Effects of extra human urine volume application in plant and soil

Although it has been known that human urine could be reused as nutrients for plant, too much application may cause an accumulation of sodium (Na) and/or nitrogen (N) in soil and eventually inhibit plant growth. A study was carried out to evaluate the effects of extra urine application in plant and soil. Thus, pot test was conducted in greenhouse using synthetic urine, Komatsuna and sandy soil. 34.86 ml of synthetic urine (U-V0) which contained 140 mg-N and corresponded to N-based standard requirement for Komatsuna, 69.72 ml of synthetic urine (U-2V0), 104.58 ml of synthetic urine (U-3V0), 58.82 ml of modified Hoagland solution (V-H) which contained 140 mg-N as positive control and nonfertilizer (C) were applied into different pots (1/10000a). The results indicate that U-2V0 and U-3V0 had no inhibition effect in plant height, shoot and root dry biomasses after one time cultivation, since low amount of Na was applied through urine in soil and Komatsuna is salt moderately plant. However, low K/Na ratio in plant shoot and root, defined as a primary salt stress, was observed in all urine treatments and this phenomenon was especially accentuated in U-3V0. Furthermore, the “unknown-N” calculated from N-balance before and after cultivation could be N-volatilization from pot and was higher in U-2V0 (28.75%) and U-3V0 (24.37%) compared to U-V0 (17.1%). The results suggest that, application of adequate human urine volume based on plant N requirement is a better option for its reuse.