Rain-fed Paddy Research Articles

Pemberdayaan Petani Padi Sawah dalam Meningkatan Efisiensi Usaha Tani dengan Pembuatan dan Aplikasi Herbisida Organik di Desa Botolempangan Kabupaten Maros

Botolempangan Village in Bontoa Sub-district is one of the centers of paddy rice production in Maros Regency, with characteristics of rain-fed paddy fields that have many obstacles to weed infestation, especially if the dry season is abandoned from rice farming activities, before being planted during the rainy season where farmers are very dependent on the use of herbicides. Dependence on the use of synthetic (inorganic) herbicides occurs from the pre-growth period of seeds, seedlings to the maintenance process. High costs result in considerable inefficiencies in rice farming. Training in technology transfer efforts to make Organic Herbicide Formulations, and their applications are carried out to increase the Empowerment and Efficiency of rice farming on Rainfed Rice Fields. With the efficiency target is to increase the profit of paddy rice farming, minimizing inorganic herbicide inputs. The output of this activity ultimately produces products that can be applied to at least reduce or reduce the use of inorganic herbicides. At the end of the activity, farmer business groups are able to produce and apply Organic Herbicide Formulations on Demoplots on Farmer-Owned Land.

The study of soil organic carbon rate in Gunungsewu Karst Area, Pracimantoro District

Karst landscape has a notable role in carbon cycles. The role isn’t merely through the karstification (solutional) process but also on soil since Soil Organic Carbon (SOC) is the biggest terrestrial organic carbon stock. The purpose of this research was to discover characteristic and calculate organic carbon within rainfed paddy, dry land seasonal crops, shrubland, and homogenic forest in Gunungsewu Karst, Pracimantoro District. The soil sampling method was determined by purposive, then computed through a laboratory test to figure out the soil texture, permeability, bulk density, particle density, porosity, and organic carbon percentage. C-organic assessment refers to the calculation by National Standardization Agency. Permeability is the obvious parameter that was discovered. Soil permeability in the agricultural land uses has a higher value than in non-agriculture land uses. This matter is caused by soil tillage as a human agriculture activity. The result of the SOC assessment is that non-agriculture land use has a higher rate than agriculture land use. SOC within the homogenic forest was the highest rate (30,03 tonnes ha-1), and the dry land seasonal crops was the lowest rate (18,9 tonnes ha-1), whereas the rainfed paddy and shrubland, respectively 21,63 tonnes ha-1 and 23,62 tonnes ha-1. It caused by the litter on the agriculture land use was slightly than the litter that piled up on the non-agriculture land use because the land was tillage and cleaned as an agriculture activity. Research like this should be undertaken in order to gain information about soil or karst roles within carbon cycles as a mitigation to climate change.

Effect of irrigation on farm efficiency in tribal villages of Eastern India

Irrigation is an important adaptation strategy to cope with climate change which reduces vulnerability to water stress and improves crop productivity to feed millions. There is evidence of crop yield stagnation in many developing countries, and irrigation efficiency is claimed to increase crop productivity. Therefore, this paper uses data envelopment analysis to evaluate the farmer’s productivity through technical efficiency (TE), i.e., the relationship between resource inputs and outputs of 513 paddy farmers in Eastern India. The results show that the farms are, on average operating at 14% TE, leaving a considerable scope to improve up to 86% to reach the optimal level. A significant difference is observed between irrigated and rain-fed paddy farmers, such that10% of the irrigated farms achieved efficiency scores over 40% and only 2% of rain-fed farms achieved the same. The tobit and beta fit regression models are estimated to find out the factors that influence the TE. Both surface water and groundwater sources of irrigation are used as predictors, along with other socio-demographic factors. Access to surface water irrigation is identified to be a significant determinant of farm efficiency, however, surface water irrigation, such as canal irrigation, is accessible only to farmers living on plain land. Farmers living on highlands need to explore other sources of irrigation practices, such as drip and sprinkler, that can increase TE and farm productivity. Therefore, this paper calls for government intervention to provide extensive training and facilities for these micro-irrigation practices.

