Nutritional Status and Nitrogen Uptake Dynamics of Waxy-Type Winter Wheat Under Liquid Organic Fertilization

The growing demand for sustainable farming has increased interest in niche crops, including waxy wheat (Triticum aestivum L.). However, their nitrogen (N) nutrition characteristics from organic and mineral fertilizers are not sufficiently studied. In this research, the effects of pig slurry and liquid anaerobic digestate, as a sustainable alternative, were investigated and compared to ammonium nitrate, on waxy winter wheat, using N application rates of 0, 60, 120, and 120 + 50 kg ha^-1 (the additional 50 kg ha^-1 was applied as ammonium nitrate). The experiments were conducted in the northern part of Lithuania at the Joniškėlis Experimental Station of the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry (LAMMC) on clay loam Cambisol and repeated over two years (2019/2020 and 2020/2021) by reseeding winter wheat. The study evaluated mineral N in the 0-60 cm soil layer during active growing and autumn-non-vegetation periods, N accumulation in plant biomass, wheat grain and straw yield, fertilizer N use efficiency (NUE), and total energy yield. It was found that more than half of the total N required by the crop was taken up during the first half of the vegetation period (in favourable years-56%; in less favourable years-75% of the total required N). The optimal N rate for waxy winter wheat was 60-120 kg ha^-1. The fertilizer's NUE depended on the N rate; in favourable years, NUE values were 50-75% for N60, 19-43% for N120, and 29-40% for N120 + 50. Results indicate that biogas slurry can serve as a sustainable alternative for winter wheat main N fertilization, contributing to improved environmental outcomes.