Page 41 - Enzymes in Tropical Soils

Enzymes in Tropical Soils 29

The above data shows that organic residues contain significant amounts of
N, P, and K, three major nutrient elements greatly needed by plants but sometimes
are not available in soils. Some organic residues show greater contents of
particular elements than others. For example, residues of grasses and Eceng
Gondok show greater K contents. Using this materials in soils may alleuviate the
problems of K deficiencies. Bones contains more P than other organic residues. In
soils this residue may increase the content of P.

Table 3.4. The nutrient contents of some organic wastes*.

Residue Contents (%)
N P K
Vegetables 2.0 – 2.9 0.5 – 0.6 0.7 – 1.8
Bones 1.0 – 4.0 9.0 – 13.0 -
Coffee 4.0 – 10.0 0.14 0.2
Egg Sceleton 1.20 0.17 0.1
Grasses 2.0 – 2.4 0.5 1.7
Leaves 1.0 – 4.0 0.04 – 0.06 0.3 – 0.6
Rice Stems 0.3 – 0.5 0.05 0.6
Green Manure 1.5 – 2.6 0.07 0.3
Corn Stems 0.3 0.05 0.3
Peanut Sceleton 0.8 0.05 0.5
Eceng Gondok 2.2 – 2.5 0.3 4.4
*After Bintoro (2008)

The uses of organic residues in agriculture have been reported by several
workers (Allaway, 1986; McCalla et al.,1986; Banuwa et al., 2003a; 2003b; Banuwa
and Damai, 2003; Yusnaini et al., 2007; Diaz et al., 2011). Banuwa et al. (2003a;
2003b) and Banuwa and Damai (2003) used ‘night soils’ (human residues) in corn
culture. They showed that ‘night soils’ significantly increased the soil Total N,
Available P, Exchangeable K as well as corn heights and corn dry and wet weights as
shown later in Table 5.14. Yusnaini et al. (2007) substituted commercial fertilizers
with green manure and chicken manure and found that these materials increased
the organic C, total N, and available P. They showed that chicken manure was
more effective in enhancing these plant nutrients as shown later in Table 5.13.
These observations indicate that even though organic residues in the environment
posseses some problems, they also have potentials as nutrient sources for plants.

Abdul Kadir Salam - 2014