JWSS - Journal of Water and Soil Science

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A 4x4 factorial experiment with a completely randomized design with three replications was conducted separately on two major pistachio varieties, Ohady and Kaleghoochy, to investigate the effects of shaking amplitude and frequency on pistachio nut and cluster detachment. Four levels of shaking frequencies used for Ohady were 5, 7.5, 10 and 12.5 Hz, while those of Kaleghoochy were 7.5, 10, 12.5 and 15 Hz. Four levels of shaking amplitude for Ohady were 20, 40, 60 and 80 mm, while those of the Kaleghoochy were 40, 60, 80 and 100 mm. Analysis of variance and mean comparison showed that the effects of shaking amplitude and frequency on pistachio nut and cluster detachment were significant on both varieties. It was found that in Ohady, at frequency of 12.5 Hz and amplitude of 80 mm, the maximum effective nut detachment occurred. But considering the need to limit both yield loss and limb damage to 5% and minimizing the power requirement of the limb shaker, applying shaking amplitude of 60 mm and frequency of 10 Hz, which detaches 95% of the nuts, is considered as the most suitable combination of shaking amplitude and frequency. Also, at amplitude of 80 mm and frequency of 12.5 Hz, the highest percentage of cluster detachment occurred. Here again, by considering limb damage and power requirement, applying shaking frequency of 12.5 Hz at 60 mm amplitude with 69% cluster detachment was selected as the most suitable combination. In Kaleghoochi, at amplitude of 100 mm and frequency of 15 Hz, nut detachment was 100%, while the need to limit limb damage and power consumption, the combination of 60 mm amplitude and 15 Hz frequency with 97.2% nut detachment was selected as the most suitable one. For cluster harvesting of Kaleghoochy, shaking amplitudes of 60 and 40 mm and frequency of 12.5 Hz with cluster detachment of 75 and 69 percent, respectively were selected as the most suitable ones. The average ratio of tensile force required for removing pistachio nut to its weight (F/W), and the ratio of tensile force required for removing pistachio cluster to its weight (V/W), which could be considered as an index of ease of detachment, were measured 6.2 and 37 for Ohady and 9 and 37.8 for Kaleghoochy, respectively. Finally, we may conclude that by applying the suitable combination of shaking amplitude and frequency, shake harvesting of pistachio could be practiced successfully.

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Microbial transport in soil is critical in different ways, especially in groundwater contamination and bioremediation of groundwater or soil. The main objectives of this research were quantitative study of bacterial transport and deposition under saturated conditions in calcareous soils. A series of column leaching experiments were conducted. Breakthrough curves (BTCs) of Pseudomonas fluorescens and Cl- were measured. After leaching experiment the bacteria was measured in difference layers of the soil columns. The HYDRUS-1D one- and two-site kinetic attachment-detachment models were used to fit and predict transport and deposition of bacteria in soil columns experiments. The results indicated that two-site kinetic model leads to better prediction breakthrough curves and bacteria retention in the calcareous soil in comparison with one-site kinetic model. Interaction with kinetic site 1 was characterized by relatively fast attachment and slow detachment, whereas attachment to and detachment from kinetic site 2 was fast. Fast attachment and slow detachment of site 1 was attributed to soil calcium carbonate that has favorable attachment site for bacteria. The detachment rate was less than 0.01 of the attachment rate, indicating irreversible attachment of bacteria. Most of the cells were retained close to the soil column inlet, and the rate of deposition decreased with depth. Microbial reduction rate for the soil was 4.02-4.88 log m-1. High reduction rate of bacteria was also attributed to soil calcium carbonate that has favorable attachment site for bacteria.