Non-chemical weed control on traffic islands: a comparison of the efficacy of five weed control techniques

The efficacy of five non‐chemical weed control methods for reducing weed cover on traffic islands was investigated in the growing season of 2004. Three trial sites were divided into six treatment areas which were treated with either flame, steam, hot air, hot water, brushes or left untreated. The treatments were carried out at regular intervals throughout the growing season. The percentage weed cover was measured every second week using a 75 × 75 cm quadratic frame with 100 squares. In the control areas, a rapid increase in weed cover was observed, whereas all treatments reduced weed cover. Hot water was the most effective method, although not significantly better than hot air or steam. Hot air treatment was more effective than brushing, whereas hot water was more effective than both flaming and brushing. The doses that were used were relatively high (150–355 kg ha^?1), partly because of the irregular shape of the traffic islands and the treatment intervals were quite short in comparison with those in similar studies. However, the treatments could keep down the weeds only to a certain extent. The present knowledge of the efficacy of various weed control methods, as well as an increase in our knowledge of adequate treatment intervals, supports an optimisation of hard‐surface weed control. Data and experience gained from these trials were used to develop further calibrated application studies.     

Integrating preventive and curative non‐chemical weed control strategies for concrete block pavements

Reduction in herbicide use in non‐agricultural areas is being imposed by a growing number of governments, triggering the development of alternative strategies for weed prevention and control. This study aimed to determine the weed preventive abilities of different paving types, the required treatment frequency of non‐chemical weed control scenarios on these pavements and the associated weed species composition. A test parking area, constructed with four concrete paving types, was sown with a mixture of dominant weed species. Six scenarios with repeated use of a single weed control method (brushing with waste removal, hot air, selective application of hot water and three scenarios with flaming) and two scenarios with alternating use of brushes and hot air were applied to control the weeds during two growing seasons. Treatments were applied at well‐defined intervention moments, based upon weed development. Over 2 years, the paving types differed in weed coverage (up to a fourfold difference) and required varying treatment frequency (up to a 11‐fold difference) with lowest values for pavings with porous pavers. Within most paving types, up to 28% lower treatment frequencies were found for selective application of hot water, as compared with all other single method scenarios. Shifts in weed composition occurred in plots treated repeatedly with the same technique. Paving type determined the chances for the establishment of different weed species and alternating non‐chemical control methods with different modes of action offered the best opportunity to keep weeds under control.     

Weed flora and weed management in established olive groves in Albania

Weed flora were surveyed during 2000 and 2001 in 10 established olive groves that were located in the area of Vlora, in south‐western Albania. The effectiveness of six weed management treatments (soil tillage, straw mulch, cover cropping [a mixture of rye with peas], and grazing, as well as glyphosate and diuron application) on the weed flora, olive yield, and fruit quality also were investigated in two locations during 2000, 2001, and 2002. More than 80 weed species were recorded, representing a total of 14 families, in which the families Poaceae, Fabaceae, Asteraceae, Ranunculaceae, and Rosaceae predominated. The glyphosate application provided the highest and most consistent level of weed control, whereas diuron achieved sufficient weed control. The straw mulch provided acceptable weed control but the cover crop and the grazing did not sufficiently control the weeds. The highest fruit and oil yields were produced by the trees treated with the straw mulch as a result of the highest mean fruit weight in each year, followed by the soil tillage treatment. However, the olive trees in the plots treated with glyphosate or grazing provided lower or equal, respectively, fruit and oil yields than did those in the untreated plots (control). The results indicated that certain non‐chemical weed control methods, such as straw mulch, can be implemented successfully in established olive groves, providing satisfactory control of weeds and promoting the highest fruit and oil yields.     

Influence of developmental stage and time of assessment on hot water weed control

Summary The influence of plant developmental stage in hot water weed control was studied on the test weed Sinapis alba in field experiments. The dose was measured as thermal energy in the hot water (kJ m⁻²) and the response as reduction in plant weight. The energy dose for a 90% reduction in plant weight was 340 kJ m⁻² at the two-leaf stage, which is one-third of the energy required for the same reduction at the six-leaf stage. Treatment at an early stage saves energy, increases the driving speed and lowers the costs. Hard surface areas with naturally developed weeds were used to study the required treatment interval and the influence of time of assessment on the reduction in weed cover. The required treatment interval was 25 d on average, which is similar to that of flame weeding. A longer lasting effect requires a higher energy dose. A 50% higher energy dose was needed to obtain a 90% reduction in weed cover that lasted for 15 d instead of 7 d. After 3–4 weeks, hardly any reduction could be recorded because of regrowth of perennial weeds. However, hot water weed control has a potential on urban hard surfaces and railroad embankments, especially where the use of herbicides is restricted.     

