Rotary Hoe Research Articles

Influence of Organic Fertilization and Soil Tillage on the Yield and Quality of Cold-Pressed Camelina [Camelina sativa (L.) Crantz] Seed Cake: An Alternative Feed Ingredient

Camelina [Camelina sativa (L.) Crantz] oilseed cake has been identified as an alternative protein feedstuff and as a valuable feed resource. Moreover, over the last decades, there has been an increased interest in the organic production of feed supplements. A 2-year field experiment was conducted in a split-plot design with three replications, two main plots (conventional tillage: moldboard ploughing at 25 cm followed by rotary hoeing at 10–15 cm, and minimum tillage: chiseling at 25 cm depth followed by rotary hoeing at 10–15 cm), and three sub-plots (organic fertilization type: untreated, vermicompost, and compost) to evaluate the fertilization and tillage system effect on the yield and quality of cold-pressed camelina seed cake. Seed yield and cake yield were only affected by organic fertilization, with the highest values observed in the compost treatment. Crude protein was influenced by both factors examined, and the greatest content was found under conventional tillage and compost application. As for the fatty acid composition of oilseed cake, this can be characterized as a major source of polyunsaturated fatty acids (~52% of total FAs), particularly linoleic acid and α-linolenic acid, which were only affected by fertilization, with the highest values found after compost application. To conclude, the cold-pressed cake from camelina seed cultivated under compost fertilization and conventional tillage appears to be an effective alternative to conventionally used protein feed ingredients.

Interactions between Intrinsic Soil Properties and Deep Tillage in the Sustainable Management of Perennial Crops

Choosing the appropriate management system is essential for sustainable agricultural practices. Yet, soil-specific properties at the subsurface are seldom considered when choosing the appropriate tillage system. This study assessed the effect of tillage depth on physical–hydraulic properties in three contrasting soil classes in the establishment of perennial crops. Tillage practices were evaluated in soils with natural dense layers (Inceptisols and Ultisols), and soils with very small and stable granular structure (Oxisols). From least to most aggressive, tested tillage systems included surface furrowing + plant holes (MT); plowing followed by two diskings + furrowing (CT); plowing followed by two diskings + subsoiling (SB); and plowing followed by two diskings + rotary hoeing (DM). Physical indicators with the greatest explanatory power were relative field capacity (RFC, 97%), aeration capacity (AC, 95%), macroporosity (Pmac, 95%), the S index (Sgi, 89%), and bulk density (Bd, 81%). DM caused the greatest modification in soil structure, especially at the surface. It increased values of AC, Pmac, and Sgi, and reduced Bd values. Only deep tillage systems (DM and SB) improved soil structure in deeper layers. Highest Bd values were observed for MT (1.47 g cm−3), and lowest for DM (1.21 g cm−3). Soil classes responded differently to soil tillage systems. DM was most effective in soils with densified layers (Inceptisol and Ultisol). Effects were less expressive in the studied Oxisol. Comparing MT and DM, Pmac increased by more than 100% in the studied Ultisol, but by less than 20% in the Oxisol. No tillage system affected the Oxisol’s soil structure in deeper layers, due to its small and stable granular structure. The choice of optimal tillage strategies should consider soil-specific properties, especially at greater depths, to guarantee more productive and sustainable crop systems.

Deep Tillage Strategies in Perennial Crop Installation: Structural Changes in Contrasting Soil Classes.

Tillage modifies soil structure, which can be demonstrated by changes in the soil’s physical properties, such as penetration resistance (PR) and soil electrical resistivity (ρ). The aim of this study was to evaluate the effect of deep tillage strategies on three morphogenetically contrasting soil classes in the establishment of perennial crops regarding geophysical and physical-hydric properties. The experiment was conducted in the state of Minas Gerais, southeastern Brazil. The tillage practices were evaluated in Typic Dystrustept, Rhodic Hapludult, and Rhodic Hapludox soil classes, and are described as follows: MT—plant hole; CT—furrow; SB—subsoiler; DT—rotary hoe tiller; and DT + calcium (Ca) (additional liming). Analyses of PR and electrical resistivity tomography (ERT) were performed during the growing season and measurements were measured in plant rows of each experimental plot. Undisturbed soil samples were collected for analysis of soil bulk density (Bd) at three soil depths (0–0.20, 0.20–0.40, and 0.40–0.60 m) with morphological evaluation of soil structure (VESS). Tukey’s test (p < 0.05) for Bd and VESS and Pearson linear correlation analysis between Bd, ρ, and PR were performed. Soil class and its intrinsic attributes have an influence on the effect of tillage. The greatest effect on soil structure occurred in the treatments DT and DT + Ca that mixed the soil to a depth of 0.60 m. The ρ showed a positive correlation with Bd and with PR, highlighting that ERT may detect changes caused by cultivation practices, although ERT lacks the accuracy of PR. The soil response to different tillage systems and their effects on soil structure were found to be dependent on the soil class.

