Tillage system with variable fertilizer application

1. An agricultural implement, comprising:

a frame;

a plurality of ground engaging tools connected to the frame;

a fertilizer device configured for applying at least one liquid fertilizer and comprising a plurality of fluid lines and a plurality of fertilizer applicator assemblies fluidly connected to the plurality of fluid lines, and each fertilizer applicator assembly comprising an applicator connected to the frame and a valve fluidly connected to the applicator, and the valve being configured for varying a rate of the at least one liquid fertilizer through the applicator; and

an electronic control unit operably connected to the valves of the plurality of fertilizer applicator assemblies and configured for automatically adjusting the valve of at least one fertilizer applicator assembly of the plurality of fertilizer applicator assemblies to vary the rate of the at least one liquid fertilizer, dependent upon a fertilizer requirement characteristic, the electronic control unit being configured for adjusting a depth of the plurality of ground engaging tools dependent upon a compaction layer characteristic, wherein the electronic control unit is configured to determine the compaction layer characteristic based at least upon a crop yield map data and upon real-time compaction layer data determined by a compaction layer sensor.

2. The agricultural implement of claim 1 , further comprising a global positioning system (GPS) sensor operably connected to the electronic control unit and configured for providing a position signal indicative of a position of the agricultural implement.

3. The agricultural implement of claim 2 , wherein the fertilizer requirement characteristic is determined from the position signal of the GPS sensor, estimated fertilizer data based on yield map data, and estimated fertilizer data extrapolated from previous in-field soil measurements.

4. The agricultural implement of claim 1 , wherein the fertilizer requirement characteristic is determined from at least one of estimated fertilizer data based on yield map data and estimated fertilizer data extrapolated from previous in-field soil measurements.

5. The agricultural implement of claim 1 , wherein the electronic control unit comprises a memory which stores field agronomy data from at least one soil sample measurement.

6. The agricultural implement of claim 5 , wherein the at least one soil sample measurement is at least one in-field measurement of a soil nutrient level.

7. The agricultural implement of claim 1 , wherein the plurality of ground engaging tools comprises a plurality of coulters, and each fertilizer applicator is located behind a respective coulter.

8. The agricultural implement of claim 1 , wherein the valve of each fertilizer applicator assembly is a solenoid valve.

9. An agricultural tillage system, comprising:

an agricultural vehicle;

an agricultural implement towed by the agricultural vehicle and comprising a frame and a plurality of ground engaging tools connected to the frame;

a fertilizer device connected to the agricultural implement and configured for applying at least one liquid fertilizer, the fertilizer device comprising a plurality of fluid lines and a plurality of fertilizer applicator assemblies fluidly connected to the plurality of fluid lines, and each fertilizer applicator assembly comprising an applicator connected to the frame and a valve fluidly connected to the applicator, and the valve being configured for varying a rate of the at least one liquid fertilizer through the applicator; and

an electronic control unit operably connected to the valves of the plurality of fertilizer applicator assemblies and configured for automatically adjusting the valve of at least one fertilizer applicator assembly of the plurality of fertilizer applicator assemblies to vary the rate of the at least one liquid fertilizer, dependent upon a fertilizer requirement characteristic, the electronic control unit being configured for adjusting a depth of the plurality of ground engaging tools dependent upon a compaction layer characteristic, wherein the electronic control unit is configured to determine the compaction layer characteristic based at least upon a crop yield map data and upon real-time compaction layer data determined by a compaction layer sensor.

10. The agricultural tillage system of claim 9 , further comprising a global positioning system (GPS) sensor operably connected to the electronic control unit and configured for providing a position signal indicative of a position of the agricultural implement.

11. The agricultural tillage system of claim 10 , wherein the fertilizer requirement characteristic is determined from the position signal of the GPS sensor, estimated fertilizer data based on yield map data, and estimated fertilizer data extrapolated from previous in-field soil measurements.

12. The agricultural tillage system of claim 9 , wherein the fertilizer requirement characteristic is determined from at least one of estimated fertilizer data based on yield map data and estimated fertilizer data extrapolated from previous in-field soil measurements.

13. The agricultural tillage system of claim 9 , wherein the electronic control unit comprises a memory which stores field agronomy data from at least one soil sample measurement.

14. The agricultural tillage system of claim 13 , wherein the at least one soil sample measurement is at least one in-field measurement of a soil nutrient level.

15. The agricultural tillage system of claim 9 , wherein the plurality of ground engaging tools comprises a plurality of coulters, and each fertilizer applicator is located behind a respective coulter.

16. The agricultural tillage system of claim 9 , wherein the valve of each fertilizer applicator assembly is a solenoid valve.

17. A method for working a field, comprising:

providing an agricultural implement comprising a frame, a plurality of ground engaging tools connected to the frame, a fertilizer device configured for applying at least one liquid fertilizer and comprising a plurality of fluid lines and a plurality of fertilizer applicator assemblies fluidly connected to the plurality of fluid lines, and each fertilizer applicator assembly comprising an applicator connected to the frame and a valve fluidly connected to the applicator, and the valve being configured for varying a rate of the at least one liquid fertilizer through the applicator, and an electronic control unit operably connected to the valves of the plurality of fertilizer applicator assemblies; and

adjusting the valve of at least one fertilizer applicator assembly of the plurality of fertilizer applicator assemblies to vary the rate of the at least one liquid fertilizer, dependent upon a fertilizer requirement characteristic; and

adjusting, by the electronic control unit, a depth of the plurality of ground engaging tools dependent upon a compaction layer characteristic, wherein the electronic control unit is configured to determine the compaction layer characteristic based at least upon a crop yield map data and upon real-time compaction layer data determined by a compaction layer sensor.

18. The method of claim 17 , further including a step of computing, by the electronic control unit, the fertilizer requirement characteristic from at least one of estimated fertilizer data based on yield map data and estimated fertilizer data extrapolated from previous in-field soil measurements.

19. The method of claim 17 , wherein the agricultural implement further comprises a global positioning system (GPS) sensor operably connected to the electronic control unit, and the method further comprises a step of sensing, by the GPS sensor, a position signal indicative of a position of the agricultural implement.

20. The method of claim 19 , wherein the fertilizer requirement characteristic is determined from the position signal of the GPS sensor, estimated fertilizer data based on yield map data, and estimated fertilizer data extrapolated from previous in-field soil measurements.