Journal of Agricultural Science and Technology
Volume:8 Issue: 1, Jan 2006

Development of sensors to detect the location and depth of hard pans in real time is a major restriction on the application of Site Specific Crop Management (SSCM). In this study, a soil compaction profile sensor equipped with four horizontal operating penetrometers for on-the-go sensing and mapping of the location and intensity of hard pans artificially formed in a soil bin was developed and tested. The leading edge of a 600 mm long vertical soil cutting blade held four 8 mm diameter, 80 mm long, and 30 degree conic tip stainless steel soil penetrating rods equally spaced at 100 mm vertical intervals. With this arrangement, when the cutting blade was driven into the soil up to a 500 mm depth, the conic tips sensed soil penetration resistances at 100, 200, 300 and 400 mm depths. The penetration resistance force was transmitted by the rod end to the elastic diaphragm of a hydrostatic oil chamber beneath each rod. Each oil chamber was connected to a force magnifying piston and cylinder located off the soil engaging tools. The penetration force was magnified five times before being sensed by a strain gage load cell. Software programs with the capability of discriminating 16 levels of soil compaction intensity were developed for monitoring soil impedances sensed by the soil probes and for converting them to soil compaction maps. For conducting the tests in the soil bin, the sensor mounted on the tool carrier frame was moved along the bin, where artificially formed compacted soil blocks with various densities (1.45, 1.65 and 1.85 Mg/m³) were placed at different locations and depths (up to 500 mm deep at 100 mm increments). While the probe was cutting and advancing through the soil, the corresponding compaction map was simultaneously displayed on a PC monitor, and the soil penetration resistance data of all four sensing tips was displayed and stored in program files.

Some physical attributes of two common types of Iranian garlic cloves (white and pink) were identified and compared. A machine vision system was used to determine three dimensions and both major and minor projected areas of garlic cloves at a moisture content of 42.4% w. b. The geometric mean diameter and sphericity were calculated, as well as the unit mass and volume of cloves were measured. In the moisture range from 34.9 to 56.7% w.b., the unit density, bulk density and porosity for both types were measured. Results showed that the unit density, bulk density and porosity of cloves were affected significantly by moisture content (p<0.01). The type of garlic had a highly significant effect on the unit density and porosity (P<0.01), and a significant effect on the bulk density (P<0.05). The relationship between volume and dimensions of cloves was established using regression analysis. The effect of moisture content on physical properties of cloves was also expressed by appropriate equations.

ABSTRACT There are varying patterns for growing different varieties of branched or non-branched sesame. This experiment was conducted during a two-year period (2000-2001) to identify the optimal practice for cultivation of the uni-branched sesame in the Safi-Abad Agricultural Research Center, Khuzestan Province. The statistical design was set up as strip-plot in a randomized complete block with four replications. Rows were adopted at varying spaces of 37.5, 50 and 60 cm while the plants were arranged horizontally at 5,10,15 and 20 cm. In this way, the density of the plot was surveyed over an area ranging from 83000 to 530,000 plant/ha. Combined analysis of two years, results showed a significant effect on the yield component due to an increase in row-spacing from 37.5 to 60 cm. This increase in row-spacing from 37.5 to 60 cm. could also increase the stem diameter from 16.3 to 19.4 mm, the pod number from 59 to 84 per plant, as well as the weight per thousand seeds from 3 to 3.3 grams. Moreover, an increase in plant spacing from 5 to 20 cm caused a decrease in stem height from 180.2 to 169.7 cm, an increase in stem diameter form 15.8 to 19.8 mm, a rise in pod number from 44.6 to 96.5 and in the seed content from 59.3 to 74.4 per pod. The relevance of the seed yield and row spacing obeyed a falling linear regession curve, while the seed yield and plant intervals showed a non-linear behaviour and estimated a maximum yield at 10 cm distance. Finally, the planting density reflected a non-linear fourth power equation. The maxinum seed and oil yield was then estimated at a density of 200,000–250,000 plant per hectare. In view of higher yield at the 37.5 cm row treatment and the 10 cm plant treatment, together with regressive equations, the above pattern (37.5*10cm) shall be recommended for unibranched sesame growing in Khuzestan.

This study examines Iranian agricultural researchers’ attitudes regarding collaboration with extension workers and the variables associated with the researchers’ attitudes. Data were obtained using a questionnaire developed by Agricultural Research Centers of Charmahal and Bakhtiari, Isfahan, Safiabad and Khuzestan in 1998. The findings revealed that the researchers’ attitudes towards collaboration with the extension workers were generally positive although actual collaboration between researchers and the extension workers was at a low level. Therefore, it seems that lack of an overall strong relationship of attitudes with current behavior as well as weak collaboration is related to other factors that need to be studied more, for example management of participation or internal factors in each sub-system of extension or research etc. identified that The following factors/ characteristics of agricultural researchers were identified as having a positive correlation/ association with their attitude towards collaborating with extension workers: higher research experience, greater interaction with extension workers, a lower scientific position or possessing a higher management position, greater participation in seminars and colloquiums related to extension, and the influence/thinking of colleagues and managers.

