Yala Season Research Articles

Climate Change Impacts for Multipurpose Reservoir Planning: Basnagoda Reservoir, Sri Lanka

Climate change via rainfall and temperature changes poses threats to water resources. Traditionally, these variations are rarely considered in irrigation infrastructure planning. Integrating climate impacts into early irrigation planning ensures resilience and sustainability.This study aims to assess the climate change impacts on Basnagoda reservoir using a reservoir operation study, system designing and sizing, water use strategies and making recommendations as mitigation and adaptation strategies.This study employed reservoir operation model recommended in the Irrigation guideline, Sri Lanka to assess four climatic scenarios derived from predicted temperature and rainfall changes. Sensitivity analysis included reservoir sizing for the most critical scenario. Mitigation and adaptation methodologies such as 1) Reservoir capacity enhancement 2) Seasonal shifting 3) Conveyance enhancement were analyzed. Reservoir operations currently meet 100% of domestic demand, irrigating total 950 ha annually (380 ha Maha, 570 ha Yala) with environmental flow. Design capacity fulfils 78% of domestic demand, with environmental flow for projected period. The maximum cultivable area at the design stage while providing 25% of design domestic demand is 544 ha in Maha and 680 ha in Yala season. With a 20% rainfall reduction posing the worst scenario, domestic water fulfilment reduced to 20% (Maha) and 19% (Yala). Optimal reservoir capacity enhancement is 15%, expanding cultivable area to 390 ha, while providing 25% of design domestic demand. Conveyance enhancement increases cultivable area from reservoir water by 15%. This study is unique for integrating climate change impacts into reservoir infrastructure planning and design stages.

Performance of UAV-derived Normalized Difference Vegetation Index (NDVI) for Early Estimation of Rice Yield

Traditionally, the rice yield is measured after the harvest, which is too late then to revert any agronomic practices to improve yield. The aerial spectral reflectance images of crops captured by a multispectral camera mounted in an Unmanned Aerial Vehicle (UAV) are capable of quantitatively measuring the internal physiological condition of crops directly associated with their health status. The aim of this study was to evaluate the performance of UAV-multispectral image derived-NDVI as a method for estimating rice yield. Multispectral drone images including single band images were acquired from a controlled rice field at Rice Research and Development Institute (RRDI), Sri Lanka. Rice variety Bg 300 was cultivated in the Yala season under four levels of Nitrogen (N) fertilizer treatment plots. According to the regression co-relation analysis the derived NDVI values at 15 and 25 m flying heights from the rice crops at the booting stage were moderately (R2=0.65 and R2=0.67, p<0.05, respectively) associated with the actual yield. The derived NDVI values indicated the rice crop vigor at the booting stage is a useful indicator for early estimation of the rice yield prior to actual harvest.

Effect of Change of Agronomic Practices on Nutritive Value of Hybrid Fodder Sorghum Cultivated in Lowland Paddy Fields of the Dry Zone of Sri Lanka

This study was conducted to investigate the effect of low fertilizer rate and irrigation along with increased plant density on nutritive value of hybrid fodder sorghum cultivated in lowland fallowed paddy fields in dry zone during May to September. Seeds were sown in Yala season and continued as a ratoon crop to inter-monsoonal (Third) season. Four agronomic management packages (AMP1, AMP2, AMP3 and AMP4), which differ in fertilizer application rates, plant spacing, and irrigation intervals were tested with two fodder sorghum varieties (SX-17 and Dairygreen) in a split-plot design. The initial and first ratoon crops were harvested at dough grain stage. High fertilizer rate in combination with short irrigation interval, resulted in high (P<0.05) crude protein content in the initial harvest. AMP2 and AMP4 produced equally high (P<0.05) total dry matter yield (DMY) for SX-17 (24.7 and 20.9 MT/ha, respectively) and Dairygreen (27.7 and 25.7 MT/ha, respectively) varieties. Total digestible organic matter, crude protein and metabolizable energy yields were higher under AMP2 and AMP4 compared to other two packages for both varieties. Nutritive value was high in SX-17 under AMP1 for ratoon crop. In conclusion, AMP4 with plant spacing of 45 x 15 cm, low fertilizer rate (338-47-28 kg/ha, urea-TSP-MOP) and extended irrigation interval, could be recommended for cultivation of hybrid fodder sorghum in lowland paddy fields in the dry zone during Yala season. However, for cultivating SX-17 targeting to produce fodder with high nutritive level, AMP1 with spacing of 45 x 30 cm, high fertilizer rate (400-62-37 kg/ha of urea-TSP-MOP) and frequent irrigation could be recommended.

