Correlation study of soil test on phosphorus in ultisol soil for shallots (Allium ascalonicum l.)

Abstract

The research objective was to determine the best soil P extraction method for shallot plants in Ultisols. This study used a single location approach. The selected location was in Kentrong village, Malangsari Village, Cipanas, Lebak, Banten Province. The research was conducted from March 2015 to May 2016, consisting of two stages, namely the creation of P nutrient status and correlation testing through planting in polybags in a greenhouse. Preparation of soil P nutrient status using phosphoric acid (H3PO4) from very low to very high (0X, 1 / 4X, 1 / 2X, 3 / 4X, and X), where X is half of the maximum absorption of 1033.3 kg P ha−1 . Fertilizer P was incubated for three months, then taking soil samples in each plot for analysis of soil P content. Soil P content analysis used five different extraction methods, namely Bray I (0.025 N HCl + 0.03 N NH4F solution), Bray II (NH4F 0.03 N + HCl 0.10 N), Mehlich I (0.0125 M H2SO4 + 0.05 M HCl), Morgan Wolf (NaC2H2H3O2.3H2O; pH 4.8), and Truog (0.02 N H2SO4 + (NH4) 2SO4). The planting of shallots in polybags was carried out in the greenhouse of Jakarta Assessment Institute for Agricultural Technology, using a completely randomized design (CRD), with five replications. The results showed that the best soil P nutrient extraction method for shallot plants in Ultisols was the Truog method with a correlation coefficient of 0.77 and 0.84 for the correlation between soil P content and relative yields of plant dry weight and the correlation between soil P content and Uptake P. The results of this study can be used to determine recommendations for P fertilization on shallots in an Ultisol soil.