Page 38 - Enzymes in Tropical Soils

26 Enzymes In Tropical Soils

returned to the soil system, the nutrient elements transferred through the food
chains may return to the soil system and may preserve the soil fertility. By
assuming the nutrient leaks are minimum, the fertilizer needs are minimum.
However, in an open system, where parts or most of the organic matters are
exported out of the soil system, the soil – plant – animal/human relationship may
lower the soil fertility, particularly when other nutrient leaks are significant. The
amounts of available nutrients may become relatively limited. In this case, fertilizer
inputs may become a very significant issue.

3.2 Organic Matters and Organic Wastes: Problems and

Potentials

The accumulation of organic matters in the soil system is probable. The
accumulation is accelerated by plant residues during harvest time. Generally,
farmers harvest only a very small part of plants. The rest of the plants are usually
left or burned in the fields. The amounts of the accumulated organic matters are
probably huge. For example, organic wastes accumulated by rice production in
several areas in Jakarta and West Java in the period of 1996 – 2003 are listed in
Table 3.1. The organic waste of rice plants in Bogor was much higher than those in
Purwakarta and Jakarta. The daily rates of accumulation suggest that the organic
waste from various crop plants may cause problems in the environment. The
problems may become more significant in the centers of crop plant production,
such as paddy fields in the northern parts of West Java and rubber plantations in
Sumatra, Indonesia.
Animals may also leave some organic wastes in the soil environment. Some
selected animals give great amounts of residues to the environment in
Purwakarta, West Java, Indonesia (Table 3.2). Sheeps gave residues in the order of
-1 -1
200s Mg day , while goats and chicken in the order of 50s and 10s Mg day . These
figures also suggest that great amounts of organic residues from animals are
accumulated and may cause environmental problems.
In big towns or cities with high populations and high level of life-styles, the
accumulation of organic wastes may cause also significant problems. For example,
the current accumulation of organic wastes in several towns/cities in Jakarta,
Banten, and West Java, Indonesia, is listed in Table 3.3. The accumulation of
organic waste is threatening, particularly related to the selection of where these

Abdul Kadir Salam - 2014