ARS | Publication request: Soil test and microbial biomass phosphorus levels impacted by potato cropping system and water management

Submitted to: International Symposium on Phosphorus Dynamics in the Soil Plant Continuum
Publication Type: Abstract Only
Publication Acceptance Date: July 13, 2010
Publication Date: September 20, 2010
Citation: He, Z., Honeycutt, C.W., Olanya, O.M., Larkin, R.P., Halloran, J.M. 2010. Soil test and microbial biomass phosphorus levels impacted by potato cropping system and water management. International Symposium on Phosphorus Dynamics in the Soil Plant Continuum. September 19-23, 2010. CD-ROM.

Technical Abstract: Potato crops generally require high amounts of phosphorus (P) fertilizer to reach economically acceptable yields. However, high inputs of P not only increase production cost, but also may increase the environmental risk of P runoff. We evaluated soil test P and microbial biomass P in soils from five different potato cropping systems with and without irrigation. Olsen and ammonia oxalate extractable P were not significantly influenced by crop rotation. The modified Morgan P level differed between soils from different cropping systems. Correlation analysis revealed that modified Morgan P in soil sampled in the Spring was negatively correlated with potato yield from the previous Fall. Microbial biomass-P was measured by both microwave irradiation and chloroform fumigation. P concentrations measured after microwave treatment were always lower than their control counterparts, indicating inapplicability of this method for soil microbial biomass P measurement. Upon using chloroform fumigation, we observed more microbial biomass P under rainfed management (18.9 – 32.7 mg/kg) than under irrigated management (12.3 – 21.2 mg/kg). Both soil test P and microbial biomass P data indicated that crop rotation can impact soil P status. However, more data from longer term field studies are needed to confirm and more fully quantify this impact.