Efficacy and reduced fuel use for hot water weed control on pavements

Non‐chemical weed control on pavements needs more frequently repeated treatments than the application of glyphosate and often uses large amounts of fuel. To obtain effective hot water control with minimum energy consumption, an in‐depth study of efficacy‐influencing factors was performed. Three dose–response pot experiments were conducted outdoors to investigate the impact of growth stage (39, 60 and 81 day old), water temperature (78, 88 and 98°C), time of the day (2, 7 and 12 h after sunrise) and treatment interval (2, 3, 4 and 6 week intervals) on hot water sensitivity of seven weed species that are hard to control on pavements. Responses to hot water were quantified by weed coverage and total dry biomass. In general, hot water sensitivity was highest for species with large planophile leaves and lowest for grasses with small erectophile leaves. Most species were twofold to sixfold more sensitive to water at 98°C than at 78 and 88°C, particularly when treated at early growth stages. Among treatment intervals, treating at 3‐week intervals was up to twofold more effective and energy efficient than treating at 6‐week intervals. Sensitivity was about twofold lower in the morning than in the afternoon. For effective control of weeds, while using less fuel, it is recommended to apply hot water in the late afternoon, to operate at high water temperature (98°C) and to treat plants as young as possible at 3‐week intervals.     

Assessing the efficacy and impact of management of an invasive species in a protected area: Poa annua on sub‐Antarctic Macquarie Island

Plant eradication is difficult, particularly in remote, protected areas. The Southern Ocean Islands are very isolated and highly protected, but the flora contains many alien plants. Small restricted populations have been eradicated, but eradication of established species has proven difficult. A better understanding of the efficacy of control methods at sub‐Antarctic temperatures and their off‐target impacts may increase eradication success. With interest in controlling non‐native Poa annua in the region, we aimed to determine if physical and chemical methods can control P. annua (the sub‐Antarctic biotype) in sub‐Antarctic conditions and examined their impact on native plants. We quantified the effectiveness of physical control methods on P. annua in situ on sub‐Antarctic Macquarie Island through field‐based experiments and assessed their selectivity on P. annua compared with native grasses. We also quantified the effectiveness of several herbicides on P. annua at sub‐Antarctic temperatures and assessed their selectivity on native grasses. Of the four physical disturbance methods tested, none effectively reduced P. annua cover as one‐off treatments. Of the herbicide treatments, glyphosate and trifloxysulfuron sodium were effective and were less damaging to native grass species, indicating potential selectivity. Physical control was of limited effectiveness, but did not affect native species richness. An integrated weed management programme utilising the strategic use of selective herbicides with follow‐up chemical and physical intervention may balance control and biodiversity outcomes. This research highlights the importance of site‐specific testing of control methods and understanding off‐target impacts of control when managing alien plant species in protected areas.     

Weed control in conventional and herbicide tolerant winter oilseed rape (Brassica napus) grown in rotations with winter cereals in the UK

Two winter oilseed rape (Brassica napus) cultivars, tolerant to glyphosate and glufosinate, were compared with a conventional cultivar at three sites over 4 years, in 3‐year crop rotations in the UK. The winter oilseed rape was grown in Years 1 and 4, with winter cereals, which received uniform herbicide treatments, in the intervening years. The second winter oilseed rape treatments were applied to randomised sub‐plots of the original plots. Weed densities were recorded in autumn and spring and weed biomass was measured in summer. At most sites, there was only one application of glufosinate or glyphosate, whereas two products were often used on the conventional variety. The timing of glyphosate and glufosinate application was, on average, 34 days later than that of the conventional broad‐leaved weed control treatments. Overall weed control, across all sites and years, was not statistically different between the conventional, glyphosate and glufosinate treatments. However, glyphosate achieved higher control of individual weed species more frequently than the other treatments. Glufosinate and the conventional treatments were similar in performance. The treatments in Year 1 sometimes affected weed populations in the subsequent cereal crops and, in rare instances, those in the rape in Year 4. Carry‐over effects were small after most treatments. In general, weed survival was greater in the oilseed rape crops, irrespective of the treatment, than it was in the intervening cereal crops.     

