There are no current estimates given for the impacts of climate change, and
enzymatic activity, on the N footprint but a simple theoretical framework can be
developed based on the literature available.
2 Soil Quality, Nutrients and Crop Production
Soil quality is key to sustaining crop production in a context where the population is
expected to increase up to 9.7 billion in 2050. Although soil quality is a decisive
factor to ensure nutrient supply for plants’ growth, current trends of soil use have led
to soil quality decline, compromising soil capacity to produce enough food. Indeed,
since the green revolution and the increased use of inorganic fertilizers for crop
growth, it has been estimated that an exponential increase in crop production has
allowed half of the world’s population to be alive today [6]. The necessary increase
in food production cannot be maintained for much longer due to its impactful
environmental costs through the excessive mining of soil organic matter (SOM) and
other nutrients from the soil, in addition to those supplied by fertilizers and by
chemical pesticides to suppress diseases. Additionally, the impact of climate change
in agriculture is still uncertain but already noticeable in different regions of the world
through extremes in rainfall and drought. The increase in crop productivity is
declining and the need for inorganic fertilizer is increasing accordingly, misleading
farmers to believe that over-applying fertilizers enhance yields proportionally,
thereby further decreasing the soil biological quality. The decline of soil organic
matter content reduces the nutrient transformation from SOM mineralization and
therefore the availability of plant nutrients in the soil solution [7]. For example, the
release of N taking place during SOM breakdown and subsequent transformations
are a critical part of the nitrogen (N) cycle in soil [8]. On the contrary,
over-application of inorganic fertilizers leads to soil contamination, e.g. phosphorus,
and water contamination or nitrate excess to the demand of plant and soil biota.
Furthermore, reduction in SOM leads to poor water retention in soils enhancing the
susceptibility to drought. So, for sustainable crop production today’s agriculture
requires appropriate management of nutrients including good soil management (light
weight machinery, reduction of pesticides, crop rotation systems including grain and
nitrogen fixers) and in addition the right application rate, timing, type of fertilizer and
mode of application vis-a-vis plant and soil biota requirements, bearing in mind that
nutrient availability is affected by climatic conditions and soil physical, chemical,
and biological properties, including the effects of root exudates in the soil [9].
3 Relevance of Enzymes in Soils
Soil fertility depends upon three different but interacting components: chemical,
physical and biological. Soil biological fertility regulates many functions that are
beneficial to plant production: (i) releasing nutrients from soil organic matter
136
C. M. d. S. Cordovil et al.
enzymatic activity, on the N footprint but a simple theoretical framework can be
developed based on the literature available.
2 Soil Quality, Nutrients and Crop Production
Soil quality is key to sustaining crop production in a context where the population is
expected to increase up to 9.7 billion in 2050. Although soil quality is a decisive
factor to ensure nutrient supply for plants’ growth, current trends of soil use have led
to soil quality decline, compromising soil capacity to produce enough food. Indeed,
since the green revolution and the increased use of inorganic fertilizers for crop
growth, it has been estimated that an exponential increase in crop production has
allowed half of the world’s population to be alive today [6]. The necessary increase
in food production cannot be maintained for much longer due to its impactful
environmental costs through the excessive mining of soil organic matter (SOM) and
other nutrients from the soil, in addition to those supplied by fertilizers and by
chemical pesticides to suppress diseases. Additionally, the impact of climate change
in agriculture is still uncertain but already noticeable in different regions of the world
through extremes in rainfall and drought. The increase in crop productivity is
declining and the need for inorganic fertilizer is increasing accordingly, misleading
farmers to believe that over-applying fertilizers enhance yields proportionally,
thereby further decreasing the soil biological quality. The decline of soil organic
matter content reduces the nutrient transformation from SOM mineralization and
therefore the availability of plant nutrients in the soil solution [7]. For example, the
release of N taking place during SOM breakdown and subsequent transformations
are a critical part of the nitrogen (N) cycle in soil [8]. On the contrary,
over-application of inorganic fertilizers leads to soil contamination, e.g. phosphorus,
and water contamination or nitrate excess to the demand of plant and soil biota.
Furthermore, reduction in SOM leads to poor water retention in soils enhancing the
susceptibility to drought. So, for sustainable crop production today’s agriculture
requires appropriate management of nutrients including good soil management (light
weight machinery, reduction of pesticides, crop rotation systems including grain and
nitrogen fixers) and in addition the right application rate, timing, type of fertilizer and
mode of application vis-a-vis plant and soil biota requirements, bearing in mind that
nutrient availability is affected by climatic conditions and soil physical, chemical,
and biological properties, including the effects of root exudates in the soil [9].
3 Relevance of Enzymes in Soils
Soil fertility depends upon three different but interacting components: chemical,
physical and biological. Soil biological fertility regulates many functions that are
beneficial to plant production: (i) releasing nutrients from soil organic matter
136
C. M. d. S. Cordovil et al.