Pedosphere 30(2): 253--262, 2020
ISSN 1002-0160/CN 32-1315/P
©2020 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effect of soil pore size distribution on plant-available water and least limiting water range as soil physical quality indicators
Mehdi ZANGIABADI1, Manoochehr GORJI1, Mehdi SHORAFA1, Saeed KHAVARI KHORASANI2, Saeed SAADAT3
1Department of Soil Science, University of Tehran, Karaj 31587-11167 (Iran)
2Department of Seed and Plant Improvement, Khorasan-Razavi Agricultural and Natural Resources Research Centre, Mashhad 91659-66416 (Iran)
3Department of Sustainable Land Management, Soil and Water Research Institute, Karaj 31779-93545 (Iran)
ABSTRACT
      Soil pore size distribution (SPSD) is one of the most important soil physical properties. This research investigated the relationships of location and shape parameters of the SPSD curves with plant-available water (PAW) and least limiting water range (LLWR) of the light-textured soils at the Torogh Agricultural Research Station in north-eastern Iran. Soil moisture release curve (SMRC), PAW and LLWR in matric heads of 100 and 330 hPa for the field capacity and location and shape parameters of the SPSD curves of 30 soils with different texture and organic carbon contents were determined, and the variable relationships were statistically analyzed. The results showed that the median equivalent pore diameter (de), mean de, standard deviation (SD*), and skewness of the SPSD curves were significantly correlated with PAW (PAW330) and LLWR (LLWR330) measured in a matric head of 330 hPa. Decrease in de and increase in the diversity of soil pore size (SD*) increased PAW330 and LLWR330. The SD* values of all the soil samples were lower than the optimal ranges suggested in literature. Neither PAW nor LLWR values were significantly different in the soils with the optimal modal de and those with non-optimal modal de. Optimal values of median and mean equivalent pore diameters and kurtosis of SPSD curves led to a significant improvement of PAW330 and LLWR330 as soil physical quality indicators. It was recommended to revise the optimal ranges for SD* and modal de for future studies.
Key Words:  equivalent pore diameter,kurtosis,location parameter,matric head,shape parameter,skewness,soil pore size distribution curve,soil water availability
Citation: Zangiabadi M, Gorji M, Shorafa M, Khavari Khorasani S, Saadat S. 2020. Effect of soil pore size distribution on plant-available water and least limiting water range as soil physical quality indicators. Pedosphere. 30(2): 253-262.
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