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    Optimal nitrogen fertilizer decisions for rice farming in a cascaded tank system in Sri Lanka: An analysis using an integrated crop, hydro-nutrient and economic model
    (Elsevier B V, 2023-04-01) Kanthilanka H; Ramilan T; Farquharson RJ; Weerahewa J; Timsina J
    CONTEXT: The ancient irrigation systems in Sri Lanka, known as village tank cascade systems, were developed to ensure an adequate and sustainable supply of good quality water to communities. However, there is growing concern about health and environmental issues related to the degradation of water quality caused by excessive nitrogen (N) levels from the overuse of chemical fertilizer. Subsidies for chemical fertilizer have encouraged fertilizer use for rice production in Sri Lanka. OBJECTIVES: The objective was to evaluate the use of N fertilizers for rice production in the Thirappane cascaded tank system and its impact on nitrate water quality. An optimal rate of N use was determined based on private (farm-level) decisions on fertilizer use. However, the private optimal fertilizer rate is not adequate for overall social welfare due to market failures such as incomplete information and the lack of a market to account for the negative impact of fertilizer use on tank water quality. The hypothesis is that the social optimal fertilizer rate is lower than the private optimal rate due to this discrepancy. The study aims to identify the sources of inefficiency in the sub-optimal use of fertilizers from a social perspective. METHOD: We developed an integrated crop, hydro-nutrient and economic model to analyze fertilizer decisions in the rice production process. The method involved conducting a marginal economic analysis based on simulated yield responses to N fertilizer and prices for inputs and outputs. The analysis was performed for three soil types across the Maha (rainy) and Yala (dry) seasons and for three different weather scenarios within each season. RESULTS AND CONCLUSIONS: When the negative impact of nitrate contamination on water quality is taken into account, the optimal N fertilizer rate from a social perspective is always lower than the optimal rate determined solely by private economic considerations. These optimal rates varied based on factors such as soil type, season, weather conditions during the growing season, and fertilizer prices. At unregulated, higher, fertilizer prices, the crop yields achieved at the social optimum were only slightly lower than those achieved under the private economic optimum. However, under regulated, lower, fertilizer prices, achieving the social optimum would require a larger reduction in N fertilizer use and result in a greater decrease in crop yields. SIGNIFICANCE: A systematic analysis that takes into account the social costs can serve as a guide for creating effective policies aimed at enhancing fertilizer decision making
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    Breakdown of rice and wheat-based foods during gastric digestion and its implications on glycemic response : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand
    (Massey University, 2022) Nadia, Joanna
    The composition and structure of starch-based foods determine their breakdown behavior in the digestive tract and consequently their glycemic response. The glycemic response of starch-based foods is known to be influenced by their gastric emptying rate. However, the role of gastric digestion in regulating this process has not been well-understood, especially on how food breakdown behavior in the stomach may be related to the glycemic response. In this project, the link between food structure, food breakdown during gastric digestion, gastric emptying, and glycemic response was investigated in vivo using a growing pig model. Durum wheat- and white rice-based foods of varying physical structures (semolina porridge, rice- and wheat couscous, rice grain, rice noodle and wheat noodle/pasta) were studied. It was found that the foods with smaller-sized particles (semolina porridge and couscous products) had faster gastric breakdown rate and gastric emptying rate, resulting in higher glycemic impact (maximum change from the baseline and the overall impact) compared to the foods with larger-sized particles (rice grain and noodle products). The faster gastric breakdown rate of the smaller-sized foods was related to their acidification rate in the stomach, which caused their dilution or dissolution by gastric secretions. For larger-sized foods, their gastric breakdown rate and gastric acidification rate were slower, which extended their contact time with salivary amylase in the proximal stomach. To elucidate further the role of the proximal and distal phases of gastric digestion in solid food breakdown, a static in vitro digestion was conducted with the same food products. In the smaller-sized foods, both the proximal and distal phases led to their dissolution. Meanwhile, for the larger-sized foods, the extended contact time with α-amylase in the proximal phase contributed to the leaching of starch particles from the food, which was important to aid their breakdown during gastric digestion. The distal phase contributed to the softening of the larger-sized foods, but its softening effect was limited. The knowledge on the contributions of the phases of gastric digestion and the identified link between food structure, gastric digestion, and glycemic response in this thesis may be useful for structuring starch-based foods with controlled glycemic properties. 
