10.5 Biowastes Management
IBM is a smart tropical agroecosystem management system that could be
implemented to solve a tropical environment problem (Agus 2018, 2019). Based
on Vandermeer (2002), the tropical environment is unique in many ways, from the
lack of a biological down season (winter) to generally poor soil conditions, to a
reliance on traditional methods of agriculture in an undeveloped society. At a time
when the sustainability of natural resource use in the tropics has become an important issue, tropical agroecosystems provide a critical scientific foundation for developing a sustainable agriculture component within this process.
In lowland tropics, the net annual primary productivity may be higher than
anywhere else in the world (Janzen 1973). This productivity is the primary factor
controlling litterfall production. If there is no appreciable consumption by direct
grazing, organic substances return to the soil mainly as litterfall, timber fall, and dead
roots (Wanner 1970). In tropical environments, the fine litterfall in the biowaste
represents the primary process that determines the potential return of organic matter
and nutrients to the soil, which supports plant development and soil biota. However,
nutrient recycling is achieved when the litter is decomposed by soil biota (León and
Osorio 2014).
Fine litter production and decomposition are two critical processes that provide
the primary input to form soil organic matter and regulate nutrient cycling in forest
ecosystems (León and Osorio 2014). Those are controlled by biological and physical
processes such as the activity and composition of soil and litter macro- and microfauna and climate variations, in particular, rainfall and temperature (Sanches et al.
2008). The rates at which both processes occur determine the thickness of the litter
layer on the forest soil. Thus, the role of litter in plant nutrition is determined by its
turnover time (León and Osorio 2014).
The year-round warmth of the lowland tropics is a mixed blessing. High yearround soil temperatures lead to a very rapid breakdown of litter, with subsequent
leaching of soil nutrients before they can be taken up by plants (Janzen 1973). León
and Osorio (2014) stated that if the nutrients are quickly released, they could be lost
by leaching or volatilization. If the decomposition occurs, the nutrient supply slowly
to plant roots will be insufficient, thus limiting plant growth and development. For
these reasons, the rates at which litter decomposition and subsequent nutrient release
occur constitute key factors for ecosystem functioning.
Soils in the tropical lowlands are often a nutrient reservoir or deficient capacity.
Plant ash from burning, ions from the very rapid litter breakdown, and chemical
fertilizers are rapidly leached from the soil if not taken up by plants. There is
generally a deep layer of nutrient-poor material over an unweathered rock (Janzen
1973). Therefore, the organic matter return is the best biowaste management in a
tropical agroecosystem.
Regular addition of locally available biowaste and organic resources like litter,
crop residues, green manures, green leaf manures, cover crops, vermicomposting,
and tank silt improve soil organic matter (SOM) in agroecosystems. SOM plays an
essential role in maintaining the productivity of tropical soils because it provides
222
C. Agus et al.
IBM is a smart tropical agroecosystem management system that could be
implemented to solve a tropical environment problem (Agus 2018, 2019). Based
on Vandermeer (2002), the tropical environment is unique in many ways, from the
lack of a biological down season (winter) to generally poor soil conditions, to a
reliance on traditional methods of agriculture in an undeveloped society. At a time
when the sustainability of natural resource use in the tropics has become an important issue, tropical agroecosystems provide a critical scientific foundation for developing a sustainable agriculture component within this process.
In lowland tropics, the net annual primary productivity may be higher than
anywhere else in the world (Janzen 1973). This productivity is the primary factor
controlling litterfall production. If there is no appreciable consumption by direct
grazing, organic substances return to the soil mainly as litterfall, timber fall, and dead
roots (Wanner 1970). In tropical environments, the fine litterfall in the biowaste
represents the primary process that determines the potential return of organic matter
and nutrients to the soil, which supports plant development and soil biota. However,
nutrient recycling is achieved when the litter is decomposed by soil biota (León and
Osorio 2014).
Fine litter production and decomposition are two critical processes that provide
the primary input to form soil organic matter and regulate nutrient cycling in forest
ecosystems (León and Osorio 2014). Those are controlled by biological and physical
processes such as the activity and composition of soil and litter macro- and microfauna and climate variations, in particular, rainfall and temperature (Sanches et al.
2008). The rates at which both processes occur determine the thickness of the litter
layer on the forest soil. Thus, the role of litter in plant nutrition is determined by its
turnover time (León and Osorio 2014).
The year-round warmth of the lowland tropics is a mixed blessing. High yearround soil temperatures lead to a very rapid breakdown of litter, with subsequent
leaching of soil nutrients before they can be taken up by plants (Janzen 1973). León
and Osorio (2014) stated that if the nutrients are quickly released, they could be lost
by leaching or volatilization. If the decomposition occurs, the nutrient supply slowly
to plant roots will be insufficient, thus limiting plant growth and development. For
these reasons, the rates at which litter decomposition and subsequent nutrient release
occur constitute key factors for ecosystem functioning.
Soils in the tropical lowlands are often a nutrient reservoir or deficient capacity.
Plant ash from burning, ions from the very rapid litter breakdown, and chemical
fertilizers are rapidly leached from the soil if not taken up by plants. There is
generally a deep layer of nutrient-poor material over an unweathered rock (Janzen
1973). Therefore, the organic matter return is the best biowaste management in a
tropical agroecosystem.
Regular addition of locally available biowaste and organic resources like litter,
crop residues, green manures, green leaf manures, cover crops, vermicomposting,
and tank silt improve soil organic matter (SOM) in agroecosystems. SOM plays an
essential role in maintaining the productivity of tropical soils because it provides
222
C. Agus et al.