Evaluation of urea ammonium polyphosphate (UAPP) II. Chemical environment in the soil surrounding banded UAPP

Abstract

A laboratory experiment was set up to determine whether NH₃ and/or NO₂‐N accumulates near banded UAPP. Soil was sampled concentrically at two distances (radii of .95 to 2.54 cm and 2.54 to 3.81 cm) surrounding a fertilizer band at 3, 6, 12, 18, and 24 days after application. Fertilizer materials used were UAPP (36–18–0 and 28–28–0) and an ammonium nitrate plus concentrated superphosphate mixture (AN + CSP) with each carrier being used at two ratios of N and P and two rates of each ratio.

Only treatments containing UAPP (36–18–0 at rates of 56+28+0 and 112+56+0 kg/ha) produced NO₂‐N in excess of 10 ppm during the sampling period. All rates and ratios of UAPP provided conditions necessary for free NH₃ accumulation, i.e., intermediate or higher levels of NH₄‐N in conjunction with high soil pH.

Key words:

• Chemical environment
• fertilizer placement
• ammonia and nitrite accumulation

Notes

Former Research Assistant (now Soil Specialist), and Professor of Soil Science, respectively.