Effect of different weed management systems on the weed populations, and seedbank composition and distribution in tropical coconut plantations

Weeds are a perennial problem in coconut plantations and cause significant losses in the nut yield. The occurrence of a wide range of weeds also causes difficulties in their eradication. The influence of five different weed management practises on the distribution and composition of the soil weed seed bank in coconut plantations in the low-country dry zone of Sri Lanka was evaluated. The treatments imposed included the application of glyphosate (N-[phosphonomethyl]-glycine), cover cropping with Pueraria phaseoloides , tractor harrowing, tractor slashing, and tractor plowing. All the treatments were applied twice per year, except for the cover cropping treatment. In terms of a reduction in the weed biomass, the application of glyphosate and cover cropping ( Pueraria ) were more efficient in reducing the ground weed population. These methods were very effective in reducing the weed seed density in the top soil layers. Plowing and harrowing significantly reduced the seed bank in the top soil layers and shifted significant numbers of weed seeds to deeper soil profiles. However, the total germinated weed seed count increased by 123.5, 691.4, 1133.1, and 1216.5% in the 10–15, 15–20, 20–25, and 25–30 cm soil depths, respectively, compared with the initial germinated weed seed count in the plowing treatment. Considering all the soil layers, the decline in the germinating weed seed count was very high in the treatment plots with cover cropping and the application of glyphosate; thus, these are considered to be the best practises to reduce the germinating weed seed count in the soil of coconut plantations.     

A review of non-chemical weed control on hard surfaces

Weed control research to date has mainly focused on arable land, especially regarding herbicides, but also regarding non‐chemical methods. Some of these experiences can be applied to hard surface areas. However, weeds on hard surface areas cause problems that are different from those on arable land. Additionally, crop tolerance does not need to be considered when choosing an appropriate weed control method on these areas. The aim of this review is to describe current knowledge of weeds and weed control methods on hard surface areas and reveal potential ways of advancement. One of the shortcomings of non‐chemical weed control on hard surfaces thus far, is a lack of proper definition of efficiency of the weed control methods. To obtain effective control, more frequently repeated treatments are required than chemical weed management, thereby increasing the costs of labour and fuel. One way to reduce costs can be by adjusting the level of control to the required visual street quality. Weeds are adapted to the hard surface environment and may be less susceptible to certain control methods. This review indicates that for efficient weed control on hard surfaces there is a need for combining weed control techniques, applying sensors for detecting weeds, adapting the energy dose to type of weed flora and prevention of weeds by improved construction of new surfaces.     

Benchmark study on glyphosate-resistant cropping systems in the United States. Part 4: Weed management practices and effects on weed populations and soil seedbanks

BACKGROUND: Weed management in glyphosate‐resistant (GR) maize, cotton and soybean in the United States relies almost exclusively on glyphosate, which raises criticism for facilitating shifts in weed populations. In 2006, the benchmark study, a field‐scale investigation, was initiated in three different GR cropping systems to characterize academic recommendations for weed management and to determine the level to which these recommendations would reduce weed population shifts. RESULTS: A majority of growers used glyphosate as the only herbicide for weed management, as opposed to 98% of the academic recommendations implementing at least two herbicide active ingredients and modes of action. The additional herbicides were applied with glyphosate and as soil residual treatments. The greater herbicide diversity with academic recommendations reduced weed population densities before and after post‐emergence herbicide applications in 2006 and 2007, particularly in continuous GR crops. CONCLUSION: Diversifying herbicides reduces weed population densities and lowers the risk of weed population shifts and the associated potential for the evolution of glyphosate‐resistant weeds in continuous GR crops. Altered weed management practices (e.g. herbicides or tillage) enabled by rotating crops, whether GR or non‐GR, improves weed management and thus minimizes the effectiveness of only using chemical tactics to mitigate weed population shifts. Copyright © 2011 Society of Chemical Industry     

Impact of Indian mustard growth and incorporation on annual weed population dynamics and communities

