Can Paddy-Compost Eliminate N Fertilization for Climate-Smart Sugarcane?

Paddy straw burning and its consequences on the ecosystem forced to reuse of this paddy compost (PC) in long-standing sugarcane crops, which also supposes to reduce the N fertilizations. To date, no such study has been carried out in the region where differential reductions of N fertilizers were tested with a fixed PC dose in terms of their effects on the sugarcane growth, yield, and quality parameters. Keeping this under consideration, present experiments were carried out at the Research Station of Punjab Agricultural University. Ludhiana, Punjab, India, of regional level situated at Kapurthala district during Spring 2021-2022 season in randomized block design under different treatments, viz. T-1: 25% higher N than RDN + 5.5 qt PC ha(-1); T-2: RDN + 5.0 qt PC ha(-1); T-3: 15% reduction in RDN + 4.5 qt PC ha(-1); T-4: 25% reduction in RDN + 4.0 qt PC ha(-1). Cane germination decreased to the tune of 6.7, 10.5, and 13.9% in the T-2, T-3,T- and T-4 treatments as compared to the T-1 plots. Periodic brix (degrees) at 283, 300, and 318 DAP as compared to the T-1 plots, in the T-2, T-3,T- and T-4 plots reduced to the tune of 1.3, 0.3, and 4.9%; 3.6, 5.0, 2, and 3.3%; and 2.1, 2.3 and 2.9%. Nodes per cane as compared to T-1 plots recorded to significantly decrease to the tune of 6.5, 5.8, and 10.6%; and 1.2, 0.9, and 5.5%, respectively, at T-2, T-3,T- and T-4 plots with similar but statistically at the par response at 100 and 147 DAP. Chlorophyll content as recorded by the SPAD meter reported to decrease to the tune of 8.8, 9.2, and 7.1%; 6.9, 11.9, and 17.5 in T-2, T-3,T- and T-4 plots at 216 and 243 DAP in comparison with T-1 plots with a similar but at par values at 63, 112 and 162 DAP, respectively. However, normalized difference vegetation index (NDVI) readings as recorded through Green Seeker reported to significant decrease to the tune 7.7, 9.2, and 21.1% and 8.0, 9.8, and 10.9% in T-2, T-3,T- and T-4 plots as compared to T-1 plots with a similar but at par trends at 90, 146, and 304 DAP, respectively. In the 12th month, among cane quality parameters, only Brix and Pol reported significant reductions to the tune of - 3.6, 1.1, and 1.8% and - 1.4, - 0.1, and 2.7%, respectively, in T-2, T-3,T- and T-4 plots while all followed the similar but at par trends as compared to T-1 plots. Root length density and cane yield were reported to be significantly reduced to 0.4, 0.5, and 3.0%; and 5.9, 16.9, and 31.6% in T-2, T-3, and T-4 plots compared to T-1 plots, respectively. According to reports, the sugar yield (t ha(-1)) in the spring season was significantly lower in T-2, T-3,T- and T-4 plots than in T-1 plots by amounts of 5.6, 16.5, and 35.8%, respectively. Finally, 25% higher than RDN + 5.5 qt PC ha(-1) was reported with significantly higher sugarcane yield and quality parameters at sandy loam N-deficient soils of the region.