Management of rice production systems to increase productivity

3.3.5. SRI with Compost and Different Urea Topdressing Rates
109
Compost, unlike inorganic fertilizer, is accessible to most farmers in
The Gambia. It is inexpensive and can be produced by the farmers from crop
residues and farmyard manure. Compost is currently used primarily for
horticulture production where plot sizes are smaller. In lowland rice
production compost is rarely is used in The Gambia, however, recently
because of increased inorganic fertilizer prices, more lowland rice farmers are
turning to alternate soil fertility amendment sources such as compost. The
Extension Services of the Department of State for Agriculture in The Gambia
has been promoting composting, but the adoption rate by lowland rice
farmers has been low, because yields from compost applied fields were not as
high as those where inorganic fertilizer was applied. This was probably due
to the current water management system of continuous flooding, which does
not allow beneficial microbial activity and rapid mineralization of N from
organic matter during the cropping season, thus insufficient N is made
available to the crop.
It is thought that SRI management practices can increase the efficacy of
compost applied to lowland rice due to aeration of the soil, increase in
microbial activity and mineralization. In 2002 an evaluation of SRI
management practice with the use of compost was conducted in Sapu, The
Gambia. Although farmers are familiar with the benefits of compost use,
accumulating large quantities of compost is not an easy task. Rice straw and
rice husk are the most abundant compostable material in the rice production
system, and are used in compost production.
In this trial, 5 t/ha of compost made from rice straw, rice husk and
farm‐yard manure was applied 6 weeks prior to transplanting. After