Effect of Aquasorb and Organic Compost Amendments on Soil Water Retention and Evaporation with Different Evaporation Potentials and Soil Textures

Abstract

Aquasorb PR3005A, a hydrophilic polymer (a salt copolymer polyacrylamide), and garden waste compost were added to a loamy sand and a loam soil in pots to assess their impact upon soil physical properties at two different evaporation potentials. Compost was mulched and incorporated, the Aquasorb was incorporated, and their effect on temperature and amelioration of soil water content and evaporation was investigated. Mulching with compost reduced evaporation and increased soil temperature. Maize (Zea mays var. single cross 704) was sown in the same pots later, and growth indicator factors (plant height, fresh and dry weight, root weight, and leaf area) were compared. It was concluded that compost mulch application is beneficial to soil water retention whereas compost incorporation did not show these benefits. Compost mulch advances seedling emergence and enhances early growth through hydrologic soil amelioration. High rates of Aquasorb were also beneficial in advancing the emergence and early growth of maize seeded in loamy sand. The hydration capacity of Aquasorb is reduced as the electrolyte concentration and electrical conductivity are increased. Increased electrolyte concentration in soil solution, through drying, may result in gel dehydration and water release at potentials greater than field capacity, which may be lost to drainage. Furthermore, it is concluded that pot experiments with amendments fail to simulate field conditions.

Keywords:

• Aquasorb, compost incorporation, compost mulch, evaporation, field simulation with pots, hydrophilic polymer, water retention

Acknowledgments

The authors thank Mohammad Zaman Alaodin and Mohammad Ajami for their technical assistance and Saeed Hassani for statistical advice. This research was funded by Gorgan University of Agriculture (Iran).