The Impact of Climate change on Water Resources in Northern Sri Lanka: Stakeholder Perspectives

Climate change is a global phenomenon affecting the entire planet, including Sri Lanka. The Northern Province of Sri Lanka is particularly vulnerable to the impacts of climate change, especially regarding water resources. Public awareness of climate change and its impact on water resources is crucial for sustainable water management practices in the study area. In this context, this study attempted to analyze public perception of the climate change impact on the water resources of Northern Sri Lanka. There are different groups of water users in the study area. They were stratified as agriculture water users, industrial water users, fishing water users and domestic and drinking water users. Accordingly, a questionnaire survey was conducted using a stratified sampling method to identify consumer perceptions, and the collected data were analyzed using the SPSS tool. 87% of the consumers believe that climate change has a significant impact on water resources, and 50% of the people expressed vulnerability of the agriculture sector to the climate change impact on water resources. Water scarcity during the yala season became a crucial threat to paddy cultivation in the study area. Other kind of water users such as industrial water users, fishing water users and drinking and domestic water users face difficulties in obtaining water resources for their needs during the SWMS and FIMS. Furthermore, drinking and domestic water users mentioned that they face water quality issues especially during July, August and September. During the southwest monsoon season, water users face difficulties in obtaining water for their domestic needs due to water scarcity. Majority of the water users know about climate change, but many of them don’t know how climate change affects their water sources. Water suppliers should implement special projects regarding climate change impacts on water resources in the study area. This will lead the water users to use water efficiently and protect the water sources sustainably.

Selection of traditional rice varieties for Galle District based on agronomic characteristics and farmer-consumer preferences

In response to the growing trend of cultivating traditional rice varieties in the Galle District this study aimed to select suitable varieties that align with the preference of farmers and consumers. A survey of traditional rice varieties cultivated in the Galle district led to the collection of thirty traditional rice accessions from the Germplasm collection of the Plant Genetic Resource Center (PGRC) for preliminary evaluation with 4 traditional varieties from the Rice Research Station Labuduwa (RRSLd). Preliminary evaluations were conducted during the 2017 Yala season at the RRSLd. Subsequently, five accessions/varieties from the preliminary evaluations, six varieties from Regional Rice Research and Development Center-Bombuwala (RRRDCBw/RRSBw), and two improved rice varieties; (Ld 368 and Bw 372) were further evaluated during the 2017/18 Maha season using a Randomized Complete Block Design with two replicates in RRSLd. The evaluations involved the active participation of farmers, researchers, consumers, and traders. Varieties were assessed on eight morphological characteristics. using the pair-wise ranking method of the Participatory Rural Appraisal (PRA) approach. Data analysis was performed using the Kruskal Wallis One Way ANOVA model. Bw 372 and Ld 368 received above-average rankings, with Suwandal (RRSLd) achieving the highest score for cooked rice quality. In the overall evaluation Ld 368, Kahawanu (4250), Kuruluthuda (RRSBw), and Suwandal (RRSLd) emerged as preferred choices. These selections were tested in farmer fields during the 2018 Yala season with Ld 368, Kuruluthuda (RRSBw), and Kahawanu recording higher yields. In the 2018/19 Maha season, all the varieties tested in the 2018 Yala season were tested in farmer fields except Kahawanu (4250). Ld 368 and Bw 372 outperformed others in farmer fields. Based on farmer preference and yield performance, Gonabaru (farmer selected) and Kuruluthuda (RRSBw) were the most preferred traditional rice varieties, followed by Suwandal (RRSLd) and Rathdal (RRSLd).

