Urine-derived fertilizer keeps phosphorus available in tropical soil for maize

Struvite recovered from human urine produced strong early maize growth and left more plant-available phosphorus in a tropical Oxisol than other options.

Editorial illustration — not from the study.

Researchers evaluated human urine-derived struvite (a phosphorus mineral) in a tropical Oxisol under maize cultivation. They found that the urine-derived struvite achieved substantial shoot biomass under tropical soil conditions, though a common mineral fertilizer (monoammonium phosphate) generally produced higher shoot dry mass at the highest phosphorus application rates.

The key difference was what remained in the soil after the crop grew: plants grown with urine-derived struvite left substantially higher residual phosphorus that could be extracted with Mehlich-1, an indicator of labile or readily available phosphorus. The authors link this to struvite’s controlled-release behavior and reduced phosphorus immobilization in a highly weathered tropical soil.

How the struvite behaved in soil

In a tropical Oxisol maize system, human urine-derived struvite (HU-Struvite) produced substantial shoot biomass during early vegetative growth. At the highest phosphorus rates, monoammonium phosphate generally produced higher shoot dry mass than HU-Struvite. After cultivation, plots treated with HU-Struvite had substantially higher residual Mehlich-1 extractable phosphorus, indicating sustained labile phosphorus availability and reduced phosphorus immobilization in the highly weathered soil.

Why tropical phosphorus release matters

Tropical soils often bind phosphorus, which can limit how much fertilizer phosphorus becomes usable to plants. This study suggests that controlled phosphorus release from urine-derived struvite can maintain plant-available phosphorus over time during maize’s early growth, which the authors connect to less rapid fixation by soil minerals rich in iron and aluminum.

Evidence and study limits

This is an agronomic and soil-chemistry study testing HU-Struvite versus a mineral phosphorus fertilizer within a single soil–plant system in a tropical Oxisol. The abstract does not provide the experimental design details, replication, durations beyond early vegetative growth, or how broadly the results apply beyond the specific soil and crop conditions tested, limiting how far conclusions can be generalized from the abstract alone.

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