Effect of synthetic and natural water absorbing soil amendment soil physical properties under potato production in a semi-arid region

Effect of synthetic and natural water absorbing soil amendments on soil physical properties, fresh tuber yield and size of potato production was investigated in a field experiment 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 compound amendments (natural combined with a synthetic) and a no amendment control. Soil amendments had highly significant effect (P ≤ 0.01) on soil water holding capacity, soil cone penetration resistance and soil aggregate size fractions, but had no significant effect (P > 0.05) on soil bulk density. Soil amendments increased fresh tuber yield by 4.2-32.9%, increased the proportion of tuber size category 1 (>150 g) and decreased size category 3 (<75 g) in all the three years. The compound amendment, with PAM + HA, showed best effect of all amendment treatments on soil physical properties in potato production, and deserves further research.