval_Timer) measures the time since the last soil sample was initiated; it is compared to a first reference time (Ref_Time_ 1 ) at block  232  to determine when it is time to initiate soil sample collection, and to a second reference time (Ref_Time_ 2 ) at block  242  to determine when it is time to raise the soil collection knife  18  and expel the collected soil sample. 
     As mentioned above, block  230  will initially be answered in the negative, and block  232  is executed to compare Sample_Interval_Timer to Ref_Time_ 1 . The timer Sample_Interval_Timer is initialized to zero at system initialization, and block  232  will be answered in the negative until it reaches Ref_Time_ 1 , which may correspond to a calibrated time interval such as 45 seconds, where 45 seconds at 5 MPH yields a distance of 330 feet between samples. When block  232  is answered in the negative, the controller  112  is directed back to block  212  of  FIG. 15 a   , as indicated by the circled letter B. When Sample_Interval_Timer reaches Ref_Time_ 1 , it is time to collect a soil sample, but block  234  is executed first to make sure the movable spout  27   a  is retracted; if not, the blocks  236  and  238  are executed to notify the operator and to suspend sampling until the spout  27   a  is retracted. If the spout  27   a  is retracted, block  240  is executed to pressurize air bag  15  for producing additional down force on the in-line disk  14 , to lower the soil collection knife  18 , to reset Sample_Interval_Timer, and to note the GPS latitude and longitude readings and tag them to the storage cup identification code scanned at block  208 . In subsequent executions of the routine, block  230  will be answered in the affirmative so that the controller  112  will skip blocks  232 - 240  as indicated. 
     Once the soil collection knife  18  has been lowered to initiate soil sampling, the controller  112  periodically executes block  242  to determine if it is time to raise the soil collection knife  18  and expel the soil sample. As indicated above, block  242  compares Sample_Interval_Timer to Ref_Time_ 2 , which may correspond to a calibrated time interval such as 7 seconds. Initially, of course, block  242  will be answered in the negative, and the controller  112  is directed back to block  212  of  FIG. 15 a   , as indicated by the circled letter B. When Sample_Interval_Timer reaches Ref_Time_ 2 , it is time to raise soil collection knife  18 , but block  244  is executed first to make sure the movable spout  27   a  is retracted; if not, the blocks  246  and  248  are executed to notify the operator and to suspend sampling until the spout  27   a  is retracted. If the spout  27   a  is refracted, block  250  is executed to relieve the pressure in air bag  15 , and to raise soil collection knife  18 . Then block  252  is executed to extend the movable spout  27   a , to temporarily activate the air nozzle  91 , and to cycle the armature  84  a preset number of times (two, for example) to expel the collected soil through the soil release opening  86  and into the movable spout  27   a  positioned thereunder. Finally, block  254  is executed retract the movable spout  27   a  and to rotate the cup translating member  30   a  of cup mover assembly  30  by 180 degrees so that the storage cup  50  holding the new soil sample is transferred to the cup storage area of platform  52 , and the empty storage cup  50  dispensed at block  206  is rotated into the soil receiving station. The controller  112  is then directed back to block  206  of  FIG. 15 a   , as indicated by the circled letter A, where another empty storage cup  50  is dispensed into the cup mover assembly  30 , as described above. 
     Referring to  FIG. 15 c   , the flow chart for the manual sampling mode is similar to the above-described auto-sample flow chart, with one notable exception: the soil collection knife  18  is only lowered to collect a soil sample when the operator activates a Manual Sample Command via controller  112 . In the flow chart, the Manual Sample Command is designated as a flag that changes from False to True when the operator activates a manual sample command. To begin the routine, the block  260  is executed to determine if the soil collection knife  18  is lowered. Initially, of course, block  260  will be answered in the negative, and block  262  is executed to determine if the Manual Sample Command is True. If not, the controller  112  is returned to block  220  of  FIG. 15 a   , as indicated by the circled letter C. If block  262  is answered in the affirmative, block  264  is executed to make sure the movable spout  27   a  is retracted; if not, the blocks  266  and  268  are executed to notify the operator and to suspend sampling until the spout  27   a  is retracted. If the spout  27   a  is retracted, block  270  is executed to pressurize air bag  15  for producing additional down force on the in-line disk  14 , to lower the soil collection knife  18 , to reset Sample_Interval_Timer, and to note the GPS latitude and longitude readings and tag them to the storage cup identification code scanned at block  208 . In subsequent executions of the routine, block  260  will be answered in the affirmative so that the controller  112  will skip blocks  262 - 270  as indicated. 
