Sustainable Organic Corn Production with the Use of Flame Weeding as the Most Sustainable Economical Solution

Flame weeding is an alternative method of weed control. Essentially, it is a supplement to other physical and mechanical processes used in organic production. Weed control costs have a large share of the total cost of crop production. This study aimed to investigate hand weed hoeing’s cost-effectiveness, accompanied by inter-row cultivation and flame weeding applied in organic maize production using two different machines to determine the economically best solution. For this purpose, the prototype flame weeder and commercial flame-weeding machinery were used. Designed primarily for smaller fields, the prototype flame weeder was equipped with a cultivator and a 70 kg propane bottle. Commercial Red Dragon flame weeder, fitted with an 800 kg propane tank and featuring no cultivation implements, is designed for larger areas. The analysis has shown that hand hoeing produced a higher yield (8.3 t/ha in total), but it contributed significantly to the production costs. The costs per hectare decreased when the prototype flame weeder and the commercial Red Dragon flame weeder were used compared to hand hoeing. More beneficial economic impacts were recorded when the prototype flame weeder was used (489.39 €/ha) than in applying the Red Dragon flame weeder (456.47 €/ha). The efficacy of flame weeding is somewhat limited and could be enhanced by additional hand hoeing, if the effect of the machine in terms of weeding is observed. However, the analysis has shown that, in this case, investments in additional hand hoeing are not economically justified because the operating costs incurred therein (168 €/ha) were not met by a yield increase of 500 kg/ha, i.e., a surplus revenue of 100 €/ha. Moreover, the economic impacts of flame weeding would be considerably more significant in larger fields.

Flame-weeding: Impact on soybean plants and soil microorganisms

Flame-weeding is a very useful method for weed control, especially in organic production where the use of herbicides is prohibited. With this method heat sup?presses weeds in row within a second. Apart from this, heat also affects growing crop plants and surrounding soil. The aim of this paper was to determine the effect of different propane doses, on photosynthetic and polyphenolic (total flavonoids and anthocy?nins) pigments in soybean leaves, as well as the number of microorganisms in the soil. Soybean plants exposed to flame showed a different reaction to high temperature stress, which was reflected in differ?ent content of analyzed biochemical parameters, but the most responsive were anthocyanins. Actinomycetes turned out to be the most sensitive group of soil microorganisms affected by weed flaming, while fungi were the most tolerant.

Flaming to control weeds in seashore paspalum (Paspalum vaginatum Sw.) turfgrass

Weed control is crucial to ensure that turfgrass is established effectively. Although herbicides are commonly used to control weeds in turfgrasses, environmental and public health concerns have led to limiting or banning the use of synthetic herbicides in urban areas. The species seashore paspalum (Paspalum vaginatumSw.) is susceptible to such herbicides. Flame weeding could be an alternative to the use of synthetic herbicides for selective weed control in seashore paspalum. In this study, five different liquefied petroleum gas (LPG) doses of flaming (0, 61, 91, 157 and 237 kg ha-1) were tested in order to find the optimal dose, in terms of weed control and costs. The aim was to maintain a seashore paspalum (cultivar ‘Salam’) turf free of weeds during spring green-up, and at the same time avoid damaging the turfgrass. Using a self-propelled machine designed and built at the University of Pisa, flaming was applied three times when weeds started growing and the turfgrass started green-up. Our results highlight that an LPG dose of 157 kg ha-1was the most economic dose that led to a significant reduction in initial weed cover and density, enabling the turfgrass to recover three weeks after the third application.

Flaming to control weeds in seashore paspalum (Paspalum vaginatum Sw.) turfgrass

Weed control is crucial to ensure that turfgrass is established effectively. Although herbicides are commonly used to control weeds in turfgrasses, environmental and public health concerns have led to limiting or banning the use of synthetic herbicides in urban areas. The species seashore paspalum (Paspalum vaginatum Sw.) is susceptible to such herbicides. Flame weeding could be an alternative to the use of synthetic herbicides for selective weed control in seashore paspalum. In this study, five different liquefied petroleum gas (LPG) doses of flaming (0, 61, 91, 157 and 237 kg ha–1) were tested in order to find the optimal dose, in terms of weed control and costs. The aim was to maintain a seashore paspalum (cultivar ‘Salam’) turf free of weeds during spring greenup, and at the same time avoid damaging the turfgrass. Using a self-propelled machine designed and built at the University of Pisa, flaming was applied three times when weeds started growing and the turfgrass started green-up. Our results highlight that an LPG dose of 157 kg ha–1 was the most economic dose that led to a significant reduction in initial weed cover and density, enabling the turfgrass to recover three weeks after the third application.

