Patent Publication Number: US-2021190754-A1

Title: Soil sensing systems and implements for sensing different soil parameters

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/573,408, filed on Oct. 17, 2017 entitled: SOIL SENSING SYSTEMS AND IMPLEMENTS FOR SENSING DIFFERENT SOIL PARAMETERS, the entire contents of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to systems and implements for sensing, analyzing, and displaying different soil parameters. 
     BACKGROUND 
     It is well known that proper and uniform seed trench depth, accurate placement of seed within the seed trench (at the proper depth and proper spacing), good seed-to-soil contact, and minimal crop residue within the seed trench are all critical factors in uniform seed emergence and high yields. Accordingly, various planter improvements have been proposed to achieve each of these factors. While conducting spot checks of the seed trench may help to provide some assurances that these critical factors are being achieved, such spot checks will only identify the conditions at the specific location being checked. Accordingly, there is a need for a system that will image the seed trench to verify and ensure these critical factors are being achieved during planting operations and to enable automatic or remote adjustment of the planter while on-the-go based on the images. There is a similar need for below-soil-surfacing-imaging and control for other types of agricultural implements, including tillage implements, sidedress or in-ground fertilizing implements and agricultural data gathering implements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example, and not by way of limitation, in the Figures of the accompanying drawings and in which: 
         FIG. 1  schematically illustrates one embodiment of a work layer sensor, in elevation view, disposed in relation a seed trench. 
         FIGS. 2A-2C  are representative examples of work layer images generated by the work layer sensor of  FIG. 1 . 
         FIG. 3  schematically illustrates another embodiment of a work layer sensor, in plan view, disposed in relation to a seed trench. 
         FIGS. 4A-4B  are representative examples of work layer images generated by the work layer sensor of  FIG. 3 . 
         FIG. 5  schematically illustrates another embodiment of a work layer sensor, in elevation view, disposed in relation to a seed trench. 
         FIG. 6  is a representative example of a work layer image generated by the work sensor of  FIG. 5 . 
         FIG. 7  is a side elevation view of an embodiment of a row unit of an agricultural planter incorporating a work layer sensor of  FIG. 1, 3 or 5 . 
         FIG. 8  illustrates an embodiment of a work layer implement monitoring, control and operator feedback system. 
         FIG. 9  is a chart showing a process for work layer implement monitoring, control and operator feedback. 
         FIG. 10  schematically illustrates another embodiment of a work layer sensor, in plan view, disposed in relation to a seed trench. 
         FIG. 11  schematically illustrates another embodiment of a work layer sensor, in plan view, disposed in relation to a seed trench. 
         FIG. 12  schematically illustrates another embodiment of a work layer sensor, in side view, disposed in relation to a seed trench. 
         FIG. 13  schematically illustrates, in side view, a spatial relationship between a transmitter and a receiver. 
         FIG. 14  schematically illustrates another embodiment, in side view, of a laser system. 
         FIG. 15  is representative example of work layer image generated by any of the work layer sensors. 
         FIG. 16A  illustrates raw soil data at different depths in accordance with one embodiment. 
         FIG. 16B  illustrates processed soil data at different depths in accordance with one embodiment. 
         FIG. 17  illustrates a monitor displaying soil density data. 
         FIG. 18  illustrates a monitor displaying soil density data. 
         FIG. 19  illustrates a monitor spatially displaying the depth of a first soil density change across a field. 
         FIG. 20  illustrates a monitor displaying soil density variability. 
         FIG. 21  illustrates a monitor displaying soil surface roughness. 
         FIG. 22  illustrates a monitor displaying residue mat thickness. 
         FIG. 23  illustrates a monitor spatially displaying residue mat thickness. 
         FIG. 24  shows an example of a system  1200  that includes a machine  1202  (e.g., tractor, combine harvester, etc.) and an implement  1240  (e.g., planter, sidedress bar, cultivator, plough, sprayer, spreader, irrigation implement, etc.) in accordance with one embodiment. 
         FIG. 25  illustrates a method  2500  of measuring residue mat thickness of residue in a field. 
         FIG. 26  illustrates a method  2600  to generate processed soil data. 
         FIG. 27  illustrates a method  2700  of measuring soil characteristics in a field. 
     
    
    
     BRIEF SUMMARY 
     Embodiments of the present disclosure relate to systems and implements for sensing, analyzing, and displaying different soil parameters. 
     DETAILED DESCRIPTION 
     All references cited herein are incorporated herein in their entireties. If there is a conflict between a definition herein and in an incorporated reference, the definition herein shall control. At least one of A, B, and C refers to a selection of A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A and B and C. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIGS. 1, 3 and 5  schematically illustrate alternative embodiments of a work layer sensor  100  to generate a signal or image representative of the soil densities or other soil characteristics throughout a soil region of interest, hereinafter referred to as the “work layer”  104 . The representative image or signal generated by the work layer sensor  100  is hereinafter referred to as the “work layer image”  110 . In one particular application discussed later, the work layer sensors  100  may be mounted to a planter row unit  200  ( FIG. 7 ) for generating a work layer image  110  of the seed trench as the planter traverses the field. The work layer image  110  may be displayed on a monitor  300  visible to an operator within the cab of a tractor and the planter may be equipped with various actuators for controlling the planter based on the characteristics of the work layer  104  as determined from the work layer image  110 . 
     The work layer sensor  100  for generating the work layer image  110  may comprise a ground penetrating radar system, an ultrasound system, an audible range sound system, an electrical current system or any other suitable system for generating an electromagnetic field  102  through the work layer  104  to produce the work layer image  110 . It should be understood that the depth and width of the work layer  104  may vary depending on the agricultural implement and operation being performed. 
       FIG. 1  is a schematic illustration of one embodiment of a work layer sensor  100 - 1  disposed in relation to a seed trench  10  formed in the soil  11  by a planter, wherein the seed trench  10  comprises the soil region of interest or work layer  104 . In this embodiment, the work layer sensor  100 - 1  comprises a transmitter (T 1 ) disposed on one side of the seed trench  10  and a receiver (R 1 ) disposed on the other side of the seed trench  10  to produce the electromagnetic field  102  through the seed trench to generate the work layer image  110 . 
     In some embodiments, the work layer sensor  100  may comprise a ground-penetration radar subsurface inspection system such as any of the following commercially available systems: (1) the StructureScan™ Mini HR available from GSSI in Nashua, N.H.; (2) the 3d-Radar GeoScope™ Mk IV coupled to a 3d-Radar VX-Series and/or DX-Series multi-channel antenna, all available from 3d-Radar AS in Trondheim, Norway; or (3) the MALA Imaging Radar Array System available from MALA Geoscience in Mala, Sweden. In such embodiments, the commercially available system may be mounted to the planter or other implement, or may be mounted to a cart which moves with the implement; in either case the system is preferably disposed to capture an image of a work layer in the area of interest (e.g., the seed trench). In some embodiments, the work layer image  110  may be generated from the signal outputs of the work layer sensor  100  using commercially available software such as GPR-SLICE (e.g., version 7.0) available from GeoHiRes International Ltd. located in Borken, Germany. 
