摘要
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Field trials were conducted to validate farm pond sizes for supplemental irrigations during 2004-2011 at the Central Institute for Cotton Research, Nagpur ('21 degrees 09'N, 79 degrees 09'E.). Ten farm ponds 200 to 15,120 m<sup>3<...
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Field trials were conducted to validate farm pond sizes for supplemental irrigations during 2004-2011 at the Central Institute for Cotton Research, Nagpur ('21 degrees 09'N, 79 degrees 09'E.). Ten farm ponds 200 to 15,120 m<sup>3</sup> size resulted in a runoff storage of about 60, 75 and 28, 36, 58% (2007, 2010 and 2008, 2009, 2011) in normal and drought years at the end of August month. During actual drought the water availability was 0 and 18% only of the capacity designed in 2011 and 2008 July seedling droughts. Special recharging techniques like opening borewells/percolation tanks etc in under ground storages and using it with sprinkler irrigation during seedling droughts is the only option. Two supplemental irrigations at flowering stage along with application of deficient micronutrients on shallow and medium soils to Bt hybrid cotton (<i>G. hirsutum</i> L.) resulted in increased seed cotton yield by 50% and 44%, which was verified during 2008 and 2009 seasons in Yeotmal district. The minimum economical catchment was found to be 21 ha or 0.7 ha m pond size, with which 25% and 50% area could be irrigated by conventional and alternate furrow/sprinkler irrigation respectively, with a payback period (PBP) of 2 years in Bt hybrid cotton. Rotational soybean (<i>Glycine max</i> (L.) Merrill) could be irrigated to the extent of 16 and 33% catchment area with improved water use efficiency (WUE) from 250 to 500 kg/ha-cm for 1.5 and 3.5 years of pay back period (PBP) under conventional and sprinkler irrigation, respectively, during drought conditions. The same sprinkler and drip irrigation systems could also be used to irrigate subsequent wheat [<i>Triticum aestivum</i> (L.) emend. Fiori & Paol] crop with a gravitational well, covering 14 and 57% of catchment area with WUE of 180 kg/ha-cm with a PBP of 11 and 21 years.
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