The formation of productivity of grain crops with introducing hydrogels under model soil drought and in field conditions

The use of water-absorbing hydrogels capable to regulate the soil water regime allows for a significant increase in crop production in arid and semi-arid climatic zones. Polyacrylamide and poly-acrylonitrile hydrogels cyclically (over several years) absorb and release moisture, so they are most effective in agriculture. This paper shows that three polymer gels of different origin have similar effect on the yield structure and productivity of grain crops compared under controlled soil drought and in field tests. Domestic gels had the greatest effect on the 1000-grain weight. The type of hydrogel (either sodium or potassium base) did not significantly influenced the yield structure parameters. This work aimed to evaluate grain crops' productivity and yield structure as affected by polymer gels V-415 K and Ritin-10 (Russia) under simulated soil drought compared to the polymer Aquasorb (France) under field conditions of a zone of insufficient moisture. Microfield trials were performed on spring barley ( Hordeum vulgare L.) cv. Leningradsky in 2015, spring wheat ( Triticum aestivum L.) cv. Daria in 2016 and spring barley cv. Ataman using bottomless pots (Agrophysical Institute, Menkovsky branch, Leningrad Province) using pots without a bottom with an area of 0.075 m2 and a volume of 0.0025 m3. The pots were filled with sod-podzolic sandy loamy soil according to the soil horizons' order. The treatments were a control (N90P90K90); N90P90K90 + Ritin-10 at 10-12 cm depth; N90P90K90 + V-415 K at 10-12 cm depth; N90P90K90 + Ritin-10 at 20-22 cm depth; N90P90K90 + V-415 K at 20-22 cm depth. The dose of each hydrogel was 4 g/m2, the seeding rate was 50 pcs/pot. Soil moisture in the pots was measured twice a week to calculate necessary watering rate. The effect of soil drought (55-60 % water holding capacity) was assessed from the tillering phase to full ripeness. The productivity of winter wheat ( T. aestivum ) cv. Steklovidnaya 24 as influenced by polymer gel Aquasorb (SNF s.a.s., France) was studied in the Republic of Kazakhstan in 2015-2017 (experimental fields of the Kazakh Research Institute of Agriculture and Plant Growing). Two doses of the absorbent (20 and 40 kg/ha) and their combination with nitrogen supplementation (N45) were tested. The total number of plants per pot (per 1 m2 in field trials), the number of productive plants, and productive bushiness coefficient, the ear length, the number of grains per ear, the grain mass per ear, and the 1000-grain weight were determined. The grain yield under a controlled “drought” when the hydrogels were introduced into the root layer (10-12 cm) differed slightly from the control (an increase by only 3-4 %). For the 20-22 cm depth, the yield exceeded the control by 25.0-27.7 % (р function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }