Rainfed lowlands account for nearly 90% of the total rice area in Cambodia. Annual rice production from the rainfed lowlands is over 7 million tonnes accounting for 77% of total rice production. However, the majority of rainfed lowland farm households are resource-poor, owning less than a hectare of paddy land, and, given the monsoonal (wet-dry) climate, grow only a single low-yielding rice crop per year in the wet season (WS), primarily for subsistence. This lowland rice farming system is subject to various pressures from unreliable rainfall, poor soil fertility, insect and weed pests, the use of traditional varieties and cropping practices, restricted access to irrigation, and limited farm resources. Moreover, there are few options for earning cash income, given the reliance on subsistence rice cultivation in the WS and the inability to use land and labour productively in the dry season (DS).
The research reported in this thesis aimed to explore the potential for agricultural development and poverty reduction in the rainfed lowlands of Cambodia, with particular emphasis on the role of irrigation. First, the thesis sought to evaluate the situation, constraints, and management of farms in rainfed lowland villages in southern Cambodia. Next, it compared the options available to farm managers and village communities in similar biophysical and socioeconomic environments but with different degrees of access to irrigation. Finally, it identified the potential development pathways and adaptive responses of farm managers in the rainfed lowland environment.
The research was carried out in rainfed lowland districts in Takeo and Kampong Speu Provinces, representing a typical lowland rice-growing region that was densely-populated and with low per-capita ownership of paddy land. A comparative case-study design was used with multiple units of analysis. Three villages were selected that experienced similar biophysical and socioeconomic environments but had different degrees of access to irrigation, with Trapeang Run depending on small houseyard ponds, Snao using tubewells to extract groundwater, and Ta Daeng Thmei benefiting from gravity-fed irrigation from a medium-size reservoir. Each village was considered as an individual case, with cross-case comparison used to develop generalisations about the research objectives.
A range of research methods were employed between 2010 and 2013 for data collection, including reconnaissance visits, household surveys, discussions with village heads, key informant interviews, analysis of market trends, farm walks and direct observation, use of village data manuals and documents, surveys of pond-water and groundwater, analysis of rainfall data, soil surveys, and field crop experiments. Analytical methods applied to the analysis of household survey data and other data comprised conventional descriptive statistics, multivariate statistical techniques, and conventional farm management economics, adapted to the perspectives of semi-commercial farm households.
Trapeang Run was typical of rainfed lowland villages in Cambodia, with farmers having small areas of paddy land (averaging 0.9 ha) all cultivated with WS rice. Many households opted to cultivate early-wet-season (EWS) rice on a small plot of paddy land (0.15 ha) to make up for a rice deficit or to earn extra cash income, but yields and returns to labour were low. Though most households secured rice self-sufficiency and a modest net cash return, around a third experienced a rice deficit. The lack of other cropping options meant that two thirds of households’ limited cash income came from non-farm employment, mainly younger household members labouring in construction sites and garment factories in Phnom Penh.
Snao was also typical of rainfed lowland villages, with even less access to WS paddy land (averaging 0.6 ha), but farmers’ initiative to develop on-farm irrigation by sinking tubewells to pump groundwater had allowed the majority to intensify and diversify the cropping system to include two crops of radish (or cucumber) in the DS on more than half their paddy land and a similar area of EWS rice, in addition to a traditional crop of WS rice. The entire cropping system utilised labour and material inputs more intensively and, despite the small farm size, generated rice for subsistence and sale and more than double the cash income of Trapeang Run, with the most important single source of income being DS non-rice crops.
Ta Daeng Thmei, located in a similar lowland environment, had access to a long-established, medium-scale, gravity-fed irrigation scheme, as well as having somewhat more paddy land (averaging 1.3 ha). The larger farms and access to irrigation enabled most households to produce a considerable marketable surplus from WS rice, as well as using a portion of the paddy land (around 0.2 ha) to grow peanuts in the DS and rice in the EWS. This more intensive cropping system gave considerably higher farm cash income than Trapeang Run, though not as high as Snao. The most important sources of cash income were WS rice and livestock.
The comparative analysis showed that small-scale, resource-poor farmers in the rainfed lowlands with access to on-farm irrigation, especially groundwater, could substantially improve their livelihoods by pursuing more intensified, diversified, and market-oriented farming systems. The potential for farmers with somewhat more land to intensify and commercialise cattle production based on irrigated forages was also identified but not yet observed in practice. The research shows that adaptive farm managers pursuing irrigation-based agricultural development in the lowlands can achieve a more secure supply of rice for subsistence, higher cash income, greater utilisation of the household’s resources of land and labour, improved soil resources, and more diverse and therefore resilient farm and livelihood systems, with less reliance on low-skilled urban wage employment. Research on the longer-term implications for the sustainable management of groundwater resources will need to be given high priority.