inorganic and organic), (in)organic N content, application rate and mulching
materials [65]. For instance, the application of N fertilizer and leaf mulching has
significantly increased the activities of dehydrogenase and b-glucosidase [66]. Soil
mulched with white clover and crown vetch also considerably increases the activity
of soil urease, invertase and alkaline phosphatase [67, 68] observed a higher
enzymatic activity from mulching when compared to mulched no-till treatments,
which is a typical practice of conservation agriculture, particularly popular in
drylands. Additionally, mulching can enhance enzyme activity when coupled with
earthworms during rice and wheat cropping systems [68] and under bare soil [69],
soil compaction [70] which can negatively impact nutrient availability and crop
production [71]. Indeed, soil compaction can be arguably more important than N
fertilization regarding soil enzymatic activity [29]. Red clover mulches and different
levels of N fertilization were found to significantly impact the activity of different
enzymes (e.g. acid phosphatase, protease) [72]. Furthermore, [20] showed a 10–
26% increase in the enzymatic activity when applying lower N fertilization rates to
catch crops (40 and 80 kg N ha
− 1 year
− 1 ), while the opposite was found following the application of poultry organic manures [73, 74] also found higher
enzymatic activity following the N fertilization of organic fertilizers compared to
inorganic fertilizers. In addition, the application of N fertilizers over longer periods
of time positively affects enzyme activity [75].
By contrast, N fertilizers can negatively affect enzyme activity such as nitrogenase. Nitrogenase enhances soil N availability by catalyzing atmospheric biological N fixation. N fertilizers also affect nitrifying bacteria that convert ammonia
to nitrate (NO 3
−
) according to the cultivar and to the diazotrophs present in the
environment [50]. Conversely [77], observed a strong negative effect of
L-asparaginase, a N-acquiring enzyme, to C-acquiring enzyme (BG) ratio, on total
N concentration in an agricultural field previously amended with different fertilization plans. It is therefore worth mentioning that plant production is generally N
limited, while soil microorganisms may be carbon (C) or N limited.
9 Climate Change Impact and Mitigation, and Related
Effects on Nitrogen Footprint
The most recent concerns about climate change impacts on soil processes, along
with a growing depletion of soil quality worldwide have stimulated experimental
research towards the development of methods of fighting and adapting to these
impacts. Improving carbon sequestration and promoting plant nutrition from biobased sources have become priorities. In fact, the use of natural processes to restore
soil quality while retaining C to decarbonize production, and monetization of
microbially mediated soil nutrients resources (e.g. N) are undoubtedly the pathway
for environmental recovery.
Nitrogen Footprints and the Role …
145
materials [65]. For instance, the application of N fertilizer and leaf mulching has
significantly increased the activities of dehydrogenase and b-glucosidase [66]. Soil
mulched with white clover and crown vetch also considerably increases the activity
of soil urease, invertase and alkaline phosphatase [67, 68] observed a higher
enzymatic activity from mulching when compared to mulched no-till treatments,
which is a typical practice of conservation agriculture, particularly popular in
drylands. Additionally, mulching can enhance enzyme activity when coupled with
earthworms during rice and wheat cropping systems [68] and under bare soil [69],
soil compaction [70] which can negatively impact nutrient availability and crop
production [71]. Indeed, soil compaction can be arguably more important than N
fertilization regarding soil enzymatic activity [29]. Red clover mulches and different
levels of N fertilization were found to significantly impact the activity of different
enzymes (e.g. acid phosphatase, protease) [72]. Furthermore, [20] showed a 10–
26% increase in the enzymatic activity when applying lower N fertilization rates to
catch crops (40 and 80 kg N ha
− 1 year
− 1 ), while the opposite was found following the application of poultry organic manures [73, 74] also found higher
enzymatic activity following the N fertilization of organic fertilizers compared to
inorganic fertilizers. In addition, the application of N fertilizers over longer periods
of time positively affects enzyme activity [75].
By contrast, N fertilizers can negatively affect enzyme activity such as nitrogenase. Nitrogenase enhances soil N availability by catalyzing atmospheric biological N fixation. N fertilizers also affect nitrifying bacteria that convert ammonia
to nitrate (NO 3
−
) according to the cultivar and to the diazotrophs present in the
environment [50]. Conversely [77], observed a strong negative effect of
L-asparaginase, a N-acquiring enzyme, to C-acquiring enzyme (BG) ratio, on total
N concentration in an agricultural field previously amended with different fertilization plans. It is therefore worth mentioning that plant production is generally N
limited, while soil microorganisms may be carbon (C) or N limited.
9 Climate Change Impact and Mitigation, and Related
Effects on Nitrogen Footprint
The most recent concerns about climate change impacts on soil processes, along
with a growing depletion of soil quality worldwide have stimulated experimental
research towards the development of methods of fighting and adapting to these
impacts. Improving carbon sequestration and promoting plant nutrition from biobased sources have become priorities. In fact, the use of natural processes to restore
soil quality while retaining C to decarbonize production, and monetization of
microbially mediated soil nutrients resources (e.g. N) are undoubtedly the pathway
for environmental recovery.
Nitrogen Footprints and the Role …
145