ROLE OF EARTHWORMS IN IMPROVING SOIL FERTILITY
Mukhtiar khatoon solangia, Sardar khatoon solangib, Sheeraz aleem brohic
Department of Soil Science, Sindh Agriculture University, Tandojam
Institute of Plant Sciences, University of Sindh, Jamshoro
Department of Land and Water Management, Sindh Agriculture University, Tandojam
The fertility of a soil can be defined as its capacity to produce crops and is dependent on many physical, chemical and biological properties of the soil. Earthworms can play a significant role in enhancing soil fertility and plant productivity in a number of direct and indirect ways. It is generally accepted that soil biota benefits soil productivity but very little is known about the organisms that live in the soil and the functioning of the soil ecosystem. The role of earthworms in soil fertility is known since 1881, when Darwin (1809–1882) published his last scientific book entitled “The formation of vegetable mould through the action of worms with observations on their habits.” Since then, several studies have been undertaken to highlight the soil organism’s contribution to the sustainable function of all ecosystems.
Soil macrofauna, such as earthworms, modify the soil and litter environment indirectly by the accumulation of their biogenic structures (casts, pellets, galleries, etc.). The cycling of nutrients is a critical ecosystem function that is essential to life on earth. Studies in the recent years have shown increasing interest in the development of productive farming systems with a high efficiency of internal resource use and thus lower input requirement and cost.
At present, there is increasing evidence that soil macroinvertebrates play a vital role in soil organic matter transformations and nutrient dynamics at different spatial and temporal scales through perturbation and the production of biogenic structures for the improvement of soil fertility and land productivity. Earthworms are a major component of soil fauna communities in most natural ecosystems of the humid tropics and comprise a large part of macrofauna biomass. In cultivated tropical soils, where organic matter is frequently related to fertility and productivity, the communities of invertebrates especially earthworms could play an important role in soil organic matter dynamics by the regulation of the mineralization and humification processes.
Special earthworms called red wigglers or African night crawlers are used in the composting process. Earthworms enrich the soil by speeding up decomposition of organic matter. As earthworms eat and digest plant material they mix organic and mineral soil particles. The organic matter is enriched and then passed out of the worm’s body in the form of casts, which are the richest and finest quality of humus. In this way, they help build and maintain the soil structure. Their casts contain nitrogen, phosphorus, potassium, magnesium and calcium. Earthworms also improve drainage and prevent soil erosion and water logging.
For vermicomposting, the earthworms convert the nutrients in the soil into plant available form. As they deposit their castings, their mucous is deposited into the soil. It helps to slow the release of nutrients and prevents them from being washed away with the first watering. Earthworm manure or casts are richer in minerals than the soil in which the earthworms work to breakdown their organic matter.
Benefits of Vermicomposting
- The most important aspect of compost produced by earthworms is that it is 100% organic. There are no harmful chemicals and it does not need to be mixed with anything.
- Vermicomposting produces a product that is naturally designed to benefit plants in several different ways. The most significant benefit is that the nutrients in earthworm compost are very easily absorbed by the roots of plants.
- Unlike chemical fertilizers, vermicompost is not easily flushed from the soil because of the worm mucus that it contains. Plants have longer to obtain the nutrients and get the maximum benefit.
- As the compost is passing through the body of the worms it is enriched with bacteria and microbes. These help plants to become more disease resistant and also repel some plant pests.
- Among the hormones that earthworm compost contains are hormones that help plants to grow. Germination of seeds is encouraged, the growth of the plant is stronger and the crop yield improved.
- This natural support for the plants is not available with chemical fertilizers. The distribution of the compost through the soil also helps to encourage healthy root growth.
- Using earthworms creates a product that is natural and behaves naturally. The cycle of regularly over-dosing the soil is broken. Plant health is promoted by long term exposure to nutrients and the soil condition will continue to improve.