Crude Protein, Economics and Water Use Efficiency of Ryegrass under Different Irrigation Regimes and Nitrogen Levels

Abstract

A field experiment was undertaken at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat during 2017-2018 and 2018-2019 in order to study the effect of irrigation regimes and nitrogen levels on crude protein, economics and water use efficiency of ryegrass. The experiment was laid out in split-plot design with three replications. The treatments consisted of five levels of irrigation in main plot viz., I0: Rainfed, I1: Irrigation at critical growth stages, I2: Irrigation at IW: CPE (Irrigation Water : Cumulative Pan Evaporation) ratio of 1.0, I3: Irrigation at IW:CPE ratio of 1.2 and I4: Irrigation at IW:CPE ratio of 1.4 along with four levels of N - N0: 0 kg N/ha, N1: 30 kg N/ha, N2: 60kg N/ha and N3: 90 kg N/ha in sub- plots. The soil of the experimental site was sandy loam in texture, acidic in reaction, medium in organic carbon, medium in available N, available P2O5 and low in available K2O. The study revealed that application of irrigation at IW:CPE ratio of 1.4 recorded the highest crude protein yield (7.69 q/ha and 7.31 q/ha, respectively in both the years), highest value in terms of evapotranspiration (26.33 cm and 24.74 cm, respectively in both the years), total water use (26.65 cm and 25.16 cm, respectively in both the years), crop water use efficiency (324.49 kg/ha-cm and 324.12 kg/ha-cm, respectively in both the years), field water use efficiency (322.69 kg/ha-cm and 318.84 kg/ha-cm, respectively in both the years), gross return (Rs. 78073.00 and Rs. 78254.00, respectively in both the years), net return (Rs. 51252.00 and Rs. 52433.00, respectively in both the years) and B:C ratio (1.87 and 1.99, respectively in both the years). Application of 90 kg N/ha recorded the highest crude protein yield (6.54 q/ha and 6.64 q/ha, respectively in both the years). The highest values in terms of evapotranspiration (21.40 cm and 18.89 cm, respectively in both the years), total water use (21.33 cm and 19.05 cm, respectively in both the years), crop water use efficiency (343.19 kg/ha-cm and 376.87 kg/ha-cm, respectively in both the years), field water use efficiency (344.33 kg/ha-cm and 372.88 kg/ha-cm, respectively in both the years), gross return (Rs. 72376.00 and Rs. 70383.00, respectively in both the years), net return (Rs. 45038.00 and Rs. 43645.00, respectively in both the years) and B:C ratio (1.63 and 1.62, respectively in both the years) were observed under 90 kg N/ha.