       FIGS. 2A-2C  are intended to be representative examples of work layer images  110  generated by the work layer sensor  100 - 1  of  FIG. 1  showing various characteristics of the seed trench  10 , including, for example, the trench depth, the trench shape, depth of seed  12 , the seed depth relative to the trench depth, crop residue  14  in the trench, and the void spaces  16  within the trench. As described in more detail later, the work layer images  110  may be used to determine other characteristics of the work layer  104 , including, for example, the seed-to-soil contact, percentage of trench closed, percentage of upper half of trench closed, percentage of lower half of trench closed, moisture of the soil, etc. 
       FIG. 3  schematically illustrates, in plan view, another embodiment of a work layer sensor  100 - 2  disposed with respect to a seed trench  10 . In this embodiment, a transmitter (T 1 ) is disposed on one side of the seed trench  10 , a first receiver (R 1 ) is disposed on the other side of the seed trench  10 , and a second receiver (R 2 ) is disposed adjacent and rearward of the transmitter (T 1 ).  FIG. 4A  is a representative illustration of the work layer image  110  generated through the trench between the transmitter (T 1 ) and the first receiver (R 1 )) and  FIG. 4B  is a representative illustration of the work layer image  110  generated between the transmitter (T 1 ) and the second receiver (R 2 ) providing an image of the undisturbed soil adjacent to the seed trench. 
       FIG. 5  is an elevation view schematically illustrating another work layer sensor embodiment  100 - 3  disposed with respect to a seed trench  10 . In this embodiment, the work layer sensor  100 - 3  comprises a plurality of transmitter and receiver pairs disposed above and transverse to the seed trench  10 . 
       FIG. 6  is a representative illustration of the work layer image  110  generated by the work layer sensor  100 - 3  of  FIG. 5  which provides a view not only of the seed trench but also a portion of the soil adjacent to each side of the seed trench. 
       FIG. 10  schematically illustrates, in plan view, another embodiment of a work layer sensor  100 - 4  disposed with respect to a seed trench  10 . In this embodiment, a transmitter (T 1 ) is disposed over the seed trench  10 . Disposed rearward to transmitter (T 1 ) in a direction of travel are three receivers (R 1 ), (R 2 ), and (R 3 ). Receivers (R 1 ) and (R 3 ) are disposed over each side of seed trench  10 , respectively. Receiver (R 2 ) is disposed over seed trench  10 . Work layer images similar to those shown in  FIGS. 2A to 2C  can be generated by work layer sensor  100 - 4 . 
       FIG. 11  schematically illustrates, in plan view, another embodiment of a work layer sensor  100 - 5  disposed with respect to a seed trench  10 . In this embodiment, transmitter (T 2 ) is disposed over the seed trench  10 , and transmitters (T 1 ) and (T 3 ) are disposed over each side of seed trench  10 , respectively. Disposed rearward to transmitters (T 1 ), (T 2 ), and (T 3 ) in a direction of travel are three receivers (R 1 ), (R 2 ), and (R 3 ). Receivers (R 1 ) and (R 3 ) are disposed over each side of seed trench  10 , respectively. Receiver (R 2 ) is disposed over seed trench  10 . Work layer images similar to those shown in  FIGS. 2A to 2C  can be generated by work layer sensor  100 - 5 . 
       FIG. 12  schematically illustrates, in side view, another embodiment of a work layer sensor  100 - 6  disposed with respect to seed trench  10 . In this embodiment, transmitter (T 1 ) is disposed over the seed trench  10  and has a transmitting angle that encompasses both sides of seed trench  10 . Receiver (R 1 ) can be disposed adjacent to or rearward to transmitter (T 1 ). By having a transmitting angle that reaches both sides of seed trench  10 , the reflected signal received by receiver (R 1 ) is then an average of both sides of seed trench  10 . This provides a single measurement that is an average of the distance from the transmitter (T 1 ) to the seed trench  10 . 
     Any of the work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6  can also produce a work layer image as illustrated in  FIG. 15 .  FIG. 15  is a profile of an open seed trench  10 , shown with an optional seed. 
     For each of the work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6  the frequency of operation of the work layer sensors  100  and the vertical position of the transmitters (T) and receivers (R) above the soil and the spacing between the transmitters (T) and receivers (R) are selected to minimize signal to noise ratio while also capturing the desired depth and width of the soil region of interest (the work layer  104 ) for which the work layer image  110  is generated. In an embodiment illustrated in  FIG. 13 , the height of the receiver (R) above the ground can be less than the height of the transmitter (T) above the ground. An angle a formed between the transmitter (T) and the receiver (R) can be 0 up to 80°. 
     In an embodiment illustrated in  FIG. 14 , a laser (L 1 ) is positioned above a seed trench  10  and projects a laser into seed trench  10 . A receiver (R 1 ), such as a camera, is positioned to receive the reflected laser signal. Receiver (R 1 ) is at a height above ground that is less than the height of laser (L 1 ) above the ground. An angle b formed between the laser (L 1 ) and the receiver (R) can be greater than 0 up to 80°. The same control system can be used, with laser (L 1 ) replacing a transmitter (T). 
     In one embodiment, the transmitter frequency selected can be one that can penetrate vegetation and see the soil below. By not seeing the vegetation, a more accurate measurement is obtained for the depth of seed trench  10 . It has been determined that the higher the frequency, the more the radar signal is reflected by vegetation. In one embodiment, the frequency is 24 GHz. In another embodiment, the frequency selected can be one that can penetrate dust. Dust can be generated as an agricultural vehicle traverses a field. Frequencies in a range of 1 to 100 GHz can penetrate dust. In any of the work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6 , any of the transmitters (T) or receivers (R) can have a frequency that penetrates vegetation and dust. In another embodiment, any of the work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5  any of the transmitters (T) or receivers (R) can be replaced by multiple transmitters (T) or receivers (R) at the locations illustrated with each transmitter (T) or receiver (R) having a different frequency, such as one that will penetrate through vegetation and one that will penetrate through dust. A composite of the two work layers can be used to generate the profile of seed trench  10 . 
     In one embodiment, the radar is Doppler radar. Doppler radar can provide the speed of a row unit  200 , which can then be used in a control system to change the rate of application of an agricultural input to obtain a selected application per linear distance or area. Agricultural inputs include, but are not limited to, seed, fertilizer, insecticide, herbicide, and fungicide. The Doppler radar can be coherent pulsed, pulse-Doppler, continuous wave, or frequency modulation. The Doppler radar can be used with any of work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6 . 
