Drought is a great concern in agricultural production, because it restricts normal plant growth, brings about enormous economic loss and deteriorates ecological environment. Proper use of super absorbent polymers (SAP) is helpful in the agricultural and horticultural industry in arid and semi-arid areas, because SAP can ease the burden of water shortage. Because porosity is one of the most important soil physical properties, it is a priority to study SAP to quantitatively express the swelling of watered SAPtreated soil. This study was aimed to evaluate the bulk density curve of watered SAP-treated soil and to construct and test the model for porosity change of watered SAPtreated soil. The results showed that the application of SAP can reduce soil bulk density, improve soil permeability and cause soil swelling. In addition, using three factors, i.e., water content, change in swelling ratio and SAP application rate, the paper constructed a model for porosity change of watered SAP-treated soil, which is {ln[(P m -P)(P m -This is a generic model. Two soil samples, namely, loam and sandy loam, were used to calculate the parameters and test the model. The results of the model were satisfying, thus this model is reliable.

Despite the vast extent of desert soils on the earth's surface, our understanding of the moisture dynamics of near-surface desert soils (i.e., the top centimeters to few meters of the soil profile) remain limited. The goal of this study was to explore the use of the Peters-Durner-Iden (or PDI) instead of bimodal van Genuchten (or BVG) hydraulic functions to improve water redistribution simulations using HYDRUS-1D for drier soils in desert environments. The PDI hydraulic functions take capillary and film flow into account, whereas BVG hydraulic functions are limited to capillary flow. By comparing measured with simulated water content data, we found that moisture redistribution simulations were improved by using PDI instead of BVG soil water retention and hydraulic conductivity functions. Compared with the BVG simulations, the PDI simulations particularly improved for drier soil conditions (i.e., volumetric water contents ranging from 6 to 10%; suction heads between pF 2 and pF 3.8, and saturation degrees between 19 and 32%, respectively) for the studied sandy soil of Scaling Environmental Processes in Heterogeneous Arid Soils (SEPHAS) Lysimeter 1. For pF >3, the PDI functions predicted higher hydraulic conductivity than the BVG functions, which confirmed the hypothesis that a hydraulic conductivity function, which can capture film flow, may improve moisture distribution simulations for dry soils. For pF between 2 and 3, however, simulation results improved due to the difference in the water retention rather than the hydraulic conductivity function.

Flagellins have emerged as important microbial patterns. This work focuses on flagellin duplication in some plant-associated Pseudomonas . Our findings on the divergence of duplicated flagellins provide a conceptual framework for better understanding the functional determinant flagellin and its peptide in multiple-flagellin plant-growth-promoting rhizobacteria.