This project (ASEM/2000/109 - Farming systems research for crop diversification in Cambodia and Australia) has been a collaborative effort of researchers at the Cambodian Agricultural Research and Development Institute (CARDI) and New South Wales Department of Primary Industries (NSW DPI). The Cambodian priority was to increase focus on non-rice upland crops for the purpose of poverty reduction. Crop intensification and diversification were priorities for CARDI research. The Australian priority was to examine cultural and crop choice dimensions for crops other than wheat in northern NSW. The parallels in these priorities allowed a common theme of activities in each country which could be serviced by the project team. Specific objectives of the project were to: 1. Identify and overcome constraints to the adoption of non-rice upland crops in Cambodia and non-cereal crops in north-eastern Australia by analysis of on-farm data and experimentation 2. Develop simple diagnostic and analysis tools that farmers and advisers can use to monitor the performance of their crops and how they fit into the farming system 3. Produce appropriately packaged technical and financial information. In Cambodia, a total of 153 on-farm experiments and demonstrations were conducted between 2004 and 2006: variety evaluation (43); insect pest and disease (19); reduced tillage (22); agronomy & farming systems (69). This work has impacted significantly on the CARDI approach to research in the uplands. A significant response to inoculation of rhizobium on legumes was identified during the Project research, and rhizobium inoculation techniques have been demonstrated to advisers in Cambodia. A rapid soil nitrate test has also been demonstrated to advisers and tested on 100 on-farm sites in Cambodia. Field guides were produced for insect pest and weed identification in upland crops as well as Field Crop Manuals for soybean and maize in Cambodia. A 60 page book was also produced on gross margin analyses and general marketing information for the 6 focus crops in Cambodia is under preparation. This information could potentially impact on the economic improvement of on-farm profitability leading to poverty reduction.

A weed identification guide for farmers and extension workers in the upland cropping systems of Cambodia. Sponsored by the Australian Centre for International Agricultural Research, the NSW Department of Primary Industries, and the Cambodian Agricultural Research and Development Institute. This book is part of a series of publications produced by ACIAR in support of the on-going rollout of on-farm demonstrations for upland crops in Cambodia.

Crops are subject to attack from a wide range of insect species in the wet tropical environment of Cambodia, resulting in extensive damage and economic losses. This illustrated field guide will assist with the identification of the major insect pests of the main upland crops in Cambodia - cowpea, maize, mung bean, peanut, sesame and soybean. However, not all insects found in the crops are pests; some insects and spiders play a significant role in keeping the insect pests under control. The guide provides a brief description of insect pests and the damage they cause, as well as information on a range of beneficial insects and spiders that can be found in upland crops in Cambodia. The impact of beneficial insects can be increased by integrated pest management and careful use of pesticides.

Cambodia has achieved food security with respect to rice production and now has an opportunity to pay more attention to boosting production of upland crops such as maize (corn), soybean, sesame, mungbean, cassava, peanut and cowpea. While rice remains the main crop in Cambodia, the production of other crops is undergoing a rapid expansion and will be especially important for the development of those parts of the Kingdom unsuited to lowland rice. We present results from socio-economic surveys carried out in the Battambang, Kampong Cham and Takeo Provinces to identify available resources, management practices and key constraints for emerging upland cropping systems. These are mainly cash crops, so the important issues to consider are profitability, technological and management changes, and household and social issues. The surveys were conducted in the Districts of Kamrieng, Sampov Lun, Rotonak Mondol and Banan in Battambang Province, Chamkar Leu, Ou Reang Ov and Tbong Khmum in Kampong Cham Province, and Tramkak in Takeo Province. Sample sizes were 181 in Battambang and Kampong Cham, and 50 in Takeo. Generally farm families had a male head aged in the mid-40s, with 3 to 4 years of schooling. However, there are significant numbers of female farmers among survey respondents. Family size averaged 5 to 6 persons; with 2 to 3 being dependents and levels of off-farm work very low. Average farm size was 2 to 8 ha, and capital items owned included draft animals, ox carts and mouldboard ploughs, as well as tractors and disc ploughs in some areas. The main reasons given for not growing crops were poor yield performance, lack of knowledge (especially about insects), concerns about profitability, land/soil constraints, labour/equipment issues, and agronomic and climate risk (including drought). These results point to the need for focused research on new technologies and management as they affect crop yields and profits, and for increased extension of this information to Cambodian farmers.

