Plow Power Requirements for Forestry Site Preparation
Abstract In this field study, data were collected to determine power requirements required by a trailing site preparation plow and the magnitudes of dynamic forces experienced by a plow during normal operation and during impact with stumps or other obstructions. Drawbar pull data were collected from five different tillage treatments on a recently harvested loblolly pine (Pinus taeda) site in central Alabama. The five treatments were: 1) a coulter, ripping shank, and four bedding disks; 2) a coulter, ripping shank, and two bedding disks; 3) a coulter and ripping shank; 4) a coulter alone; and 5) a ripping shank alone. A 330 kN [75 000 lb] capacity tension load cell was used to measure the drawbar load, a GPS receiver recorded tractor speed, four direct current displacement transducers (DCDT’s) monitored the depth of the disks, and two optical tachometers measured the speed of the tractor’s front and rear drive shafts. Each treatment produced significantly different drawbar loads (to alpha levels less than 0.001). The resulting mean loads were 46.0 kN [10 300 lb], 33.5 kN [7530 lb], 31.5 kN [7080 lb], 15.8 kN [3560 lb], and 43.4 kN [9760 lb] for treatments one through five, respectively. Maximum recorded drawbar load during a collision with a stump was 338.9 kN [76 188 lb].
Soil compaction caused by high axle loads— review of concepts and experimental data
Abstract Current concepts, theoretical analysis and experimental data on soil compaction under high axle loads are critically reviewed and analyzed. Based on theoretical considerations and experimental data it is suggested that subsoil compaction is expected to occur under specific conditions (wet, homogeneous, and deep soil under high contact pressures). Measured changes in soil bulk density, physical properties, and crop yields (published in the literature), attributed to high axle load induced soil compaction, are not uniquely proven and can be attributed to other processes as well. Further research directed towards understanding and forecasting changes of soil properties under traffic loads is recommended.
Prediction of draft requirement—Soil compaction relations in tilling moist soils
Abstract A stepwise simulation procedure was developed to assess soil compaction produced by machinery traffic on moist soil. Initial bulk density and water content distributions, soil compressibility and tractor wheel sizes, weight distributions and two or four wheel drive options were used as input data. The results obtained include draft, induced compacting stress and consequent soil bulk density distributions in the soil. The predicted results were compared with field measured data. It was found that the predicted bulk densities were always higher than the observed ones by 3–9% and 1–5% at depths of 5 and 25 cm, respectively. Nevertheless, the results obtained from the model used are of great importance in formulating recommendations and operational decisions for various field operations and for specific machinery and implement selection aimed at obtaining required tilth while maintaining low compactive hazard. The predicted compaction levels being higher than the observed ones suggest the uppermost limit of compaction attainable and indicate the direction to be taken to improve the model.