     Once the soil collection knife  18  has been lowered to initiate soil sampling, the controller  112  periodically executes block  272  to determine if it is time to raise the soil collection knife  18  and expel the soil sample. As in the auto-sample mode, block  272  compares Sample_Interval_Timer to Ref_Time_ 2 , which may correspond to a calibrated time interval such as 7 seconds. Initially, of course, block  272  will be answered in the negative, and the controller  112  is directed back to block  220  of  FIG. 15 a   , as indicated by the circled letter C. When Sample_Interval_Timer reaches Ref_Time_ 2 , it is time to raise soil collection knife  18 , but block  274  is executed first to make sure the movable spout  27   a  is retracted; if not, the blocks  276  and  278  are executed to notify the operator and to suspend sampling until the spout  27   a  is retracted. If the spout  27   a  is refracted, block  280  is executed to relieve the pressure in air bag  15 , and to raise soil collection knife  18 . Then block  282  is executed to extend the movable spout  27   a , to temporarily activate the air nozzle  91 , and to cycle the armature  84  a preset number of times (two, for example) to expel the collected soil through the soil release opening  86  and into the movable spout  27   a  positioned thereunder. Finally, block  284  is executed retract the movable spout  27   a  and to rotate the cup translating member  30   a  of cup mover assembly  30  by 180 degrees so that the storage cup  50  holding the new soil sample is transferred to the cup storage area of platform  52 , and the empty storage cup  50  dispensed at block  206  is rotated into the soil receiving station. The controller  112  is then directed back to block  206  of  FIG. 15 a   , as indicated by the circled letter A, where another empty storage cup  50  is dispensed into the cup mover  30  assembly, as described above. 
     Finally, the flow chart of  FIG. 15 d    represents a number of background routines periodically executed by the controller  112 . These include, for example, updating various counters (block  290 ), scanning sensors and setting flags accordingly (block  292 ) and updating failure checking and operator warnings (block  294 ). More pertinent to the present invention, the blocks  296 - 298  designate a background routine for controlling rotation of carousel  25 . The block  296  checks the status of a flag representing the state of the chute sensor  25   d ; the flag (Carousel_Cup_Tube_Empty) is False when one or more empty storage cups  50  remain in the active cup tube  25   a  (i.e., the cup tube vertically aligned with the cup dispensing chute  48 ), and True when no empty storage cups  50  remain in the active cup tube  25   a . Thus, whenever block  296  is answered in the affirmative, block  298  is executed to extend the slide gate  49  to cover the opening  47   a  between carousel  25  and chute  48 , to activate the servomotor  40  to rotate the carousel  25  until a full plastic tube  25   a  is vertically aligned with the chute  48 , and then to retract the slide gate  49  to uncover the opening  47   a  so that the empty storage cups  50  stacked in the new cup tube  25   a  drop into the chute  48 . 
     In the manner described above, the soil sampler  12  of this invention efficiently carries out automatic or manually-triggered soil sampling and collection while the soil sampler  12  is being drawn through a field by the tractor  10 . The samples are collected and stored while the tractor  10  is on the move, and the sample locations are automatically and accurately logged and associated with the respective storage cups  50 . Moreover, each soil sample accurately represents a composite of the soil profile at the sampling location, enabling an accurate assessment of the soil nutrient levels. In a typical application, with the soil of a given field being sampled on a one-half acre grid, up to 500 acres (i.e., 1,000 samples) can be sampled in a single day. 
     While the soil sampler  12  and its operation have been described with reference to the illustrated embodiment, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope and essence of the disclosure. In addition, many modifications may be made to the teachings of the disclosure in order to adapt to a particular situation without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims.