Gouranga Kar

Spatial variability studies of soil hydro-physical properties using GIS for sustainable crop planning of a watershed of eastern India and its testing in a rainfed rice area

In this study soil hydro-physical properties such as soil texture, available water capacity, and organic carbon, along with existing land use and topography of a representative watershed of eastern India (Kadalipal watershed, 20.80–20.86°N and 85.54–86.50°E, Dhenkanal district, Orissa), were spatially mapped after collecting data from different sources (ground-truthing, profile survey, remote sensing satellite imagery). Since availability of water is confined to the south-west monsoon period (rainy season, June–September), eastern India is mainly mono-cropped, dominated by rice but second crops can be planned based on the soil hydro-physical properties, mainly water retention and available water of the soil profile utilising residual soil moisture. Keeping the existing land use as a base and considering the potential and prospects of soil hydro-physical properties in different topographies, in this investigation, an alternative land-use plan was developed in different parts of the watershed and tested in its rainfed rice area. Since direct measurement of available water capacity or soil water constants over a large area is time-consuming, pedo-transfer functions were also developed to predict soil water constants using easily measured parameters (e.g. cation exchange capacity, organic carbon, oven-dry bulk density, soil texture, calcium carbonate, etc.) of arable land of the watershed. Results of implementation revealed that the new cropping system was practical for increasing production, productivity, profitability, and sustainability of the rainfed rice area of the eastern India.

Deep-water rice production as influenced by time and depth of flooding on the east coast of India

The saucer-shaped landform, high rainfall due to the south-west monsoon (June–September) and poor drainage conditions make certain parts of the east coast of India susceptible to waterlogging during the rainy season. There is no alternative other than to grow rice in the coastal lowlands, where surface water accumulation of 0.5–2.0 m occurs during the rainy season. In this study, the physical environments of a representative deep-water ecology were characterized and the performance of improved deep-water rice (DWR) varieties (Hangseswari, Saraswati, Ambika, Sabita) was compared with that of local varieties (Bankei, Dhalakartik) at three water depths (shallow flooded [0.6–0.8 m], medium flooded [0.8–1.2 m] and deep flooded [>1.2 m]). The rainfall–flooding depth relationship was also studied and the probability of successful crop production in relation to the time and depth of waterlogging was investigated, based on historical (34 years) flood data from the region. Among the varieties studied, ‘Hangseswari’ was found to have superior physiological traits for growth, development and production of grain yield and hence may be considered for inclusion in further DWR breeding programs. With the introduction of improved DWR varieties, productivity during the rainy season was enhanced and farmers received good yield (2.05–2.95 t ha−1) and net return (4500 Rs ha−1).

Organic manure supplementation effects on rice–pulse cropping system productivity

The effects of organic manure supplementation on rice–pulse cropping system productivity were studied. Three pulses, viz., blackgram, greengram and pea were grown after rice on the same plots to explore the feasibility of growing second crops with carry-over residual soil moisture and residual soil fertility. The study revealed that during the rainy season, 30%–35% higher rice grain yield was obtained when both inorganic and organic sources of nutrients were applied compared with the full dose of inorganic fertilizer, and the rice grain yield was 65%–78% higher than obtained following farmers’ practices. In the post-rainy season, pea crop recorded the highest grain yield of 490 kg ha-1 under the treatment combination of Sesbania and inorganic fertilizer. Organic carbon, and available N, P, K also enhanced yield by 20%–29%, 5.0%–29.4% to 7.9%–39.9% and 22.4%–60.3%, respectively when 25% N was applied through different organic sources of nutrients (green manure/press mud/farmyard manure).