Water Requirement Satisfaction Index Research Articles

Prospects of growing yellow sarson under rainfed condition in the new alluvial agroclimatic zone of West Bengal

Using 100 years of weekly rainfall data for Baharampur, profile moisture at sowing were simulated for coarse, medium and fine textured soils for six different sowing weeks starting from 38th (Sep 17 – 23) standard meteorological week (SMW) at two weeks interval and associated climatic risk was quantified using climatological water balance approach for yellow sarson, an important rainfed rabi crop of West Bengal. Same database was also used to run a FAO crop specific water balance model at weekly time steps to assess model outputs for Binoy variety. Yield prospects were estimated from water requirement satisfaction index (WRSI). At least 100 mm moisture is present to start sowing upto 42nd and 46th SMW in medium and fine textured soil respectively, at 75 percent probability level, for good initial growth of the plant. At least mediocre crop yield, in every alternate year, is possible when sown upto 40th SMW in medium and upto 44th SMW in fine textured soil. Prospect of getting good yield exist in more than 20 percent of the year if sown within 7th October in fine textured soil.

Impact of global warming on cowpea bean cultivation in northeastern Brazil

This study evaluated the effects of climate change on cowpea bean crop grown in northeastern Brazil based on the reports of the Intergovernmental Panel on Climate Change (IPCC). The water balance model combined with Geographic Information System techniques was used to identify regional areas where the cowpea bean crop will suffer yield reduction due to climate changes. Model input variables were: rainfall, crop coefficients, potential evapotranspiration and duration of the crop cycle. A limit value of 0.5 was adopted for the water requirement satisfaction index (WRSI), being the ratio of actual to maximum evapotranspiration. The acceptable seeding date was defined as the date at which the water balance simulation presented a WRSI value greater than the limit value, with a frequency of at least 80%. An increase in air temperature will cause a significant reduction in the areas currently favorable to cowpea bean crop growth in northeastern Brazil, and it is recommended that bean varieties better suited to high-temperature conditions should be planted.

Assessment of moisture stress using water requirement satisfaction index in kharif maize

A field experiment was conducted to study the impact of moisture stress at different growth phases in maize using Water Requirement Satisfaction Index (WRSI) during kharif 2004 at Agricultural Research Institute (ARI) farm, ANGRAU, Rajendranagar. The experiment was laid out in RBD (Factorial) with four dates of sowing starting from onset of monsoon at 15 days interval and four “irrigation schedules” viz. irrigation as per water requirement, skipping of irrigation at vegetative, flowering stages and rainfed. Reduced yields were recorded when irrigation was withdrawn during reproductive phase. A significant positive correlation between WRSI and yield was observed (r = 0.79). Higher WUE was observed with skipping of irrigation at vegetative stage and in rainfed treatments.

Trends of Rainfall and Maize Productivity in Malawi

Daily rainfall data between 1966 and 2005 across all Agricultural Development Areas (ADDs) in Malawi was investigated to determine changes in selected rainfall characteristics and their impact on Maize productivity. Rainfall indices analyzed included rainfall amounts (annual and seasonal), onset, cessation, dry spells and length of rainy season. Man Kendal’s trend test was applied to the time series of these indices to detect any trends in the time series. WaterRequirement Satisfaction Index (WRSI) for maize crop was used to study the spatial-temporal variation of maize productivity and thus its linkage to rainfall. Definition of onset and cessation adopted from the Department of Meteorological Service (DMS) Malawi was used in demarcating seasons to extract seasonal rainfall amount, length and other parameters. The results of the study indicate that with the exception of Karonga ADD located at the Northern tip of the country there were no significant trends in all variables related to crop productivity including onset, cessation, rainfall amount and dry spells. The spatial and temporal variability of maize production in Malawi was captured quite well by the WRSI. The relationship between long-term average WRSI and maize yield (tonnes/ha) for different stations in Malawi had a correlation coefficient of 0.82 while the relationship of countrywide average WRSI and maize yield had a correlation coefficient of 0.75. Areas with low long term average WRSI like Shire valley also showed low productivity while those with higher WRSI like Mzimba and Salima ADD had a good yield. On average Malawi has sufficient rainfall to sustain rain-fed maize crop as most of the time (67%) rain-fall is enough to give an average yield. It was also foundout that Malawi experience droughts and hence food shortages when WRSI value is close to or below 60%.

Remote Sensing Sensors and Applications in Environmental Resources Mapping and Modelling.

The history of remote sensing and development of different sensors for environmental and natural resources mapping and data acquisition is reviewed and reported. Application examples in urban studies, hydrological modeling such as land-cover and floodplain mapping, fractional vegetation cover and impervious surface area mapping, surface energy flux and micro-topography correlation studies is discussed. The review also discusses the use of remotely sensed-based rainfall and potential evapotranspiration for estimating crop water requirement satisfaction index and hence provides early warning information for growers. The review is not an exhaustive application of the remote sensing techniques rather a summary of some important applications in environmental studies and modeling.

Grid‐cell‐based crop water accounting for the famine early warning system

AbstractRainfall monitoring is a regular activity of food security analysts for sub‐Saharan Africa due to the potentially disastrous impact of drought. Crop water accounting schemes are used to track rainfall timing and amounts relative to phenological requirements, to infer water limitation impacts on yield. Unfortunately, many rain gauge reports are available only after significant delays, and the gauge locations leave large gaps in coverage. As an alternative, a grid‐cell‐based formulation for the water requirement satisfaction index (WRSI) was tested for maize in Southern Africa. Grids of input variables were obtained from remote sensing estimates of rainfall, meteorological models, and digital soil maps. The spatial WRSI was computed for the 1996–97 and 1997–98 growing seasons. Maize yields were estimated by regression and compared with a limited number of reports from the field for the 1996–97 season in Zimbabwe. Agreement at a useful level (r = 0·80) was observed. This is comparable to results from traditional analysis with station data. The findings demonstrate the complementary role that remote sensing, modelling, and geospatial analysis can play in an era when field data collection in sub‐Saharan Africa is suffering an unfortunate decline. Published in 2002 by John Wiley & Sons, Ltd.

Commencement of growing season and productivity groundnut in Rajkot district

Frere and Popov's concept of water requirement satisfaction Index was utilize, to determine the risk of low productivity of groundnut in Rajkot district of Gujarat State. The average productivity, of groundnut for the years 1974 to 1984 was 720 kg/ha, The productivity was observed to be less than average, during the years with water requirement satisfaction index below 81 per cent, The risk of below average production Increased with delay in commencement of growing season beyond 2 July.

Quantification of crop yields under rainfed conditions using a simple soil water balance model

The concept of water requirement satisfaction index was used to quantify the crop yield under rainfed conditions, choosing pearl millet as an example. The relationship between the water requirement satisfaction index and yield was observed to beY = exp (— 18.023+4.173 lnx), indicating the exponential behaviour of the yield as affected by the water availability to the crop. The correlation between the observed and expected yields was found to be 0.94. Yields were simulated for the years 1901–85 using the mathematical relationship. Simulation results showed that the years with commencement of rainy season from 25th to 28th week are most suited for millet production in the study area. The maximum crop failures were observed with 7 years per decade during the years 1901–40. The results also showed that the concept ofWRSI can be used in assessing the effects of soil moisture stress on crop yields at field level.