Measurement and evaluation of hydraulic and chemical parameters of growing media for yield of ryegrass

Growing media are made for horticultural use as a mixture of various organic and mineral components. In this study, a total of 34 commercially available growing media were tested for the performance of biomass growth in ryegrass. The aim of the study was to determine which properties of growing media have a greater influence on the performance of grass plant growth. The influence of the chemical and hydraulic properties of growing media on the growth of ryegrass was tested. These results are intended to help in subsequent investigations to find alternative mixing components for the substitution of peat.The variables for the hydraulic assessment were the water capacity in the slightly plant-related area, the air capacity and the capillary water increase. The hydraulic parameters were measured with the HYPROP system (HYdraulicPROPerty Analyzer). The chemical properties (carbon, nitrogen, phosphorous, potassium, magnesium,) were determined by analyzing the total and plant-available nutrients. Additionally, substance loss was determined during the vegetation period. Effects of the chemical and hydraulic properties on ryegrass biomass growth were tested via multiple regression analysis. Ryegrass biomass growth varied widely over the different growing media. The multiple regression showed that substrate loss, plant-available nitrogen (N-av) and phosphorus (P-cal) were significantly associated with increases of yield. Overall, the model explains 44.6% of the variance of Yield. N-av explains 21%, loss 13% and P almost 10% of the variance. Moreover, substance loss was significantly correlated with biomass growth. We also found a higher biomass yield on peat-rich substrates compared to peat-free substrates. These results show in conclusion that commercially available potting soils vary strongly in their content and properties, and confirm the importance of peat for horticulture. Further studies are needed to quantify the importance of chemical and hydraulic properties under consideration of the peat content.