Paddy and Water Environment

The present study utilizes soil water balance and HYDRUS-1D for estimating and predicting potential recharge in groundwater declining region of central Punjab, respectively. A field experiment was conducted at Punjab Agricultural University, Ludhiana. Two treatments viz direct-seeded (DSR) and transplanted rice (TPR) with three replications, were sown/transplanted during kharif season of 2019. The amount of water applied through rainfall/irrigation was recorded and bottom flux was measured using frequency domain reflectometry (FDR) and then predicted using HYDRUS-1D in order to assess potential groundwater recharge which was further compared with deep percolation determined using soil water balance. The performance of the HYDRUS-1D was evaluated using RMSE, NSE, and R2 and found to be performing well. The paired t-test (t = 1.28 and t = 1.30 for TPR and DSR, respectively) was found to be non-significant at P = 0.05 which showed the correspondence between predicted and estimated parameters. The percentage change between estimated and predicted potential groundwater recharge was found to be 0.7% and 2.32% in TPR and DSR, respectively. The study revealed that there was 9% water saving and 14.6% more deep percolation (cumulative bottom flux) in DSR as compared to TPR that may potentially contribute to groundwater recharge.

Burning of rice straw is a common practice in northwest India, where rice–wheat cropping system is extensively followed. The practice results in loss of nutrients, atmospheric pollution and emission of greenhouse gases. A field experiment was conducted at Indian Agricultural Research Institute, New Delhi, India during the rabi season (November to April) of 2002–2003 to evaluate the efficacy of the various modes of rice straw recycling in soil in improving yield and soil fertility and reducing not only carbon dioxide emission but also nitrous oxide (N2O) emission. The treatment with no rice straw incorporation and application of recommended doses of fertilizer (120, 26 and 50 kg N, P and K ha−1, respectively), gave the highest yield of wheat. Treatments with the incorporation of rice straw at 5 Mg ha−1 with additional amount of inorganic N (60 kg N ha−1) or inoculation of microbial culture had similar grain yields to that of the treatment with no straw incorporation. The lowest yield was recorded in the plots where rice straw was incorporated in soil without additional inorganic N and with manure application. All the treatments with rice straw incorporation had larger soil organic C despite the effect on the mineralisation of soil organic matter. Emission of N2O was more when additional N was added with rice straw and secondary when straw was added to the soil because of higher microbial activity. The study showed that burning of rice straw could be avoided without affecting yield of wheat crop by incorporating rice straw in soil with an additional dose of inorganic N or microbial inoculation. However, the reduction of N2O emission due to avoiding burning is in part counterbalanced by an increase in emission during the subsequent wheat cultivation.

Insecticides have been recognized as the most important water pollutants. Nowadays, diazinon (DIZ) is an organophosphate pesticide that is widely used in agriculture as a pesticide. However, DIZ residues have been found in the aquatic ecosystems of Iran. In this study, the removal efficiency of the prepared adsorbents (from rice husk) was investigated upon the DIZ residues from water. To achieve the carbonized product, rice husk was mixed with polytetrafluoroethylene (PTFE) at a 1:2 weight ratio; then, it was then placed in a furnace based on the temperature–time schedule. The influence of the following parameters was investigated on the performance of carbonized rice husk: pH, contact time, adsorbent amount, and pesticide concentration. The measured DIZ concentrations were detected by high-performance liquid chromatography (HPLC). The results of this study showed that the optimum conditions for DIZ removal were achieved at pH = 9, the contact time of 40 min, and the adsorbent dosage of 0.1 gL−1. Therefore, the maximum removal percentage of the insecticide and the adsorption process at 10 ppm were more consistent with the Langmuir isotherm (R2 > 0.99). This study has resulted that the prepared adsorbent from rice husk can be used as an efficient adsorbent to remove DIZ from aqueous media.

Water management is increasingly important for rice productivity to maintain soil temperature and fertility with the presence of global warming. Meanwhile, rice production in Japan is in urgent need to reduce the costs through improving the efficiency and market competitiveness. This paper aims to measure effect of water depth and water temperature on rice yield of individual paddy fields and improve the practice of water management for them. In the first stage, we measure the production efficiency of rice yield through the adoption of data envelopment analysis. The results indicate that enlarged scale of the paddy fields increases the efficiency, and rice quality can be improved more than quantity. Moreover, the most inefficiently used inputs include the amount of fertilizer nitrogen and the soil capacity, which is a compound measurement of 21 soil chemical properties. In the second stage, after comparing the 20 paddy fields with highest and lowest technical efficiency, an observation shows that the rice yield is much more affected by water temperature than by water depth. The data of all the variables used in this study were sampled in 2015 and comprised of 110 paddy fields of Koshihikari, one of the most popular Japanese rice varieties, from a large-scale farm located in Kanto Region of Japan. In the analysis, the outputs include yields of raw paddy, paddy with 15% moisture, unsorted brown rice, sorted brown rice, milled grain rice, and perfect grain rice. The inputs include the field area, air temperature, solar radiation, fertilizer nitrogen, soil capacity, and farming conditions.

