Boosting Crop Growth Rates of Hybrid Rice (Pukhraj) through Synergistic Use of Organic Nitrogen Sources in Conjunction with Urea Nitrogen

Abstract

In Northwestern Pakistan’s rice-based cropping systems, the prevalent reliance on inorganic nitrogen fertilizers (INF) has led to insufficient nitrogen (N) contributions from soil organic manures (OM). This study aims to evaluate the impact of organic sources (OS), including animal manures (AM) and crop residues (CR), on crop growth rates (CGR) in a rice-wheat rotation. A two-year field experiment involving hybrid rice (Oryza sativa L., Pukhraj) was conducted in Batkhela, Khyber Pakhtunkhwa. Various OS and inorganic-N (urea) combinations were applied, emphasizing their influence on CGR. The findings highlight poultry manure (PM) application as the most impactful on CGR, while wheat straw (WS) application resulted in the lowest CGR among the six OS investigated. Additionally, the use of AM showcased superior CGR compared to CR. In the initial year, the highest CGR occurred, with 75% of N sourced from urea and 25% from OS. In the second year, a balanced 50% N application from each source yielded the highest CGR. Urea and PM demonstrated the most robust CGR among OS combinations, while urea and WS yielded the lowest. Notably, onion leaves, a cost-effective option, delivered promising results comparable to berseem residues, indicating their potential as organic manure, especially in sulfur-deficient soils. These findings underscore the viability of onion residue management as a cost-effective alternative to ammonium sulfate fertilizers with global applicability. The abstract recommends promoting organic sources, particularly poultry manure and onion leaves, alongside inorganic-N fertilizers to enhance CGR and reduce dependence on costly alternatives. However, further research and field trials are necessary to explore the long-term impacts of these organic sources on soil health, nutrient cycling, and the sustainability of rice-based cropping systems in Northwestern Pakistan and beyond. In conclusion, this study investigates the influence of organic sources on CGR in rice-wheat rotations, emphasizing the superiority of poultry manure and onion leaves. The findings highlight cost-effective alternatives to conventional fertilizers, emphasizing the need for further research to validate long-term sustainability and applicability beyond the study area.