Journal of Food, Agriculture and Environment

Soil test phosphorus and microbial biomass phosphorus in potato fields

Author(s):

Zhongqi He ^*, C. Wayne Honeycutt, O. Modesto Olanya, Robert P. Larkin, John M. Halloran

Recieved Date: 2010-10-16, Accepted Date: 2011-01-03

Abstract:

Appropriate evaluation of soil phosphorus (P) availability is a prerequisite for best P management in potato production systems. Consequently, we evaluated soil test P and microbial biomass P in 10 rainfed and irrigated potato field soils which had a three-year crop rotation. Ammonium oxalate extracted P was the highest with a level of >1400 mg kg^-1. Olsen P was moderate and ranged from 100 to 120 mg kg^-1. Modified Morgan inorganic P (MMPi) was lowest (<10 mg kg^-1). However, only the MMP_i levels were statistically and significantly impacted by crop rotation. Furthermore, MMP_i quantified in spring was negatively correlated with the previous year’s potato yield for fields receiving the same amount of P fertilizer and had R²values of 0.92 (α = 0.05), 0.78 (α = 0.1), and 0.59 (α = 0.05) for rainfed, irrigated, and for both fields, respectively. This observation implied that the decrease of MMP_i levels was due to the P uptake of potato tuber growth and the modified Morgan extraction procedure was a good indicator of P utilization. Our data indicated that fumigation was more effective than microwaving in releasing microbial biomass P from these soils. Irrigation increased microbial biomass P in the continuous potato soils, but decreased it in the field soils of soil conserving, soil improving, disease suppressive, and status quo rotation treatments. Our observations suggested that crop rotation impacted both soil test and microbial biomass P in these potato fields. Further research is required to determine if these changes consistently occur over longer periods.

Keywords:

P availability, ammonium oxalate P, Olsen P, modified Morgan inorganic P, crop rotation, microbial biomass P

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Journal: Journal of Food, Agriculture and Environment
Year: 2011
Volume: 9
Issue: 1
Category: Environment
Pages: 540-545

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