JWSS - Journal of Water and Soil Science

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Paleosols provide invaluable data on paleoclimatic conditions of the area. These soils widely exist in central Iran. Micromorphology and clay mineralogy are among valuable techniques which are useful for interpretation and identification of these soils. The present research was performed to compare the micromorphology and clay mineralogy of paleosols and modern soils of Jiroft area. After field studies, 4 pedons (located on different geomorphic surfaces including stable mantled pediment, stable and unstable transitional surfaces of pediment and alluvial plain, and stable surface of alluvial plain) were sampled for physicochemical, micromorphological, and clay mineralogical analyses. Clay coatings in argillic horizons of paleosols were found during micromorphology observations. On the other hand, clay coatings in present soils were only found in natric horizons, which were attributed to high amounts of Na in these soils. Moreover, smectite, palygorskite, illite, chlorite, and kaolinite clay minerals were recognized in paleosols, but chlorite was not detected in modern soils. The presence of palygorskite in the soils under study was related to the stability of geomorphic surface. Results of the present research showed that a more humid climate was present at the time of paleosols formation.

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In order to study the effect of depth of drip placement in soil in subsurface drip irrigation, and fertilization time during irrigation events, on tuber yield of potato, an experiment was carried out in Jiroft area in 1389. This experiment was in a completely randomized block design with four replications, with depth placement of drip tape as the main plot, and fertilization time as the sub-plot. Results showed that depth placement of drip tape had a significant effect on tuber yield, plant height, number of stems, stem diameter and dry plant weight at 1% level, number of tubers in plant, and wet plant weight and stolen height at 5% level. Fertilization time had a significant effect on tuber yield, stem diameter, stem number in plant, and plant height at 1% level and on dry plant weight and plant tuber number at 5% level. But, it did not show any significant effect on other attributes. Also, interactional effects of treatments were significant on tuber yield per plant, stem diameter, plant height, and number of tubers at 1% level, and on dry plant weight at 5% level, but the effect on other traits was not significant. According to the statistical results, the highest yield was obtained from the depth of 15 cm and middle time of fertilization.