Table 1 Technical index requirements for rice seedling cultivation substrate Item index bulk density (g/cm3) 0.2~0.8 Conductivity (mS/cm) ≤3.5 pH value 5.5~8.5 Organic matter (on a dry basis), (%) ≥30.0 Total nutrient content ( N+P2O5+K2O) ≥1.5 Moisture (%) ≤55 Table 2 Limit index requirements for rice seedling raising substrate Project requirements Total arsenic (As, on a dry basis) (mg/kg) ≤25 Total mercury (Hg, on a dry basis On a dry basis) (mg/kg) ≤0.5 Total lead (Pb, on a dry basis) (mg/kg) ≤160 Total cadmium (Cd, on a dry basis) (mg/kg) ≤0.3 Total chromium ( Cr, on a dry basis) (mg/kg) ≤300 Number of fecal coliforms (count/g) ≤100 Ascarid egg mortality (%) ≥95