Evaluating the Effect of Mixing Different Amounts of Municipal Solid Waste (MSW) Compost with Soil on Root Properties of Tall Fescue (Festuca arundinaceae Schreb.) Under Moisture Stress Conditions

Significant impact of green space in the beautification of urban space and creating attractive face for cities has caused to per capita of urban green space be introduced as an important factor in urban development, especially in metropolitan areas. Meanwhile, the important role of covert plants, especially lawn grasses, in creating green spaces has caused to add quickly the area of these beautiful plants in the cities. On the other, existence of plants with high water requirements between the lawn grasses, have created limitations in terms of water requirements supply. The grass planted in the country is mainly from imported seed types that are not so compatible with dry and semi-arid conditions in our country. Sometimes from this point of view, they create limitations in terms of water supply. Hence, given the limited water resources in Mashhad city and the grass surface area in this city (which is more than 400ha), attempts at the removal of this limitation are necessary. Thus, this research was done with aim of evaluating the effect of mixing different amounts of MSW compost with soil on some root properties of Tall Fescue native grass, under moisture stress conditions. The present study, was conducted in the form of two experiments, in research greenhouse of Ferdowsi University of Mashhad in 2016. The first experiment was conducted in a completely randomized design with four replications. The experimental treatments consisted of ten different levels of compost mixing with soil (10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 ton ha-1) and control treatment (agronomic soil without mixing compost). According to the results of the first experiment, three superior compost ingredients were selected and included in the second experiment. In the second experiment, these were considered, three values of 70, 80 and 90 tons of compost per hectare plus control (no compost consumption) as the first factor and three levels of moisture stress of 25, 50 and 100 percent of field capacity as intense stress, mild stress and non-stress, respectively as the second factor. They were compared in factorial pattern by a completely randomized design with four replications. So that, their effects should be investigated on some of the characteristics of the grass root of Tall fescue. The Results of the first experiment showed that the amounts of 70, 80 and 90 tons per hectare increased significantly the percentage and the rate of grass emergence due to increased fertility and higher water holding capacity and in these treatments, the positive effect of rising water holding capacity has been dominated on negative effect of electrical conductivity of the soil and this topic has led to an improvement in the percentage of grass emergence in these treatments. Furthermore, in the amounts of 70, 80 and 90 tons of compost per hectare, the bulk density of soil significantly decreased and the C/N ratio dramatically increased. In the second experiment, the interactions between different amounts of compost and drought stress levels were significant on all studied traits of grass root. So that, with increasing drought stress severity in different amounts of compost, characteristics of total length of root, volume of root and level of root would be increased and traits of drought weight of root and average thickness of root would be decreased. The results showed that in the treatment of 90 tons of compost per hectare, the plant has understood less level of the stress due to increased water holding capacity. Therefore, the lower part of the dry matter allocated to the development of roots. By increasing severe of drought stress characteristics of total length of root, volume of root and level of root were increased and traits of drought weight of root and average thickness of root were decreased, it seems that tall fescue grass cleverly has tried to deal with for confronting drought stress with target of increase the amount of moisture available for itself. Also, based on the findings of this study, application of 90 tons of compost per hectare significantly improved root studied traits for tall fescue grass in drought stress conditions. Therefore, using this amount of compost for tall fescue grass in low water conditions and occurrence of moisture stresses is recommended.