Biofumigation from Brassica cover crops may be used to control soilborne pests and weeds. A study was conducted to understand the influence of biofumigation on key processes of annual weed population dynamics. Five combinations of Indian mustard (M) and oat (O) cover crop treatments were assessed in a 3 year field study at two locations in Québec, Canada. Treatments included four spring/fall cover crop combinations (M/M, M/O, O/M, O/O) and a weedy check control with no cover crop. Prior to mowing and incorporation of cover crops, weed identification, count and biomass measurements were recorded to evaluate the total weed density, to calculate the relative neighbour effect (RNE) and weed diversity metrics and to perform principal co‐ordinates analyses. Indian mustard cover crops had no impact on weed establishment in 2014 due to low biofumigant potential compared to the oat cover crop. In 2015 and 2016, Indian mustard isothiocyanate (ITC) production increased and weed establishment within the Indian mustard cover crop decreased. Moreover, post‐cover crop incorporation decreased the next year spring weed emergence. Allelopathic interference of Indian mustard was significant when plant tissues produced more than 600 μg of allyl‐ITC g^?1. It is now possible to rationalise the use of Brassica cover crops and biofumigation for weed control with an enhanced understanding of the impact of biofumigation on key processes of weed population dynamics.     

Effects of weed harrowing and undersown clover on weed growth and spring cereal yield

Weed competition and nutrient scarcity often restrict organic cereal production, especially where the availability of livestock manure is limited. While harrowing of annual weeds and legume cover crops can be used, these methods are both executed in early spring and may hinder each other. Two cycles of a 2‐year crop rotation were carried out in south‐east Norway (60°42′N, 10°51′E, altitude 250 m) with weed harrowing and undersown cover crops (WHCC) at two fertiliser rates (40 and 100 kg nitrogen ha^?1). The effect of the WHCC treatments was measured by weed density and species, weed biomass, changes in weed seedbank and grain yield. The weed density depended on the interaction between WHCC, fertiliser and year. On average, pre‐emergence weed harrowing reduced weed density by 32% and weed biomass by 49%, while pre‐ and post‐emergence weed harrowing reduced weed density by 59% and weed biomass by 67% compared with the untreated control. Spergula arvensis became more abundant at low rather than at high fertiliser rates. On average, white clover cover crop sown after pre‐emergence weed harrowing resulted in the highest yields for both oat (+12.1%) and wheat (+16.4%) compared with the untreated control. Despite differences in weed population density and biomass among WHCC treatments within years, the weed biomass, weed density and seedbank increased for all WHCC treatments over the 4‐year period. More research is required into improving the efficacy of mechanical and cultural weed suppression methods that organic systems rely on.     

Thermal weed control technologies for conservation agriculture—a review

Research and development activities on non-chemical weed control methods to date have mainly focused on mechanical and thermal applications. Selectivity in mechanical weed control is obtained using dynamically actuated harrows. Selectivity in thermal weed control is obtained through a certain heat tolerance of the crop. In conservation agriculture (CA), weed emergence is partially suppressed by constant soil cover with crops or cover crops. Large amounts of plant residues therefore remain on the soil, which make mechanical methods inefficient or difficult to implement. And thermal methods need to prevent not only crop damage but also fire from situationally dry plant residues. In this review, technologies that can potentially be used for in-crop weed control in CA are discussed. The technologies reviewed include spot-flaming, electric resistance heating, electromagnetic irradiation and steam/hot water application. Their evaluation focuses on efficiency and specificity (spatial precision). This review indicates that existing equipment does not fulfil the spatial precision required in CA and that further research and development is required on this topic. In particular, the authors suggest further research on the use of laser diodes, micro-flames and capacitive coupling of electric fields. It seems that the use of automated imaging systems for weed/crop differentiation is a prerequisite in CA to enable automatisation of weed control.     