Erratic Rainfall and its Upshot on Rice Production in Kerala

In recent years, rainfall irregularities have affected crop production in Kerala. Rice, a water-reliant crop, is the staple food of people in Kerala. It is challenging to revive paddy if the soil loses even 10 to 20 per cent of its moisture. Due to erratic rains and frequent dry spells, rain-dependent paddy cultivation is nearly impossible in Kerala. Among the three seasons of paddy cultivation in Kerala, the autumn season entirely depends on rainfall. According to 2020-21 Kerala agriculture statistics, the majority of the rice is cultivated under irrigated conditions in the state. This loss in rain-fed paddy cultivation was due to the decline in autumn rice cultivation after the mid-1990s. The study analysed the annual and seasonal rainfall variability and their relationships with autumn rice production in Kerala. The variability and concentration in the annual and seasonal rainfall were analysed using the coefficient of variation and the precipitation concentration index, respectively. The results revealed that the overall rainfall distribution pattern in Kerala was moderate to irregular. The seasonal index was estimated for the monthly rainfall data, and it was found that in June and July, the rainfall was the maximum. Production and productivity of autumn rice showed a high correlation with rains in June and July. The variability in rice production was positively influenced by rainfall and negatively influenced by the standard deviation of precipitation.

Synthetic aperture radar polarised backscattering behaviour in partially inundated agricultural fields

ABSTRACT A methodology for classifying rainfed paddy fields based on their hydrological conditions is lacking. This study analysed the behaviour of synthetic aperture radar (SAR) backscatter coefficients at each polarisation and cross-polarisation ratio index in a rainfed rice paddy field with a partially waterlogged surface. The SAR polarisations used were the VH and VV of the C-band SAR Sentinel-1 and the HV and HH of the L-band SAR Palsar-2. The relationship between backscatter coefficient and terrains including topographic categories and local relative elevation, which affect waterlogging conditions in rainfed paddy fields, were evaluated. The VV of C-band, and HH and HV of L-band showed different patterns in the time series variation according to the topographic categories. We observed that the combination of L-band HH and HV could be used to assess waterlogging conditions because they differ depending on variations in local elevation. The study results suggest that future studies can evaluate the microtopography and associated local hydrological environment using the combination of L-band HH and HV backscatter coefficient.

Land evaluation and crop suitability analysis – A case study on Karachchi Divisional Secretariat, Kilinochchi District, Sri Lanka

Agricultural development in any region needs knowledge about the soils, their properties, and spatial distribution. Crop-land maps created using land evaluation are essential for land management. The research was conducted to develop a crop-land suitability map with “Highly Suitable”, “Moderately Suitable” and “Currently Not Suitable” categories for Karachchi Divisional Secretarial Division (DSD) (438.2 square kilometers) by analyzing soil quality. Twelve parameters and 63 sample locations were selected. Weather data such as rainfall, temperature, and relative humidity were collected from secondary sources. A slope map was created using the Digital Elevation Model (DEM) file, and the constructed questionnaire was used to obtain the drainage details. Soil depth was deduced from the wells and soil pits. The collected soil samples were analyzed to determine the parameters such as pH, electric conductivity, the sum of basic cations, base saturation, soil texture, and organic carbon. Each parameter was reclassified using ArcGISTM 10.4.1 to create parameter maps. After that, an analytical hierarchical process (AHP) was applied to each crop, and then each parameter was reclassified again with reference to FAO’s 1993 crop requirement criteria. Finally, the Weighted Overlay Analysis (WOA) was conducted to obtain the crop-land suitability map. The study revealed that 50% of the study area falls under the “Highly Suitable” category for coconut cultivation. Rain-fed paddy shows that 45% of the study area is “Moderately Suitable”. Irrigated paddy has a “Moderately Suitable” area of 48%, while nearly 51% is “Moderately Suitable” for onion. 17% of the land is “Highly Suitable” for groundnuts. The pineapple is “Highly Suitable” for 12% of the study area. A crop-land suitability map for Karachchi DSD was created. This map will be a guide for land planning decision-makers.

