The effect of different subsurface drip irrigation lateral depths on the yield, quality parameters and root growth of alfalfa, planted in alone and mixture, in Kirklareli conditions

This research was planned to present the effect of subsurface drip irrigation system on the yield and quality parameters of alfalfa of alone and mixture planted form in order to close the roughage deficit in the limited irrigable agricultural lands to the regional producer in Kırklareli conditions. The field experiment was carried out in a total of 24 plots with four replications in 2019 and 2020 according to the "Factorically Arranged Random Blocks Trial Design" on the land of Kırklareli Atatürk Soil Water and Agricultural Meteorology Research Institute. Two planting methods from alone planting (clover) and mixed planting consisting of alfalfa (Medicago sativa L.), Orchardgrass (Dactylis glomerata L.), perennial grass (Lolium perenne) and smooth brome (Bromus inermis L.) were used in the study. As the irrigation method, precipitation-based conditions, drip irrigation laterals placed at a depth of 20 cm in the soil and a subsurface drip irrigation system using drip irrigation laterals placed at a depth of 40 cm were preferred. Plant roots were observed with the minirhizotron technique, with the root tracking device that transfers the images taken by the scanner that rotates 360º inside the flexiglass transparent tubes placed in the soil to the computer environment. In the research, the highest plant height (59.19 cm), the highest stem thickness (2.87 mm), the highest green grass yield (1.1031.19 kg/da), the highest hay yield (1,880.51 kg/da) and the highest root length (240.40 cm) was obtained from irrigated alone planting with laterals placed at a depth of 40 cm. In mixed planting, the highest yield of green (10,166.32 kg/da) and hay yield was obtained in the plots irrigated with laterals placed at a depth of 20 cm. In both planting forms, the lowest yield was obtained from the treatments based on precipitation. Plots grown based on precipitation were the subjects with the least root length. When the effect of the months on the roots was examined, it was seen that the plants reached the maximum root length in May and the least root length was in March. In both planting methods, it was determined that the plants started to form new roots in April and there was a decrease in root density from June. While the maximum root length was obtained (177.64 cm) in irrigated with laterals placed at 20 cm depth in mixed plots, it was obtained in subjects irrigated with laterals placed at a depth of 40 cm in alone planted plots (240.40 cm). As a result of the economic analysis, it was seen that the highest net profit was obtained 1.021.49 TL/da from the alone planted alfalfa irrigated with laterals placed at a depth of 40 cm. In mixed planting, the parcel grown based on precipitation emerged as the most profitable parcel. The profit obtained was higher than the profit obtained from the irrigated parcels.