Linear and Cyclophosphates as Sources of Phosphorus for Corn

Abstract

Cyclophosphates are not adsorbed by soil constituents and can be mobile in the soil profile. Mobile phosphorus (P) sources are of interest in soil science and for agronomic practices. Cyclotri (Na₃P₃O₉; C3P), and cyclotetraphosphate (Na₄P₄O₁₀; C4P) were compared to linear, ortho‐, pyro‐, and tripolyphosphate in four soils with different chemical, physical, and biological properties to determine their mobility and availability to corn (Zea mays, L.) in laboratory and greenhouse experiments. Cyclophosphate (C3P and C4P) hydrolysis products were evaluated by ion chromatography after incubating for 6 to 192 h with 100 and 200 µg P g⁻¹ soil. Phosphorus distribution and mobility, and plant availability and uptake with time, were determined in 45‐cm columns for four soils. Cyclophosphates sorbed less and moved deeper in all soils compared to the linear phosphates. The results showed that after 24 h a large proportion of cyclophosphates (34% of C3P and 37% of C4P) remained unhydrolyzed in Falba sandy acid soil. Split application of C3P and C4P at planting and at booting stage increased corn yield in sandy acid soil. Results of this experiment suggest that P deficiency after plant establishment can be corrected with cyclophosphates in soils with a low potential for cyclo‐P hydrolysis.

Keywords:

• Condensed phosphate
• cyclophosphate
• cyclophosphate hydrolysis
• linear phosphate
• P‐deficiency correction
• pyrophosphate
• split P application
• tripolyphosphate