Fragmentation of Irrigated and Rainfed Paddy Field in Cianjur Regency, West Java

Paddy field is the agriculture land that produces rice and needs to be protected because of the threat of high conversion. In the period 2003-2013, paddy field in West Java Province has decreased by 9098 ha, while all of Indonesia increased by 235 538 ha (2014) because of the new paddy field outside Java. In the period January-September 2022 national production reached 45.43 millian ton. Conversion of paddy field into built up area, especially in Java will affect to fragmentation level of paddy field themsefves. The purpose of this research is to analyze the fragmentation of irrigated and rainfed paddy field in Cianjur Regency. Fragmentation index that used in this research are Class Area (CA), Number of Patch (NumP), Mean Patch Size (MPS), Patch Size Standard Deviation (PSSD), Mean Sharp Index (MSI). The results showed that rainfed paddy field are more fragmented than irrigated paddy field, which is indicated by greater NumP values. Clutering of districts based on irrigated and rainfed paddy fields fragmentation index, each of which produces 3 groups . The high group has an increasingly fragmented tendency that identified by the high value of area (CA) and the number of patchs (NumP), while the other parameters are less able to characterize fragmentation difference. The fragmentation of irrigated and rainfed paddy fields in northern Cianjur Regency is influenced by the land conversion while in central and southern due to sloping topography.

RESOURCE USE EFFICIENCY IN RAIN-FED PADDY RICE PRODUCTION: A CASE STUDY OF DONGA LOCAL GOVERNMENT AREA OF TARABA STATE, NIGERIA

The study examined resource use efficiency in rain-fed paddy rice production in Donga Local Government Area of Taraba State. A total of 106 rice farmers were randomly selected for the study. Data was collected through the use of a questionnaire. Data was analyzed using descriptive statistics and multiple regression analysis. The result showed a mean age of 38 years for rice farmers. About 73.8% of the respondents were males and, 71.7% were married with a mean household size of 12 persons per household. Majority (73.8%) had at least primary education and 96.2% had no contact with extension agent. An R2 of 0.76 implied that 76% variations in yield were accounted for by the explanatory variables included in the regression model. Farm size was not significant at P≤0.01, while seed quantity, fertilizer and labour were significant at P≤0.01. Rate of technical substitution (RTS) of 0.70 was obtained, indicating that rice production was at stage II. Seed quantity (0.67) and labour (0.15) were over utilized with each having a less than one resource use efficiency ratio. High cost of fertilizers, high cost of hired labour and inadequate extension contact ranked 1st, 2nd and 3rd, respectively, among the constraints to paddy rice production. Therefore, it was concluded that rice farmers had favourable socioeconomic characteristics, but were not efficient in the use of resources. It was recommended that necessary inputs (at affordable prices) and extension services should be made available and adequate to rice farmers in order to optimize rice production.

IMPACT STUDY OF SOLAR BASED LIFT IRRIGATIONIN SOHAGPUR BLOCK (MP)

The Study is conducted to see impact of Solar Lift Irrigation System (SLIS) on farmers livelihood and income. the project takes place in a small region Sohagpur block of Shahdol (MP); in Sohagpur block 46 SLIS has been installed which is impacting 30 villages with 250 families with a total of more than 200 acres of cultivated area. Before this intervention farmers usually used the T.C. Connection pump or diesel pump for irrigation, but it was costly and not feasible after this intervention there was a huge change in their life and farming. Some of the beneficiaries changed their cropping patterns and some of them increased their variety of crops. Before this, they depend on rain-fed paddy production only, but they are producing vegetables, wheat, chana, paddy, arhar, etc. SLIS has been distributed here in small groups so everyone can benefit from it, thus an increase in their income and livelihood can be seen there. Some farmers also started brick manufacturing units on their farms as a side business to increase their livelihood and income. As Solar energy is form of renewable energy so it can be future for human in upcoming days and for farmers it is very helpful now, they do not need to suffer from lack of electricity or they don't need take risk in night for irrigation purpose only because of availability of electricity in Night now they can irrigate their farm in day as per their convenience even in summer time they are now able to do farming with different types of crops.