     In one embodiment, the radar is a phased array radar. With a phased array radar, the signals generated by the phased array can be moved from side to side in seed trench  10  to provide a more detailed profile of seed trench  10 . The phased array radar can be used with any of work layer sensor embodiments  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6 . 
     Planter Applications  FIG. 7  illustrates one example of a particular application of the work layer sensors  100  disposed on a row unit  200  of an agricultural planter. The row unit  200  includes a work layer sensor  100 A disposed on a forward end of the row unit  200  and a work layer sensor  100 B disposed rearward end of the row unit  200 . The forward and rearward work layer sensors  100 A,  100 B may comprise any of the embodiments of the work layer sensors  100 - 1 ,  100 - 2 ,  100 - 3 ,  100 - 4 ,  100 - 5 ,  100 - 6  previously described. 
     The forward work layer sensor  100 A is disposed to generate a reference work layer image (hereinafter a “reference layer image”)  110 A of the soil prior to the soil being disturbed by the planter, whereas the rearward work layer sensor  100 B generates the work layer image  110 B, which in this example, is the image of the closed seed trench  10  in which the seed has been deposited and covered with soil. For the reasons explained later, it is desirable to obtain both a reference image  110 A and the work layer image  110 B for analysis of the soil characteristics through the work layer  104 . 
     It should be appreciated that the forward and rearward work layer sensors  100 A,  100 B referenced in  FIG. 7  may employ any of the embodiments  100 - 1 ,  100 - 2  or  100 - 3 . 100 - 4 ,  100 - 5 ,  100 - 6  previously described. However, it should be appreciated that if the embodiments  100 - 2 ,  100 - 3 ,  100 - 4 , or  100 - 5  are employed, the forward work layer sensor  100 A may be eliminated because the embodiments  100 - 2 ,  100 - 3 ,  100 - 4 , and  100 - 5  are configured to generate the work layer images  110  of undisturbed soil adjacent to the seed trench  10  which could serve as the reference layer image  110 A. 
     With respect to  FIG. 7 , the row unit  200  is comprised of a frame  204  pivotally connected to the toolbar  202  by a parallel linkage  206  enabling each row unit  200  to move vertically independently of the toolbar  202 . The frame  204  operably supports one or more hoppers  208 , a seed meter  210 , a seed delivery mechanism  212 , a downforce control system  214 , a seed trench opening assembly  220 , a trench closing assembly  250 , a packer wheel assembly  260 , and a row cleaner assembly  270 . It should be understood that the row unit  200  shown in  FIG. 7  may be for a conventional planter or the row unit  200  may be a central fill planter, in which case the hoppers  208  may be replaced with one or more mini-hoppers and the frame  204  modified accordingly as would be recognized by those of skill in the art. 
     The downforce control system  214  is disposed to apply lift and/or downforce on the row unit  200  such as disclosed in U.S. Publication No. US2014/0090585. 
     The seed trench opening assembly  220  includes a pair of opening discs  222  rotatably supported by a downwardly extending shank member  205  of the frame  204 . The opening discs  222  are arranged to diverge outwardly and rearwardly so as to open a v-shaped trench  10  in the soil  11  as the planter traverses the field. The seed delivery mechanism  212 , such as a seed tube or seed conveyor, is positioned between the opening discs  222  to deliver seed from the seed meter  210  and deposit it into the opened seed trench  10 . The depth of the seed trench  10  is controlled by a pair of gauge wheels  224  positioned adjacent to the opening discs  222 . The gauge wheels  224  are rotatably supported by gauge wheel arms  226  which are pivotally secured at one end to the frame  204  about pivot pin  228 . A rocker arm  230  is pivotally supported on the frame  204  by a pivot pin  232 . It should be appreciated that rotation of the rocker arm  230  about the pivot pin  232  sets the depth of the trench  10  by limiting the upward travel of the gauge wheel arms  226  (and thus the gauge wheels) relative to the opening discs  222 . The rocker arm  230  may be adjustably positioned via a linear actuator  234  mounted to the row unit frame  204  and pivotally coupled to an upper end of the rocker arm  230 . The linear actuator  234  may be controlled remotely or automatically actuated as disclosed, for example, in International Publication No. WO2014/186810. 
     A downforce sensor  238  is configured to generate a signal related to the amount of force imposed by the gauge wheels  224  on the soil. In some embodiments the pivot pin  232  for the rocker arm  230  may comprise the downforce sensor  238 , such as the instrumented pins disclosed in U.S. Pat. No. 8,561,472. The seed meter  210  may be any commercially available seed meter, such as the fingertype meter or vacuum seed meter, such as the vSet® meter, available from Precision Planting LLC, 23207 Townline Rd, Tremont, Ill. 61568. 
     The trench closing assembly  250  includes a closing wheel arm  252  which pivotally attaches to the row unit frame  204 . A pair of offset closing wheels  254  are rotatably attached to the closing wheel arm  252  and angularly disposed to direct soil back into the open seed trench so as to “close” the soil trench. An actuator  256  may be pivotally attached at one end to the closing wheel arm  252  and at its other end to the row unit frame  204  to vary the down pressure exerted by the closing wheels  254  depending on soil conditions. The closing wheel assembly  250  may be of the type disclosed in International Publication No. WO2014/066650. 
     The packer wheel assembly  260  comprises an arm  262  pivotally attached to the row unit fame  204  and extends rearward of the closing wheel assembly  250  and in alignment therewith. 
     The arm  262  rotatably supports a packer wheel  264 . An actuator  266  is pivotally attached at one end to the arm and at its other end to the row unit frame  204  to vary the amount of downforce exerted by the packer wheel  264  to pack the soil over the seed trench  10 . 
     The row cleaner assembly  270  may be the CleanSweep® system available from Precision Planting LLC, 23207 Townline Rd, Tremont, Ill. 61568. The row cleaner assembly  270  includes an arm  272  pivotally attached to the forward end of the row unit frame  204  and aligned with the trench opening assembly  220 . A pair of row cleaner wheels  274  are rotatably attached to the forward end of the arm  272 . An actuator  276  is pivotally attached at one end to the arm  272  and at its other end to the row unit frame  204  to adjust the downforce on the arm to vary the aggressiveness of the action of the row cleaning wheels  274  depending on the amount of crop residue and soil conditions. 
     It should be appreciated that rather than positioning the work layer sensors  100  as shown in  FIG. 7 , the work layer sensors may be positioned after the row cleaner assembly  270  and before the trench opening assembly  220  or in one or more other locations between the trench opening discs  222  and the closing wheels  254  or the packing wheel  264  depending on the soil region or characteristics of interest. 
