Productivity and Energy Efficiency of Hybrid Sorrel (Rumex tianschanicus × Rumex patientia) Under Various Mowing and Fertilization Regimes

Abstract

Hybrid sorrel (Rumex patientia × Rumex tianschanicus) is a multi-purpose crop that serves as both a fodder source and a potential biofuel feedstock.  Despite growing interest in perennial forage and energy crops, limited information is available on the performance of hybrid sorrel (Rumex tianschanicus × Rumex patientia) under varying mowing and fertilization regimes, particularly in continental climates. This study aimed to evaluate the green mass yield, forage quality, and total energy output of hybrid sorrel under different mowing phases and mineral fertilization levels in the southern forest-steppe of Western Siberia. It is characterized by good winter hardiness, unpretentiousness to growing conditions, a long period of use of seven years or more, an 18% increase in green mass yield, and a 29% increase in total energy output under balanced compound fertilization compared to the unfertilized control. To maintain the long-term productivity of sorrel, research was conducted to determine the optimal mowing regimes with and without the use of balanced compound fertilizer. The study established that annual mowing in the flowering phase or alternating first mowing stages (budding, fruiting, flowering) over the years optimizes productivity; with these modes of use, the green mass of the crop is obtained up to 34.5-37.2 t ha^-1, the total energy output 76.6-89.4 GJ ha^-1. The use of mineral fertilizers (N₉₀P₉₀K₉₀) in sorrel crops enables the production of up to 40.4-44.6 t ha^-1 of green mass under these regimes, resulting in a 13-18% increase in productivity. It is more effectiveness to apply the fertilizer rate in two steps: annually in the spring before the grass grows back (45 kg a.i. ha^-1) and after the first mowing (45 kg a.i. ha^-1).