Suitable seedbed preparation and adequate rate of seeding are necessary to obtain desirable plant population. These management practices are more important for plants with small seeds such as rapeseed. In this research, the effect of different TILLAGE systems and seeding rates on MACHINERY parameters, grain yield and yield components of rapeseed, cv. Orient, was studied in a split-split plot arrangement using randomized complete block design with three replications at the Kabutarabad Agricultural Research Station, Isfahan, Iran in 2003-2004 cropping season. Four primary TILLAGE systems: moldboard plow to a depth of 20-25 cm, chisel to a depth of 15- 20 cm and 8-10 em and disk to a depth of 8-10 cm were assigned to main plots and two SECONDARY TILLAGE methods: disk and rotary tiller to a depth of 8-10 cm and three seeding rates; 4, 8 and 12 (kg.ha-1) were randomized sub-plots and sub-sub plots, respectively. TILLAGE methods showed no significant effect on mean weighed diameter of clods. Disk and rotary tiller had maximum and minimum MACHINERY effective field capacity, respectively. By increasing seeding rate from 4 to 8 and then to 12 kg.ha-1, number of days from planting to the end of flowering and flowering duration decreased. Increases in seeding rate increased plant population. Using of 8 kg.ha-1 of seeds produced higher grain yield (2521 kg.ha-1) than 4 kg.ha-1 seeds (2400 kg.ha-1), but was not significantly different from 12 kg.ha-1 (2426 kg.ha-1). Based on these results, it might be concluded that disk harrow method as the SECONDARY TILLAGE with 8 kg.ha-1of seeds as desireable agronomic practices under conditions similar to this study. However, when rotary tiller is used, the seeding rate might decrease to less than 8 kg.ha-1.

Introduction: The working day is an important component in selection and analysis of farm MACHINERY systems. The number of working days is affected by various factors such as climate, soil characteristics and type of operation. Daily soil moisture models based on weather long-term data and soil characteristics were almost used for calculating probability of working days. The goal of this study was to develop a simulation model to predict the number of working days for SECONDARY TILLAGE and planting operation in fall at 50, 80 and 90% probability levels. …

About 60% of the mechanical energy consumed in mechanized agriculture is used for TILLAGE operations and seedbed preparation. On the other hand, unsuitable TILLAGE system resulted in soil degradation, affecting soil physical properties and destroying soil structure. The objective of this research was to compare the effects of three types of SECONDARY TILLAGE machines on soil physical properties and their field performances. An experiment was conducted in a wheat farm in Jouybar area of Mazandaran as split plots based on randomized complete block design with three replications. The main independent variable (plot) was soil moisture with three levels (23.6-25, 22.2-23.6 and 20.8-22.2 percent based on dry weight) and the subplot was three types of machine (twodisk perpendicular passing harrow, Power harrow and Rotary tiller). The measured parameters included: clod mean weight diameter, soil bulk density, specific fuel consumption, machine efficiency and machine capacity.The effects of treatments and their interactions on the specific fuel consumption, machine efficiency and machine capacity and also the effects of treatments on bulk density were significant (P<0.01). The bulk density decreased 15.3%, the specific fuel consumption increased 11.8%, whereas the machine efficiency and machine capacity increased and decreased with the decrease in soil moisture, respectively. The maximum value of the bulk density and machine efficiency were obtained by the use of rotary tiller and the maximum value of the specific fuel consumption and machine capacity were obtained by the use of power harrow. A criterion was defined for selecting machine type and moisture content for optimum condition. The results suggested power harrow working at soil moisture condition of 24.3% (based on dry weight).

