Table 3 shows the pH (average values) and quantity of NNH4
+ and
NNO3
− lost in the runoff and leachate solutions. The pH of the runoff
water was acidic (~5.6), as well as the leachate solution for the control
treatment in the first year of the experiment (5.8). In contrast, the pH of
the leachate was neutral or slightly alkaline (~7.4) for the manure, compost
and vermicompost and for the control in the second and third years
of the experiment. Organic amendment led to a significant reduction in
NNH4
+ and NNO3
− leaching (P b 0.05), with a stronger effect for compost
and vermicompost, without a significant difference between them
(P N 0.05). The use of biochar also led to a significant reduction in
NH4
+ and NO3
− leaching for the mineral and vermicompost treatments
(P b 0.05). As a consequence, the total quantity of NNH4
+ and NNO3
− lost
by runoff and leaching water was higher for the control treatment,
with around 4 g and 26 g, respectively. These quantities were signifi-
cantly reduced when OM was applied and the effect was more pronounced
in the presence of vermicompost than buffalo manure
(P b 0.05). The application of compost led to intermediate results.