Influence of Zinc Application on Yield, Economics, and Soil Zinc Status in Paddy

Rice (Oryza sativa L.) is a staple food crop for more than half of the world's population and is pivotal in global food security. To achieve sustainable productivity, the availability of essential nutrients, particularly micronutrients like zinc, is critical. Zinc deficiency in soils is a widespread problem, particularly in regions with high pH, low organic matter, or intensive agricultural practices. It adversely affects plant growth, grain yield, and quality, ultimately threatening food security (Alloway, 2008).

Zinc is vital for plants' physiological and biochemical processes, including enzyme activation, protein synthesis, and membrane integrity. Its deficiency is known to impair growth, reduce chlorophyll content, and limit carbohydrate metabolism, leading to reduced grain production (Cakmak, 2008). Studies have indicated that applying zinc fertilizers, such as zinc sulphate, significantly improves the availability of zinc in the soil and enhances crop productivity. Prasad et al., (2012) observed a positive correlation between zinc application and rice yield, noting improvements in grain weight and number per panicle.

While the benefits of zinc application on crop yield and soil health have been established, there is a growing need to evaluate its residual effects and economic viability under varied field conditions. This study examines the influence of zinc sulphate application on paddy yield, economics, and soil zinc status over two consecutive Kharif seasons. It aims to provide insights into the sustainability of zinc application practices for maximizing productivity and profitability while maintaining soil health.

The study was conducted during the Kharif seasons of 2019–20 and 2020–21 across 12 farms in four villages: Palem, Yellampalli, Dasireddygaripalli, and Gayamvaripalli. The experimental fields comprised clay soils with neutral pH, low electrical conductivity, high organic carbon content, low available nitrogen, and medium phosphorus and potassium levels. The paddy variety RNR 15048 was chosen for its adaptability and yield potential. Treatments in 2019–20 included the application of zinc sulphate at 25 kg/ha (T1) and a control plot without zinc (T2). In 2020–21, three treatments were established: control plots with no zinc application (T1), residual plots to assess the carryover effect of previous zinc application (T2), and continuous zinc-treated plots where zinc sulphate was applied at 25 kg/ha (T3).The experiment involved land preparation followed by the basal application of zinc sulphate in treatment plots. Seeds were soaked in gunny bags for 12 hours, sprouted over three days, and sown in a nursery in July. Transplantation of one-month-old seedlings into the main field was carried out with standard agronomic practices, including irrigation, weed management, and pest control. NPK fertilizers were applied per local recommendations, and a foliar spray of zinc sulphate was performed one month after the basal application. Harvesting occurred in November, and grain yield was measured after threshing and sun-drying.

Initial and final soil samples were collected from five random spots within each treatment plot and analyzed for zinc content through Atomic Absorption Spectrometry in the laboratory. The cost of cultivation, gross, and net returns were calculated based on prevailing market prices, and the benefit-cost ratio was derived. Statistical data analysis was conducted using SPSS software to evaluate the significance of treatment effects.

Table 4. Effect of zinc sulphate application on soil zinc status:

The study demonstrates that zinc sulphate application significantly enhances paddy yield, economic returns, and soil zinc status, with continuous application offering the highest benefits. Zinc-treated plots consistently outperformed control plots regarding grain yield and profitability across two consecutive Kharif seasons. The residual effects of zinc application further underline its potential for sustainable nutrient management. Additionally, improved soil zinc levels highlight the role of zinc in maintaining soil fertility, ensuring long-term productivity. These findings advocate for integrating zinc fertilization into paddy cultivation practices, particularly in zinc-deficient soils, to optimize yield, improve farmer incomes, and support sustainable agriculture. Future studies could explore the optimization of zinc application rates and methods to enhance its efficiency and minimize environmental impacts.

Alloway, B. J. (2008). Zinc in soils and crop nutrition. International Zinc Association and International Fertilizer Industry Association, Brussels.

Cakmak, I. (2008). Enrichment of cereal grains with zinc: Agronomic or genetic biofortification? Plant and Soil, 302(1–2), 1–17. https://doi.org/10.1007/s11104-007-9466-3Prasad, R., Shivay, Y. S., & Kumar, D. (2012). Agronomic biofortification of cereal grains with iron and zinc. Advances in Agronomy, 116, 55–91. https://doi.org/10.1016/B978-0-12-800137-0.00002-9

Shivay, Y. S., Kumar, D., & Prasad, R. (2010). Zinc-enriched urea improves grain yield and quality of rice. Better Crops, 94(2), 26–28.