GreenSeeker-based nitrogen scheduling in wheat (Triticum aestivum) for higher nitrogen-use efficiency and productivity

A field experiment was conducted during winter (rabi) season of 2014–15 and 2015–16 at Ludhiana, Punjab to study the effect of nitrogen scheduling using Green Seeker on growth, productivity and nitrogen-use efficiency (NUE) of wheat (Triticum aestivum L.). The soil of the experimental field was loamy sand, low in organic carbon and available nitrogen and medium in available phosphorus and potassium. The experiment was conducted in complete randomized block design with eight treatments, viz. control, recommended N application (150 kg/ha) in 3 equal splits (50 kg N at sowing: 50 kg N at first irrigation: 50 kg N/ha at second irrigation), 3 treatments with fer-tilizer application in 3 splits up to 2^nd irrigation using optical sensor GreenSeeker (GS): 60 kg N/ha + GS_{2nd irri}(30: 30: 61/51 kg/ha), 84 kg N/ha + GS_{2nd irri}(42: 42: 53/46 kg/ha), 120 kg N/ha + GS_{2nd irri}(60: 60: 44/41 kg/ha) and 3 treatments with fertilizer application in four splits i.e. upto 3^rd irrigation using GreenSeeker: 60 kg N/ha + GS_{3nd irri}(20: 20: 20: 14/20 kg/ha), 84 kg N/ha + GS_{3nd irri}(28: 28: 28: 6/20 kg/ha), 120 kg N/ha + GS_{3nd irri}(40: 40: 40: 6/13 kg/ha). Treatment 120 kg N/ha + GS 2^nd or 3^rd irrigation had resulted in better growth and yield of wheat. Application of 160–164 kg N/ha with GreenSeeker at 2^nd irrigation (60 kg N at sowing + 60 Kg N at first irrigation + 40/44(GS) kg N/ha) recorded higher but statistically similar grain yield in comparison to the blanket application of 150 kg N/ha. Delayed application of N GreenSeeker up to third irrigation (40: 40: 40: 6/13 kg N/ha) resulted in N saving of 17–24 kg/ha, upto 59.5% N recovery and 2.5% higher grain yield than 150 kg N/ha application.