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    Mapping of multitemporal rice (Oryza sativa L.) growth stages using remote sensing with multi-sensor and machine learning : a thesis dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Earth Science at Massey University, Manawatū, New Zealand
    (Massey University, 2022) Ramadhani, Fadhlullah
    Rice (Oryza Sativa) plays a pivotal role in food security for Asian countries, especially in Indonesia. Due to the increasing pressure of environmental changes, such as land use and climate, rice cultivation areas need to be monitored regularly and spatially to ensure sustainable rice production. Moreover, timely information of rice growth stages (RGS) can lead to more efficient of inputs distribution from water, seed, fertilizer, and pesticide. One of the efficient solutions for regularly mapping the rice crop is using Earth observation satellites. Moreover, the increasing availability of open access satellite images such as Landsat-8, Sentinel-1, and Sentinel-2 provides ample opportunities to map continuous and high-resolution rice growth stages with greater accuracy. The majority of the literature has focused on mapping rice area, cropping patterns and relied mainly on the phenology of vegetation. However, the mapping process of RGS was difficult to assess the accuracy, time-consuming, and depended on only one sensor. In this work, we discuss the use of machine learning algorithms (MLA) for mapping paddy RGS with multiple remote sensing data in near-real-time. The study area was Java Island, which is the primary rice producer in Indonesia. This study has investigated: (1) the mapping of RGS using Landsat-8 imagery and different MLAs, and their rigorous performance was evaluated by conducting a multitemporal analysis; (2) the temporal consistency of predicting RGS using Sentinel-2, MOD13Q1, and Sentinel-1 data; (3) evaluating the correlation of local statistics data and paddy RGS using Sentinel-2, PROBA-V, and Sentinel-1 with MLAs. The ground truth datasets were collected from multi-year web camera data (2014-2016) and three months of the field campaign in different regions of Java (2018). The study considered the RGS in the analysis to be vegetative, reproductive, ripening, bare land, and flooding, and MLAs such as support vector machines (SVMs), random forest (RF), and artificial neural network (ANN) were used. The temporal consistency matrix was used to compare the classification maps within three sensor datasets (Landsat-8 OLI, Sentinel-2, and Sentinel-2, MOD13Q1, Sentinel-1) and in four periods (5, 10, 15, 16 days). Moreover, the result of the RGS map was also compared with monthly data from local statistics within each sub-district using cross-correlation analysis. The result from the analysis shows that SVM with a radial base function outperformed the RF and ANN and proved to be a robust method for small-size datasets (< 1,000 points). Compared to Sentinel-2, Landsat-8 OLI gives less accuracy due to the lack of a red-edge band and larger pixel size (30 x 30 m). Integration of Sentinel-2, MOD13Q1, and Sentinel-1 improved the classification performance and increased the temporal availability of cloud-free maps. The integration of PROBA-V and Sentinel-1 improved the classification accuracy from the Landsat-8 result, consistent with the monthly rice planting area statistics at the sub-district level. The western area of Java has the highest accuracy and consistency since the cropping pattern only relied on rice cultivation. In contrast, less accuracy was noticed in the eastern area because of upland rice cultivation due to limited irrigation facilities and mixed cropping. In addition, the cultivation of shallots to the north of Nganjuk Regency interferes with the model predictions because the cultivation of shallots resembles the vegetative phase due to the water banks. One future research idea is the auto-detection of the cropping index in the complex landscape to be able to use it for mapping RGS on a global scale. Detection of the rice area and RGS using Google Earth Engine (GEE) can be an action plan to disseminate the information quickly on a planetary scale. Our results show that the multitemporal Sentinel-1 combined with RF can detect rice areas with high accuracy (>91%). Similarly, accurate RGS maps can be detected by integrating multiple remote sensing (Sentinel-2, Landsat-8 OLI, and MOD13Q1) data with acceptable accuracy (76.4%), with high temporal frequency and lower cloud interference (every 16 days). Overall, this study shows that remote sensing combined with the machine learning methodology can deliver information on RGS in a timely fashion, which is easy to scale up and consistent both in time and space and matches the local statistics. This thesis is also in line with the existing rice monitoring projects such as Crop Monitor, Crop Watch, AMIS, and Sen4Agri to support disseminating information over a large area. To sum up, the proposed workflow and detailed map provide a more accurate method and information in near real-time for stakeholders, such as governmental agencies against the existing mapping method. This method can be introduced to provide accurate information to rice farmers promptly with sufficient inputs such as irrigation, seeds, and fertilisers for ensuring national food security from the shifting planting time due to climate change.
