Effect of synthetic and natural water absorbing soil amendments on soil microbiological parameters under potato production in a semi-arid region

Abstract The effect of water absorbing soil amendmentson soil microbiologicalproperties (soil enzyme activity and soil microbial biomass) was investigated in a field experiment under potato production in a semi-arid region in northern China in 2010–2012. Treatments included two different synthetic water absorbing amendments(potassium polyacrylate-PAA, polyacrylamide-PAM) and one natural amendment(humic acid-HA), both as single amendments, and combined amendments(natural combined with a synthetic) and a no amendmentcontrol. Soil amendmentshad a highly significant effect ( P ≤ 0.01) on soil enzyme activity (catalase, invertase, ureaseand phosphatase) and soil microbial biomass (carbon, nitrogen and phosphorus). The PAM + HA amendmenttreatment achieved the greatest effect on soil microbiologicalproperties of all of the amendmenttreatments, both in all soil layers between 0 and 40 cm, and at all four measurement periods during the growing season. Soil amendmentsimproved the catalase, invertase, ureaseand phosphate by 4.6–39.8%, 4.4–27.7%, 3.7–40.4% and 0.9–29.8% respectively and increased soil microbial biomass carbon, nitrogen and phosphorus by 2.5–27.3%, 2.4–28.1% and 3.5–31.6% respectively in all three years. Water absorbing soil amendmentsimproved soil qualityby increasing soil moisture content and its microbiologicalstatus, as reflected in the values of microbial biomass and enzymatic activity.