     Planter Control and Operator Feedback  FIG. 8  is a schematic illustration of a system  500  which employs work layer sensors  100  to provide operator feedback and to control the planter row unit  200 . Work layer sensors  100 A,  100 B are disposed to generate a reference layer image  110 A of undisturbed soil and a work layer image  110 B of the closed seed trench (i.e., after seed is deposited, covered with soil by the closing wheel assembly  250  and the soil packed with the packing wheel assembly  260 ). As previously described, the work layer sensors  100 A,  100 B may be separate work layer sensors disposed forward and rearward of the row unit  200  as illustrated in  FIG. 7 , or the work layer sensors  100 A,  100 B may comprise a single work layer sensor with transmitters (T) and receivers (R) disposed to generate both a reference layer image  110 A and a work layer image  110 B. 
     The work layer image  110 B may be communicated and displayed to the operator on a monitor  300  comprising a display, a controller and user interface such as a graphical user interface (GUI), within the cab of the tractor. 
     The monitor  300  may be in signal communication with a GPS unit  310 , the row cleaner actuator  276 , the downforce control system  214 , the depth adjustment actuator  234 , the trench closing assembly actuator  256  and the packer wheel assembly actuator  266  to enable operational control of the planter based on the characteristics of the work layer image  110 B. For example, if the work layer image  110 B indicates that residue in the seed trench  10  is above a predetermined threshold (as explained below), a signal is generated by the monitor  300  to actuate the row cleaner actuator  276  to increase row cleaner downforce. As another example, if the seed depth is less than a predetermined threshold (as explained below), a signal is generated by the monitor  300  to actuate the downforce control system  214  to increase the downforce and/or to actuate the depth adjustment actuator  234  to adjust the gauge wheels  234  relative to the opening discs  232  to increase the trench depth. Likewise if the seed depth is greater than a predetermined threshold, a signal is generated by the monitor  300  to actuate the downforce control system  214  to decrease the downforce and/or to actuate the depth adjustment actuator  234  to decrease the trench depth. As another example, if the upper portion of the trench has more than a threshold level of void space (as explained below), a signal is generated by the monitor  300  to actuate the trench closing wheel assembly actuator  256  to increase the downforce on the closing wheels  254 . As another example, if the lower portion of the trench has more than a threshold level of void space (as explained below), a signal is generated by the monitor  300  to actuate the packer wheel assembly actuator  266  to increase the downforce on the packer wheel  264 . 
     In still other examples, the work layer image  110 B may identify and/or analyze (e.g., determine depth, area, volume, density or other qualities or quantities of) subterranean features of interest such as tile lines, large rocks, or compaction layers resulting from tillage and other field traffic. Such subterranean features may be displayed to the user on the monitor  300  and/or identified by the monitor  300  using an empirical correlation between image properties and a set of subterranean features expected to be encountered in the field. In one such example, the area traversed by the gauge wheels (or other wheels) of the planter (or tractor or other implement or vehicle) may be analyzed to determine a depth and/or soil density of a compaction layer beneath the wheels. In some such examples, the area of the work layer image may be divided into subregions for analysis based on anticipated subterranean features in such sub-regions (e.g., the area traversed by the gauge wheels may be analyzed for compaction). 
     In other examples, the monitor  300  may estimate a soil property (e.g., soil moisture, organic matter, or electrical conductivity, water table level) based on image properties of the work layer image  110 B and display the soil property to the user as a numerical (e.g., average or current) value or a spatial map of the soil property at geo-referenced locations in the field associated with each soil property measurement (e.g., by correlating measurements with concurrent geo-referenced locations reported the GPS unit  310 ). 
     Alternatively or additionally, the monitor  300  could be programmed to display operational recommendations based on the characteristics of the work layer image  110 B. For example, if the work layer image  110 B identifies that the seed  12  is irregularly spaced in the trench  10  or if the seed  12  is not being uniformly deposited in the base of the trench, or if the spacing of the seed  12  in the trench does not match the anticipated spacing of the seed based on the signals generated by the seed sensor or speed of the seed meter, such irregular spacing, nonuniform positioning or other inconsistencies with anticipated spacing may be due to excess speed causing seed bounce within the trench or excess vertical acceleration of the row unit. As such, the monitor  300  may be programmed to recommend decreasing the planting speed or to suggest increasing downforce (if not automatically controlled as previously described) to reduce vertical acceleration of the planter row units. Likewise to the extent the other actuators  276 ,  214 ,  234 ,  256 ,  266  are not integrated with the monitor controller, the monitor may be programmed to display recommendations to the operator to make manual or remote adjustments as previously described based on the characteristics of the work layer image  110 B. 
       FIG. 9  illustrates the process steps for controlling the planter and providing operator feedback. At steps  510  and  512 , the reference image  110 A and work layer image  110 B is generated by the work image sensor(s)  100 . At step  514 , the work layer image  110 B may be displayed to the operator on the monitor  300  in the cab of the tractor. At step  516 , the reference layer image  110 A is compared with the work layer image  110 B to characterize the work layer image. At step  518 , the characterized work layer image  110 B is compared to predetermined thresholds. At step  520 , control decisions are made based on the comparison of the characterized work layer image  110 B with the predetermined thresholds. At step  522 , the planter components may be controlled by the monitor  300  generating signals to actuate one or more of the corresponding actuators  276 ,  214 ,  234 ,  256 ,  266  and/or at step  524 , corresponding 0 recommendations may be displayed to the operator on the monitor display. 
     To characterize the work layer image  110 B at step  516 , the monitor  300  compares one or more characteristics (e.g., density) of the reference image  110 A with the same characteristics of the work layer image  110 B. In some embodiments, a characterized image may be generated comprising only portions of the work layer image differing from the reference image by at least a threshold value. The characterized image may then be used to identify and define features of the work layer image  110 B, such as the trench shape, the trench depth, residue in the trench, seeds and seed placement within the trench, void spaces within the trench, and density differences of the soil within the trench. 
     For example, to determine the seed depth, the seed is identified or identifiable from the work layer image  110 B by determining regions within the work layer image having a size or shape corresponding to a seed and having a density range empirically corresponding to seed. Once a region is identified as a seed, the vertical position of the seed with respect to the soil surface is readily measurable or determined. 
     As another example, the amount of residue in the trench can be determined by (a) defining the area of the trench cross-section (based on soil density differences between the reference image  110 A and the work layer image  110 B); (b) by identifying the regions within the trench having a density range empirically corresponding to residue; (c) totaling the area of the regions corresponding to residue; and (d) dividing the residue area by the trench cross-sectional area. Other Applications—It should be appreciated that work layer sensors  100  may be employed with other agricultural implements and operations, such as, for example, tillage operations and/or side-dress fertilization operations, or in connection with agricultural data gathering operations to view or analyze below-surface soil characteristics, seed placement, root structure, location of underground water-management features such as tiling, etc. 