Bundled climate-smart agricultural solutions for smallholder farmers in Sri Lanka

Smallholder farmers are among the most vulnerable to climate shocks in Sri Lanka. Lack of education and technical skills, poverty, risks inherent to agricultural investments, limited assets, and financial capital are major reasons for low investments in enhancing adaptive capacity. The study explores the use of agricultural technologies in improving smallholder resilience to water-related disasters and their opportunities for recovery. We tested four bundled services to promote climate-smart agriculture practices namely weather index insurance (WII), agronomic advisories dissemination via SMS, weather services, and climate-resilient seeds of maize and rice. The integrated solutions are referred to as Bundled Solutions of Index Insurance with Climate Information and Seed Systems (BICSA) to manage agricultural risks in Sri Lanka. The study conducted the bundled solutions in three agroecological regions spread over five districts and covering more than 2,500 farmers in three cropping periods ofMahaandYalaseasons. The results demonstrate that providing bundled solutions significantly protects smallholders against moderate drought events. The satellite-based weather index insurance can offset the long-term consequences of severe yield losses and mitigate the long-term drop in farm productivity. Our findings demonstrate the importance of bundled insurance to mitigate financial risks associated with extreme weather events and enhance resilience to climate change among vulnerable smallholders. It is evident from the study promoting a viable business model among seed companies, insurance companies, and technological partners, along with public institutions such as agricultural extension services can help production-level improvements and develop strategies at both the farm and policy levels that will support a transition to a more resilient farming system.

Flow alterations due a constructed reservoir in the Menik Ganga basin, Sri Lanka

Natural water flows and their ecosystems are altered due to manmade hydraulic structures like dams. However, limited research on hydrologic alteration has been carried out in developing countries. This research explores the hydrologic alterations which occurred in the Menik Ganga basin, Sri Lanka due to the Weheragala reservoir constructed in 2009 for inter basin transfer. The hydrologic variations of the flow regime due to the construction of the reservoir was analyzed using Indicators of Hydrologic Alterations (IHA). For this purpose, we compared the calculated IHAs for streamflow at the Kataragama station (located downstream of Weheragala) during pre-construction (1990–2009) and post construction (2010–2019) periods. Also, the IHAs of simulated flows from the Water Evaluation And Planning (WEAP) model during 2010–2019 was compared with observed gauge discharge during the same period. The monthly observed flows in the “Maha” rainfall season (September to March) demonstrated a decreasing trend in post dam period with respect to pre dam period (highest decrease of 77 m3/s during October), whilst it showed an increasing trend (highest increase of 5 m3/s during August) in the Yala season (May to August) in the post-reservoir construction scenario. This was further visualized by comparing the indicators of the simulated flows with observed for post reservoir period, in which highest percentage differences occurred in June (− 4000% in 2016) and November (− 300% in 2010) for Yala and Maha periods respectively. Large alterations of the river flow due to the impoundment depicted by higher percentage differences. These alterations are extensively examined by other indicators as well. The fluctuations of flows have been decreased due to the construction of the reservoir which resulted in reductions of low and high pulses. The results are highly appealing to the authorities who are in water resources management to reach sustainable goals.

Effects of storage period and cultivated season on grain quality characteristics of selected improved and traditional rice (<em>Oryza sativa</em> L.) varieties in Sri Lanka

