STANDARDIZATION OF IRRIGATION AND FERTIGATION REQUIREMENT FOR AMARANTH UNDER POLYHOUSE

Abstract

The study entitled “Standardization of irrigation and fertigation requirement for Amaranth under polyhouse” was taken up to compute the crop water requirement, irrigation schedule and fertigation schedule of amaranth (Amaranthus retroflexus) crop and to find out the best treatment which gives maximum yield under polyhouse conditions in Tavanur region. The CROPWAT 8.0 model studied in previous year Precision Farming Development Center project. The required soil, crop and climate data inputs were given to the model and the crop water demand and irrigation schedule for amaranth was obtained. Average ETo was found to be 3.62 mm/day. Water requirement for amaranth was found as 194.2 mm and the gross irrigation requirement as 276.4 mm at a 100% irrigation efficiency. Field experiment was conducted inside the naturally ventilated polyhouse in the research plot of Precision Farming Development Centre situated at KCAET, Tavanur, during the period November 2020 to February 2021. In the present study, 60%, 80% and 100% of ETc were selected as irrigation treatments and 100%, 125% and 150% of RDF were selected as fertigation treatment. The plot was divided into 10 beds having 9 treatments with three replications. Fertigation include both macro and micro nutrients applied as water soluble fertilizers through fertigation system with venturimeter. Analysing the effect of different treatments, it was found that in amaranth crop, better performance was found in the treatment T 3 R 3 (irrigation 100% of ETc and fertigation 150% of RDF).The highest plant height (41.3 cm), number of leaves (38 nos), stem girth (5.7 cm) and yield from plant (0.176 kg) was noticed in T 3 R 3 . The lowest yield was for T 1 R 1 (irrigation 60% of ETc and fertigation 100% of RDF). The highest IWUE (Irrigation water use efficiency) was for T 1 R 3 (93.3 kg/ha.mm) and lowest was for T 3 R 2 (52.1 kg/ha.m). On economic analysis, Benefit Cost Ratio was found to be 1.15 Hence drip fertigation with 100% of ETc and fertigation of 150% of RDF has been standardized for cultivation of amaranth under poly house of PFDC, KCAET, Tavanur, Kerala. The results of the study can be used as a guide for the farmers to plan their irrigation and cropping pattern. Also the results can be extrapolated to the future to analyse the trends in future crop water demands.