Grain Yield and Gross Return above Fertilizer Cost with Parameters Relating to the Quality of White Rice Cultivated in Rainfed Paddy Fields in Cambodia

This study aims to compare the grain yield, gross return above fertilizer cost (GRAFC: (paddy sales)–(fertilizer cost)), and several parameters relating to the quality of white rice cultivated with different soil-specific nutrient management in 14 provinces where different soil types are distributed. The grain yield tended to increase with increased fertilizer application; however, the relationship between the fertilization rate and the yield was not linear in areas where clay soil dominates. In cases of popular varieties cultivated from the northern to southern province, the amount of fertilizer applied was up to 163 kg ha−1 (sum of N-P2O5-K2O), and the GRAFC and the fertilization rate showed a nonlinear relationship, with a peak of around 120 kg ha−1 fertilization. The nitrogen concentration recognized as a negative factor for the quality of rice tended to increase with an increasing fertilization rate, and the carbohydrate concentration and carbohydrate/protein ratio that are a positive factor for the quality were related negatively with the fertilizer rate. The amylopectin concentration in white rice was positively related with the carbohydrate concentration, which decreased with an increasing fertilization rate. The levels of fertilizer application required to achieve a higher yield, GRAFC, and the maintenance and improvement of parameters relating to grain quality were different.

Sustainable Development Strategies of Rainfed Paddy Fields in Central Java, Indonesia: A Review

Rainfed paddy fields have a great potential to be developed in Indonesia, especially in Central Java. However, water irrigation management, drought stress, pest and disease infestation and low nutrients that affect paddy yield remain the constraints. Unpredictable climate pattern is also a limiting factor in the cultivation of rainfed paddy fields. This narrative review aims to identify and discuss solutions to problems that exist to increase the yield of rainfed paddy fields with several techniques that support sustainable agriculture. This review paper was prepared by collecting government data and interviews with several farmer group leaders as complementary data. Based on field conditions, farmers in rainfed paddy fields provide fertilization inputs that are not following the fertilizer recommendations. Moreover, field conditions with limited water availability have caused paddy cultivating in several locations only once a year with low yields. Water storage can help farmers meet the need for water, especially during dry and water-stress conditions. The farmers also need to pay attention to the appropriate fertilization doses and the use of additional organic matter derived from cultivation residues, which are expected to increase the availability of nutrients in the soil. The use of short-life and drought-resistant varieties can aid in overcoming the problem of crop failure in the middle phase caused by water scarcity. Finally, we identify and emphasize that rainfed paddy fields generally have a limiting factor for water and nutrients and several technologies are needed to contribute to increasing more sustainable paddy yields.

The Situation of Rice Production and Trade of Farmers in the Upper Northern Region of Thailand

This study aims to study the situation of organic rice production and trade of farmers in the upper northern region of Thailand. This is qualitative research. The research area was organic rice for single and group farmers in Chiang Rai, Phayao, Chaing Mai, Lamphun, and Lampang. Target groups of important informants were model farmers who have been certified for organic rice production, local scholars and representatives of organic rice farmers, and organic rice academics using purposive sampling methods under the criteria and qualifications set by the researchers. There were three different kinds of research: questionnaires, interview forms, and group discussions. Data collection consisted of document research, interviews, observation, and small group discussions. The data was then analyzed, the content synthesized and descriptive reports were written. The results of the research revealed that rice production and trade of farmers in the upper northern region of Thailand in five provinces research areas are mainly for consumption and food security because most areas rely on rainwater, have fewer irrigated areas, and have less farming space than other sectors. The methods of farming are transplanting paddy fields, dry broadcasting paddy fields, wet broadcasting paddy fields, and drop broadcasting paddy fields. Most of the 82 percent are transplanting paddy fields and in some areas in the foothills where rice is planted in July and harvested from October to December. The most cultivated type of rice is glutinous rice, followed by white jasmine 105 rice, Pathumthani fragrant rice, brown rice, and organic rice respectively. The rice trade for farmers was divided into two levels: paddy marketing and rice marketing. Farmers store a portion of their products for household consumption and another portion for seed cultivation. Some farmers entered the loan program for delaying the sale of rain-fed paddy fields. For the rest of the products, farmers would sell paddy to merchants, Rice Farmers' groups, agricultural institutes (cooperatives), and private mills.