The production of quality rice is determined by many properties and these properties affect the consumer preferences and commercial value of rice. Therefore, this study was done to investigate the several physical, physicochemical, and milling properties of 12 selected improved and traditional rice (Oryza sativa L.) varieties grown experimentally in plots using randomized complete block design, in three seasons (2022 Yala, 2021/22 Maha, and 2021 Yala). These rice varieties were cultivated and harvested at the Rice Research and Development Institute, Bathalagoda, Sri Lanka. Statistical analysis was done using SAS software package version 9.3. Significant (p<0.05) differences between rice varieties in the relevant seasons and between seasons were observed for all test parameters. The brown rice and hull percentages varied from 75-79% and 20-24%, respectively while the head rice yield varied between 56-71% for raw rice in the 2021 Yala season. In the 2021/22 Maha season, the brown rice and hull percentage varied from 74–80% and 20–25% for selected varieties. Except for the variety suduheenati, At 311 and At 362, the head rice yield varied between 50-67% in the 2021/22 Maha season. The brown rice and hull percentages varied from 75-79% and 21-25%, respectively while the head rice yield varied between 55-74% for raw rice, except for the variety At 311 and Bg 374 in the 2022 Yala season. Majority of rice varieties harvested in all three seasons showed an intermediate gelatinization temperature (70–74 ºC). At 362 rice variety in all three seasons showed low gelatinization temperature of 55-69ºC. Except for At 311, many varieties had high amylose contents during the 2021/22 Maha and 2022 Yala seasons. In the 2021/22 Maha season, there were significant (p<0.05) differences in bulk density, grain elongation, and thousand-grain weight and there was no significant (p>0.05) difference between the 2021 and 2022 Yala seasons. The information obtained can be used to choose suitable rice varieties for commercial cultivation in Sri Lanka and to plan post-harvest practices.

Performance of the Napier Hybrid Cultivars CO-5 (Pennisetum glaucum × P. Purpureum schumach) and Sampoorna (Pennisetum pedicillatum × P. americanum) Harvested at Five Intervals

Low pasture biomass production and fodder scarcity are among the major challenges affecting productivity of dairy cattle farms in Sri Lanka. As a potential solution to this, two Napier hybrid cultivars, CO-5 and Sampoorna, were recently introduced, and a field experiment was conducted to evaluate their growth, dry matter production, and nutritional composition from May to September 2020 to identify the optimum stage of harvest during the Yala season of the year. Plant measurements and samples were collected at five harvest intervals (4, 6, 8, 10, and 12 weeks after planting, respectively), with the plant samples subjected to biomass and nutritional assessments. The number of tillers and leaf length significantly differed (p = 0.01) between the two cultivars at 4 weeks harvesting interval (HI), whilst the number of leaves differed at 12-week HI, respectively. Dry matter yield increased (p = 0.16) almost linearly, whilst crude protein declined exponentially with CO-5 greater than Sampoorna (p = 0.057; 9.3% vs. 8.7%), with increasing harvesting intervals, respectively. In vitro organic matter digestibility and in vitro metabolizable energy contents were similar across weeks 4, 6, and 8 but then decreased. This study demonstrates that higher dry matter yields (12.54 t/ha) can be obtained through harvesting both cultivars at 12 week HIs, but from a nutritional perspective, harvesting at 6 week HIs during Yala season of the year would be optimum for farmers.

Impact of climate change on paddy crop failure under different water regimes in Sri Lanka

This study highlighted the severity of paddy harvest failure under various water regimes by elaborating on spatiotemporal variations, and estimating the influence of climatic variation on such crop failure in Sri Lanka. A panel data set obtained from 18 districts from 1981 to 2019 was analysed. The Unharvest Index (UI) (i.e., an index that was developed to measure the intensity of crop failure) was estimated according to seasonal water regimes for each district. The panel data regression method was used for analysis. On average, 5 per cent of areas planted for paddy was unharvested annually, fluctuating with the coefficient of variation at 60 per cent with remarkable spatial variation. Harvest failure was more prominent in rainfed production as compared to irrigated cultivation; in dry and intermediate zones as opposed to wet zones; and in the Maha season (October to March) rather than the Yala season (April to September). Climate variability during the crop season significantly altered UI, especially during the early growth phase (Growth Phase I) as compared to the later growth phase (Growth Phase II). Temperature variability increased UI in rainfed production; an increase in the number of days above optimum temperature in Growth Phase I affected UI in minor irrigation; higher rainfall during Growth Phase I reduced UI in rainfed production; and higher rainfall variation reduced UI under all water regimes. Our findings suggest the importance of formulating localized climate‐smart adaptation policies and specific crop insurance programs for rainfed paddy production.

