Showing 5 results for Taxonomy
S. Ayoubi, A. Jalalian, J. Givi,
Volume 5, Issue 1 (4-2001)
Abstract
Qualitative land suitability evaluation is based on the physical parameters affecting the yield agricultural crops. The socio-economic factors are not considered in such evaluations. This study was carried out to assess the qualitative land suitability for irrigated wheat, barley, maize and rice in northern Baraan. Five soil series and 25 different phases were first delineated. Land utilization types commonly practiced in the region with intermediate input levels were considered. Physical requirements of the crops were determined and ranked using the available information. FAO framework and the proposed method of Sys were used for the evaluation. Qualitative evaluation was carried out according to both simple limitation and parametric methods by comparing land and climatic characteristics with crop requirements.
It was shown that in addition to climatic factors, soil salinity, drainage and some soil physical properties such as texture, gravel and lime are the most limiting factors. Land physical suitability for rice production was very low in most land units. The results from physical evaluation by parametric method were very close to those from the simple limitation approach.
A. A. Fadaei Tehrani, A. Kheiri,
Volume 9, Issue 1 (4-2005)
Abstract
Plant parasitic nematodes of Dorylaimida occur only in the Longidoridae. Longidorus is one of important genera in this family, which it,s species are parasite on many plants and act as a vector for some of plant viruses. From 1999 to 2001, more than 250 soil samples were collected from several localities of Iran. Nematodes were extracted, fixed (De Grisse, 1969) and mounted on glass slides in dehydrated glycerine. Using a light microscope equipped with a drawing tube, morphological and anatomical characteristics of nematodes were studied, body parts were drawn, measurements were carried out and the species of nematodes were determined. Species were compared with the original descriptions and variations reported from other regions of the world. Differences and similarities of the species with main description and closely related species were discussed. Three species, Longidorus africanus, L. iranicus and L. pisi were identified the latter species is first record for Iran. L. africanus were mainly occurred in southern regions while L.iranicus were mostly found in northern areas.
A. Jafari, H. Khademi, Sh. Ayoubi,
Volume 16, Issue 62 (3-2013)
Abstract
Digital soil mapping includes soils, spatial prediction and their properties based on the relationship with covariates. This study was designed for digital soil mapping using binary logistic regression and boosted regression tree in Zarand region of Kerman. A stratified sampling scheme was adopted for the 90,000 ha area based on which, 123 soil profiles were described. In both approaches, the occurrence of relevant diagnostic horizons was first mapped, and subsequently, various maps were combined for a pixel-wise classification by combining the presence or absence of diagnostic horizons. Covariates included a geomorphology map, terrain attributes and remote sensing indices. Among the predictors, geomorphology map was identified as an important tool for digital soil mapping approaches as it helped increase the prediction accuracy. After geomorphic surfaces, the terrain attributes were identified as the most effective auxiliary parameters in predicting the diagnostic horizons. The methods predicted high probability of salic horizon in playa landform, gypsic horizon in gypsiferous hills and calcic horizon in alluvial fans. Both models predicted Calcigypsids with very low reliability and accuracy, while prediction of Haplosalids and Haplogypsids was carried out with high accuracy.
M. Bahmani, M.h Salehi, I. Esfadiarpoor,
Volume 18, Issue 67 (6-2014)
Abstract
One of the main objectives of soil classification systems is to identify the differences of soil properties for management purposes. In this study, the efficiency of American and WRB soil classification systems were compared in order to describe some of soil physical, chemical and mineralogical properties in arid and semiarid regions of central Iran. Khatoon-Abad and Mobarekeh plains as arid regions and Koohrang and Shahrekord plains as semiarid regions were selected. Then, representative pedons of each plain were chosen from 16 excavated pedons and soil samples were taken from the genetic horizons to determine soil classification. Results showed that soil orders of both Koohrang and Khatoon-Abad plains are vertisols according to American soil classification system whereas based on WRB system, these soils are classified as cambisols and calcisols, respectively. On the other hand, both Mobarekeh and Shahrekord soils are classified as calcisols in WRB system whereas these soils are classified as aridisols and inceptisols, respectively, according to American soil taxonomy. None of soil classification systems could show the existence of gypsum in horizons lower than 100 cm of the soil surface for Mobarekeh soil. Clay mineralogy indicates that smectite is the dominant clay mineral in Koohrang soil as explains well at the family level of American soil classification system. Results suggest that WRB has somewhat higher efficiency rather than American soil classification system for the studied soils.
Sh. Ahmadi-Qolidaraq, A. Abbasi-Kalo, A. Esmali-0uri,
Volume 23, Issue 4 (12-2019)
Abstract
Soil is one of the most important natural resources of countries in which erosion occurs. In this research, the effect of soil characteristics on the amount of erosion at the suborder level was studied. For this purpose, 77 soil samples (0-30 cm) were prepared and the parameters were determined in the laboratory. The semi-variograms of soil parameters and their spatial distribution maps were prepared with GS+ and GIS, respectively. The study area was divided into work units by combining land use and geology maps and water erosion was estimated at each unit by the EPM method. By drilling profiles in different parts of study area, soil suborders were determined by Soil Taxonomy and the average values of parameters in each suborder was estimated. The principle components analysis (PCA) was then used for data analysis. The results showed that three parameters of silt, organic carbon and electrical conductivity could account for 30.384% as the first main component; clay, sand and vegetation could explain 11.189% as the second main component; and slope and height covered 15.330% as the third main component; in total, 63.805% percent of erosion variation could be justified by three main components. The lowest and highest amounts of erosion (69.12 and 343.57 m3/km2, respectively) were estimated in Xeralfs and Fluvents suborders. The erosion class of suborders at the study area was determined to be “few” and “medium”.