Nesting Refuge Structures Are Ineffective at Protecting Bell's Turtle (Myuchelys bellii) Nests from Red Fox (Vulpes vulpes) Depredation

Invasive red foxes (Vulpes vulpes) are a serious conservation issue for Australia's freshwater turtle species, including the endangered Bell's turtle (Myuchelys bellii). As many as 96% of Australian freshwater turtle nests may be depredated in a season by foxes. Current methods of turtle nest protection rely on early detection of nesting activity, followed by nest-specific structures to prevent predation. An alternative method to provide protection against fox raiding was tested: nesting refuge structures based on a design successfully used in the United States to protect diamondback terrapin (Malaclemys terrapin) nests. Six wood and chicken wire structures were placed at different sites beside large riverine pools on the Macdonald and Gwydir rivers, northeastern New South Wales, Australia, in the summers of 2019–2020 and 2020–2021. Sites were chosen for known previous nesting activity or presence of mature females, and each structure was placed in typical Bell's turtle nesting habitat at known nesting sites. Prior to placement, the soil was tilled with a rotary hoe to make the interior of the structure more enticing as nesting habitat, because Bell's turtles had been previously seen to nest in disturbed soils. Although females did approach the structures and in one case entered, no females were recorded nesting inside. Further, severe flooding in both years damaged and/or displaced 4 of the 6 structures. Rigid nest protection structures were therefore not shown to be an effective nest protection method for this species, despite their success in other regions for other species. Negative results such as these are important for conservation studies because they guide conservation efforts away from expending limited resources on ineffective methods and strategies.

Impacto do manejo do solo nas propriedades físicas de um latossolo vermelho da região de ‘Campos de Cima da Serra’, Rio Grande do Sul

The expansion of cultivation areas, especially in the last decade, has changed the landscapes of ‘Campos de Cima in Serra’ ofRio Grande do Sul state, where livestock activity has been developing for 300 years. The introduction of silviculture, grain crops, andorchards, in addition to the cultivation of vegetables, have imposed different managements on the soils, ranging from direct planting to the use of rotary hoes. This work sought to evaluate the impact of different types of soil management on the physical properties and water infiltration capacity of a ferralsol, typical of this region of the north of Rio Grande do Sul state. The soil under the management of native grazing fields showed lower particle and bulk densities and resistance to penetration, while soil planted on garlic crops showed greater resistance to penetration, particle and bulk densities, and lower total porosity and macroporosity. The average infiltration speed was 29.2 mm∙h-1 for the native field under grazing (T1), 65.4 mm∙h-1 for planting on soybean straw (T2), and 20.0 mm∙h-1 for planting on garlic crop (T3). It was observed that intensive management, such as the use of the rotary hoe, had a considerable negative impact on the physical properties and the speed of water infiltration in the soil and, consequently, potential damage to the replenishment of underground deposits, when compared with direct planting and the native field.

Pamuk ekim alanlarında Ipomoea triloba L. (pembe çiçekli akşam sefası)’nın mücadele olanaklarının belirlenmesi

Cotton (Gossypium hirsutum L.) is used as the raw material in more than fifty industries and is also the main source of raw materials used in the textile, the oil, the animal feed, and the paper industries. Additionally, it is a crop of great economic importance for its producer countries with the added value and employment opportunities. Cotton is among the crops sensitive to weed competition and its yield decreases with the weeds. For this reason, weed control treatments should be employed effectively to obtain high yields in cotton fields. In the recent years, Ipomoea triloba (IPOTR), which has increased in its importance in the agricultural areas of the Mediterranean Region, prevents the development of the cotton because of its invasive features and causes the harvest difficulties during by hand or machine harvest. The aim of this study is to create an effective control program against IPOTR in cotton. Field experiments were carried out in Ceyhan, Adana, Turkey in 2018 and 2019. For this purpose, impact of the treatments including Pyroxasulfone 85% (PYRS) Trifloxysulfuron sodium 75% (TRFS), Pyrithiobac-sodium 383 g/l (PYBS), Glyphosate isopropylamine salt 480 g/l (GLYI), S-metolachlor 915 g/l + Benoxacor 45 g/l + hand hoe (SMEC), inter-row rotary hoe + intra-row hand hoe (FÇEÇ) were investigated 28 day-after treatment and at the harvest during two years. It has been determined that TRFS and PYBS have an efficacy over 90%, while FÇEÇ, SMEÇ, TRFS and PYBS applications have an efficacy over 60%. Applications against IPOTR have increased the cotton lint and yield. However, crop injury was observed after GLYI application (20%).