Phenology-based delineation of irrigated and rain-fed paddy fields with Sentinel-2 imagery in Google Earth Engine

ABSTRACT Paddy rice agriculture is practiced in both rain-fed and irrigated ecosystems in the Philippines. However, small farms are prevalent in the region, and current satellite-based mapping techniques do not distinguish between the two ecosystems at farm scales. This study developed an approach to rapidly map irrigated and rain-fed paddy rice in Iloilo, Philippines at 10 m resolutions using Google Earth Engine. This approach used an ensemble of classifiers based on time-series vegetation indices to produce dry and wet seasonal maps for the entire province. Results showed a predominance of rain-fed rice areas in both seasons, with irrigated rice making up only one-fourth of the total rice area. The overall accuracy was achieved at 68% for the dry season and 75% for the wet season based on ground-acquired points and very high-resolution imagery. The two types of paddies were classified at accuracies up to 87%. Furthermore, the land cover maps showed a strong agreement with the municipal statistics. The resultant maps complement current official statistics and demonstrate the prowess of phenology-based mapping to create paddy inventories in a timely manner to inform food security and agricultural policies.

Assessing land suitability for rainfed paddy rice production in Zambia

Rice is one of the staple food crops and is a profitable smallholder cash crop in Zambia. It has the potential to contribute significantly to increased incomes and employment among rural producers. However, rice is the only staple crop in the country for which domestic production does not meet or exceed domestic demand. Low productivity is one of the factors that contribute to this. One necessary step towards addressing this problem is the identification of land with greatest potential for rice production, as well as the identification of land-based limitations which might be overcome by improved management. The aim of this study was to develop a land suitability index for rainfed paddy rice production reflecting expert opinion and published studies based on climatic, topographic and soil properties. Land suitability was evaluated using a method which accounts for important multiple factors, and which considers their joint effect in terms of a hierarchical model of constraints. The suitability classes were ranked according to the FAO land suitability classification as: Highly Suitable (S1), Moderately Suitable (S2), Marginally Suitable (S3), Currently Not Suitable (N2), and Permanently Not Suitable (N1). Results showed that there is limited potential for rainfed paddy rice production in Zambia with <20% of the land classified as either highly or moderately suitable. Therefore, the potential of irrigated and upland rice production in Zambia needs to be assessed as this would help expand the potential production area of rice.

Multiyear analysis of the dependency of the planting date on rainfall and soil moisture in paddy fields in Cambodia, 2003\u20132019

The dependencies of the planting date on rainfall and soil moisture in paddy fields in Cambodia were analyzed to quantify farmers’ empirical knowledge regarding their decision of the planting date. Remote sensing data from multiple satellites covering the 2003–2019 period were analyzed. The planting dates in rain-fed paddies ranged from April to August, with large spatial variations and year-to-year fluctuations. In years when planting was suppressed in April and May, planting was extensively enhanced in June and August compared to normal years, and vice versa. Over the northeastern side of Tonle Sap Lake and south of Phnom Penh city, the areas planted in April and May were found to have positive correlations with rainfall and soil moisture, suggesting that wetter-than-average conditions encouraged farmers to plant earlier in the season. In contrast, this relationship was unclear on the western side of Tonle Sap Lake, where the rainfall amounts were larger throughout the year than in other areas in Cambodia. In this region, the relationship between the planting area and soil water availability was either unclear or was even slightly negative from June to August. Since more frequent dry spells have been detected after the onset of the rainy season in recent years, further studies and disseminations of potential changes in dry spells are important for the agronomic adaptation of planting dates under climate change.