Evaluation of Intercropping System for Climate Resilient Agriculture of Yala Season in Up Country Intermediate Zone of Sri Lanka

Evaluation of Intercropping System for Climate Resilient Agriculture of Yala Season in Up Country Intermediate Zone of Sri Lanka

Resource-use efficiency and environmental sustainability in the village tank cascade systems in the dry zone of Sri Lanka: An assessment using a bio-economic model

IntroductionVillage tank cascade systems (VTCSs) were built in ancient Sri Lanka as autonomous and climate-resilient agro-ecological systems. This study examines crop choices, farming profitability, and environmental sustainability under alternative rainfall regimes and market interventions in the Mahakanumulla VTCS of the Anuradhapura district.MethodA bio-economic model was developed to represent farming activities in the VTCS for the 2018-19 Maha and 2019 Yala cultivation seasons with data gathered from secondary sources and a key informant survey. The objective function of the model was the maximization of profits from farming. Resource limits were set for four types of land (highlands and lowlands in the Maha and Yala seasons), two types of labor (hired and family), and twelve-monthly water constraints. Six different models were developed for the six sub-divisions of the VTCS, considering the water-management hierarchy of the system. The models were simulated under alternative rainfall regimes and market interventions. The optimal crop mixes, farm profits, and shadow prices of resources associated with the baseline scenarios were compared with those of the counterfactual scenarios.Results and discussionThis analysis clearly illustrated that water and labor are the key determinants of the system. Also, when 922 ha of lowlands and 205 ha of uplands were allocated per annum for crop cultivation under normal environmental conditions, the annual profitability of the VTCS was LKR 111 million. During drought periods, a sharp reduction in profits was observed in the Maha season. Year-round drought caused a 77% profit reduction compared to the baseline. The Maha drought alone caused a reduction of 47%. The introduction of a buy-back arrangement for chili and maize helped farmers to increase profits by 185 and 28%, respectively, under normal climate scenarios, turning to 954 and 5% during extreme drought scenarios, compared to the baseline. The least nitrate leaching and soil losses occurred in green chili cultivation. The introduction of market-based solutions is recommended to address extreme climate events experienced by the rural communities dependent on the VTCSs in Sri Lanka.

Evaluation of Inter-Cropping System for Climate Resilient Agriculture of Yala Season in up Country Intermediate Zone of Sri Lanka

Evaluation of Inter-Cropping System for Climate Resilient Agriculture of Yala Season in up Country Intermediate Zone of Sri Lanka

Developing a Combined Drought Index to Monitor Agricultural Drought in Sri Lanka

Developing an agricultural drought monitoring index through integrating multiple input variables into a single index is vital to facilitate the decision-making process. This study aims to develop an agricultural drought index (agCDI) to monitor and characterize the spatial and temporal patterns of drought in Sri Lanka. Long-term (1982 to 2020) remote sensing and model-based agroclimatic input parameters—normalized difference vegetation index (NDVI), land surface temperature (LST), 3-month precipitation z-score (stdPCP), and evaporative demand drought index (EDDI)—were used to develop agCDI. The principal component analysis (PCA) approach was employed to qualitatively determine the grid-based percentage contribution of each input parameter. The agCDI was apparently evaluated using an independent dataset, including the crop yield for the major crop growing districts and observed streamflow-based surface runoff index (SRI) for the two main crop growing seasons locally, called Yala (April to September) and Maha (October to March), using 20-years of data (from 2000 to 2020). The results illustrate the good performance of agCDI, in terms of predominantly capturing and characterizing the historic drought conditions in the main agricultural producing districts both during the Yala and Maha seasons. There is a relatively higher chance of the occurrence of moderate to extreme droughts in the Yala season, compared to the Maha season. The result further depicts that relatively good correlation coefficient values (> 0.6) were obtained when agCDI was evaluated using a rice crop yield in the selected districts. Although the agCDI correlated well with SRI in some of the stations (>0.6), its performance was somehow underestimated in some of the stations, perhaps due to the time lag of the streamflow response to drought. In general, agCDI showed its good performance in capturing the spatial and temporal patterns of the historic drought and, hence, the model can be used to develop agricultural drought monitoring and an early warning system to mitigate the adverse impacts of drought in Sri Lanka.