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    Factors affecting the continued use of the mobile flash dryers by farmer co-operatives, Nueva Ecija, Philippines : a thesis submitted in partial fulfilment of the requirements for the degree Master of Applied Science (Agricultural Systems Management), Massey University, Palmerston North, New Zealand
    (Massey University, 1999) Rodriguez, Amelita C
    Harvest of the Philippines second and larger rice crop occurs during the end of the wet season. For members of the rice industry this wet season harvest poses a problem: grain cannot be dried reliably using traditional sundrying methods. Poor drying results in quality reductions and hence farmers receive lower returns. To address this situation the Philippines Government introduced locally manufactured mechanical dryers. This study was undertaken to examine variables which enhance or limit the continued use of the mobile flash dryers in farmers' co-operatives in Nueva Ecija, the Philippines. Two case studies, each consisting of three farmers' co-operatives were investigated using semi-structured interviews. One case comprised co-operatives that continue to use the dryer while the other comprised those that have stopped using it. Results showed that a combination of factors influenced the adoption decisions of the co-operatives. Economic factors, especially the volume of rice handled by the co-operative appeared to be most important. Furthermore, the way that the dryer fitted with the other postharvest systems in the co-operatives was a determinant of adoption decisions. In particular, the co-operatives with rice milling operations or with inadequate alternative drying options utilised the mechanical dryers. The leadership and management of the co- operative appeared also to be a factor. These results indicate that both organisational factors and the characteristics of a technology need to be considered in the development and extension of innovation. Overall the results of this work support the individual and organisational adoption literature. Further work could explore this issue on a wider basis across more co-operatives within the region and across more regions in the country. Key words: Technology adoption, co-operatives, mechanical grain dryer.
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    Effectiveness of botanical preparations for the control of rice weevil (Sitophilus oryzae) during rice seed storage and their impact on the rice seed viability : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Seed Technology at Massey University, Palmerston North, New Zealand
    (Massey University, 2001) Sartie, Alieu Mortuwah
    Food security and the maintenance of seed quality from harvest to planting are key issues for peasant farmers. In Sierra Leone, up to 28% of rice seed can be damaged by rice weevil in the six months storage period. The use of chemical insecticides to control this insect is not practical for traditional farmers. Some tribes use pepper powder (Capsicum spp.) as a seed protectant. In this study, I have compared the effects of neem (Azadirachta indica) oil, neem powder, pepper (Capsicum frutescens cv. "Habanero") powder and lentil (Lens culinaris cv. "Raja") powder on the survival of adult rice weevil (Sitophilus oryzae) and weevil offspring during rice (Oryza spp.) seed storage, and on the germination of the rice. Treatment of stored rice with neem oil, neem powder and lentil powder gave some protection from rice weevil damage. Neem oil at the rate of 0.005ml/kg rice seed effectively controlled weevil damage without reducing the seed germination. Lentil and neem powders at the rate of 0.02g/kg rice seed gave effective protection against rice weevil damage with no reduction in viability of the seeds. Pepper powder did not kill adult rice weevil. Neem oil reduced the development of weevil offspring in rice seed, but the powders of neem, lentil and pepper did not. Low relative humidity of 42.5% in seed storage environment and a reduction in seed moisture content below 10% enhanced the mortality of adult rice weevils on rice seed.