Weed infestation and tea growth under various weed management methods in a young tea (Camellia sinensis[L.] Kuntze) plantation

A field experiment was conducted in the low country of Sri Lanka, during the period 1994–1995 to investigate the severity of weed infestation and tea growth in relation to weed management methods in newly established tea ( Camellia sinensis [L.] Kuntze). Manual weeding (hand and slash weeding) at various intervals was compared with various herbicides, with or without mulching. Weed control with herbicides was superior to that of hand weeding at 6-week intervals or more. Weed control with oxyfluorfen at 0.29 kg ai ha⁻¹ + paraquat at 0.17 kg ai ha⁻¹ or glyphosate at 0.99 kg ai ha⁻¹ + kaolin at 3.42 kg ha⁻¹ were superior. Plots unweeded for 12 weeks or more produced significantly greater ( P  < 0.05) weed biomass than plots unweeded for 6 weeks. Although the least weed dry weight ( P  < 0.05) and the greatest number of weed species were recorded with hand weeding at 2 week intervals, there was no particular benefit on tea growth when compared with hand weeding at 6 and 12 week intervals. Inter row mulching in chemically treated plots was more favorable for tea growth than no mulching, while living weed cover in unmulched slash weeded plots suppressed tea growth. A combination of mulching and herbicides, particularly oxyfluorfen and paraquat, followed by hand weeding at least every 6–8 weeks was considered the most appropriate weed management system for young tea.     

Reduced weed growth with different paving constructions

The recent phaseout of herbicide use on public pavements in Flanders has triggered the development of alternative weed control strategies. Besides the search for effective non‐chemical curative methods, there is also a need for strategies that prevent or reduce weed growth on pavements. In this study a paving experiment was set up under a rain shelter to investigate the effects of four construction factors on weed growth: joint filling material, joint width, organic pollution of the joint filling material and type of bedding layer. Paving mini‐plots were oversown with a mixture of dominant, hard‐to‐control weed species found on pavements. The inhibitory effect on weeds was determined by examining initial weed density and weed coverage over a 2‐year period. More weed growth was found in pavings with wide joints and organically polluted joint filling materials. High permeability of the bedding layer resulted in higher weed cover. The coarse‐grained filling materials and the sodium silicate‐enriched sand Dansand^® were associated with less weed cover than the fine‐grained filling materials. Our results show there is potential for preventing weed growth using suitable paving materials and appropriate high‐standard construction and maintenance of pavements.     

Weed control in glyphosate‐tolerant maize in Europe

Maize growing in the EU27 increased to over 13 million ha in 2007, most of which (>80%) was grown in just eight countries (France, Romania, Germany, Hungary, Italy, Poland, Spain and Bulgaria). The number of herbicides used to control the wide spectrum of weeds occurring in all these countries is likely to decline in the future as each current active ingredient is reassessed for toxicological and environmental safety under Directive 91/414/EEC. Glyphosate has already been approved under this directive. Glyphosate, applied alone or in combination with currently available residual herbicides to genetically modified varieties tolerant to glyphosate, can provide a viable, flexible and profitable alternative to conventional weed control programmes. Glyphosate usage with glyphosate‐tolerant varieties also provides an environmentally sustainable weed control option as long as sufficient diversity of weed management options (crop rotation, chemical diversity, multiple cultural and mechanical practices, buffer strips) is maintained within the farm management system. Appropriate product stewardship measures will be required to maximise the long‐term overall benefits of the glyphosate‐based system. Specifically, care will need to be taken to manage potential weed shifts to more difficult‐to‐control species and to reduce the risk of selection for glyphosate‐resistant weeds. Copyright © 2009 Society of Chemical Industry     

Comparison of different weed management systems and their effects on yield of coconut plantations in Sri Lanka

The influence of five different weed management systems on nut yield of coconut were evaluated to determine an economical and effective method of controlling weeds in coconut plantations in the low country, dry zone in Sri Lanka. Treatments imposed included slashing and mulching around the palms with slash (T1), slashing and removing the slash (T2), application of glyphosate (N-(phosphonomethyl)-glycine) alone at 1.44 kg ai ha⁻¹ (T3), application of glyphosate alone at 2.88 kg ai ha⁻¹ (T4) and cover cropping with Pueraria phaseoloides (T5). All treatments were applied twice a year, except for the cover cropping treatment, T5. Based on a reduction in weed biomass, treatments T3, T4 and T5 were found to be significantly effective over other treatments. Coconut yield was increased significantly ( P  < 0.05) in glyphosate-applied plots at both tested rates. Control of weeds with the lower concentration of glyphosate (1.44 kg ai ha⁻¹) resulted in a 25% increase in nut yield over the uncontrolled weed plots. At this rate, it was found to be the most effective and economical method of controlling weeds in coconut plantations. Cover cropping with Pueraria phaseoloides was effective in controlling weeds in the long-term, but was not economical compared with the glyphosate application.     

