Availability and leaching of nutrients after biofilm biofertilizer applications into a Red Yellow Podsolic soil

R P Hettiarachchi,A Thewarapperuma,R S Dharmakeerthi,T Gunathilake,E De Silva,A N Jayakody,G Seneviratne,C K Maheepala

doi:10.4038/jrrisl.v94i0.1824

Abstract

Nutrient leaching in RYP soils lowers the fertilizer use efficiency in plantation agriculture of Sri Lanka. The study was conducted to determine nutrient leaching and their availability in a rubber (Hevea brasiliensis Mull Arg.) growing RYP soil supplied with biofilm biofertilizers (BFBF). Microorganisms isolated from rubber roots were formulated as BFBF under in-vitro conditions, and applied with or without 50% and 100% recommended chemical fertilizers into rubber seedlings growing in RYP soils packed in PVC columns. Combine use of inorganic fertilizer with BFBF reduced leaching loss of soil organic carbon throughout the experimental period. The application of BFBF had a marginal influence on leaching losses of K but it significantly reduced Mg losses. The leaching loss of N was not affected in the first two months, but from three months onward a significant reduction was observed with combine use of full recommended inorganic fertilizer with BFBF (100%F+BFBF) compare to inorganic fertilizer alone (100%F). Available nutrients, organic carbon and cations exchange capacity (CEC) in these two treatments were also comparable. Reduced leaching losses of some nutrients in the combine use of inorganic fertilizer with BFBF treatments (50%F+BFBF &100%F+BFBF) were not reflected in the nutrient status of the top soil layer (0-5 cm) but high plant dry matter accumulation was observed in BFBF treated plants. There is a possibility to reduce leaching loss of some nutrients and induce dry matter accumulation of rubber plants by BFBF application into RYP (Hapludults) soils.

Highlights

Many individual rubber plantations have undergone around four planting cycles since their first establishment
All of the combinations of biofilm biofertilizers (BFBF) were found to enhance soil organic carbon status compared to their non BFBF application (Table 2) and BFBF only treatment gave significantly higher value for soil organic carbon over no fertilizer application control
Dissolved organic carbon may be produced by microbial processes, physical deposition in the surface layer, microbial decomposition and sorption processes affect DOC fluxes in the deeper part of the soil profile (Neff et al, 2000)

Summary

Introduction

Many individual rubber plantations have undergone around four planting cycles since their first establishment. The continuous cultivation of monocultural cropping system lower fertility and productivity of soils due to deteriorated of physical, chemical and biological properties as a result of soil erosion and nutrient removal by and crop as well as leaching loss. With the increased usage of chemical fertilizers alone, in an unbalanced manner, problems such as diminishing soil productivity and multiple nutrient deficiencies has appeared. Biofertilizers have found to be highly advantageous in enrichment of soil fertility and fulfilling the plant nutrient requirements by supplying the nutrients through microorganisms and their byproducts. The BFBFs have showed increased biological nitrogen fixation (BNF), mineral nutrient release in the soil, organic acids and plant growth hormone production etc., compared to mono or mixed cultures of the microbes without biofilm formation (Seneviratne et al, 2008a). The aim of the study was to examine the effect of BFBFs on nutrient availability of soil and their effect on leaching loss of nutrients

Objectives

Methods

Results

Conclusion