Soil conditioner effects on runoff and potato yield under sprinkler irrigation

Synthetic polymers can be used as soil conditioners, but studies of their effects have addressed laboratory simulations much more than cultivated fields. The objective of this work was to study the effects of a low-molecular-weight, nonionic polymer (P-101) on seal formation, infiltration rate (IR), runoff, erosion, and potato (Solanum tuberosum L.) yield. The experiment comprised (i) a laboratory rainfall simulator study and (ii) irrigation of a field in the Negev, Israel with a moving sprinkler irrigation system (MSIS) fitted with various emitters. The emitters were Sprayer No. 1, Spinner, and Super Spray, with discharges of 1254, 2713, and 1777 L h^-1, respectively. The studied soil was Calcic Haploxeralf. Under simulated rain, polymer applications of 50, 25, 10, 5, and 0 (control) kg ha^-1 resulted in final IR values of 31, 28, 27, 19, and 17 mm h^-1, respectively, and erosion rates of 0.9, 0.9, 1.9, 3.5, and 6.1 t ha^-1, respectively. In the field, the 40 kg ha^-1 polymer treatment, applied with Sprayer No. 1, Spinner, and Super Spray emitters, reduced runoff by 75, 60, and 62%, respectively, compared with the control treatment. The irrigation efficiencies (the ratios between plant yield and total water application) of the MSIS with Sprayer No. 1, Spinner, and Super spray were 56, 31, and 43 kg mm^-1, respectively, on untreated soil and 66, 49, and 65 kg mm^-1, respectively, under the 40 kg ha^-1 polymer treatment.