Variation of Water Productivity in Paddy Cultivation within a Tank Cascade: A Case Study in <em>Ulagalla</em>, Sri Lanka

The village tank cascade systems are identified as an important invention of the hydraulic civilization of Sri Lanka. Water productivity is a widely used indicator to measure the performance of these types of systems. A combination of agronomic and socioeconomic factors acts as key elements influencing water productivity in paddy cultivation and its variation. The current study focused on variations and determinants of the upstream and downstream water productivity of a cascade. The study was carried out as a comparative study investigating how the factors affect upstream and downstream water productivity in paddy cultivation separately in the Ulagalla tank cascade system in dry zone Sri Lanka during the Maha and Yala seasons over the years 2019-2021. The study revealed water productivity in paddy cultivation of the upstream and the downstream Ulagalla tank cascade was at satisfactory levels with reference to global standards. Wildlife conflicts, previous crop losses due to natural disasters, and length of the field canal displayed significant, negative relationships with paddy water productivity. Farm size, command area, activities of farmer organization, water head, and availability of lining in the field canal displayed significant, positive relationships with water productivity in paddy cultivation.

The Effect of Nutrient Management and Crop Rotation on Weed Dynamics in Rice under Dry Zone (DL1B) of Sri Lanka

The Integrated weed management (IWM) is widely used to manage we eds in diverse cropping systems. Crop rotation and diverse n utrient management strategies are essential components in IWM. However, the effect of crop rotation and nutrient management systems on weed dynamics in Sri Lankan rice-based cropping systems is scarce. Therefore, an experiment was conducted to identify weed density, biomass, and abundance of two different nutrient management systems (Synthetic; SNM and Integrated; INM) and under rice monoculture and rice-maize rotation during four seasons within the farm premises of the Faculty of Agriculture, Rajarata University of Sri Lanka. Rice variety Bg300 and maize hybrid Pacific-998 were cultivated. Growing maize in the Yala season increased weed density and weed biomass compared to growing rice in both crop rotation cycles. During the first cycle, weed den sity was high under INM in the Rice crop phase. However, in the second cycle, both crop phases (rice and maize) had low weed density under INM compared to SNM. A higher density of sedges was reported with the crop rotation in the Yala season s, and grasses were dominant in the mono-cropping in both seasons. Grass biomass did not change with the nutrient manageme nt systems, while the biomass of sedges increased with synthetic fertilizer only. High weed density and biomass in maize during the first cycle were substantially reduced in the second cyc le for both nutrient management systems. Overall, reducing chemical fertilizer by 50% and incorporating organic matter, INM, substantially supported weed management in both rice and maize crops.

Rotational tenure and land productivity: farm level evidence from low country wet zone paddy lands in Sri Lanka

Rotational tenure systems of Thattumaru – Kattimaru is a special system which is peculiar to certain parts of the country specially the Mid and Low country Wet zone paddy lands. Even though the original features are slowly waning, it still survives most persistently in areas where land is limited, and agriculture remains the predominant occupation. Therefore, this study was conducted to determine the paddy production performance and resource use efficiency in the rotational tenure paddy lands. Data from comprehensive field survey conducted in Ratnapura, Kalutara and Galle districts in 2018/2019 Maha and 2019 Yala season was used for the study. Technical efficiency and determinates of the efficiency were estimated using stochastic frontier approach. Results of the efficiency analysis reveal that inefficiencies do exist in paddy production under rotational tenure and estimated production loss due to inefficiencies is 45 percent. Land, labour and seeds have significant impact on the yield. Level of productivity can be enhanced making relevant resource adjustment while combining it with social factors.

