Optimum Population Size of Indigenous P-solubilizing Bacteria to Correct P Availability in Acid Soils

Sabaruddin Sabaruddin,Desti Desti,Marsi Marsi

doi:10.5400/jts.2011.v16i1.55-62

Abstract

Indonesian acid soils were used to determine an optimum population size of indigenous P-solubilizing bacteria (PSB) for solubilizating fixed P. The experiment consisted of two sub-experiments. Sub-experiment I was to isolate the indigenous PSB from Ultisols, Fresh-water lowland Inceptisols, and tidal-swamp Inceptisols. Subexpriment II was to study the capacity of the isolated PSB to correct P availability in acid soils by inoculating the isolated PSB into the tested soils at 0, 105, 1010, and 1015 cells. The population of the indigenous PSB in the tested soils increased as a result of the inoculation. Both Al-P and Fe-P content in the three tested soils decreased as compared with the initial content. The increases of available P were significantly correlated with the decreases both in Al-P (r2 = 0.68 for the Ultisols; r2 = 0.51 for the fresh-water Inceptisols; and r2 = 0.35 for the tidal-swamp Inceptisols) and in Fe-P (r2 = 0.91 for the Ultisols; r2 = 0.45 for the fresh-water lowland Inceptisols; and r2 = 0.78 for the tidal-swamp Inceptisols). The increases of available P were significantly correlated with the increases of thepopulation of the PSB (r2 = 0.60 for the Ultisols; r2 = 0.55 for the fresh-water lowland Inceptisols; and r2 = 0.69 for the tidal-swamp Inceptisols). The available P in the three tested soils sharply increased if the population size of the PSB was about 1 × 109 cfu g-1 of soil.Keywords: Al-P, Fe-P, fresh-water lowland, isolated, Pikovskaya medium, tidal swamp

Highlights

The important role of arbuscular mycorrhizal (AM) fungi in the capture of nutrients from the soil of all ecosystems is wellknown
The results of this study indicated that the function of arbuscular mycorrhizal fungi (AMF) in supplying P was mainly derived from unavailable P in the soil
The population of arbuscular mycorrhizal fungi (AMF) on six soil sampling locations varied from 135 AMF spores per 100 g of soil until 497 spores per 100 g soil

Summary

Introduction

The important role of arbuscular mycorrhizal (AM) fungi in the capture of nutrients from the soil of all ecosystems is wellknown. It is often neglected in the soil and crop management about the impact of AM fungi on fertilizer application quantitatively, especially phosphorus (P). Phosphorus is the second essential nutrient after nitrogen (N) and it is required for plant growth and found in soils in organic and complex inorganic forms. Due to its low solubility and mobility, plants cannot readily utilise P in an organic or complex inorganic form (Schachtman et al 1998). The function of AM fungi are to enhance the uptake of phosphorus from the soil, which is translocated to the host plant through hyphal networks in the soil (OwuzuBennoah and Wild 1980)

Results

Discussion

Conclusion