Crop yields are declining in Northwest Cambodia and crop failure in the pre-monsoon season is commonplace with 69% of farmers surveyed stating that drought is a constraint to production. Farmers currently lack knowledge to adopt more sustainable farming practices. A trial was conducted in Samlout District, Battambang Province, Northwest Cambodia to investigate the feasibility of a sowing time two months later than typical local practices. The aim of the shift in sowing time was to increase crop yield and reduce crop failure due to heat and drought stress throughout the season. A secondary aim was to compare sequences of continuous maize ('Zea mays' L.), and maize in rotation with peanut ('Arachis hypogaea'), sun- flower ('Helianthus annus'), sorghum ('Sorghum bicolor'), cowpea ('Vigna unguiculata') or mungbean ('Vigna radiata'). Sunflower and sorghum would be new crop type introductions, whilst the other crops are part of the traditional farming system in this region. The trial was undertaken for four cropping seasons over two years, during which time crops produced successful yields from the new sowing time windows. However, it was the maize-sunflower sequence that produced the highest gross margins. Maize-sunflower returns were $514 per hectare per annum more than the typical planting of continuous maize, and over $1100 per hectare per year higher than the other maize-legume and maize-sorghum rotations. Continuous maize produced the most stable yields across the four seasons and maize-sunflower produced the second highest mean yield. Results from modelling of soil moisture suggest that a shift in sowing time may avoid the extreme heat of the pre-monsoon season, and align crop growth stages with periods of more reliable rainfall. Site specific surface soil moisture data and rainfall was entered into the APSIM model to predict the soil profile moisture throughout the growing season (r² = 0.73). Both the modelling and on-farm research resulted in higher crop yields compared with traditional practices and expectations, and a low probability of crop failure. Crops of maize, sunflower and sorghum grew well from an early October sowing date into the post monsoon season and produced good yields on stored soil water with low plant stress due to mild seasonal conditions. Delayed sowing may prove to be the best option for farmers in the Northwest upland, achieved by a simple shift of sowing dates.

Soybean ('Glycine max') is a tropical legume that can be grown on many soil types under a wide range of climatic conditions. It is a native of eastern Asia and originally grew wild in China, Manchuria, Korea and Japan. This manual outlines how to grow soybean successfully in Cambodia under rainfed upland conditions. Soybean production in Cambodia has been growing steadily since 1980 (Figure 1) and exceeded 100,000 tonnes per year in 2005. The main soybean production area for the past 30 years has been the province of Kampong Cham. However, in recent years, soybean production has increased in north-western Cambodia, especially in the province of Battambang. Soybean is also grown in other provinces, including Siem Reap, Kandal and Takeo. Soybean is usually grown in the main wet season, and the crop fits well in an upland rotation in combination with maize, sesame and peanut. The roots of legume crops such as soybean have nodules formed by rhizobium bacteria ('Bradyrhizobium' spp.), which obtain nitrogen from the atmosphere; this nitrogen becomes available to both the soybean and following crops. Rhizobia are not always present in the soil and may need to be added to the seed at sowing time (see Section 8).

The purpose of this book is to help extension workers and farmers to identify plants that are weeds or are considered to have the potential to become weeds in the upland cropping systems of Cambodia. Not all of the plants included are currently regarded as weeds, and many of them have useful purposes. However, with changing agricultural practices such as reduced or zero tillage, plant species currently controlled by ploughing could become weeds. These include perennial species and those with underground stems and rhizomes. Some important species known to be weeds of upland crops have not been included in this volume because of our inability to identify them or to obtain suitable photographic images. These will be included in a future revised edition.