Evaluation of crop water demand for sustainable crop production using geospatial tools in a canal command of West Bengal

The agricultural sector is the primary consumer of water resources around the world, and the need for additional food production for growing population further exerts more pressure on water resources. In this study, crop water demand was assessed spatially and temporally for a case study area, Damodar Canal Command (DCC) using geospatial techniques. Crop evapotranspiration was estimated for all the crop seasons using reference evapotranspiration and Fraction of Vegetation cover (FV) that was used as a surrogate for crop coefficient. The reference evapotranspiration (ET ) was calculated using the FAO o Penman-Monteith method. FV was computed based on Normalized Difference Vegetation Index (NDVI) derived from MODIS satellite imagery and its value ranges from 0 to 1. The maximum and minimum reference evapotranspiration values were estimated as 8.44 and 1.88 mmday-1 in May and September, respectively during the normal year 2004. The average monthly crop water demand was maximum in May i.e. 8.08 mmday-1. Among all crop seasons, Boro season has the maximum crop water demand followed by Aus and Aman seasons with maximum ET as 496, 438 and 328 mm, respectively. Total annual crop c water demand for normal year, 2004 was estimated at 1237 mmyr-1 in the study area. Spatially and temporally distributed crop water demand estimates help the irrigation planners to devise the strategies for effective irrigation management

Trends in water requirements of wheat crop under projected climates in India

Various global circulation models predict a change in net irrigation requirements worldwide due to the impacts of climate change and in India, depending upon the region, irrigation requirements are likely to change by different magnitudes. The spatial distribution of trend in crop and irrigation water requirements of wheat projected for two climatic periods (2021-50 and 2051-80) across major wheat growing districts of the country were analyzed, making use of climate change projection data from  NorESM1-M model of the CMIP5 in combination with RCP 4.5. Decreasing trends in water requirements were projected over 90 per cent of wheat growing districts in 2021-50, whereas increasing trends in crop and irrigation water requirement are expected over 95.4 per cent and 62.4 per cent areas, respectively in 2051-80 climatic periods. Results showed that decreasing/increasing trends projected in water requirements of wheat crop is due to change in crop growing period, which is projected to decrease across entire wheat growing area in 2021-50, whereas it is likely to increase over 78.2 per cent in 2051-80 climatic periods

Impact of projected climate on wheat yield in India and its adaptation strategies

Wheat is highly sensitive to climate change especially temperature changes experienced in the later phase of crop season. Hence, it is of immense importance to know how and to what extent climate change will affect wheat yields and to assess the adaptive strategies for mitigating possible negative consequences on wheat production. Wheat yield responses to three future climatic periods (2025, 2050 and 2075) were studied by driving DSSAT-Wheat (v4.5) model with daily weather from three CMIP-5 climate models’ (GFDL-ESM2M, MIROC5, and NorESM1-M) as the basic input at four sites (Ludhiana, Raipur, Akola and New Delhi) representing three major wheat growing zones of the country. Projected changes in growing season (November-March) day and night temperatures at four sites differed substantially both in direction and magnitude. Day temperatures are projected to rise conspicuously at Ludhiana, representing northwest parts of the country, and moderately over central parts of India (Akola and Raipur). Positive rainfall anomalies at Ludhiana (+76%) and negative anomalies at Raipur (-15%) are projected in future climates. With these anticipated changes, wheat is likely to experience warmer days (+1.1 °C) at Ludhiana and nights at Raipur (+2.8 °C) and more seasonal moisture availability at Ludhiana in future climates. Negative impacts of climatic change in these sites are found to be minimized by adapting one or a combination of management practices, which are site specific.