Rice (Oryza sativa L.) is the most important staple food crop in the southern region of Asia, and Indian subcontinent being one of the major producers. Production of conventional transplanted rice requires a large amount of irrigation water, labor, and energy. The scarcity of irrigation water has encouraged farmers to adopt an alternative rice production system, i.e. the direct-seeded rice (DSR), which is proposed to be farmers’ friendly with a potential to save water. Our study reports the performance of DSR with respect to yield and water expense efficiency based on different irrigation regimes and dates of sowing. A field experiment was conducted in the semi-arid region of northern India during the rainy season of 2011 with two treatment combinations (dates of sowing: 15th May and 5th June and three irrigation regimes: irrigation scheduled at irrigation water-to-cumulative potential evapotranspiration; IW/CPE ratio of 1.0, 1.5 and 2.0) in a completely randomized design. We found statistically higher water expense efficiency of DSR sown on 5th June as compared to DSR sown on 15th May without any significant differences in growth and yield. A significant yield difference between DSR grown with irrigation regimes of IW/CPE 1.0 and 1.5 and DSR grown with irrigation regimes of IW/CPE ratio 2.0 were observed. The DSR grown with irrigation regimes of IW/CPE ratio of 1.5 resulted in significantly higher water expense efficiency than the one with IW/CPE ratio of 2.0. Obtaining a higher yield of DSR under scarce irrigation water might be a trade-off between optimum water use and maximum yield avoiding excess ground water exploitation in sub-tropical semi-arid regions of India. Our study suggests that sowing time and irrigation regimes are two important aspects of “rice production” to attain “win–win” solution. Thus, strategic and judicial use of irrigation water with management of sowing time could potentially escalate the rice production in water scarce regions of India.

This study examines farmers’ preferences for weather index insurance (WII) in the Ayeyarwady Delta, Myanmar, using discrete choice experiments. It employs data taken from a survey of 317 rice farmers in the district of Labutta in the Ayeyarwady Region, which was conducted in March 2019. After being informed about WII and the trigger conditions, farmers were asked to answer discrete choice questions on WII packages. The hypothetical WII packages consisted of three attributes: the types of disaster that the insurance covers, the insurance coverage rate, and the annual insurance premium rate. A random parameter logit model analysis of the responses reveals that farmers prefer the WII packages covering cyclones, floods, and droughts to that for salt damage. The probabilities of selecting 64 hypothetical WII packages calculated from the estimates indicate that more than 50% of farmers can be expected to purchase seven WII packages for cyclones, floods, and droughts.

The 2011 Offshore Pacific Coast Tohoku Earthquake, with a moment magnitude (M) of 9.0, damaged a large number of agriculture facilities in Tohoku and Kanto areas. In this study, in order to clarify factors related to the damages of facilities, especially earth dams, which are one of the most important facilities in the irrigation of Japan, we analyzed relationships between damage costs, relative locations to the epicenter and seismic intensities. In the process, we introduced some indexes: damage density, mean and 1 km mesh seismic intensities, and damage ratio for earth dams and angle of dam axis with respect to the epicenter. It was found from the analysis that damages by the Tsunami and by earthquake motions were clearly identified by the damage density; the damages by Tsunami were approximately 40 times higher than for earthquake motions; the damage densities in earth dams increased with an increase in seismic intensities; and when the dam axes were normal to the epicenter, the damages of dams were likely to be large.

Việc sử dụng phân bón hóa học một cách mạnh mẽ cho cây trồng có thể là nguyên nhân dẫn đến sự tích tụ nitơ và photpho trong cả nước ngầm và nước mặt. Lưu lượng trở lại ô nhiễm do các chất dinh dưỡng không chỉ làm hạn chế các mục tiêu tái sử dụng nước mà còn gây ra nhiều vấn đề môi trường, bao gồm sự phát triển tảo nở hoa và độ phì nhiêu hóa tại các nguồn nước lân cận, gây ra mối nguy tiềm ẩn cho sức khỏe con người. Nghiên cứu này nhằm đánh giá tác động của việc áp dụng phân bón N từ các cánh đồng bậc thang đến chất lượng nước lưu lượng trở lại. Việc giám sát chất lượng nước đã được tiến hành trong hai chu kỳ canh tác xung quanh các nguồn nước khác nhau, bao gồm nước tưới, nước thoát ra tại điểm đầu ra của cánh đồng bậc thang thí nghiệm, và nước ngầm nông tại một cánh đồng thí nghiệm nằm ở huyện Hsin-chu, phía Bắc Đài Loan. Kết quả phân tích cho thấy nồng độ của ammonium-N (NH4 +-N) và nitrate-N (NO3 −-N) trong nước thoát bề mặt và nước ngầm đã tăng rõ rệt chỉ trong giai đoạn áp dụng phân bón cơ bản, sau đó giảm xuống nồng độ tương đối thấp (<0.1 mg/l và <3 mg/l, tương ứng) trong thời gian còn lại của vụ trồng trọt. Kết quả thí nghiệm cho thấy tải trọng ô nhiễm nitơ tiềm năng có thể được giảm bằng cách kiểm soát nước thoát hợp lý và áp dụng các thực hành phân bón.

This paper sets forth the accomplishments to date of the international collaborative study program on efficient and equitable transfer of water from agriculture to other uses. The research consists of several components. First a bibliographical review was prepared of literature available on the practice of inter-sector water transfer. Second, nine case studies have been prepared that illustrate inter-sector water transfer under a variety of physical and economic and political environments. Third, a framework has been developed for characterizing and comparing water transfer options and compensation among case studies. We discuss the pricing of irrigation water in determining compensation. We develop a decision tree that traces the paths to the various sector water transfer options. Finally, we discuss water transfer policy options with specific reference to Taiwan, though they have more general relevance. Three options are identified which reflect different objectives for government intervention.