Twenty four ecto- and endo- parasite species were found in different organs of eight native and exotic fish species in Zarivar Lake situated in the far west of Iran. Overall, 1000 fish specimens belonging to the Dactylogyridae, Gyrodactylidae families the Cyprinidae, Poeciliidae and Mastacembelidae families were examined during 2001 and 2002. Of them, five Protozoans, including Trichodina pediculus, Trichodina sp and Myxobolus molnari, a pansporogenic stage of the Myxosporean plasmodia and Ichthyophthirius multifiliis were recorded. Of the Metazoan parasites, 12 monogenean species, mostly belonging to the Dactylogyridae, Gyrodactylidae families and the Ancyrocephalinae subfamily, were found and identified at species and genus level. The number of helminthes reached 15 by adding one Digenea metacercaria (Diplostomum spathaceum) and 2 coelozoic Cestoda species. Crustacean species found on both of native and exotic fishes, belonging to Copepoda and Branchiora orders comprised of Argulus foliaceus and Lernaea cyprinacea, in addition an unknown Argulus was also found on skin and gills of spiny eel which identified to genus level. The only nematode found in the intestine of common carp was identified as Pseudocapillaria tomentosa. Besides the first record of parasites of spiny eel, the seasonal prevalence of ligulosis is presented. Additionally, zoogeographical analysis and species composition of parasitic fauna of Zarivar Lake are discussed.

ABSTRACT River bank erosion can result in considerable riparian land loss and the delivery of large volumes of sediment to reaches downstream. Consequently, the ability to predict the stability and failure geometry of eroding river banks is an important prerequisite for estimating the rate of bank erosion and sediment yield associated with bank erosion. In this paper a new model capable of analyzing the stability of layered river banks is introduced. The new model takes into consideration the effects of positive pore water pressure in the saturated portion, and negative pore water pressure in the unsaturated portion, of the bank. Also, the role of hydrostatic confining pressure due to the water level in the river and the effects of the water in tension crack on stability analysis is accounted for. Unlike many previous analyses, the failure plane is not constrained to pass through the toe of the bank. However, it considers only planar-type failure mechanism. Finally the bank profile geometry is not restricted to a special case. The new model has been tested using field data sets from a site on the Sieve River in Italy and a site on Goodwin Creek in Mississippi. The results show some agreement between the predicted and observed values of bank stability.

To evaluate the relationships between soil inorganic phosphorus P (Pi) fractions, the soil P test and plant parameters such as plant P uptake, dry matter yield, tissue P concentration and relative yield, glasshouse experiments and chemical analyses were conducted on 13 calcareous soils from six agricultural and seven adjacent bushland (virgin soil) sites. Four rates of P (0, 15, 30, 60 mg/kg soil) were applied as reagent-grade KH2PO4 to the soils in a randomised complete block design with three replications. Perennial ryegrass (Lolium perenne cv. Roper) was grown and forage was harvested five times over a period of 210 days. Successive harvesting resulted in the depletion of plant available P as measured by NaHCO3-extractable P, which coincided with the decrease in the plant dry matter yield and P uptake. After five harvests, the order of reduction in Pi fractions induced by cropping without added P was Ca10-P>Al-P>Ca2-P>Ca8-P>occluded-P>Fe-P for the virgin soils and Ca2-P>Al-P>Ca10-P>Ca8-P>Fe-P>occluded-P for the agricultural soils. The order of abundance of Pi fractions for P treated-soils was non-occluded Al and Fe phosphate (Al-P+Fe-P)>secondary Ca-bound P (Ca2-P+Ca8-P)>acid-extractable P (Ca10- P)>occluded-P for both virgin and agricultural soils. Although a marked proportion of added P was transformed into less soluble Al and Fe phosphates, successive harvesting had depleted considerable percentages of these fractions. Highly significant (p<0.001) relationships were found for P uptake vs. Olsen-P, P uptake vs. Pi fractions (Ca2-P, Ca10-P, Al-P, Ca8-P, Fe-P) and Olsen-P vs. Pi fractions. NaHCO3-extractable P seems to be adequate for evaluating plant available P in calcareous soils. However, the closer relationship for the Fe-P fraction vs plant P uptake than for Olsen-P versus plant P uptake indicates that NaHCO3 may not provide the best estimate of plant available P for calcareous soils. Using stepwise regression analysis, it was found that the Ca2-P fraction was most predictive of P uptake (60%), total dry matter (68%), relative yield (74%) and Olsen-P (69%), followed by the Fe-P fraction.