Torque and power demand of agricultural equipment activated by power take-off

The agricultural tractor is the main mobile energy source in rural companies, with power take-off being one of the most important uses of the energy produced by the engine. This study evaluates the torque and power demand required to activate active parts of agricultural equipment through tractor power take-off in different working condi­tions. For this, a boom sprayer, an atomizer, a rotary hoe, and a rotary ditcher were used. The experimental de­sign for the sprayers was completely randomized, with working pressures of 150, 240, and 310 kPa for the boom sprayer and flow rates of 11.5, 13.0, and 22.0 L min h -1 for the atomizer. The randomized block experimental design, in a bi-factorial design (3 x 2), was used for the rotary hoe and rotary ditcher, with three speeds (2.10; 2.60 and 3.10 km h -1 ) and two soil conditions for the rotary hoe (one harrowing and two harrowings) and two working depths for the rotary ditcher (0.10 m and 0.20 m). Torque and power values were obtained using a torque indicator installed between the power take-off and the universal joint shaft, which links the tractor to the equip­ment. From the data obtained, it was concluded that the boom sprayer demanded the highest torque and power at the highest working pressure. The rotary ditcher increased torque and power demand as speed and working depth increased.

Slow movement of alkali from surface-applied lime warrants the introduction of strategic tillage for rapid amelioration of subsurface acidity in south-western Australia

Conventional surface-application of agricultural lime takes many years to increase pH deeper in the soil profile, which is a barrier to increased adoption of liming. We conducted a series of experiments to measure the rate of vertical movement of alkali and identify the factors that determine this movement into the subsurface, to evaluate the feasibility of ameliorating acidic subsurface soil using residual (undissolved) lime (CaCO3) at Wongan Hills (30.85°S, 116.74°E) and Merredin (31.48°S, 118.21°E) and to test whether deep tillage and lime incorporation can significantly speed up the amelioration of subsurface soil acidity at Kalannie (30.42°S, 117.29°E). Multiple applications of lime to the surface of the soil at higher rates (total 6–8.5 Mg ha–1) significantly increased subsurface soil pH but only in the 0.10–0.20 m depth by 0.049 pH units per year over 10–24 years. A large proportion of the surface-applied lime was stratified in the top few centimetres of the soil and incorporation of this undissolved lime with a rotary hoe to a depth of 0.25 m significantly increased soil pH (by 0.63 units) within a year in the Wongan Hills field experiment. Deep incorporation of 6 Mg ha–1 lime to a depth of 0.45 m through excavation and spading with a small rotary hoe also increased soil pH by more than a unit and decreased Al concentration to below the toxic level within two months in the Kalannie experiment, allowing wheat (Triticum aestivum L.) plants to produce root systems up to 0.59 m deep compared with 0.26 m for the control. Our soil column leaching experiment indicated that surface incorporation of lime in higher rainfall regions can be useful to treat subsurface soil acidity but that the rate of improvement in subsurface pH was slow. Therefore, deeper incorporation of lime using cost-effective strategic deep tillage is likely to be necessary.

Strategic tillage of a long-term, no-till soil has little impact on soil characteristics or crop growth over five years