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    Collective action : improving smallholder rice farmers' value chain in Yogyakarta, Indonesia : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriCommerce, at Massey University, Manawatu, New Zealand
    (Massey University, 2017) Ahmad, Shaf Rijal
    Collective action has been widely accepted as one of the strategies to improve smallholder farmers’ capability to gain benefit from the agrifood value chain. This is also part of the working policy of the Government of Indonesia. Nevertheless, there is little empirical evidence for staple food farmers, particularly rice, in organising collective action and many such attempts have not met the policy’s implementation objectives. Considering the importance of rice agribusiness in Indonesia, therefore, there is a need to investigate experiences of smallholder rice farmers who work collectively and are able to improve their value chain and gaining benefit from it. The objectives of this study were to identify and describe what benefit captured through collective action and how, and; to identify and describe how these farmers act collectively within a group and why. The research question was answered and objectives addressed by using a qualitative single case study. A farmer group named Gapoktan Sidomulyo was selected, as it was identified by the central and local government as a well-developed collective farmers’ group. Data was collected through semi-structured interviews with farmers and other actors relevant to the group development. This study found that collective action helped smallholder rice farmers to build a competitive advantage. This action enabled them to improve production capacity and product quality, as well as human capability and bargaining power. This also helped them to reduce the number of intermediaries. Therefore, they can capture the potential value offered by the rice value chain. This study also highlighted essential factors for smallholder rice farmers’ collective action: Firstly, this action required incentives and support as well as a motivated group of farmers. Even when collective action was supported by government, it was essential to motivate farmers to act collectively and see the benefits for doing so. Secondly, trust and a shared vision between members of the farmer group was important element for collective action. These formed the basis for building horizontal relationships between farmers. This affected the reciprocity between them and their commitment. Thirdly, in a group that was heterogeneous, in terms of religion and reliance on farming as an income source, group cohesion could be achieved through effective group management, which means management that promoting transparency and active communication between farmers and the leadership team, and giving an opportunity for each actor within the group to play their role. These reduced the potential of conflict and maintain the farmers’ awareness on the group so that they keep engaged within the group. Fourthly, leadership with strong motivation, good interpersonal skills, social awareness, as well as administration and marketing skills were essential for the group’s development. Unlike to what has been identified in many studies, the leadership could also be provided by a team of people, instead of relying on an individual. Fifthly, maintaining the active members and the leadership team’s participation was essential as they were the key actors within the group. For the active farmers, this was achieved through: facilitating members to raise their voice and be involved in decision making, involving them to enforce rules, and conducting activity that attract them to attend regular meetings. Meanwhile, for the leadership team members, this could be achieved through conducting an appropriate leadership team selection process and acknowledging their effort in fostering the group. Lastly, despite there was a culture to work as a group, it was important for having trusted external agents to facilitate farmers and motivate them to act collectively, particularly when this required money in initiating the action. The support from external agents, such as technology and finance, was also important to build farmers capability in improving the value chain. In addition, this case highlighted that only some farmers were able to gain benefit through this action and they were who can produce consistently volume beyond their household requirements. Keywords: Smallholder farmers, collective action, rice value chain, agriculture, rice, Yogyakarta, Indonesia.
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    Rice and fertilizer policies in Indonesia : a thesis presented in partial fulfillment of the requirements for the degree of Masters of Agricultural Economics, Massey University
    (Massey University, 1993) Hutabarat, Sakti
    To promote rice production, the government of Indonesia implemented various agricultural policies. Some agricultural inputs had been subsidised heavily, particularly fertilizers. The combination of lower inputs prices, improved technology and better infrastructure such as irrigation schemes increase rice production significantly. However, higher rice production and lower fertilizer prices encouraged farmers to use more fertilizers. In some areas the use of fertilizers has exceeded that recommended and in some areas production has even declined. It is likely that higher farm incomes that resulted from higher production and increased product prices affected the demand for fertilizers and other inputs to production. As demand for fertilizer increased the cost of the fertilizer subsidy became an important part of government expenditure. In recent years, the government of Indonesia has introduced policies to reduce the fertilizer subsidy. These policies have had substantial impacts on farmers' costs and incomes. On the one hand, the reduction of the fertilizer subsidy reduced demand for fertilizers. However, this policy was estimated to have little effect on rice production since the use of fertilizer was in general more than was recommended. On the other hand, while the rice price had been hold constant, increased farm costs reduced farmers' incomes. In order to offset the increased farmers' costs the government could allow the rice price increases. This study is concerned with the effects of the reduction in urea subsidy and the increase in rice support price to maintain self-sufficiency, or to offset the producers loss, due to the increase in urea price. A model developed by Baker and Hayami is adopted for this analysis, to examine their effects on demand for urea, rice production, producers surplus, government expenditure, and foreign exchange earnings. The results indicate that the joint policies can meet either the income compensation or self-sufficiency goals, but not without increasing government expenditure. In addition, these policy actions would distort the rice and urea markets.
