Document Type: Research Paper
Cambodian Agricultural Research and Development Institute (CARDI), Ministry of Agriculture, Forestry and Fisheries (MAFF), Phnom Penh, Cambodia.
System Approaches in Agriculture Program, Department of Plant Science and Agricultural Resources, Khon Kaen University, Khon Kaen, Thailand.
International Center for Tropical Agriculture (CIAT), Bangkok, Thailand.
In Cambodia, cassava is mostly grown with little or no fertilizer inputs, but the
magnitudes of nutrient balances are not known. This study was conducted to assess
nutrient balances for cassava cultivation in Kampong Cham province in Northeast
Cambodia. Forty five households in four cassava production zones were
interviewed in relation to their cultural practices and crop residue management,
upon which sources of nutrient inputs and outputs were based. Chemical fertilizer,
manure, planting materials and rainfall were the defined inputs, while cassava roots
and stumps were the outputs. Crop cutting was undertaken in the cassava fields of
the 45 households to obtain weights of roots and other plant parts. Nutrient
balances were calculated for the individual fields based on nutrient contents of the
component sources obtained from the literatures. The results showed negative
balances for all the nutrients evaluated. The imbalances were most serious for N, K
and Ca with the averages of -64.45 kg N, -52.83 kg K and -10.83 kg Ca ha-1, but
were less serious for P and Mg with the averages of -2.85 kg P and -7.20 kg Mg ha-1.
These negative balances were the consequence of low nutrient inputs in current
practices where only a few farmers applied low rates of chemical fertilizer or
manure. Continued use of current practices will threaten the sustainability of
cassava production in Cambodia. For long term productivity of the crop, the
application of organic manures together with lime and chemical fertilizers high in
N and K is recommended.