الملخص الإنجليزي
Lawns are used for increasing the aesthetic value of landscapes, providing natural ground covers and improving the ecological microclimate. Accordingly, vast areas within the Sultanate of Oman are allocated to turf that is planted with perennial grass lawns. During the last few years, the Directorate General of Agriculture and Veterinary Services of the Diwan of the Royal Court has answered to the rising concerns over the mowing quality of the lawns within its domain. The complaints of uneven mowing, drop in the aesthetic level of the lawns, reduced grass vigor and other undesirable characteristics of the cut grass such as pale green color. Hence a study was undertaken to help overcome the concerns and complaints. This thesis presents the results of the study conducted at Diwan's in Seeb in Oman's coastal area to address those problems.
An experiment was conducted at an open lawn area, which was planted with Bermuda grass (Cynodon dactylon). The experiment tested the effect of three variables namely mower type, mowing height and speed of cut on turf quality and machine performance over a period of six weeks. The design of the experiment was a split-split plot, four-factor factorial design with four replicates. Each replicate consisted of 12 plots resulting from a 2x2x3 combination of two random levels of (Machine Type), two random levels of (Mowing Height) and three random levels of (Forward Speed of the Machine). The plots were cut once a week (Week of Cut) over a period of six weeks.
Clippings were collected from every plot after each cut and the yield was weighed. Samples of 10 – 20 g were collected then from every cut and analyzed in the lab for the degree of grass leaf maceration and presence of foreign material. Rate of blade degeneration and fuel consumption of the used mowers was measured at the end of every weekly cut.
Analyses of variance of the contributions of the different factors revealed that only a number of those factors along with their interactions were significant. For example, the week of cut had the greatest effect on percent foreign material while mowing height had the highest impact on grass yield among the other factors. The outcomes of this research have thus clearly demonstrated that lawn quality after mowing is a result of a complex process involving the effect of various factors and the interaction between numbers of parameters. The following recommendations can be drawn from this research:
No single set of mowing parameters should be used as a general standard. However an optimal solution, which balances between the value of the lawn (output) and the value of input factors especially production inputs (irrigation water, fertilizers and pesticides), labor, machine and handling costs must be reached for every set of cutting condition. In general, lawns must be mowed at cut heights above the currently used levels. The rotary mower should be used at low height of cut since it gave excellent visual quality with high savings on the inputs. Further studies should be done on correlating digital color to visual quality.