The introduction of canola (oilseed rape; Brassica napus L.) as a new source of vegetable oil production in Iran prompts evaluation of the performance of this crop under different TILLAGE systems. A field experiment was conducted to determine the impact of depth and intensity of TILLAGE on soil physical properties, crop establishment and yield of irrigated winter canola in a loam soil (Typic Haplargids) near Isfahan in central Iran. In a split-plot design, three primary TILLAGE treatments consisted of moldboard plowing to 20 cm (MP20), two passes of a cultivator first to 10 and then to 15 cm (2TC15), and one single pass of cultivator to 10 cm (TC10), were combined with two seedbed preparation treatments (four passes with a disk harrow as opposed to a single pass with a rotary tiller). Results showed that the soil bulk density in the 0-5 and 5-10 cm layers were not significantly affected by primary TILLAGE treatments. Soil penetration resistance (PR) in the 0-10 cm layer was significantly higher in 2TC15 compared to moldboard plowed soil; however, no significant effect of primary TILLAGE was detected on PR in the 10-20 cm depth. A single pass by a rotary tiller was as effective in seedbed preparation as four passes of a disk harrow, as assessed by bulk density, penetration resistance and the percentage of emergence. The number of plants per square meter at final emergence and at harvest was statistically similar for both the seedbed preparation methods. Mean canola total dry matter biomass was 10,020, 9,860 and 10,410, kg ha-1 and dry grain yield was 2,340, 2,410 and 2,880 kg ha-1 under MP20, 2TC15 and TC10, respectively. However, the effects on mean crop yield were non-significant (P> 0.05). The mean oil content of the 2TC15 (40.1%) was significantly lower than the MP20 and TC10 treatments, 43.7 and 42.3%, respectively. Lack of yield response to TILLAGE treatment may have been the result of achieving a good seedbed (aggregate mean diameter of less than 15 mm) under all TILLAGE methods, which help to obtain sufficient plant establishment. These results indicate that the yield of irrigated winter canola is not sensitive to reduction in the depth of primary TILLAGE or intensity of SECONDARY TILLAGE. With reduced TILLAGE, an optimum plant per unit area can also be achieved. Overall, TC10 combined with a single pass of a rotary tiller was considered to be agronomically desirable, due to the absence of grain yield difference compared with both the MP20 or 2TC15 systems and reduced tilling depth.

Reduction of TILLAGE operations in conventional systems and its replacement with a reduced TILLAGE and conservation systems is recommended in order to sustainable production in agriculture and preservation of soil and water resources. In this research, the effect of applying three types of conventional TILLAGE machines with different geometry that have less rigidity of soil TILLAGE than conventional TILLAGE machines (Chisel packer, combined tiller and offset disc) on the performance parameters of TILLAGE including Specific draft, specific TILLAGE energy, and weighted average diameter of clods, roughness of soil surface and percent of crop residue on the soil surface. TILLAGE depth is fixed in 20 cm, forward speed was in three levels (2. 5, 4. 5 and 6 km/h) and TILLAGE MACHINERY type was in three levels. Double Split plot in Randomized Complete Block Design used in the study in which TILLAGE depth (main factor), forward speed (SECONDARY factor) and the tiller type (sub-SECONDARY factor) were the independent variables. The results showed that the amount of residues remaining on the soil surface after soil TILLAGE was negatively correlated with not only special draft but also with other indices (weighted average diameter of clods and roughness of soil surface), and crop residue after soil TILLAGE was applied as a criterion for comparing soil TILLAGE MACHINERY. The results of the comparison of the ranking of treatments based on two methods (amount of crop residues after soil TILLAGE and the Component Analysis method) showed that the combined tiller and the offset disc at low velocity and Chisel packer at high velocity is recommended for conservation systems of TILLAGE.