     When employed with tillage implements, the work layer sensors  100  may be disposed forward of any tillage tools (i.e., shank, disk, blade, knife, spoon, coulter, etc.) or between 1 forward and rearward spaced tillage tools and/or rearward of any tillage tools. When employed with sidedress or other in-ground fertilization tools, the work layer sensors  100  may be disposed forward or rearward of any sidedress or in-ground tools (i.e., shank, disk, blade, knife, spoon, coulter, leveling basket harrows, etc.). 
     When employed with a dedicated measurement implement, the work layer sensors  100  may be disposed above undisturbed soil which may or may not have residue cleared by a row cleaner. 
     For the tillage implements and sidedress or in-ground fertilization tools, actuators on these implements can be automatically controlled to adjust depth of the tillage tools or the monitor  300  can be programmed to provide feedback or recommendations to the operator to manually adjust or remotely adjust the actuators as described above with respect to the planter application. For example, if the feedback or recommendations to the operator indicate that the depth of the tillage tools should be adjusted, an actuator associated with ground engaging wheels supporting the toolbar or a section of the toolbar may be actuated to raise or lower the toolbar to decrease or increase the depth of penetration of the toolbars. Alternatively, separate actuators may be associated with individual tillage tools to adjust the depth of the individual tillage tools. As another example, if the work layer images indicate that the implement is approaching more dense or compact soil, actuators associated to adjust downforce or pressure may be actuated to increase the downforce as the implement passes through the more dense or compact soil. In other embodiments if the work layer images across the width of the implement indicate that one side or the other is tilling the soil more aggressively, an actuator associated with a wing of the implement may be actuated to ensure balancing of the aggressiveness of tillage tools across the side-to-side width of the implement. Likewise an actuator associated with fore and aft leveling of the implement may be actuated to ensure aggressiveness of tools on the front of the implement are balanced with those on the back. In still other embodiments, actuators may be provided to adjust the angle of attack of a disc gang or wing of a tillage implement, or individual tillage tools depending on the work layer images and operator feedback as the implement traverses the field encountering different soil conditions. 
     In one embodiment, soil sensing information can be obtained and displayed during agricultural operations. A numeric display (e.g., average or current value) and spatial mapping of depth of soil density change can be provided on an implement (e.g., on a planter, a tillage tool, combine, sprayer, on a tractor pulling a grain wagon, or a tractor pulling any implement). The implement includes a sensor (e.g., radar, electrical conductivity (EC), electromagnetic (EM), force probe, etc.) to measure or calculate at least one of the presence of one or more soil densities existing between 0 and 30″ of soil depth, a magnitude of the density layer differences or the soil densities themselves, a rate of change of the soil density layer changes (e.g., abrupt within 1″, gradual over 6″, etc.), and a soil depth at which each density layer starts or transitions to a different density layer. 
     In one example, the implement can provide a numeric display (e.g., average or current value) of the above information that is measured by a sensor and calculated by a sensor or another device. The implement can also provide a spatial mapping of the above information at geo-referenced locations in the field associated with each soil property measurement (e.g., by correlating measurements with concurrent geo-referenced locations reported from the GPS unit  310 ). 
     In another example, a soil density change at a certain depth can be combined with a sensed moisture level at this depth or combined with soil type or texture to process raw data to generate processed data.  FIG. 16A  illustrates raw data  1600  and  FIG. 16B  illustrates processed data  1650  for different depths (e.g., 0 to 30″) of soil layers in accordance with one embodiment. The processed data  1650  includes different soil layers  1660 ,  1670 , and  1680  at different soil depths (e.g., 0 to 30 inches). A root or stone may cause a change in soil density within a layer or between layers. Depth of roots during harvest for in row versus out of row can be determined based on soil density. 
     In another embodiment, a numeric display (e.g., average or current value) and spatial mapping of depth of soil density change can be provided on an implement (e.g., on a planter, a tillage tool, combine, sprayer, on a tractor pulling a grain wagon, or a tractor pulling any implement). The implement includes a sensor (e.g., radar, electrical conductivity (EC), electromagnetic (EM), force probe, etc.) to measure or calculate one or more soil density variabilities (e.g., 0″ to 4″, 4″ to 12″, 0″ to 10″, 0 to 20″, etc.). In one example, the implement can provide a numeric display of the above information that is measured by a sensor and calculated by a sensor or another device. The implement can also provide a spatial mapping of the above information at geo-referenced locations in the field associated with each soil property measurement (e.g., by correlating measurements with concurrent geo-referenced locations reported the GPS unit  310 ). 
     In another embodiment, a numeric display (e.g., average or current value) and spatial mapping of depth of soil density change can be provided on an implement (e.g., on a planter, a tillage tool, combine, sprayer, on a tractor, or a tractor pulling any implement). The implement includes a sensor e.g., (radar, electrical conductivity (EC), electromagnetic (EM), force probe, etc.) to measure or calculate at least one of soil density variability, soil surface roughness (measured as Coefficient of Variation), and a residual material thickness (e.g., crop residue). An instantaneous surface roughness may identify an inconsistent surface at a ground level (e.g., 0″ depth). The soil surface roughness parameter can be analyzed to determine if a clod of soil at a certain depth (e.g., 0 to 3 inches) causes a change in this parameter. The soil surface roughness parameter (e.g., percentage, visual mapping) can be displayed during tillage or leveling of a field. 
     The residual material thickness can be compared in row versus out of row for rows of a field. Based on the residual material thickness parameter, a row cleaner down force of a planter may need to be adjusted. A residual material thickness can be displayed to a user while planting seed. 
     In one example, the implement can provide a numeric display of the above information that is measured by a sensor and calculated by a sensor or another device. The implement can also provide a spatial mapping of the above information at geo-referenced locations in the field associated with each soil property measurement (e.g., by correlating measurements with concurrent geo-referenced locations reported the GPS unit  310 ). 
     In one embodiment, a soil GPR (System) uses radar for sensing soil properties by measuring a soil dielectric constant of soil using an implement (e.g., planter, tillage tool, combine, tractor pulling a grain wagon, tractor pulling any implement, etc.). The system includes one or more radar transmitters, receivers, antennas or any combination of transmitters, receivers, and antennas that sense at multiple soil depths (e.g., first soil depth, second soil depth, third soil depth, etc.). Generally, a GPR system operates with a first transmitter radiating a pulse into soil, then the first receiver collects the reflected signal, and this process repeats from every pair of transmitters and receivers. An EC sensor can sense electrical conductivity of soil and this parameter corresponds to soil dielectric constant that is used to convert a transmit/receive time of a radar signal into a distance to determine a soil depth. Radar provides reflections at multiple depths to determine different soil density layers. 