Perspectives on transgenic,herbicide‐resistant crops in the United States almost 20 years after introduction

Herbicide‐resistant crops have had a profound impact on weed management. Most of the impact has been by glyphosate‐resistant maize, cotton, soybean and canola. Significant economic savings, yield increases and more efficacious and simplified weed management have resulted in widespread adoption of the technology. Initially, glyphosate‐resistant crops enabled significantly reduced tillage and reduced the environmental impact of weed management. Continuous use of glyphosate with glyphosate‐resistant crops over broad areas facilitated the evolution of glyphosate‐resistant weeds, which have resulted in increases in the use of tillage and other herbicides with glyphosate, reducing some of the initial environmental benefits of glyphosate‐resistant crops. Transgenic crops with resistance to auxinic herbicides, as well as to herbicides that inhibit acetolactate synthase, acetyl‐CoA carboxylase and hydroxyphenylpyruvate dioxygenase, stacked with glyphosate and/or glufosinate resistance, will become available in the next few years. These technologies will provide additional weed management options for farmers, but will not have all of the positive effects (reduced cost, simplified weed management, lowered environmental impact and reduced tillage) that glyphosate‐resistant crops had initially. In the more distant future, other herbicide‐resistant crops (including non‐transgenic ones), herbicides with new modes of action and technologies that are currently in their infancy (e.g. bioherbicides, sprayable herbicidal RNAi and/or robotic weeding) may affect the role of transgenic, herbicide‐resistant crops in weed management. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Punch planting, flame weeding and stale seedbed for weed control in row crops

Punch planting is introduced as a new method to reduce weeds within rows in organically grown crops. In this method a hole is punched in the soil, and a seed is dropped into it, without seedbed preparation and soil disturbance outside the hole. In 2 years, punch planting with flame weeding, normal planting with flame weeding and normal planting without flame weeding were compared in fodder beet for five planting dates. Each planting date represented a lag‐period since establishment of the stale seedbed. Over all planting times and years, punch planting with flame weeding reduced intra‐row weed densities by 30% at the two to four leaf stage of fodder beet compared with normal drilling with flame weeding. Punch planting with flame weeding also reduced intra‐row weed densities by 50% compared with normal drilling without flame weeding. In general, there was no improved performance of punch planting with flame weeding over years by later planting, but delayed planting reduced intra‐row weed densities significantly. Over 2 years, 240 day degrees Celsius (4 weeks) planting delay reduced intra‐row weed densities in the range of 68–86% depending on plant establishment procedure. Punch planting with flame weeding offers a promising method of weed control in organic farming.     

Simulating evolution of glyphosate resistance in Lolium rigidum II: past, present and future glyphosate use in Australian cropping

Glyphosate is a key component of weed control strategies in Australia and worldwide. Despite widespread and frequent use, evolved resistance to glyphosate is rare. A herbicide resistance model, parameterized for Lolium rigidum has been used to perform a number of simulations to compare predicted rates of evolution of glyphosate resistance under past, present and projected future use strategies. In a 30‐year wheat, lupin, wheat, oilseed rape crop rotation with minimum tillage (100% shallow depth soil disturbance at sowing) and annual use of glyphosate pre‐sowing, L. rigidum control was sustainable with no predicted glyphosate resistance. When the crop establishment system was changed to annual no‐tillage (15% soil disturbance at sowing), glyphosate resistance was predicted in 90% of populations, with resistance becoming apparent after between 10 and 18 years when sowing was delayed. Resistance was predicted in 20% of populations after 25–30 years with early sowing. Risks of glyphosate resistance could be reduced by rotating between no‐tillage and minimum‐tillage establishment systems, or by rotating between glyphosate and paraquat for pre‐sowing weed control. The double knockdown strategy (sequential full rate applications of glyphosate and paraquat) reduced risks of glyphosate and paraquat resistance to <2%. Introduction of glyphosate‐resistant oilseed rape significantly increased predicted risks of glyphosate resistance in no‐tillage systems even when the double knockdown was practised. These increased risks could be offset by high crop sowing rates and weed seed collection at harvest. When no selective herbicides were available in wheat crops, the introduction of glyphosate‐resistant oilseed rape necessitated a return to a minimum‐tillage crop establishment system.