Changes in the biological activity of soils when adding superabsorbing polymers to them

Abstract

Due to global climate change, which entails redistribution of intra-annual precipitation, there are continuous periods of draught, which were not typical for this territory before, which directly affects the water availability of agricultural crops. The solution of this problem is in development of various technologies and functional materials. One of such materials are superabsorbent polymers or hydrogels. Many studies prove that hydrogels favorably affect the yield of agricultural crops, due to their ability to absorb water in a volume exceeding its own in several tens of times, thereby retaining moisture in the root layer, preventing it from evaporating and flowing to deeper layers of soil. Three types of hydrogels were used in the experiment: «Ritin-10», «Aquasorb», «B415-K» – and sod-podzolic soil from the Menkovo branch of the Agrophysical Institute in the Leningrad region. Microbial metabolic coefficient (qCO2) is an integral indicator of the biological state of soils. It reflects the change in basal respiration and microbial biomass of the soil: the lower the value is, the better the condition of the microbial community is. In the control samples there was an increase in the value of the indicator by day 30, in the samples with hydrogels this indicator decreased by day 30. For all samples with hydrogels there was a noticeable decrease in the index and, consequently, an improvement in the state of microbiota occurred between day 15 and 18 of the experiment. In this experiment, is impossible to reliably establish whether hydrogel becomes available for microorganisms as a source of elements necessary for life activity, but its presence in the soil improves the state of microorganisms, and in case of hydrogel «B415-K» also contributes to the increase of biomass of microorganisms.