Strategic tillage describes the occasional use of tillage in an otherwise no-till system. The practice can provide a pragmatic solution to emerging agronomic issues in no-till systems but raises concerns about prolonged or irreversible soil damage. We investigated the impact of a single tillage event at a long-term no-till experiment under treatments with retained or annually autumn-burned crop residues. One half of each residue-treatment plot received a single pass of a rotary hoe (ST) 4 weeks before sowing in 2011, the first year of the experiment; the other half of each plot remained unchanged (NT). Soil physical, chemical and biological fertility in the surface layers (0–20 cm), as well as crop growth and yield were monitored for 5 years (2011–15). Following the ST treatment, soil bulk density and strength were initially reduced to the depth of cultivation (~15 cm) irrespective of residue treatment. Water-stable macroaggregates in the surface 0–5 cm were also reduced but recovered to pre-tillage levels within 1–2 years after ST treatment. Soil pH, total carbon (C), total nitrogen (N), and fine-fraction C and N were all initially stratified in the surface layer (0–5 cm) of the NT treatment but were redistributed more evenly throughout the 0–10 cm layer of the ST treatment and remained so throughout the 5-year period. With ST, there was an initial loss in total C stocks in the 0–10 cm layer of 2.2 t/ha, which recovered within 2 years; however, total C stocks remained lower in plots with stubble retained than with stubble burnt after 5 years. Soil Colwell P levels were not stratified and not influenced by tillage treatment, presumably because of the annual additions in the starter fertiliser at sowing. ST had no impact on crop establishment or grain yield in any year but increased the early biomass of wheat at Z30 compared with NT in the first 2 years. Annual stubble retention reduced the early growth of crops in all years, and yield of wheat in the first 3 years, consistent with long-term effects of retained stubble at the site, but there was no interaction between stubble retention and tillage treatments on soil conditions or crop growth. Crop yields of long-term, annually cultivated treatments were also similar to those of ST and NT treatments during the 5 years of the experiment. Overall, the minor short-term negative impacts on soil physical conditions, the persistent and arguably beneficial effects on soil chemistry and biology, and absence of impacts on crop production suggest that strategic tillage can be a valuable agronomic tool in sustainable production in this region.

Algorithm of engineering calculation of stability of a multifunctional unit

In the MFA under consideration, in addition to the rotary hoe, a front hopper for fertilization is installed on the front hitch of the tractor. According to G. M. Kutkov, it refers to additional equipment which expands the functionality of the tractor. The assessment of the tractor’s load capacity and stability is considered in the works of many educational institutions. We have supplemented these theoretical provisions in relation to the proposed MFA with additional technological equipment of the tractor.

Increased seeding rate and multiple methods of mechanical weed control reduce weed biomass in a poorly competitive organic crop

Weed management in organic lentil (Lens culinaris Medik.) is challenging due to its poorly competitive nature with weeds and the lack of organic herbicides for field crops. In-crop mechanical weed control methods such as rotary hoeing, harrowing and inter-row cultivation, and the cultural practice of increased crop seeding rate, are established weed management tools in organic field crops. They have however not previously been combined into an integrated weed management system for weakly competitive grain crops. The objective of this research was to determine the effect of mechanical weed control (rotary hoeing, harrowing and inter-row cultivation) and crop seeding rate alone and in combination on weed suppression and yield in organic lentil. A two-factor randomized complete block design experiment was conducted at two locations in Saskatchewan, Canada in 2016 and 2017. The factors mechanical weed control methods including the rotary hoe, the harrow and inter-row cultivation and an untreated control, and seeding rates including conventional recommended and double recommended seeding rate. All treatments were tested as stand-alone or combined in a factorial fashion. Increased crop seeding rate and mechanical weed control affected response variables independently of each other. Doubling the seeding rate of lentil reduced weed biomass by 16% and increased lentil yield by 23% averaged across the four site-years. Treatments that included only a single mechanical weed control methods resulted in poor or incomplete weed suppression at all sites. Two mechanical weed control methods were required to maximize yield, and three were required to minimize weed biomass. Early weed control with a rotary hoe, followed by inter-row cultivation prior to canopy closure was the most consistent mechanical weed control treatment across the four site-years. Averaged across the four site-years, rotary hoeing + inter-row cultivation reduced weed biomass by 70%, and increased crop yield by 65%. The treatment maintained low weed populations across the longest time duration and controlled weeds in both the inter- and intra-row spaces, while minimizing crop injury. Doubling crop seeding rate and using two appropriately timed mechanical weed control methods provided weed suppression while increasing yield by 46% in a weakly competitive organic lentil crop.

BED TEMPERATURE IN COMPOST BARNS TURNED WITH ROTARY HOE AND OFFSET DISC HARROW

ABSTRACT The success of confinement for dairy cattle in the compost barn model depends mainly on the management of the bed and consists of its turning. This paper characterises the spatial variability of the bed temperature in the compost barn confinement model, as well as verifying whether there was an effect on efficiency from turning the bed with different agricultural implements. The experiment was conducted during the summer and winter of 2016, with 8 days of collection in each period. Data were analysed with descriptive statistics methods and geostatistical modelling with semivariograms and kriging maps. The results of the t-test at a5% significance level indicated that, after turning the bed with the plough or rotary hoe, the temperature values were significantly lower. There was an efficient on bed turning based on different agricultural implements. Spatial dependence was observed on the data, with a better adjustment given by a Gaussian model. Kriging maps allowed the characterization of the spatial variability of bed temperature and the visualization across the compost barn bed at the superficial layer and 0.15 m in depth.