In order to manage cost reduction in saline land under wheat cultivation, a research was carried out as a split plot arranged in a randomized complete block design with three replications. The main factor included three soil moisture percentages during the initial plowing (10, 15, and 20%) and SECONDARY factor was four methods of land preparation and sowings (non application of chisel piler + sowing with flat planter, non application of chisel piler + sowing with furrow planter, application of chisel piler + sowing with flat planter and application of chisel piler + sowing with furrow planter). In this research, before applying the SECONDARY factor, a 24-blade disc was used for the initial plowing of the land. The results showed that the highest weight and volume of clods were found when non application of chisel piler with 20% soil moisture and the lowest one when chisel piler was applied with 10% soil moisture. The highest seed germination was with application of chisel piler + furrow planter and humidity of 20% and the lowest value was with non application of chisel piler + flat planter and soil moisture of 10%. The highest grain yield was obtained with application of chisel piler + furrow planter by 4593 kg/ha and the lowest value was obtained by 2797 kg/ha under non application of chisel piler and flat planter. In general, the results showed that the use of chisel piler and furrow planter with 20% soil moisture had a positive effect on improving germination, physiological and yield characteristics of wheat in saline lands, and it can be taken into consideration by farmers.

This experiment was conducted to evaluate the effect of soil moisture and TILLAGE and sowing MACHINERY on yield and yield components of wheat in the saline soils of Mahshahr, Iran. The experiment was carried out as a split-plot according to a randomized complete block design with three replications. Independent variables included soil moisture during TILLAGE at three levels of 10%, 15%, and 20% as the main factor. Sub-factor included the type of TILLAGE and sowing MACHINERY at four levels including 1) without the use of chisel-piler and sowing with flat seeder machine, 2) without the use of chisel-piler and sowing with furrow seeder machine, 3) one time use of chisel-piler to a depth of 20 cm and sowing with flat seeder machine, and 4) one time use of chisel-piler to a depth of 20 cm and sowing with furrow seeder machine. In order to prepare the land, irrigation was done before TILLAGE according to the region's customs to reduce the tensile strength of the soil against TILLAGE machines. After the soil moisture was suitable according to the main factors, the TILLAGE was done with a 24-bladed disk machine once to a depth of 15 cm. The maximum clod weight was obtained in the condition of not using a chisel-piler and soil moisture of 20%, and the lowest was obtained in using a chisel-piler and soil moisture of 10%. The maximum number of tiller/plant, number of spikes/m2, number of spikelet/spike, number of grain/spike, number of grain/spikelet, biological yield, and grain yield was under using chisel-piler and sowing with furrow seeder machine with 20% soil moisture, and the lowest in the treatment with no chisel-piler and sowing with flat seeder machine. In general, the results showed that the use of chisel-piler and sowing with furrow seeder machine under 20% soil moisture had the best results in terms of grain formation and yield in saline soils, which can be suggested to reduce the effects of salinity.

This study was conducted to investigate the effect of soil moisture content in primary TILLAGE and travel speed during disking operation on the performance of an offset disk harrow in a silty clay loam soil. At first, the effect of three soil moisture content ranges of (12-14), (14-16) and (16-18) percent (dry basis) on soil clod size (left from moldboard plowing) was investigated. Then, the performance of disk harrow as a SECONDARY TILLAGE tool was evaluated at three speed ranges of (3-5), (5-7) and (7-9) km/h and three clod size mean weight diameters (31, 41 and 47 mm) resulted from moldboard plowing. The experiment was of a Randomized Complete Block Design, (a factorial experiment) of three replications. The performance parameters evaluated were: draft per unit width, drawbar power requirement, tractor drive wheel slip and degree of soil pulverization. Results indicated that, draft and drawbar power requirements of disk harrow increased significantly with increase in the travel speed. Tractor drive wheel slip was highly influenced by travel speed, clod sizes and as well by their interactions. Soil moisture content was an important factor primarily affecting the size and hardness of soil clods made by plowing operation, and secondly, it played an important role in soil pulverization through disk harrowing. Overall, the optimum soil moisture content for conducting primary TILLAGE using a moldboard plow was determined as about 16 to 18%(dry weight basis), which corresponds to 91% of lower plastic limit of the experimental field. Meanwhile, the optimum speed range for disk harrowing was determined to be 5 to 7 km/h.