18.5 Factors to Consider in the Production and Use
of Organic Fertilizers
In line with principles of sustainable agriculture, farmers are called upon to improve
the soil on cropped lands through organic fertilizer inputs. Inherent poor fertility of
most soils in the tropics is a major constraint to sustainable smallholder crop
production. Synthetic fertilizers often lack essential micronutrients crucial for crop
growth on the nutrient poor soils cultivated by smallholder farmers. Application of
organic fertilizers like vermicomposts on agricultural land can complement inorganic fertilizers because they not only add mineral nutrients but also improve soil
organic matter. This in turn positively influences soil quality by reducing compaction, erosion processes and the toxicity of pollutants while also improving soil
structure, porosity, aeration, water infiltration, water holding capacity and nutrient
availability. Cocktails of beneficial bacteria and fungi found in organic fertilizers
convert nutrients into easily accessible forms and aid biological activity. Slow
nutrient release by vermicomposts reduces the risk of toxicity to plants and the
environment.
The tropics are experiencing extreme weather events due to climate change, and
these include high annual temperatures and rainfall variability. Farmers here are
facing many challenges such as unpredictable rains, soil degradation and new or
different pests and diseases. Organic farming can help to mitigate the harms of
climate variability, mostly by storing carbon in the soil and improving plant health.
In organic matter rich soils, roots develop well to exploit the supply of mineral
nutrients and to take up water to meet crop requirements for growth. Organic matter
also provides a buffer between the soil and air interface, thereby protecting the roots
from desiccation and steep gradient changes in temperature. Organic fertilizers
increase the return of carbon to the soil, and this raises productivity whilst favouring
carbon storage. Additionally, organic fertilizers help farmers to adapt to climate
change because the high cation exchange capacity (CEC) from soil organic matter
can help to reduce nutrient losses in the event of floods. Soils and plants under
organic farming are more resilient to pests, floods, droughts and land degradation
processes.
Most organic fertilizers are products of a composting or vermicomposting process. Composting organic waste to make fertilizers does not only reduce pests and
toxic compounds composition, but it also improves the handling characteristics of
nutrient rich organic waste by reducing its volume and weight while increasing
product uniformity and ease of application. Producing good organic fertilizer is a
blend of art and science. Composting techniques can be as simple as stockpiling and
turning, or more complex as in vermicomposting or active aeration or in-vessel
systems. In all essence, good aeration is the key to achieving good compost. Bad
composting can produce as many potential problems with odour and greenhouse gas
emissions. The mixing technique (method and frequency) significantly influences
chemical and biological parameters, speed of degradation, as well as the quality of
the product. Decomposition is microbial dependent and thus influenced by several
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311
of Organic Fertilizers
In line with principles of sustainable agriculture, farmers are called upon to improve
the soil on cropped lands through organic fertilizer inputs. Inherent poor fertility of
most soils in the tropics is a major constraint to sustainable smallholder crop
production. Synthetic fertilizers often lack essential micronutrients crucial for crop
growth on the nutrient poor soils cultivated by smallholder farmers. Application of
organic fertilizers like vermicomposts on agricultural land can complement inorganic fertilizers because they not only add mineral nutrients but also improve soil
organic matter. This in turn positively influences soil quality by reducing compaction, erosion processes and the toxicity of pollutants while also improving soil
structure, porosity, aeration, water infiltration, water holding capacity and nutrient
availability. Cocktails of beneficial bacteria and fungi found in organic fertilizers
convert nutrients into easily accessible forms and aid biological activity. Slow
nutrient release by vermicomposts reduces the risk of toxicity to plants and the
environment.
The tropics are experiencing extreme weather events due to climate change, and
these include high annual temperatures and rainfall variability. Farmers here are
facing many challenges such as unpredictable rains, soil degradation and new or
different pests and diseases. Organic farming can help to mitigate the harms of
climate variability, mostly by storing carbon in the soil and improving plant health.
In organic matter rich soils, roots develop well to exploit the supply of mineral
nutrients and to take up water to meet crop requirements for growth. Organic matter
also provides a buffer between the soil and air interface, thereby protecting the roots
from desiccation and steep gradient changes in temperature. Organic fertilizers
increase the return of carbon to the soil, and this raises productivity whilst favouring
carbon storage. Additionally, organic fertilizers help farmers to adapt to climate
change because the high cation exchange capacity (CEC) from soil organic matter
can help to reduce nutrient losses in the event of floods. Soils and plants under
organic farming are more resilient to pests, floods, droughts and land degradation
processes.
Most organic fertilizers are products of a composting or vermicomposting process. Composting organic waste to make fertilizers does not only reduce pests and
toxic compounds composition, but it also improves the handling characteristics of
nutrient rich organic waste by reducing its volume and weight while increasing
product uniformity and ease of application. Producing good organic fertilizer is a
blend of art and science. Composting techniques can be as simple as stockpiling and
turning, or more complex as in vermicomposting or active aeration or in-vessel
systems. In all essence, good aeration is the key to achieving good compost. Bad
composting can produce as many potential problems with odour and greenhouse gas
emissions. The mixing technique (method and frequency) significantly influences
chemical and biological parameters, speed of degradation, as well as the quality of
the product. Decomposition is microbial dependent and thus influenced by several
18 Some Perspectives on Vermicompost Utilization in Organic Agriculture
311