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In many parts of the world, conditions for small scale agriculture are worsening, creating challenges in achieving consistent yields. The use of automated decision support tools, such as Bayesian Belief Networks (BBNs), can assist producers to respond to these factors. This paper describes a decision support system developed to assist farmers on the Mekong Delta, Vietnam, who grow both rice and shrimp crops in the same pond, based on an existing BBN. The BBN was previously developed in collaboration with local farmers and extension officers to represent their collective perceptions and understanding of their farming system and the risks to production that they face. This BBN can be used to provide insight into the probable consequences of farming decisions, given prevailing environmental conditions, however, it does not provide direct guidance on the optimal decision given those decisions. In this paper, the BBN is analysed using a novel, temporally-inspired data mining approach to systematically determine the agricultural decisions that farmers perceive as optimal at distinct periods in the growing and harvesting cycle, given the prevailing agricultural conditions. Using a novel form of data mining that combines with visual analytics, the results of this analysis allow the farmer to input the environmental conditions in a given growing period. They then receive recommendations that represent the collective view of the expert knowledge encoded in the BBN allowing them to maximise the probability of successful crops. Encoding the results of the data mining/inspection approach into the mobile Decision Support System helps farmers access explicit recommendations from the collective local farming community as to the optimal farming decisions, given the prevailing environmental conditions. [ABSTRACT FROM AUTHOR]

Inland saline intrusion is occurring during the dry season in the Mekong River Delta (MRD), Vietnam. Rising sea levels, tidal fluctuations, drought, and changes to upstream flow contribute to extensive salinisation of rice producing areas of the MRD, leading to substantial rice crop losses. The identification, evaluation and implementation of alternative crop and soil management solutions are required to complement on-going rice production in the region. A review of scientific and grey literature was conducted regarding the nature and extent of salinisation in the MRD and the adoption and management of alternative crops to rice. Familiar crops in Vietnam (e.g., maize, soybean), as well as novel crops to the MRD (e.g., quinoa, cowpea) were explored as potential options to replace dry season rice. Management options including surface soil mulches and plastic coverings help maintain soil moisture and reduce salinity damage to plants, and the use of drainage and seed preparation techniques can improve plant establishment and yield. Factors contributing to the success of alternative crops include salt tolerance, timing and efficiency of water use, ability to grow in the dry growing season, tolerance to pests and diseases, labour intensiveness and the crops' marketability. The identification of suitable alternative crops to replace dry season rice in saline affected areas of the MRD, combined with management practices like mulching and soil moisture monitoring, could provide farmers with income opportunities to offset rice losses. Documenting the factors contributing to successful crop diversification can assist with decision-making and support initiatives among farmers, agribusiness, and government agencies. [Display omitted] • Inland saline intrusion is causing substantial rice losses during the dry season of the Mekong River Delta, Vietnam. • Alternative crops and management practices need to be identified to supplement the loss of rice income. • Numerous biophysical, environmental, and socioeconomic factors are identified that determine alternative crops suitability. • Mulching, raised beds and soil water monitoring can decrease salinity stress and improve water use efficiency. • Combining alternative crops and management practices provide farmers with options for saline affected areas. [ABSTRACT FROM AUTHOR]

Aquatic ecosystems are used for extensive rice-shrimp culture where the available water alternates seasonally between fresh and saline. Poor water quality has been implicated as a risk factor for shrimp survival; however, links between shrimp, water quality and their main food source, the natural aquatic biota inhabiting these ponds, are less well understood. We examined the aquatic biota and water quality of three ponds over an entire year in the Mekong Delta, Vietnam, where the growing season for the marine shrimp Penaeus monodon has been extended into the wet season, when waters freshen. The survival (30-41%) and total areal biomass (350-531 kg ha -1 ) of shrimp was constrained by poor water quality, with water temperatures, salinity and dissolved oxygen concentrations falling outside known optimal ranges for several weeks. Declines in dissolved oxygen concentration were matched by declines in both shrimp growth rates and lipid content, the latter being indicative of nutritional condition. Furthermore, as the dry season transitioned into the wet, shifts in the taxonomic composition of phytoplankton and zooplankton were accompanied by declines in the biomass of benthic algae, an important basal food source in these systems. Densities of the benthic invertebrates directly consumed by shrimp also varied substantially throughout the year. Overall, our findings suggest that the survival, condition and growth of shrimp in extensive rice-shrimp ecosystems will be constrained when poor water quality and alternating high and low salinity negatively affect the physiology, growth and composition of the natural aquatic biota. Changes in management practices, such as restricting shrimp inhabiting ponds to the dry season, may help to address these issues and improve the sustainable productivity and overall condition of these important aquatic ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in tfSupplementary materialhis paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)