Nitrogen Forms and Heavy Metals Leachability Following Biosolids Application to Sandy Soil.

Leaching poses a significant concern in dry regions with sandy soils due to their inherentcharacteristics of low fertility, coarse texture, very low organic matter content, and limited waterretention capacity. The aim of this research was to minimize environmental consequences of applyingbiosolids compost at high rates to sandy soils under arid conditions in terms of inorganic nitrogen andheavy metals pollution. This investigation used a pot experiment that was incubated at a constanttemperature (25 0C) and comprised four application rates (0.0, 20, 40, and 60 t/ha) of compost, twomethods of application (mulching and incorporating) and two intermittent irrigation intervals (3 and 6days). Results of this experiment revealed that the nitrate concentration in soil leachate exceeded 50mg/L, a value considered highly poisonous if it exists in drinking water. Ammonia concentrationsexceeded 20 mg/L in the second leachate fraction but decreased to under detection limits in the lastfifteen leachate fractions for all compost treatments. The suggested maximum contamination level forgroundwater is 1.5 mg NH4-N-1. NO3-N concentrations in all soil leachate fractions were substantiallyabove the acceptable threshold in drinking water for people (10 mg/L) but far below the recommendedlevel in drinking water for cattle (100 mg/L). The findings provided strong evidence that the environmentis well safeguarded in terms of heavy metal concentrations in the soil leachate. From this research, itmay be stated that high loading rates of excellent quality compost to sandy soils is agronomicallyadvantageous with little potential environmental harm if handled effectively.