Agricultural drought monitoring in Sri Lanka using multisource satellite data

Drought is a complex phenomenon affecting agricultural, environmental, water resources, and socio-economic systems in developing regions. Climate change is going to increase the frequency and intensity of drought events and the associated socio-economic impact, including that on the food security among marginal smallholder farmers. For timely early action, it is important to have robust drought monitoring and warning in place to determine the timely drought situation to assist end-users for the decision-making process. Spatial-temporal remote sensing data provides crucial information on near real-time drought monitoring and early warning. The present study developed a composite index, i.e., Integrated Drought Severity Index (IDSI) that combines inputs from rainfall, vegetation, and temperature to determine agricultural drought progression, intensity, and frequency for entire Sri Lanka between 2001 and 2019. The study has successfully identified 10 drought events of which 2001, 2012, 2017, and 2019 reported severe droughts across the two rainy seasons, namely Yala (May–August) and Maha (October–March). We analyzed various indices meteorological drought Standardized Precipitation Index (SPI) and field-based rice Crop Yield Anomaly Index (CYA). It is evident from the study that the Yala season reported more drought events compared to the Maha season due to changes in monsoon onset and duration and its seasonal variability. The correlation coefficient for SPI with IDSI is 0.70 and IDSI with CYA is 0.68, which explains the reliability of drought monitoring information across Sri Lanka. In terms of sub-national drought events, the North, North Central, North Eastern, Eastern, and South Eastern Provinces which cover the majority of the dry zone of Sri Lanka and districts such as Anuradhapura, Monaragala, Polonnaruwa, Hambantota, Trincomalee, and Ampara are highly prone to agricultural drought impacting agricultural production and the vulnerable rural population. From the basin analysis, both Yan Oya and Malwathu Oya (Aruri Aru) are reported to have severe drought events, which highlights the need for timely action using satellite-derived agricultural drought monitoring to mitigate drought risks and reduce food insecurity.

Seasonal variation on mineral profile in rice varieties of Sri Lanka

Rice (Oryza sativa L.) is the backbone of Sri Lankan agriculture with the accomplishment of the daily nutritional requirements of humans. This study is intended to explore the cultivation seasonal variation on minerals in selected rice varieties and to examine the possible health risks due to toxic heavy metal contamination. Twenty-six different rice varieties cultivated during Maha (2018/2019-from September to March) and Yala (2019-from May to end of August) seasons were analyzed for selected twenty elements using intra-laboratory validated test methodologies combined with ICP-MS and UV–vis spectrophotometry to determine possible variations of these parameters due to cultivation seasonal differences. The concentrations of As, Cd, Pb, and Se of all analyzed rice varieties were lower than the maximum levels stipulated by FAO/WHO guidelines suggesting them to be suitable for human consumption. The present study revealed that selected rice varieties in Sri Lanka to be a potential source of valuable minerals such as, Fe, Zn, K, Ca, Mg, Na, P and the cultivation seasonal variation has a significant positive impact on the mineral profile of rice. Moreover, ANOVA, PCA, and PLS analysis confirmed that there was a distinct variation of the profile for minerals and heavy metals of analyzed rice varieties.

Trend Analysis and Forecasting for Paddy Production in Sri Lanka

Sri Lanka is mainly an agricultural country and about 40 per cent of its working population is engaged in agriculture island-wide. Rice is cultivated during two seasons; Maha season (October-March) usually accounts for about 65% of annual production with the remaining 35% coming from the Yala season (April-September). The objectives of this study are to investigate the present trend of paddy production and to develop the most appropriate time series models for paddy production in Yala and Maha seasons separately. The paddy production data were obtained from the Department of Census and Statistics in Sri Lanka from 1952 to 2020. Shapiro-Wilks test was applied to check the normality of the dataset. According to the results, the Mann-Kendall trend test, and Cox – Stuart trend test, were used to detect the presence of trends in the data. It was confirmed that there was an increasing tendency in both seasonal models but the slope of paddy production in the Yala season was less compared to the paddy production in the Maha season. In this study, Auto-Regressive Integrated Moving Average (ARIMA) method was applied to forecast based on the historical data. The well-fitted ARIMA model for the paddy production of Yala season was ARIMA (2,1,1) and paddy production of Maha season was ARIMA (2,1,0). The performances of these models were mainly validated with the Akaike Information Criterion (AIC), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) values. Finally, the best model for the Yala and Maha seasons was applied separately to predict the values of the variable over the next three years. As the result of forecasting of paddy production is a requirement for planning purposes and the import policy of rice, should be based on this kind of research.