Porosity change model for watered super absorbent polymer-treated soil

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 SAP-treated 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 SAP-treated 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) - P (0))(-1)]} beta P (0) theta = -eta (0) c theta - eta (0) a. 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.