Spectral reflectance data originating from Unmanned Aerial Vehicle (UAV) imagery is a valuable tool to monitor plant nutrition, reduce nitrogen (N) application to real needs, thus producing both economic and environmental benefits. The objectives of the trial were i) to compare the spectral reflectance of 3 turfgrasses acquired via UAV and by a ground-based instrument; ii) to test the sensitivity of the 2 data acquisition sources in detecting induced variation in N levels. N application gradients from 0 to 250 kg ha-1 were created on 3 different turfgrass species: Cynodon dactylon x transvaalensis (Cdxt) ‘Patriot’, Zoysia matrella (Zm) ‘Zeon’ and Paspalum vaginatum (Pv) ‘Salam’. Proximity and remote-sensed reflectance measurements were acquired using a GreenSeeker handheld crop sensor and a UAV with onboard a multispectral sensor, to determine Normalized Difference Vegetation Index (NDVI). Proximity-sensed NDVI is highly correlated with data acquired from UAV with r values ranging from 0.83 (Zm) to 0.97 (Cdxt). Relating NDVI-UAV with clippings N, the highest r is for Cdxt (0.95). The most reactive species to N fertilization is Cdxt with a clippings N% ranging from 1.2% to 4.1%. UAV imagery can adequately assess the N status of turfgrasses and its spatial variability within a species, so for large areas, such as golf courses, sod farms or race courses, UAV acquired data can optimize turf management. For relatively small green areas, a hand-held crop sensor can be a less expensive and more practical option.

Intra-row weed control in organic or low-input cropping systems is more difficult than in conventional agriculture. The various mechanical and thermal devices available for intra-row weed control are reported in this review. Low-tech mechanical devices such as cultivators, finger-weeders, brush weeders, and torsion-weeders tend to be used in low density crops, while spring-tine harrows are mainly applied in narrow-row high-density crops. Flame weeding can be used for both narrow and wide-row sown crops, provided that the crop is heat-tolerant. Robotic weeders are the most recent addition to agricultural engineering, and only a few are available on the market. Nowadays, robotic weeders are not yet used in small and medium sized farms. In Europe, high-income niche crops are often cultivated in small farms and farmers cannot invest in high-tech solutions. Irrespectively of the choice of low- or high-tech machines, there are several weeders that can be used to reduce the use of herbicides, making of them a judicious use, or decide to avoid them

Autonomous mowers are battery-powered machines designed for lawn mowing that require very low human labour. 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.

No abstract

Weed management is often the most troublesome technical problem to be solved in organic farming, especially in poorly competitive crops like vegetables. A four-year (2000-2003) series of trials was established to assess the possibility of adopting an innovative non-chemical weed management system in organic carrot grown on the Fucino plateau, i.e., the most important carrot-growing area in Italy. The system utilized for physical weed control was based first on a false seedbed technique followed by pre-sowing weed removal, performed with a special 2 m wide 6-row spring-tine harrow. Prior to crop emergence, a pass with a flame weeder equipped with four 50 cm wide-open flame burners was also performed. Post-emergence weed control consisted of one or more hoeing passes with a purpose-designed 11-tine precision hoe equipped with spring implements (torsion weeders and vibrating tines), in addition to hand weeding. This innovative system was applied to a novel planting pattern (sowing in ten individual rows within 2 m wide beds) and compared to the standard management system of the area (sowing within 2 m wide beds but in five bands, use of spring-tine harrowing and flame weeding pre-emergence and of traditional hoeing post-emergence). The new system was tested in different commercial farms including both early and late-sown carrot. Assessments included machine operative characteristics, labor time, weed density and biomass, crop root yield and yield quality, and economic data (physical weed control costs and crop gross margin). Compared to the standard system, the innovative system usually resulted in reduced labor time (from 28 to 40%) and total costs for physical weed control (on average -416 € ha-1). Use of the precision hoe resulted in intra-row weed reduction ranging from 65 to 90%, which also led to a marked reduction in the labor required for hand weeding. In 2001 the two systems did not differ in terms of yield and yield quality, whereas in 2002 and 2003 the innovative system showed a higher mean density of carrot plants (from 28 to 55%), root yield (from 30 to 42%), and gross margin (from 40 to 100%). Carrot yield was higher in farms which adopted an early sowing whereas root commercial quality was somewhat variable between systems and years. In general, results obtained with the innovative management system look very promising