Climate resilience and varietal choice: a path analytic model for rice in Bangladesh

PurposeRice is the primary staple crop in South Asia and is cultivated mainly on lowland ecosystems usually fed by the monsoon. With increasing climatic volatility, exclusively rain-fed rice paddies have experienced a triple threat in droughts, floods and salinity. This study investigates the linkages of these abiotic stresses on yield and subsequent farmer decisions on varietal choice.Design/methodology/approachA path analytic model is conceptualized where the relationship between yield (conditional on abiotic stresses) and the varietal choice decision is mediated by adaptation motive (latent construct) and market exposure (observed construct). The path model is validated using 2,523 observations from Bangladesh farmers to obtain parameter estimates for direct effects and mediated effects indicated above.FindingsFindings reveal that drought and flood impacts, in contrast to salinity impacts, are influential to both yield and varietal choice. The adaptation motive, however, is clear only in the case of salinity. Time preference of farmers and previous exposure to climate shocks predict adaptation motive substantively. The study reveals that market exposure is also a significant mediator of varietal choice in addition to the mediating effect of adaptation.Research limitations/implicationsThe study adopts a path analytic model which is able to capture direct, indirect and mediated effects between exogenous factors and varietal choice decision. While the models provide conclusive statistical evidence to the above hypotheses, within-area variations of behavior may not be captured adequately by the method.Originality/valueAnalyzing the complexity of varietal decision-making choice using a path analytical model is a novel contribution to the literature. The application itself is unique to the context applied. The findings complement the literature on varietal adoption in the context of climate resilient paddy systems.

Analysis of physiological characters and yield quality of several sweet potato (Ipomoea batatas L.) genotypes at various watering levels in rainfed paddy field

Analysis of the physiological characteristics of several sweet potato genotypes at various watering levels in rainfed paddy field indicated that the adaptability of sweet potato genotypes was resistant to drought stress. This research aims to determine the physiological character and yield quality of several sweet potato genotypes (Beta 1 Variety, Perbaungan Accession, and Cengkeh Turi Accession) at various levels of watering (P1 (1 month watering), P2 (2 months watering), and P3 (4 months watering)) in rainfed paddy fields. The research was carried out in the paddy field of Tandem Hilir I Village Deli Serdang and the analysis was carried out in the Tissue Culture Laboratory of the Faculty of Agriculture, the University of Sumatera Utara from March-July 2019. The results of this research indicated that some sweet potato genotypes had no significant effect on the physiological character but had a significant effect on fresh tuber grading. Cengkeh Turi accessions with orange colour tuber had the highest production in the A-class fresh tuber grading category while the Perbaungan accession with orange colour tuber had the lowest production in C-class fresh tuber grading. The watering levels treatment also did not have a significant effect on the physiological character and tuber yield quality.

Aquaculture-based production systems for the livelihood security of coastal farm families in the risk-prone agro-ecosystem of India: an appraisal

