Agriculture Reference
In-Depth Information
be utilized for the agricultural system if regulated properly. To utilize the nutrients in these materials,
detritus consumption on agricultural land has to be activated. To meet the needs of short-duration
crops, which have been adopted in the present-day agricultural systems, more and more chemical
fertilizers are currently used. The repeated use of chemicals in tropical lands is causing increasingly
adverse effects on soil properties, productivity, and fertility.
However, this alarming situation has produced a reverse in this strategy of agricultural practice
by a small percentage of agriculturists in the state. Their practices involve selecting varieties of
plants that are most resistant to pest attack and have a low demand for inorganic nutrient inputs
and practicing multiple cropping systems. This also includes the production and use of biological
insecticides and biomass as organic soil amendments. By tapping organic detritus as a resource, it
may be possible to rejuvenate the topsoil and increase production. In this organic detritus group,
earthworms can be managed to feed on varieties of organic wastes, thereby serving as tools to
hasten the process of organic degradation and release of nutrients and improving the nutrient status
of the tropical soils. The propagation of earthworms for humus production under seminatural
conditions is developing rapidly in the state and is revolutionizing its agriculture. From the situation
that was reported in 1991 to 1992 regarding the agricultural scenario in the state, the latest census
of 1998 to 2000, the available land for agriculture has decreased by 5.9% and land used more than
once for agriculture per annum by 3.6% for the expected population increase of 21%. Interestingly,
because of the awareness created about the importance of organic manures for sustainable agricul-
ture, in this decade there has been a 23% decrease in inorganic fertilizer consumption.
EARTHWORMS AS BIODEGRADERS OF ORGANIC
WASTE BIOMASS
The loss of topsoil because of practices associated with the indiscriminate use of chemicals is a
major cause of the decline in productivity status of our tropical soils. The realization of this has
begun to increase the use of organic wastes on agricultural fields. However, there is a decline in
the availability of cattle dung, and a current need is to obtain the required organic soil additives
from underused available plant biomass residues in minimum time. Various methods have come
into practice in addition to the traditional practice of pit composting. Engineering skills are used
to provide better aeration of composting materials to minimize the time of composting. Selected
groups of fungi are often used for composting of lignocellulose-based materials.
Much of the importance given to earthworm activity in temperate soils is lacking in tropical
regions, although earthworm species diversity and richness is not much less than in temperate
regions (Bano and Kale 1991). Food niches and strategies that have developed among different
species of earthworms have helped broaden their use in organic waste breakdown. Epigeic earth-
worm species, which show a greater affinity for nitrogen-rich organic matter, live in an unstable
environment. They resemble the seral stages of ecological development, with a smaller body size,
higher metabolic rate, higher fecundity, and shorter life cycle. In natural conditions, their survival
depends on environmental conditions and degree of biotic pressure from predators. These earth-
worms form the natural components of the tropical forest floor community. With the loss of natural
forests, they have adopted to the agricultural plantations.
Increased yields from the use of chemical fertilizers have led the farming community to neglect
the importance of organic manures and additives. Many farmers have been unaware that organic
manures are essential to restore the cycle of events in the soil to keep it productive. Chemicals
applied to the soil short-circuited this cycle of events and deprived the soil organisms of their
energy sources, which restore the health of the soil through their activity.
When earthworms are isolated to work on waste organic matter, their major contribution is in
fragmenting the organic matter and making it more available to microorganisms. The microenvi-
ronment they provide for the establishment and multiplication of microorganisms is of utmost
