Co-granulated urea–polyhalite improves yield and nutrient use efficiency of rainfed maize

Balanced nutrient management using multi-nutrient fertilizers has gained increasing attention for improving crop productivity and nutrient use efficiency in rainfed areas. Multi-nutrient fertilizers have received considerable attention in recent years, particularly for fields with multi nutrient deficiencies. A two-year field experiment was conducted during rainy season of 2023 and 2024 on acidic sandy loam soil to evaluate the agronomic performance of co-granulated urea–polyhalite (Urea-POLY) fertilizer in comparison with conventional farmer fertilizer practices under rainfed maize cultivation. The experiment included six nutrient management treatments comprising Farmer Practice (NP), Farmer Practice (NPK), Urea-POLY bag-for-bag, Urea-POLY recommended N, DAP + MOP and SSP + MOP treatments in randomized block design with three replications. Pooled analysis showed that Urea-POLY recommended N recorded the highest plant height (149.1 cm), leaf area index (3.14) and biomass accumulation (114.4 g plant -1 ), this was statistically comparable with Farmer Practice (NPK) (p ≤ 0.05). Similarly, Urea-POLY recommended N produced the highest grain yield (4669 kg ha -1 ), representing a 6.3% grain yield increase over Farmer Practice (NPK) and stover yield (7978 kg ha -1 ), Yield improvements were associated with enhanced cob length, grain number and test weight. Urea-POLY treatments also improved post-harvest soil available N, P, K and S along with exchangeable Ca and Mg compared to conventional control treatments, and the difference was statistically significant (p ≤ 0.05). Furthermore, in terms of nitrogen use efficiency (NUE); application of Urea-POLY rec. N resulted in more pronounced agronomic use efficiency and partial factor productivity of N, P, K and S compared with the Farmer Practice (NPK) treatment. This nutrient management strategy, which particularly emphasized the importance of N, S and K levels, optimized maize productivity and quality. However, the study was conducted at Gungal, Telangana region and the findings should be validated further across different soil types, agro climatic seasons and crops. Overall, this study showed the potential of cogranulated Urea-POLY as an efficient multi-nutrient commercial fertilizer to supply N, K, S, Ca and Mg nutrients under dryland agriculture.