     GPR is a geophysical method that uses radar pulses to image the subsurface. This nondestructive method uses electromagnetic radiation in the microwave band (UHF/VHF frequencies) of the radio spectrum, and detects the reflected signals from subsurface structures. GPR uses high-frequency (usually polarized) radio waves, usually in the range 10 MHz to 2.6 GHz. A GPR transmitter emits electromagnetic energy into the ground. When the energy encounters a buried object or a boundary between materials having different permittivities, it may be reflected or refracted or scattered back to the surface. A receiving antenna can then record the variations in the return signal. The principles involved are similar to seismology, except GPR methods implement electromagnetic energy rather than acoustic energy, and energy may be reflected at boundaries where subsurface electrical properties change rather than subsurface mechanical properties as is the case with seismic energy. The electrical conductivity of the ground, the transmitted center frequency, and the radiated power all may limit the effective depth range of GPR investigation. Increases in electrical conductivity attenuate the introduced electromagnetic wave, and thus the penetration depth decreases. Higher frequencies do not penetrate as far as lower frequencies due to frequency-dependent attenuation mechanisms though higher frequencies may provide improved resolution. 
     In another embodiment, soil system includes radar and optical soil sensing. Examples of optical soil sensing can be found in WO2014/153157, WO2015/171908, and U.S. Application Nos. 62/436,342, filed 19 Dec. 2016, 62/446,254, filed 13 Jan. 2017, and 62/482,116, filed 5 Apr. 2017. The soil system includes one or more radar transmitters, receivers, antennas or any combination of transmitters, receivers, and antennas that sense at multiple soil depths (e.g., first soil depth, second soil depth, third soil depth, etc.). The system further includes multiple radar antennas combined with one or more radar transmitters and receivers or combination transmitters or receivers. The system further includes one or more optical sensors (e.g., breaking of a light beam) to sense soil organic matter, soil moisture, soil texture, and soil cation-exchange capacity (CEC). 
     In one example, a common midpoint (CMP) antenna array can be utilized by positioning a target at a known depth, generating and receiving EM pulses, and then calculating for that depth. 
       FIGS. 17-23  illustrate a monitor  300  displaying different measured soil data. While illustrated with some data shown together and some data shown separately for illustration purposes, any of the data can be displayed together or individually.  FIG. 17  illustrates screen  2010  on monitor  300  displaying the number of different soil density layers, the density of each layer, the depth of the interface between layers, magnitude of density layer difference, and a rate of change of density.  FIG. 18  illustrates screen  2020  displaying the depth of interfaces between layers as the implement is moved across the soil.  FIG. 19  illustrates a screen  2030  on monitor  300  displaying a spatial map across a field for the depth of the first soil layer. The greater the depth, the more preferred. In this embodiment, the depths can be colored separately, such as green for 14-20″, yellow for 8-13″, and red for 1-7″.  FIG. 20  illustrates screen  2040  on monitor  300  displaying soil density variability and the soil density variability as the implement is moved across the field.  FIG. 21  illustrates screen  2050  on monitor  300  displaying soil surface roughness and soil surface roughness as the implement is moved across the field.  FIG. 22  illustrates screen  2060  on monitor  300  displaying residue mat thickness and residue mat thickness as the implement is moved across the field.  FIG. 23  illustrates screen  2070  on monitor  300  spatially displaying residue mat thickness across a field. While illustrated for residue mat thickness, any of the above soil measurements can be similarly displayed spatially. Also, color can be assigned to each thickness range. 
       FIG. 24  shows an example of a system  1200  that includes a machine  1202  (e.g., tractor, combine harvester, etc.) and an implement  1240  (e.g., planter, sidedress bar, cultivator, plough, sprayer, spreader, irrigation implement, etc.) in accordance with one embodiment. The machine  1202  includes a processing system  1220 , memory  1205 , machine network  1210  (e.g., a controller area network (CAN) serial bus protocol network, an ISOBUS network, etc.), and a network interface  1215  for communicating with other systems or devices including the implement  1240 . The machine network  1210  includes sensors  1212  (e.g., speed sensors), controllers  1211  (e.g., GPS receiver, radar unit) for controlling and monitoring operations of the machine or implement. The network interface  1215  can include at least one of a GPS transceiver, a WLAN transceiver (e.g., WiFi), an infrared transceiver, a Bluetooth transceiver, Ethernet, or other interfaces from communications with other devices and systems including the implement  1240 . The network interface  1215  may be integrated with the machine network  1210  or separate from the machine network  1210  as illustrated in  FIG. 12 . The I/O ports  1229  (e.g., diagnostic/on board diagnostic (OBD) port) enable communication with another data processing system or device (e.g., display devices, sensors, etc.). 
     In one example, the machine performs operations of a tractor that is coupled to an implement for planting applications and soil sensing of a field. The planting data and soil data for each row unit of the implement can be associated with locational data at time of application to have a better understanding of the planting and soil characteristics for each row and region of a field. Data associated with the planting applications and soil characteristics can be displayed on at least one of the display devices  1225  and  1230 . The display devices can be integrated with other components (e.g., processing system  1220 , memory  1205 , etc.) to form the monitor  300 . 
     The processing system  1220  may include one or more microprocessors, processors, a system on a chip (integrated circuit), or one or more microcontrollers. The processing system includes processing logic  1226  for executing software instructions of one or more programs and a communication unit  1228  (e.g., transmitter, transceiver) for transmitting and receiving communications from the machine via machine network  1210  or network interface  1215  or implement via implement network  1250  or network interface  1260 . The communication unit  1228  may be integrated with the processing system or separate from the processing system. In one embodiment, the communication unit  1228  is in data communication with the machine network  1210  and implement network  1250  via a diagnostic/OBD port of the I/O ports  1229 . 
     Processing logic  1226  including one or more processors or processing units may process the communications received from the communication unit  1228  including agricultural data (e.g., GPS data, planting application data, soil characteristics, any data sensed from sensors of the implement  1240  and machine  1202 , etc.). The system  1200  includes memory  1205  for storing data and programs for execution (software  1206 ) by the processing system. The memory  1205  can store, for example, software components such as planting application software or soil software for analysis of soil and planting applications for performing operations of the present disclosure, or any other software application or module, images (e.g., captured images of crops, soil, furrow, soil clods, row units, etc.), alerts, maps, etc. The memory  1205  can be any known form of a machine readable non-transitory storage medium, such as semiconductor memory (e.g., flash; SRAM; DRAM; etc.) or non-volatile memory, such as hard disks or solid-state drive. The system can also include an audio input/output subsystem (not shown) which may include a microphone and a speaker for, for example, receiving and sending voice commands or for user authentication or authorization (e.g., biometrics). 
