Journal of Environmental Biology

Determining critical value of soil Olsen P for dry direct seeded rice (Oryza sativa) in a greenhouse study in northwestern India

N. Rathore²*, R.K. Gupta¹, Y. Singh¹ and B. Singh¹

¹Department of Soil Science, Punjab Agricultural University, Ludhiana-141 004, India

²Department of Agriculture, ?Lovely Professional University, Phagwara-144 411, India

*Corresponding Author E-mail: navi00rathore@gmail.com

Key words

Critical limit,

Direct seeded rice,

Olsen P,

Phosphorus uptake,

Shoot biomass 

Publication Data

Paper received : 18.08.2015

Revised received : 04.05.2016

Re-revised received : 16.09.2016

Accepted : 09.11.2016

Abstract

Aim: In view of the looming water crisis and shortage of labour during transplanting, dry-seeded rice (DSR) is an attractive option for rice cultivation in Asia. Presently limited information is available on optimum nutrient management in DSR. Compared to puddled transplanted rice, DSR is likely to encounter less availability of fertilizer phosphorus. The main objective of the study was to determine critical value of soil Olsen P for DSR.

Methodology: A greenhouse experiment was conducted to study the effect of three levels of phosphorus (0, 6.5, 13 mg P kg^-1 soil) application on dry matter accumulation and phosphorus uptake of DSR at maximum tillering (MT), panicle initiation (PI) and flowering stages (FL) in ten different soils varying in Olsen P and texture. Bulk soil samples (0-15 cm) were collected from different locations in Punjab state of India and analyzed for initial physical and chemical properties (pH, electrical conductivity, cation exchange capacity, organic C, NaHCO₃?extractable P, NH₄OAc-extractable K, DTPA-extractable Zn, Cu, Mn, and Fe and particle size distribution). Soil samples collected at flowering stage were analyzed for Olsen P. Plant samples were analyzed for total phosphorus content. Cate and Nelson (1971) method was used to determine the critical limit of soil Olsen P.

Results: Soils low in Olsen P (<5.3 mg kg^-1 soil) showed significant increase in shoot biomass and phosphorus uptake of DSR with the application of 6.5mg P kg^-1 soil compared to control. Critical values of Olsen P for DSR, below which the crop would suffer yields determined by Cate-Nelson model, was 9.0 mg kg-1soil. Recovery of phosphorus fertilizer at 6.5 mg P kg^-1 in different soils ranged from 23.3-42.8%, with lower values for high Olsen P soils compared to control.The critical value of Olsen P was low at initial (MT and PI) growth stages than at flowering stage, suggesting that early crop growth in DSR is more sensitive to phosphorus deficiency.

Interpretation: Response of DSR to phosphorus application depends on the availability of phosphorus in soil. A critical level of Olsen P at 9 mg kg^-1 soil can be used for applying fertilizer phosphorus? to DSR.

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