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    Mathematical modelling and improvement of operating practices of sun drying of rice : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 2006) Meas, Pyseth
    In Cambodia, sun drying of rice has always been of great importance for preserving rice. The main goal of this study was to find the conditions for sun drying that maximise the throughput while minimising quality loss. A whole-bed approach was taken to investigate the conditions of the grain and the air at different layers during the drying process. Seven sets of sun-drying experiments were conducted in Cambodia using a range of methods practiced by rice farmers. These methods included drying with different bed depths (2 to 6 cm), with the bed on different pads (water-proof tarpaulin, mat, net, polystyrene or rice husk), and with different bed tempering methods (stirring regularly or shading and/or covering the bed around midday) for four Cambodian rice varieties (Pka Knhey, CAR11, Masary and IR66). The grain temperature was found to be more affected by the solar intensity than the temperature of the ambient air. Fastest drying was achieved when the bed was thin, less compacted, stirred regularly but not shaded or covered around midday, dried on a pad which allows some air and moisture movement and with high or strong solar intensity. Only the mechanical impact (MI) and milling tests of the rice quality provided useful results. Higher quality was found for grain that was dried in thin beds, stirred regularly, shaded with or without covering around midday and dried on pads with less air circulation. Among the methods used to determine the glass transition temperature of the grain, only the Differential Scanning Calorimetry method gave meaningful results. The glass transition temperature data were highly variable but generally decreased with increasing moisture content and compared quite well with the published glass transition temperatures for other varieties of rice. To provide additional detail on the local conditions within the bed, to better understand the drying process and the interactions between variables and to predict alternative parameters that might be used to correlate with the head rice yields (HRYs), a mathematical model for heat and moisture transport within the bed was developed. The model covered all the drying methods/conditions studied experimentally. A lumped parameter approach to energy and mass transfer in individual kernels was used in the bed model. The model was validated against experimental data. The predicted drying time, temperatures, moisture contents and water activities (relative humidity of the air within the bed) were found to compare very well with the experimental data except when a polystyrene pad was used. The model proved to be a very good mechanistic tool with advantages of simplicity and practical accuracy in the design and management of the sun drying system. A number of parameters related to postulated grain damage mechanisms were derived from the predicted conditions within the bed during drying. The best predictors of the grain quality were found to be rewetting the kernels when the grain is bulked (especially when the kernels are partly below and partly above critical moisture content) grain temperature and distance from the glass transition temperature line. It was concluded that in order to get the fastest drying conditions rice should be sun dried with thin bed, stirring, not shaded or covered around midday and dried on a pad with air circulation. For the highest quality grain, that is grain which would have the least breakage during milling, rice should be sun dried with a thin bed, stirring, shaded or covered around midday and dried on a pad with less air circulation. The optimal drying conditions to get the best quality combined with the fastest practical drying rate, the drying conditions should be drying with 2 cm bed depth, stirring the grain bed every hour, shading or covering the bed around midday and using a tarpaulin or net pad placed directly on the ground.
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    Chewing behavior and bolus properties as affected by different rice types
    (World Academy of Science, Engineering and Technology, 2012) Moongngarm A; Bronlund JE; Grigg N; Sriwai N; Wong, ATC; Chin, KS; XU, MM
    The study aimed to investigate the effect of rice types on chewing behaviours (chewing time, number of chews, and portion size) and bolus properties (bolus moisture content, solid loss, and particle size distribution (PSD)) in human subjects. Five cooked rice types including brown rice (BR), white rice (WR), parboiled white rice (PR), high amylose white rice (HR) and waxy white rice (WXR) were chewed by six subjects. The chewing behaviours were recorded and the food boluses were collected during mastication. Rice types were found to significantly influence all chewing parameters evaluated. The WXR and BR showed the most pronounced differences compared with other rice types. The initial moisture content of un-chewed WXR was lowest (43.39%) whereas those of other rice types were ranged from 66.86 to 70.33%. The bolus obtained from chewing the WXR contained lowest moisture content (56.43%) whilst its solid loss (22.03%) was not significant different from those of all rice types. In PSD evaluation using Mastersizer S, the diameter of particles measured was ranged between 4 to 3500μm. The particle size of food bolus from BR, HR, and WXR contained much finer particles than those of WR and PR.