Some soil physical properties and wheat root growth influenced by superabsorbent 200A polymer

The need for water storage is steadily growing because of increasing water demands by growing population in arid and semiarid areas such as Iran where droughts occur frequently. Super absorbent polymers are conditioner’s group which can absorb precipitation or irrigation water and prevent water loss. Soil amendments have more effects on soil water storage when there are more droughts in soil with the intermittent rain fall, retaining the limited humidity and decreasing evaporation losses and increasing plant available water for crop growth. Applied polymer increased soil moisture, reduced mechanical resistance and increased dry-land wheat root growth.
In this investigation, the effects of superabsorbent polymer on soil humidity absorption were assessed .The study used a split-plot design format. Main plots were potassium sulfate fertilizer at 2 levels (200 Kg per hectare and no potassium sulfate) and sub plots were superabsorbent at 4 levels (0, 500, 1000, 2000 kg/ha) with4 repetitions. The research was carried out in Gorgan University of Agriculture Sciences and Natural Resources Research Farm located at SeyedMiran during 2014-2015 growing season. Row spacing was 20 cm, used 268/5 kg ha-1 (seeds were drilled manually). Fertilizer rates were based on soil test results and which were added to soil surface before planting and incorporated. soil mechanical resistance at 6 stages during wheat growing season using a cone penetrometer (0-5cm soil depth) and so soil moisture at 0-8 and 8-16 soil depths were Measured. Data analysis include the analysis of variance and mean comparisons using LSD and correlation which carried out using SAS software.
Results show that potassium fertilizer did not affect soil moisture at 0-8 and 8-16 cm depths polymer consumption had a significant impact on soil moisture, however. 1000 and 2000 kg per hectare polymer increased soil moisture at 0-8 and 8-16 cm depths. 500 kg per hectare polymer had no impact on soil moisture. Soil moisture improvement at 0-8 cm depth, where polymer was already incorporated was comparable with the underlying 8-16 cm depth. Polymer reduced possibly evaporation from lower 8-16 cm depth as much as it enhanced soil moisture in the incorporated depth. Increased soil moisture content within 0-16cm depth lowered soil mechanical resistance and enhanced root growth.
Hysteresis does not affect polymers water because they are almost always saturated during swelling and shrinkage, except when they are nearly desiccated. Due to hysteresis however, desorbing soil which surrounds polymers remains wetter than absorbing soils further away. This explains why super-absorbents are generally wetter than the surrounding soil and are non point water resources for plant use.