Using energy requirements to compare the suitability of alternative methods for broadcast and site-specific weed control

AbstractThe widespread use of herbicides in cropping systems has led to the evolution of resistance in major weeds. The resultant loss of herbicide efficacy is compounded by a lack of new herbicide sites of action, driving demand for alternative weed control technologies. While there are many alternative methods for control, identifying the most appropriate method to pursue for commercial development has been hampered by the inability to compare techniques in a fair and equitable manner. Given that all currently available and alternative weed control methods share an intrinsic energy consumption, the aim of this review was to compare methods based on energy consumption. Energy consumption was compared for chemical, mechanical, and thermal weed control technologies when applied as broadcast (whole-field) and site-specific treatments. Tillage systems, such as flex-tine harrow (4.2 to 5.5 MJ ha−1), sweep cultivator (13 to 14 MJ ha−1), and rotary hoe (12 to 17 MJ ha−1) consumed the least energy of broadcast weed control treatments. Thermal-based approaches, including flaming (1,008 to 4,334 MJ ha−1) and infrared (2,000 to 3,887 MJ ha−1), are more appropriate for use in conservation cropping systems; however, their energy requirements are 100- to 1,000-fold greater than those of tillage treatments. The site-specific application of weed control treatments to control 2-leaf-stage broadleaf weeds at a density of 5 plants m−2 reduced energy consumption of herbicidal, thermal, and mechanical treatments by 97%, 99%, and 97%, respectively. Significantly, this site-specific approach resulted in similar energy requirements for current and alternative technologies (e.g., electrocution [15 to 19 MJ ha−1], laser pyrolysis [15 to 249 MJ ha−1], hoeing [17 MJ ha−1], and herbicides [15 MJ ha−1]). Using similar energy sources, a standardized energy comparison provides an opportunity for estimation of weed control costs, suggesting site-specific weed management is critical in the economically realistic implementation of alternative technologies.

Tillage effects on soil physical condition and root growth associated with sugarcane water availability

We hypothesized that in-row deep tillage (DT) may improve crop resilience during dry spells through change in the soil physical/hydraulic properties, in root system development and yield. The objective of this study was to gain insight into the influence of this management on soil physical properties and root growth associated with sugarcane water availability. A three-year experiment on a sandy-clay haplustox was used for the assessment of water retention, bulk density, porosity, pressure head, temperature and plant response (yield and root system). Soil carbon stocks were also assessed in the soil profile. The treatments compared of conventional tillage (CT), which consisted of a 0.3 m ploughing followed by two disking graders with 20″ discs and one light disking leveler grade, and DT, a subsoiler rod (0.8 m deep) with a rotary hoe with 16 knives to raise crop seedbed in rows. Our results reveal that DT resulted in lower bulk density and higher total porosity values than CT in most cases for the surface soil layers. Moreover, while the soil water relations did not show significant difference for total water availability, the soil water pressure head monitoring indicated a trend of more negative values under CT management, i.e., a drier condition. Additionally, DT resulted in better root system development referring to root density and root length density. However, DT resulted in lower sugarcane yield. The experiment was carried out under rainfed conditions, but rainfall distribution did not limit sugarcane production. Therefore, under the mild water stress conditions as observed in this study, the observed root biomass increase did not favor sugarcane yield.

Soil CO2 emission and short-term soil pore class distribution after tillage operations

