Productivity and profitability of upland crop rotations in Northwest Cambodia
The upland cropping region of Northwest Cambodia exhibits limited crop diversity, with maize and cassava dominating rain-fed production systems. Farmers in the Districts of Sala Krau in Pailin Province, and Samlout in Battambang Province, report soil fertility decline in upland cropping systems with associated reduced yields and profitability compared with five years ago. Research was conducted at one site in each of these Districts over a two year period. The purpose of the study was to investigate crop rotations in this system with a focus on better use of soil water throughout the year to increase crop yields and profitability. This included an experiment to investigate increasing cropping intensity from the usual two crops per year to three and evaluate which crop sequences would be feasible. Out of a total 15 crop sequences evaluated, only four were successful in producing viable grain yields. These were the same sequences at both sites and included maize-maize-fallow, maize-maize-sunflower, maize-soybean-fallow and maizesoybean-sunflower. At Pailin, the sequence with the highest overall mean yield (4.3 t/ha) and profit was maize-maize-sunflower which returned a gross margin of $USD3700/ha over two years. The sequences with a fallow instead of a third crop produced the lowest financial returns at Pailin. However, in Samlout the maize-fallow was the most profitable sequence with an overall mean yield of 3.0 t/ha, returning $1680/ha over two years. The least profitable sequences at Samlout were the two soybean sequences. This study was successful in growing five crops in two years at Pailin, but could not reach the goal of six due to cultivar maturity length. At Samloutfour crops over two years were produced, as the pre-monsoon crop was not planted in either year due to lack of sowing rainfall. Seasonal climatic factors had the greatest effect at both field sites on gross margins, which emphasized the importance of matching sowing date to rainfall to make better use of stored soil moisture to optimise yield and profitability. At Pailin, mean seasonal surface soil moisture, hundred seed weight and harvest index also impacted gross margin returns. This research validated the stability of maize in the farming system while sunflower should be further investigated in cropping sequences.
Insects of 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.
Managing soil biological decline during long-fallows in cropping systems
No-till farming in Australia has revolutionised the way many farmers crop. Some of the moisture retention advantages of no-till farming have resulted in a reduced reliance of in-crop rain as well as increasing yields and profitability. Less clear is the effect on biological properties. Early results of a survey of the no-till cropping soils of the central west of NSW showed that most no-till cropping areas have lower soil carbon levels and lower microbial activity than nearby uncropped soils. This indicates that many no-till cropping soils may not be as sustainable as first thought. A long-fallow field trial was conducted on "Magomadine" near Coonamble NSW Australia using surface applied amendments (straw, compost, feedlot manure, biochar and zeolite) to investigate their effect on biological, chemical and physical soil properties. Early results are suggesting that the application of 10t/ha of straw can significantly (P < 0.05) increased soil moisture (24%), microbial respiration (50%), microbial biomass (21%), and mean weighted diameter of soil aggregates (75%). This research has highlighted the importance that high stubble residues have in improving these soil properties during a long-fallow.
Arthropod survey on soybean crops in Cambodia: a comparison of the sweep netting and beat sheeting collection methods for estimating arthropod diversity and species richness
This is the first assessment of insect assemblages on soybean crops in Cambodia. Sweep netting and beat sheeting collection methods were used to evaluate the effectiveness of sampling arthropods and their collection efficiency in soybean crops and to determine soybean insect diversity and composition at two sites. Overall, arthropod populations sampled by sweep netting were substantially different compared to populations collected by beat sheeting. The sweep netting caught significantly higher numbers of most Orders; however, the beat sheeting caught a significantly higher number of Acari. Beat sheeting was also effective for sampling 'Nezara viridula' which is a major invertebrate pest of soybean. There was a significant interaction between location and collection methods for both Hemiptera and Hymenoptera assemblages. Selection of insect sampling method depends on many factors such as plant type, plant structure, field conditions, ease of use, cost of use and target insect species. However, the sweep netting was best for fast flying insects such as hymenopteran wasps and those located in upper parts of the plant canopy. The use of different sampling methods to assess pest, predator/parasitoid and general community structure in crops is crucial for assessing Integrated Pest Management strategies.
Yield Responses of Maize and Sunflower to Mulch under No-till Farming Conditions in Northwest Cambodia
Background: Upland farming in Northwest Cambodia experiences annual soil loss and erosion due to the combination of topography, monsoonal climate and plough based farming practices. This study investigated the potential for no-till farming as a more sustainable farming method in this region. Methodology: An experiment was conducted at two sites in neighbouring Northwest provinces to investigate the effects of varying rates (nil, 2.5, 5, 10 and 20 t ha¯¹) of maize ('Zea mays' L.) stover mulch on yields of maize and sunflower ('Helianthus annus') using no-tillage farming practices. Small plot replicated experiments were undertaken in the pre-monsoon and post-monsoon seasons. Results: The 5 t haG1 mulch treatment attained the highest yield in the pre-monsoonal maize trial. During the post-monsoon period maize yield increased by 0.4 t ha¯¹ with every 2.5 t of mulch applied, whereas nil mulch resulted in near crop failure. Post-monsoon sunflower failed to respond to mulch treatments at either site. The lack of response at the second site which received higher rainfall was probably due to mild seasonal conditions and adequate stored soil water. Maize was more responsive to mulch than sunflower in both seasons with mulch application increasing yield. Conclusion: Farmers who retain crop residues increase their chances of establishing a pre-monsoon crop and reduce the probability of crop failure. This study also demonstrated that a successful crop can be grown in the non-traditional sowing period of the post-monsoon. While farmers may not have the resources to justify applying mulch regularly, it is thought they may use the knowledge gained from this study to implement no-till farming practices and retain crop residues 'in situ'.
Crop Profit Groups and Farmer Participation in Research: Some Experiences from Cambodian Upland Regions
Reductions in poverty and improvements in food security are important issues for farmers and agricultural regions in Cambodia. In this paper we relate our approach and experience working in upland areas of Battambang Province to improve agricultural, environmental and social outcomes for farm families and villagers. Small farm sizes and observed low levels of agricultural productivity exacerbate poverty and food insecurity. We have approached this challenge by first investigating and demonstrating new agricultural methods (or technologies) in a farming systems context, through developing a network of farm trials and demonstrations. To this is added activity in contextual economic and social assessment of new versus old farming methods and management, with the objective of farmer adoption of improved methods and associated increases in farm family incomes. We have formed Crop Profit Groups of local farmers to assess the economic costs and benefits of changed management in the main cash crops of maize and soybean. We have also investigated marketing and value-chain issues since these affect upland farmers in important ways. Our approach has been to bring expertise to each situation and adopt a co-learning approach with local farmers, government officials and NGOs. Education and capacity-building of Cambodian collaborators has been an important part of the work. While our work is not yet finished we have found a genuine willingness by the Cambodian farmers to consider new 'ways of doing things' and be involved in assessing their own incentives to change. A variety of approaches are used in training and capacity building of the local researchers and officials. There seem to be substantial economic incentives to change some farming practices, but issues of farm input supply availability, markets and prices received for farm produce, transport costs and infrastructure appear to constrain improved farm and regional outcomes.
Final Report: Farming systems research for crop diversification in Cambodia and Australia
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.
Weeds of upland crops in Cambodia
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.