Assessment of surface and sub-surface waterlogged areas in irrigation command areas of Bihar state using remote sensing and GIS

Satellite remote sensing coupled with Geographical Information Systems (GIS) offers an excellent alternative to conventional mapping techniques in monitoring and mapping of surface and sub-surface waterlogged areas. In the present study, pre-monsoon and post-monsoon surface waterlogged areas were delineated in all the 132 irrigation command areas of the Bihar State, India using Indian Remote Sensing (IRS-1D) Linear Imaging Self Scanning Sensor (LISS-III) data acquired during the period 2002-2003. Normalized Difference Water Index (NDWI) was used primarily to delineate surface waterlogged areas. Perennial waterlogged and seasonal waterlogged areas were identified for the study area by integrating the waterlogged areas derived for both the pre- and post-monsoon seasons under GIS environment. Results show that the total surface waterlogged area in Bihar is 628 x 103 ha, which is 10.57% of command area (5939 - 103 ha) and spread over 132 command areas. Perennial surface inundation covers 2.95% of the waterlogged area in all the command areas. Maximum waterlogged area is observed in Gandak command (212 - 103 ha) followed by Eastern Kosi irrigation scheme (116 - 103 ha) and Sone modernization scheme (82 - 103 ha), respectively. Further, waterlogged areas induced by rise in groundwater level were also assessed spatially under GIS environment using the ground water level data pertaining to pre- and post-monsoon seasons of the year 2002-2003 which were spread all over the study area. The analysis of pre- and post-monsoon groundwater levels indicates that the area under non-critical category during pre-monsoon period was reduced from 4287 - 103 ha (72.72% of command) to 1391 - 103 ha (23.42%) in the post-monsoon. Area under most critical category during post-monsoon period increased from 0.083 - 103 ha of command area in pre-monsoon period to 50 - 103 ha. The study demonstrates utility of integration of remote sensing and GIS techniques for assessment of waterlogged areas particularly in regions where waterlogging conditions occur both due to excessive irrigation and accumulation of rain and floodwaters.

Produtividade de cultivares de arroz irrigado resultante da aplicação de doses de nitrogênio Response of rice cultivars under water logged conditions to nitrogen rates

Foi avaliada a resposta de três cultivares de arroz irrigado por inundação a diferentes doses de nitrogênio, mediante experimentos realizados em Mococa, SP, em 2000/2001 e em 2001/2002. Nas parcelas foram aplicadas quatro doses de N (0, 90, 180 e 270 kg ha-1) e nas subparcelas foram transplantadas mudas das cultivares de arroz IAC 101, IAC 103 e EPAGRI 109. O nitrogênio, tendo como fonte a uréia, foi aplicado, no transplantio das mudas, aos 20 e 40 dias após. Os componentes de produção não responderam à aplicação do nitrogênio, porém as cultivares diferiram significativamente entre si, tendo se observado na 'IAC 103' maior valor para o índice de fertilidade da panícula e o número de panículas por unidade de área. O número de panículas por unidade de área foi o componente de produção que melhor se correlacionou com a produção de grãos. Verificaram-se nas cultivares respostas quadráticas à aplicação de nitrogênio para o rendimento de grãos em casca e inteiros. A 'IAC 103' respondeu a doses maiores de N e maximizou o retorno econômico (218 kg ha-1 de N, com rendimento de 6790 kg ha-1 de grãos em casca). As doses para maior retorno das demais cultivares foram 161 (EPAGRI 109) e 179 kg ha-1 de N (IAC 101).<br>The objective of this study was to evaluate the response of three rice cultivars to N fertilizers under irrigated conditions. Two field experiments were carried out in Mococa, SP, in 2000/01 and 2001/02. Rates of N (0, 90, 180, and 270 kg ha-1) were applied in the main plots and seedlings of three rice cultivars (IAC 101, IAC 103, and EPAGRI 109) were transplanted into the subplots. Nitrogen, as urea, was split in three applications: at transplantation, 20 and 40 days later. Except for the number of spiklets per panicle, yield components did not respond to N rates, although they varied for the different plant genotypes. IAC 103 presented the higher value for panicle fertility index and number of panicles per area, and the lower plant height, compared to IAC 101 and EPAGRI 109. Number of plants per area was the yield component most closely related with grain yield. Responses to N varied with the genotype. The highest rate of N to maximize economic return (218 kg/ha N and 6790 kg/ha grain yield) was observed for IAC 103. The corresponding rates for the other genotypes were 161 (EPAGRI 109) and 179 kg/ha N (IAC 101). These rates are higher than those currently recommended for waterlogged rice in Brazil