The addition of magnesium sulfate and borax to urea reduced soil NH 3 emissions but increased N 2 O emissions from soil with grass

Nitrogen (N) use efficiency can be increased by the addition of substances to urea. Magnesium sulfate (MgSO 4 ) and boron were considered as plant nutrients, while zeolite was used as soil conditioner. The addition of these substances may affect soil NH 3 and N 2 O emissions, by increasing N use efficiency. We conducted an 30 days incubation experiment with ryegrass using fertilizer treatments (12 g N m −2 ) as follows: urea (U); urea + MgSO 4 (UM); urea + MgSO 4  + borax (UMB); zeolite + urea + MgSO 4 (Z-UM); and zeolite + urea + MgSO 4  + borax (Z-UMB). We measured NH 3 and N 2 O emissions and the aboveground N uptake of ryegrass. Cumulative NH 3 emissions of UM, UMB, Z-UM and Z-UMB were 10%, 53%, 21% and 58% lower than U, respectively, while their N 2 O emissions were 32%, 133%, 43% and 72% higher than U, respectively. Aboveground N uptake of UM, UMB, Z-UM and Z-UMB were 9%, 6%, 12% and 13% higher than U, respectively. Overall, we suggest that the addition of MgSO 4 and borax were effective in reducing NH 3 emissions and potentially increase plant N uptake. However, the risk of higher denitrification and N 2 O emissions also needs to be considered. This study reveals the considerable effect of MgSO 4 and borax in soil N cycles. Future research should evaluate how the application of urea + MgSO 4  + borax effects gaseous emissions and crop yield of dicotyledons and in drier soil conditions.