• Autonomous mower

Turfgrass management and turf quality control are two important aspects regarding sports turfs. Four trials have been carried out to develop and study different machines and solutions for improved turfgrass management and turf quality control:
1) - Autonomous mowers can increase turf quality and reduce local noise and pollution compared with gasoline-powered rotary mowers. However, very little is known about the effects of autonomous mowing on encroaching weeds. The aim of this research was to compare the effects of an autonomous mower and an ordinary gasoline-powered mower on weed development in an artificially infested tall fescue (Festuca arundinacea Schreb.) turf with different nitrogen (N) rates. A three-way factor experimental design with three replications was adopted. Factor A consisted of three N rates (0, 75, and 150 kg ha−1), factor B consisted of two mowing systems (autonomous mower vs. walk-behind gasoline rotary mower equipped for mulching), and factor C which consisted of four different transplanted weed species: (a) Bellis perennis L., (b) Trifolium repens L.; (c) Trifolium subterraneum L.; and (d) Lotus corniculatus L. Of these, B. perennis is a rosette-type plant, while the other three species are creeping-type plants. The interaction between mowing system and transplanted weed species showed that the four transplanted weed species were larger when mowed by the autonomous mower than by the rotary mower. The autonomous mower yielded larger weeds probably because the constant mowing height caused the creeping weed species to grow sideways, since the turfgrass offered no competition for light. N fertilization increased turf quality and mowing quality, and also reduced spontaneous weed infestation. Autonomous mowing increased turf quality, mowing quality, but also the percentage of spontaneous weed cover.
2) - Sports turfs often consist of hard-to-mow warm season turfgrasses, such as zoysiagrass (Zoysia sp.) or bermudagrass (Cynodon sp.). Although autonomous mowers have several advantages over manually - operated mowers, they are not designed to mow lower than 2.0 cm and are consequently not used on high quality sports turfs. An ordinary autonomous mower was modified to obtain a prototype autonomous mower cutting at a low height. The prototype autonomous mower was tested on a manila grass (Zoysia matrella (L.) Merr.) turf, and compared its performance in terms of turf quality and energy consumption with an ordinary autonomous mower and with a gasoline reel mower. A three-way factor experimental design with three replications was adopted. Factor A consisted of four nitrogen rates (0, 50, 100 and 150 kg⋅ha-1), factor B consisted of two mowing systems (autonomous mower vs. walk-behind gasoline reel mower with no clipping removal), and factor C consisted of two mowing heights (1.2 and 3.6 cm). Prototype autonomous mower performed mowing at 1.2 cm mowing height while ordinary autonomous mower mowed at 3.6 cm mowing height. The interaction between mowing system and mowing height showed that the turf quality was higher when the turf was mowed by the autonomous mower and at 1.2 cm rather than at 3.6 cm. Autonomous mowing reduced mowing quality but also reduced leaf width. Lower mowing height induced thinner leaves. Nitrogen (N) fertilization increased overall turf quality, reduced weed cover percentage, but also reduced mowing quality. These results show that autonomous mowers can perform low mowing even on tough-to-mow turfgrass species and on high quality sports turfs.
3) - Poor quality in turfgrass mowing is highlighted by the shredded leaf tips with necrotic tissues that give an unsightly brownish colour to the turf and may also lead to turf disease. Mowing quality is also typically assessed by visual rating, thus the score depends on the person doing the assessment. To make the evaluation of mowing quality not subjective, an innovative method was developed. The aim of the trial was to examine the effects of different mowing systems and two different nitrogen rates (100 and 200 kg ha−1) on two turfgrass species in order to test the new mowing quality calculation. Three different mowing systems were used: a battery-powered rotary mower set at 3000 rpm and 5000 rpm respectively and a gasoline-powered rotary mower set at full throttle. The battery-powered mower at low blade rpm produced a poorer mowing quality and turf quality than the gasoline-powered mower and battery-powered mower at high rpm, which produced a similar mowing quality and turf quality. Leaf tip damage level values showed a significant correlation with the results of the visual mowing quality assessment. Lower leaf tip damage level values (slightly above 1) corresponded to higher visual mowing quality scores (around 8).
4) - Warm-season turfgrasses can be grown successfully in the transition zone, but dormancy occurs to some extent during the winter. Overseeding with cool-season turfgrasses is necessary if winter desiccation of warm-season turfgrasses is not tolerated. The increasing availability of zoysiagrass cultivars has enabled this genius to be considered suitable for low-maintenance golf courses. Zoysiagrasses have the most rigid leaves of all turfgrass species so turfgrass mowers need more sharpening. Autonomous mowers have proven to produce a superior turf quality compared with traditional walk-behind rotary mowers, but no autonomous mower has ever been tested at a low mowing height on an overseeded warm season turfgrass. Because of this, the trial was carried out to simulate a golf tee overseeded with cool season turfgrasses, with low input fertilization rates and with one of the most difficult turf species to mow; i.e., manila grass. The trial was carried out in S. Piero a Grado, Pisa (43°40’ N, 10° 19’ E, 6 m. a.s.l.), Italy, from October 2016 to October 2018. After a two-year period the best turf quality was achieved with Festuca rubra spp. cultivars. In many cases turf quality increased after manila grass green-up since the combination of both cool season and warm season species gave a higher quality to the turfgrass, especially because of the finer leaf texture and higher shoot density. Overseeding manila grass with some cultivars of Festuca rubra spp. could be suitable for golf tees with low-input management, looking forward to the reduction of chemical inputs allowed on turfs by the European regulations.