Nitrogen uptake and economics of black rice (Oryza sativa L. indica) under different crop geometries and nitrogen management practices

Abstract

Black rice has more antioxidants than any other rice variety. It is considered to have multiple benefits in human health due to the presence of different antioxidants. A field experiment was conducted during rainy season of 2015-2016 to assess the nitrogen uptake, use efficiency and economics of black rice production under different crop geometry and nitrogen (N) manage- ment practices in Rampur, Chitwan, Nepal. The experiment was laid out in strip plot design with three replications. The experiment consisted of treatment combination of three crop geometry (20 cm × 20 cm, 20 cm × 15 cm and 15 cm × 15 cm) in vertical plots and three nitro- gen management practices (N level: 30 kg N ha-1, 60 kg N ha-1, and LCC based N-management) in horizontal plots. The results showed that the highest N uptake was recorded from closer spacing (15 cm × 15 cm) with LCC based N management. The net return and B: C ratios were higher at a closer spacing of 15 cm × 15 cm with LCC based N management and closer spacing of 15 cm × 15 cm with N application of 60 kg ha-1. The overall analysis revealed that LCC based N management under closer crop geometry (15 cm × 15 cm) was the best management practices because of high nitrogen uptake and highest monetary return with B: C ratio of 5.76.