Effect of foliar fertilization with magnesium sulfate and supplemental L-ascorbic acid on dry matter yield and chemical composition of cv. Egida timothy grass

In 2011-2013, a field experiment was conducted at the Plant Breeding Station in Polanowice near Krakow (220 m above sea level), on degraded Chernozem developed from loess. The field experiment was set up in a randomized block design with three replications. The experimental material used in this study was cv. Egida timothy grass. The aim of the study has been to test whether L-ascorbic acid supplementing for foliar fertilization with magnesium sulfate enhances magnesium absorption by plants and what effects it has on yielding and dry matter composition of timothy grass cut and used as forage. Three levels of L-ascorbic acid fertilization were applied (10, 20 and 30 g ha-1) with and without magnesium sulfate 7-hydrate. The plants were sprayed until wet, using 300 dm3 liquid per hectare. Spraying was performed 6-8 days from the onset of growth for the first harvest, and a week after cutting for the other harvests. Statistically significant improvement in yielding and forage quality was observed for the combined magnesium/ ascorbic acid fertilization. Fertilization with these two nutrients caused an increase in the total dry matter yield of timothy grass cv. Egida (together from 3 cuts), with differences reaching as much as 26% depending on the year (in the variant of combined magnesium sulfate and ascorbic acid application at 30 g ha-1). Another benefit of ascorbate application was an increase in forage quality (the content of crude protein, crude fat, water soluble carbohydrates and macronutrients). Best effects in terms of yielding and forage quality were obtained after a combined application of magnesium sulfate and ascorbic acid (30 g ha-1). Combined fertilization with magnesium sulfate and ascorbic acid tended to produce a stronger effect after periods of dry weather, which is discussed in the study.