Rice cultivation occupies about 90% of farm area and is the country's biggest source of farm income. In 2003, rice production was estimated at 4.3 million tons. (see IYR 2004). This year, rice harvest has been projected to reach about 7 million tons, and rice exports expected to expand by 1 million tons to about 3-4 million tons. (see China View report). However another report in the Phnom Penh post is abit more gloomy pointing to the global price cuts which have dampened Cambodia's competitiveness. Lower prices also restrict the ability farmers to buy rice seeds.
According to the CIA World Factbook on Cambodia, agriculture represents about 35% of Cambodia's GDP of $26.19 billion (2007 est.).
How all this will eventually impact the lives of the farmers in the deep rural regions of Cambodia is hard to tell. see Harvest.
Here is a slightly dated but useful explanation of Cambodia rice cultivation :
Cambodia has two rice crops each year, a monsoon-season crop (long-cycle) and a dry-season crop. The major monsoon crop is planted in late May through July, when the first rains of the monsoon season begin to inundate and soften the land. Rice shoots are transplanted from late June through September. The main harvest is usually gathered six months later, in December. The dry-season crop is smaller, and it takes less time to grow (three months from planting to harvest). It is planted in November in areas that have trapped or retained part of the monsoon rains, and it is harvested in January or February. The dry-season crop seldom exceeds 15 percent of the total annual production.
In addition to these two regular crops, peasants plant floating rice in April and in May in the areas around the Tonle Sap (Great Lake), which floods and expands its banks in September or early October . Before the flooding occurs, the seed is spread on the ground without any preparation of the soil, and the floating rice is harvested nine months later, when the stems have grown to three or four meters in response to the peak of the flood (the floating rice has the property of adjusting its rate of growth to the rise of the flood waters so that its grain heads remain above water). It has a low yield, probably less than half that of most other rice types, but it can be grown inexpensively on land for which there is no other use.