     The processing system  1220  communicates bi-directionally with memory  1205 , machine network  1210 , network interface  1215 , header  1280 , display device  1230 , display device  1225 , and I/O ports  1229  via communication links  1231 - 1236 , respectively. The processing system  1220  can be integrated with the memory  1205  or separate from the memory  1205 . 
     Display devices  1225  and  1230  can provide visual user interfaces for a user or operator. The display devices may include display controllers. In one embodiment, the display device  1225  is a portable tablet device or computing device with a touchscreen that displays data (e.g., planting application data, captured images, localized view map layer, high definition field maps of different measured soil data, as-planted or as-harvested data or other agricultural variables or parameters, yield maps, alerts, etc.) and data generated by an agricultural data analysis software application and receives input from the user or operator for an exploded view of a region of a field, monitoring and controlling field operations. The operations may include configuration of the machine or implement, reporting of data, control of the machine or implement including sensors and controllers, and storage of the data generated. The display device  1230  may be a display (e.g., display provided by an original equipment manufacturer (OEM)) that displays images and data for a localized view map layer, measured soil data, as-applied fluid application data, as-planted or as-harvested data, yield data, seed germination data, seed environment data, controlling a machine (e.g., planter, tractor, combine, sprayer, etc.), steering the machine, and monitoring the machine or an implement (e.g., planter, combine, sprayer, etc.) that is connected to the machine with sensors and controllers located on the machine or implement. 
     A cab control module  1270  may include an additional control module for enabling or disabling certain components or devices of the machine or implement. For example, if the user or operator is not able to control the machine or implement using one or more of the display devices, then the cab control module may include switches to shut down or turn off components or devices of the machine or implement. 
     The implement  1240  (e.g., planter, cultivator, plough, sprayer, spreader, irrigation implement, etc.) includes an implement network  1250 , a processing system  1262 , a network interface  1260 , and optional input/output ports  1266  for communicating with other systems or devices including the machine  1202 . The implement network  1250  (e.g., a controller area network (CAN) serial bus protocol network, an ISOBUS network, etc.) includes a pump  1256  for pumping fluid from a storage tank(s)  1290  to application units  1280 ,  1281 , . . . N of the implement, sensors  1252  (e.g., radar, electroconductivity, electromagnetic, a force probe, speed sensors, seed sensors for detecting passage of seed, sensors for detecting characteristics of soil or a trench including a plurality of soil layers differing by density, a depth of a transition from a first soil layer to a second soil layer based on density of each layer, a magnitude of a density layer difference between soil layers, a rate of change of soil density across a depth of soil, soil density variability, soil surface roughness, residue mat thickness, a density at a soil layer, soil temperature, seed presence, seed spacing, percentage of seeds firmed, and soil residue presence, at least one optical sensor to sense at least one of soil organic matter, soil moisture, soil texture, and soil cation-exchange capacity (CEC), downforce sensors, actuator valves, moisture sensors or flow sensors for a combine, speed sensors for the machine, seed force sensors for a planter, fluid application sensors for a sprayer, or vacuum, lift, lower sensors for an implement, flow sensors, etc.), controllers  1254  (e.g., GPS receiver), and the processing system  1262  for controlling and monitoring operations of the implement. The pump controls and monitors the application of the fluid to crops or soil as applied by the implement. The fluid application can be applied at any stage of crop development including within a planting trench upon planting of seeds, adjacent to a planting trench in a separate trench, or in a region that is nearby to the planting region (e.g., between rows of corn or soybeans) having seeds or crop growth. 
     For example, the controllers may include processors in communication with a plurality of seed sensors. The processors are configured to process data (e.g., fluid application data, seed sensor data, soil data, furrow or trench data) and transmit processed data to the processing system  1262  or  1220 . The controllers and sensors may be used for monitoring motors and drives on a planter including a variable rate drive system for changing plant populations. The controllers and sensors may also provide swath control to shut off individual rows or sections of the planter. The sensors and controllers may sense changes in an electric motor that controls each row of a planter individually. These sensors and controllers may sense seed delivery speeds in a seed tube for each row of a planter. 
     The network interface  1260  can be a GPS transceiver, a WLAN transceiver (e.g., WiFi), an infrared transceiver, a Bluetooth transceiver, Ethernet, or other interfaces from communications with other devices and systems including the machine  1202 . The network interface  1260  may be integrated with the implement network  1250  or separate from the implement network  1250  as illustrated in  FIG. 24 . 
     The processing system  1262  communicates bi-directionally with the implement network  1250 , network interface  1260 , and I/O ports  1266  via communication links  1241 - 1243 , respectively. 
     The implement communicates with the machine via wired and possibly also wireless bi-directional communications  1204 . The implement network  1250  may communicate directly with the machine network  1210  or via the network interfaces  1215  and  1260 . The implement may also by physically coupled to the machine for agricultural operations (e.g., soil sensing, planting, harvesting, spraying, etc.). 
     The memory  1205  may be a machine-accessible non-transitory medium on which is stored one or more sets of instructions (e.g., software  1206 ) embodying any one or more of the methodologies or functions described herein. The software  1206  may also reside, completely or at least partially, within the memory  1205  and/or within the processing system  1220  during execution thereof by the system  1200 , the memory and the processing system also constituting machine-accessible storage media. The software  1206  may further be transmitted or received over a network via the network interface  1215 . 
     In one embodiment, a machine-accessible non-transitory medium (e.g., memory  1205 ) contains executable computer program instructions which when executed by a data processing system cause the system to performs operations or methods of the present disclosure. While the machine-accessible non-transitory medium (e.g., memory  1205 ) is shown in an exemplary embodiment to be a single medium, the term “machine-accessible non-transitory medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-accessible non-transitory medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure. The term “machine-accessible non-transitory medium” shall accordingly be taken to include, but not be limited to, solid-state memories, optical and magnetic media, and carrier wave signals. 
     Any of the following examples can be combined into a single embodiment or these examples can be separate embodiments. In one example of a first embodiment, a soil sensing system comprises an agricultural implement and at least one sensor disposed on the agricultural implement. The sensor generates an electromagnetic field through a region of soil of interest as the agricultural implement traverses a field. The sensor comprises at least one radar transmitter and at least one radar receiver or a transceiver and the sensor measures a soil dielectric constant of the region of soil of interest. 
     In another example of the first embodiment, the soil sensing system further comprises a monitor in communication with the sensor and adapted to generate a numeric display or a spatial mapping of the soil dielectric constant for a region of a field based on the generated electromagnetic field through the region of interest. 
     In another example of the first embodiment, the implement comprises a planter. 
     In another example of the first embodiment, the implement comprises one of a tractor, a planter, a seeder, a tillage tool, a combine, a sprayer, and an agricultural toolbar. 