Effects of Flame Weeding on Organic Garlic Production

A lack of efficient machines and strategies for cropping practices are still problems on small farms and in difficult landscapes, especially in organic crop production. The aim of this study was to develop a new weed control strategy for a typical organic garlic (Allium sativum) grown in Liguria, Italy. Flaming was proposed as an additional tool for the physical weed control program. A field experiment was conducted to test the effects of different flaming doses and timing on weed control and garlic production. The treatments consisted of a broadcast flaming at 16, 22, 37, and 112 kg·ha−1 of liquefied petroleum gas (LPG) at three different crop growth stages—emergence (BBCH 9), three to four leaves (BBCH 13) and six to seven leaves (BBCH 16)—once (at each growth stage separately), twice (at BBCH 9 and BBCH 13, BBCH 9 and BBCH 16, and BBCH 13 and BBCH 16 stages) or three times (all stages combined). Treatments were compared with a weedy control and hand weeding. One flaming treatment was effective in controlling weeds during the growing season. Frequent flaming treatments did not further reduce the weed biomass measured at harvest. A higher production than the weedy control, in terms of the number of marketable bulbs and yield, was obtained for all the flaming interventions carried out at more than 16-kg·ha−1 LPG dose. Garlic flamed once at BBCH 13 at any LPG dose or three times at more than 16 kg·ha−1 led to a comparable number of bulbs as hand weeding. Three flamings at an LPG dose of 22 kg·ha−1 also gave a statistically similar yield to hand weeding. In general, garlic was shown to tolerate up to three flaming treatments without a decline in the production. The decline in yield compared with hand weeding could be offset by the economical savings of the mechanization process and by integrating flaming with other mechanical tools used for weed management.

Propelled abrasive grit applications for weed management in transitional corn grain production

Weed control is challenging to farmers who are transitioning from production systems that use synthetic herbicides to organic systems. A 2-year field study examined air-propelled corncob grit abrasion for in-row weed control efficacy and effect on corn yield. Grit was applied based on corn vegetative developmental stages with one (V1, V3 or V5), two (V1 + V3, V1 + V5, or V3 + V5), or three (V1 + V3 + V5) applications. Flame-weeding or cultivation was used after the V5 application for between-row weed control. Grit applications decreased in-row weed densities by about 60% (α = 0.05) and biomass up to 95% (α = 0.001). Between-row treatments provided similar control, and reduced weed biomass by 55% in 2013 (α = 0.01) and 86% (α = 0.001) in 2014. In-row grit treatments increased corn yield up to 44%, and yield was more influenced by in-row weeds than between row weeds. These results indicate that abrasive corncob grit for in-row weed control, supplemented with cultivation or flaming, can reduce weed biomass substantially and help maintain corn yield. However, timing and frequency of grit application need further refinement based on weed growth as influenced by climate, as treatments at similar corn growth stages did not consistently provide adequate weed control between years.

A combined flamer-cultivator for weed control during the harvesting season of asparagus green spears

Weed competition during spears harvesting reduces asparagus yields. The application of herbicides during this period is illegal, and alternative non-chemical practices are needed. This research tested the effectiveness and efficiency of a custom-built combined flamer-cultivator to control weeds (both in the inter- and intra- spears production bands) during the spears harvest season. It also analysed the effects of various liquefied petroleum gas (LPG) doses on total asparagus yield, mean spear weight, and total number of marketable spears. In both years, the asparagus spears were generally not damaged by flame weeding using LPG doses of between 43 to 87 kg/ha. The same LPG doses were effective in controlling weeds, showing the same total marketable yields as the weed-free control. At high LPG doses (e.g. 130 and 260 kg/ha), yields decreased as a consequence of the damage caused to the spears, resulting in a lower number of marketable spears. Flaming did not affect the mean spear weight, and can be applied repeatedly during harvesting to maintain the weeds at a level that does not lead to a yield reduction. The repeated use of the combined flamer-cultivator (every seven days) led to higher yields than plots where weed control was not conducted. The new machine can be used in a period when herbicides are not possible. Flaming could be introduced by asparagus producers as an alternative, or in addition to herbicides applied in the pre-emergence and post-harvest of spears.