Sundarban area of West Bengal State in India is a complex-diverse-risk prone agro-ecosystem grappled with degraded soil, water logging, brackish ground water, and marginal farm holdings. South west monsoon rain-fed paddy crop is the major production system, and the farm families have to migrate to other areas for employment during the post-monsoon season. Farm pond-based rainwater harvesting and optimally utilizing it to cultivate vegetables and rearing fish in the pond would provide them employment, income, and self-reliance on a sustainable basis which is the solution. Rainwater harvesting-based production system models, namely, land shaping for aqua-agri integration, brackishwater pond-based polyculture, and paddy-cum-fish farming, were implemented to 370 beneficiary families to enhance the livelihood security at Kakdwip and Namkhana blocks of South 24 Parganas district of West Bengal. A set of 15 indicators were identified by the subject matter scientists to assess the outcome of the interventions in enhancing the livelihood security of farm families. Impact analysis was done using “before vs after” and "control vs treatment" research design. Primary data were collected from 120 proportionate random sample beneficiary farm families using a structured questionnaire and focus group meetings. The findings substantially indicated that all the three farming models have contributed for enhancing the livelihood security levels of the farm families in terms of creation of livelihood asset mainly the farm pond, conservation of natural water for multiple cropping and aquaculture, enhanced capabilities, employment generation, improved production from the land/pond, enhanced income from farming, access to better market price, access to development institutions, minimization of migration during off-season, enhanced self-reliant, and social status of the farm families. The analyses have confirmed that all the three farming models have significantly contributed for the livelihood security of the coastal farm families (p < 0.01). Therefore, the study suggested that the government may evolve a scheme with inbuilt subsidy in up-scaling these models in the entire Sundarban region for enhancing the livelihood security of farm families.

Mapping and Evaluation of Land Rice Paddy in T District Of Gajah Hilang Timang Gajah Kabupaten Bener Meriah

This study aimed to evaluate the suitability class of land in the Timang Gajah Watershed Sub-district of Bener Meriah Regency for rainfed paddy fields. Based on a map of soil type and slope maps from maps generated from topographic, then be overlaid. This study using a survey method consisting of 4 stages: preparatory phase, preliminary stage, primary survey, and data analysis and presentation of result.The assessment of land suitability classes with appropriateness rainfed paddy fields. The result showed that the potential land suitability class LMU 2 is S3 nr-2,eh-1, LMU 5 is S3 nr-2, eh-1, LMU 8 is S3 rc-2, nr-2, eh-1, LMU 9 is S3 nr-4, eh-1,2, LMU 10 is S3 nr-2, eh-1, LMU 11 is S3 eh-1, LMU 12 is S3 eh-1, LMU 13 is S3 nr-2, eh-1, LMU 15 is S3 rc-2, LMU 16 is S3 rc-2, LMU 17 is S2 rc-1,2, nr-2, eh-1, dan LMU 18 is S3 rc-2. Potensial land area for rainfed paddy fields in the Timang Gajah Watershed Sub-district of Bener Meriah Recency is of 277,06 ha

Determination of patterns of rainfall history creating situations for accurate classification of rain-fed paddy fields with SAR backscatter coefficients

It is worthwhile to classify paddy fields based on the long-term frequency of ponding, which strongly determines the yield of rice. However, the direct measurement of the frequency requires a large number of backscatter images from synthetic aperture radar (SAR). Another approach is the indirect estimation of the relative frequency of ponding from differences in ponding frequency with the same rainfall history. Any combination of backscatter coefficients with such rainfall history should result in a high accuracy of classification of paddy fields based on the relative frequency of ponding. This study aims to establish methodologies for the classification of rain-fed paddy fields into two categories: ‘wet’ and ‘dry’ fields, based on ponding frequency using a small number of time-series SAR backscatter coefficients that depend on the flood situation and soil water content of the land surface. By analyzing 21 images acquired by the ALOS-PALSAR during 2007–2011, patterns of rainfall history with obvious large differences between the two categories of paddy fields were determined. Through supervised classifications using a random forest classifier, it was evident that the backscatter coefficients onset of rainy seasons for years with an above average precipitation, would be suitable as variables for accurate classification. In years where the precipitation (1379mm/year) neared the average (1330mm/year), the supplementary use of a quartile deviation of the backscatter coefficient within each plot, that indicated a degree of partial ponding, increased the classification accuracy. It was also evident that the effective rainfall index, which registers a rough estimate of rainwater acculturation in the soil, was useful in the determination of periods of significantly large variations in the backscatter coefficient between categories of rice fields.