     In another example of the first embodiment, the sensor to measure or calculate at least one of the presence of one or more soil densities existing between 0 and 30 inches of soil depth, a magnitude of the density layer differences or a magnitude of the soil densities, a rate of change of the soil density layer changes, and a soil depth at which each density layer starts or transitions to a different density layer. 
     In another example of the first embodiment, the sensor to measure or calculate a soil density change at a certain depth and a sensed moisture level at this depth or combined with soil type or texture to process raw data to generate processed data. 
     In another example of the first embodiment, the sensor to measure or calculate at least one of soil density variability, soil surface roughness that is measured as Coefficient of Variation, and a residual material thickness. 
     In another example of the first embodiment, the sensor generates the electromagnetic field having a frequency range of 10 MHz to 2.6 GHz. 
     In one example of a second embodiment, an implement comprises a first radar transceiver or a combination of a first radar transmitter and first radar receiver for sensing soil properties at a first depth of soil and a second radar transceiver or a combination of a second radar transmitter and second radar receiver for sensing soil properties at a second depth of soil. 
     In another example of the second embodiment, the implement comprises one of a tractor, a planter, a seeder, a tillage tool, a combine, a sprayer, and an agricultural toolbar. 
     In another example of the second embodiment, the implement comprises a planter. 
     In another example of the second embodiment, the implement further comprises a monitor in communication with the first radar transceiver or a combination of the first radar transmitter and first radar receiver and the second radar transceiver or a combination of the second radar transmitter and second radar receiver and adapted to generate a numeric display or a spatial mapping of the soil at the first depth and the second depth. 
     In another example of the second embodiment, the implement further comprises an electrical conductivity sensor to sense electrical conductivity of soil with the electrical conductivity corresponding to a soil dielectric constant. 
     In one example of a third embodiment, a soil sensing system for sensing soil properties comprises an implement, a radar transceiver or a combination of radar transmitter and a radar receiver disposed on the implement for sensing soil properties at a depth of soil and at least one optical sensor to sense at least one of soil organic matter, soil moisture, soil texture, and soil cation-exchange capacity (CEC). 
     In another example of the third embodiment, the implement is one of a tractor, a planter, a seeder, a tillage tool, a combine, a sprayer, and an agricultural toolbar. 
     In another example of the third embodiment, the implement is a planter. 
     In another example of the third embodiment, the soil sensing system further comprises a monitor in communication with the radar transceiver or a combination of the radar transmitter and the radar receiver and the optical sensor and adapted to generate a numeric display or a spatial mapping of the soil. 
     In one example of a fourth embodiment, a soil sensing system comprises an agricultural implement and at least one sensor disposed on the agricultural implement and directed to soil to measure at least one of:
         a plurality of soil layers differing by density; a depth of a transition from a first soil layer to a second soil layer based on density of each layer; a magnitude of a density layer difference between soil layers; a rate of change of soil density across a depth of soil; soil density variability; soil surface roughness; residue mat thickness; and a density at a soil layer.       

     In another example of the fourth embodiment, the sensor is one of radar, electroconductivity, electromagnetic, and a force probe. 
     In another example of the fourth embodiment, the agricultural implement is one of a tractor, a planter, a seeder, a tillage tool, a combine, a sprayer, and an agricultural toolbar. 
     In another example of the fourth embodiment, the soil sensing system further comprises a monitor in communication with the sensor and adapted to generate a numeric display or a spatial mapping of the soil. 
     In another example of the fourth embodiment, the soil sensing system further comprises a common midpoint (CMP) antenna array that is utilized by positioning a target at a known depth, transmitting electromagnetic pulses into soil, receiving electromagnetic pulses, and then calculating for that depth. 
     In one example of a fifth embodiment as illustrated in  FIG. 25 , a method  2500  of measuring residue mat thickness of residue in a field comprises traversing an implement across a field at operation  2502 . A radar transceiver or a combination of radar transmitter and a radar receiver is disposed on the implement for sensing residue on the field. At operation  2504 , the method includes measuring, with the implement, an amount of residue thickness at geo-referenced locations in the field, and storing the amount of residue thickness at each geo-referenced location in memory at operation  2506 . 
     In another example of the fifth embodiment, the method further comprises displaying on a display residue thickness at each geo-referenced location at operation  2508 . 
     In another example of the fifth embodiment, the method further comprises displaying on the display as illustrated in  FIG. 22  the residue thickness for an individual row as the implement is moved across the field at operation  2510 . 
     In another example of the fifth embodiment, the method further comprises spatially displaying with a map on the display as illustrated in  FIG. 23  residue thickness ranges for multiple rows across the field at operation  2512 . 
     In another example of the fifth embodiment, the implement is one of a tractor, a planter, a seeder, a tillage tool, a combine, a sprayer, and an agricultural toolbar. 
     In one example of a sixth embodiment as illustrated in  FIG. 26 , a method  2600  to generate processed soil data (e.g., processed soil data of  FIG. 16B ) comprises traversing an implement across a field at operation  2602 . A radar transceiver or a combination of radar transmitter and a radar receiver is disposed on the implement for sensing soil characteristics of the field. At operation  2604 , the method includes measuring, with the implement, a soil density change at a first depth. At operation  2606 , the method further includes combining the soil density change with the sensed moisture level at the first depth to generate a first processed soil data. 
     In another example of the sixth embodiment, the method further comprises measuring, with the implement, a soil density change at a second depth, measuring, with the implement, a sensed moisture level at the second depth and combining the soil density change with the sensed moisture level at the second depth to generate a second processed soil data at operation  2608 . 
     In another example of the sixth embodiment, a depth of roots during harvest for in row versus out of row are determined based on soil density. 
     In another example of the sixth embodiment, the method further comprises measuring, with the implement, soil type or texture and combining the soil density change with the soil type or texture to generate a third processed soil data at operation  2610 . 
     In one example of a seventh embodiment as illustrated in  FIG. 27 , a method  2700  of measuring soil characteristics in a field comprises traversing an implement across a field at operation  2702 . A radar transceiver or a combination of radar transmitter and a radar receiver is disposed on the implement for sensing soil characteristics of the field. At operation  2704 , the method includes measuring, with the implement, a depth of a first density layer at geo-referenced locations in the field and storing the depth of the first density layer at each geo-referenced location in memory. 
     In another example of the seventh embodiment, the method further comprises displaying with a spatial map (e.g., screen  2030  of  FIG. 19 ) on a display the depth of the first density layer at each geo-referenced location at operation  2706 . 
     In another example of the seventh embodiment, the method further comprises measuring a depth of a second density layer at geo-referenced locations in the field and storing the depth of the second density layer at each geo-referenced location in memory at operation  2708 .