Long-term leaching of nutrients from magnesium ammonium phosphate at various temperatures

Abstract

Magnesium ammonium phosphate and iron-bearing magnesium ammonium phosphate (containing ferrous ammonium phosphate) were made in a pilot-plant, and pellets were prepared trom these products by bonding with 10% by weight of potassium sulphate. These rellets and a range of conventional water-soluble fertilisers were leached on soil columns for 3-6 months .at 23°c, 37°c, and 53°c. and the .leachates were analysed. Nitrogen, phosphorus, and magnesium leached slowly oyer long periods from the magnesium ammonium phosphate pellets, and aeration increased the leaching rate; only potassium was leached rapidly. Little iron was leached from iron-bearing pellets. In contrast, nitrogen, phosphorus, and potassium all leached rapidly from the soluble fertilisers. Magnesium ammonium phosphate therefore supplies essential nutrients to the soil over extended periods. The leaching rate from magnesium ammoni.um phosphat~was at a maximum in the temperature range 2rc-37°c, lind decreased considerably at 53 c. These results suggest that magnesium ammonium phosphate in soil is predominantly leached by an aerobic microbiological mechanism involving nitrification of ammonia. rather than by a solubility mechanism. '

Safety and Effectiveness of Struvite from Black Water and Urine as a Phosphorus Fertilizer

“…This biological process is dependent on temperature, other nutrients, oxygen and microbial community composition. Further experiments with nitrification inhibitors, sterile soil, and varying temperatures support the theory that nitrification of ammonia often limits struvite dissolution (Rothbaum & Rohde, 1976). In a fertile aerobic soil, ammonium can be converted to nitrate within days, whereas some anaerobic soils have permanently high ammonium levels in which case another process might be limiting dissolution.…”

Effectiveness of Recovered Magnesium Phosphates as Fertilizers in Neutral and Slightly Alkaline Soils

“…Rothbaum and Rohde (1976) suggested that struvite dissolution might be increased by an aerobic microbiological mineralization mechanism, though this finding has not subsequently been investigated. Mackay and Syers (1986) found that high Ca concentration in the soil solution inhibited the dissolution of Ca phosphate rock.…”

Recovery of ammonium-nitrogen from landfill leachate as a multi-nutrient fertilizer

“…Improved growth of grass, fruit and various high-value crops was observed when they were fertilized with struvite, compared with conventional soluble fertilizers (Rothbaum and Rohde, 1976). Its use may be particularly advantageous when soluble fertilizers are inefficient, low soluble salts are required in the root zone, or a long residual effect is required.…”