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].
Implications of soil compaction in crop production for the quality of the environment
Abstract Evidence is presented to indicate the possible serious, widespread and long-term implications of soil compaction for the quality of the environment. Soil compaction enhances harmful physical, chemical and biological processes which, in the context of inappropriate soil management, lead to soil degradation. Soil compaction is shown to result in changes in soil properties which control the emission of greenhouse gases, the runoff of water and pollutants into surface waters, and the movement of nitrate and pesticides into ground waters. Soil compaction will also affect the amounts of fertiliser and energy used in crop production, which may have additional adverse environmental consequences. Recommendations for further research on the environmental consequences of soil compaction in crop production are made.
Palm oil shell aggregate for lightweight concrete
Publisher Summary Increased agricultural production and the development of agro-based industries in many countries of the world have brought about the production of large quantities of agricultural wastes, most of which are not adequately managed and utilized. Low-cost building materials can be produced using inexpensive indigenous raw materials. Agricultural wastes that are renewable and are found in abundance in many countries present an interesting alternative to the traditional and sometimes imported building materials, particularly for low-cost construction. The use of agricultural wastes as aggregates in lightweight concrete can provides an alternative to conventional methods for the production of lightweight concrete. Lightweight concrete results in a reduction in the overall deadweight of a structure and provides a significant saving in the overall cost of construction. The use of less expensive alternative lightweight aggregates in the production of the concrete can provide further reductions in expense. The material properties and structural performance of lightweight concrete with palm oil shells as aggregates are similar to lightweight concrete produced using the more common lightweight aggregates such as clinker, foamed slag, and expanded clay. The palm oil shells are hard and are received as crushed pieces because of the process used to release the oil. Manual sieving is necessary to remove the large amount of fine particles. The shells are then air-dried before use. Because the palm oil shells are lighter than the cement matrix, the shells tend to segregate in wet concrete mixes. On the other hand, dry mixes using palm oil shells are relatively more difficult to work with when compared to ordinary concrete. Trial mixes are necessary to achieve a good mix design.