Alongside the agricultural development in Brazil, concerns have arisen about its environmental impacts, such as the emissions of CO2 resulting from soil cultivation and management practices in agricultural production systems. The aim of this study was to investigate the temporal variation in CO2 emissions and soil physical attributes in response to the process of soil particle rearrangement after soil tillage operations. The study was conducted in three adjacent areas of 10 × 3 m, subjected to two soil tillage systems: (i) rotary hoe + conventional leveling harrow, representing an intensive soil tillage (IT); (ii) disc harrow + leveling harrow, characterizing a reduced tillage (RT). The soil of the third area was not tilled, representing the no-tillage (NT) system. Daily measurements of soil CO2 emission (FCO2), soil temperature, soil moisture, pore class distribution, bulk density, penetration resistance, water-free pore space, weighted mean diameter, aggregate stability index, total organic carbon, and particulate organic carbon were performed during a period of 29 days after soil tillage. On the first day after tillage, FCO2 was 87% higher in the plot under IT (3.86 μmol m−2 s−1) than RT (2.06 μmol m−2 s−1) and 147% higher than in the plot under NT (1.56 μmol m−2 s−1). The variations in soil density and penetration resistance declined as of the 12th day after tillage. This effect was considered a natural process of soil consolidation and influenced the temporal variation of soil CO2 emissions. Pore class distribution is an essential physical attribute to explain the temporal variations of soil CO2 emissions, and these classes are influenced by the applied management. Therefore, the study of these attributes must be taken into account when assessing the variation of CO2 emissions from agricultural soils.

Auto-steering based precise coordination method for in-field multi-operation of farm machinery

Multi-operation within a field and multi-machinery within a machinery operation are common in the scene of scaled farm machinery service, especially with soaring usage of automated steering system in small and medium machinery cooperatives. The object of this study was to explore a precise and efficient in-field coordination method to realize flow-shop scheduling for farm machinery fleet equipped with RTK-GNSS based auto-steering system. The new method is based on three-dimensional coordinate system (XYZ), within which the concept of field, operation strip, and operation task were defined. Under this concept framework, the operation strip state was further defined and its updating algorithm was designed, which can be used for optimization simulations and experiments. To evaluate the method, the waiting time between simulation and a real-world case was compared, and one cloud based prototype system was developed to demonstrate the practicability in the field by using NX200+ automated steering system. The simulations showed that the in-field coordination can shorten the waiting time between two adjacent operations. The waiting time between rotary hoeing and seeding can be shortened from 4 h to 6.3 min. The field experiment showed that the prototype system could keep good consistency of ridges for a fleet by sharing the guidance line. Keywords: GNSS, auto-steering system, in-field coordination operation, farm machinery, method, simulation DOI: 10.25165/j.ijabe.20181105.3827 Citation: Wang J, Zhu Y T, Chen Z B, Yang L L, Wu C C. Auto-steering based precise coordination method for in-field multi-operation of farm machinery. Int J Agric & Biol Eng, 2018; 11(5): 174–181.

Methods of Soil Management and Depths of Sowing in Corn Cultivation

Corn (Zea mays L.) is one of the most cultivated grains in the world. It provides widely used products such as food, feed, raw materials for industry and ethanol, mainly due to the quantity and nature of its reserves accumulated in the grains. The objective of this research was to evaluate different depths of sowing and the use of different initial methods of soil preparation for growing corn. A randomized-complete blocks design was applied in a split plot with subsoiling, tillage, rotary hoe, ploughing, manual weeding and three sowing depths. Analysis of variance showed a significant difference (p &lt; 0.01) of stem diameter (SD), plant height (PH), root fresh mass (RFM), root dry mass (RDM), aerial dry mass (ADM), aerial fresh mass (AFM), while number of leaves (NL) showed no differences statistically. Regarding to stem diameter, the methods with subsoiling, ploughing and rotating hoe showed the best results. In relation to plant height, the treatments of subsoiling, tillage, ploughing and rotating hoe had the best performances. The use of the subsoiling method showed the best results between the characteristics of the plant and corn yield. The corn yield presented better yields with the subsoiled and rotary hoe preparation.

Meteorological and Management Factors Influencing Weed Abundance during 18 Years of Organic Crop Rotations

AbstractOrganic crop production is often limited by the inability to control weeds. An 18-yr data set of weed cover in organic crop rotations at the long-term Farming Systems Project at Beltsville, MD, was analyzed to identify meteorological and management factors influencing weed abundance. A path analysis using structural equation models was employed to distinguish between the direct effect of factors on weed cover and the indirect effect on weed cover through effects on crop competitiveness. Grain yield of corn (Zea maysL.) and soybean [Glycine max(L.) Merr.] served as a surrogate for crop competitiveness and was found to be the most important factor influencing weed cover. Precipitation during late vegetative and early reproductive crop growth had a strong positive effect on crop yield, and thereby a negative indirect effect on weed cover, but this effect was partially offset by a positive direct effect on weed cover. Delayed crop planting date and crop rotational diversification including crops other than summer row crops had a moderate negative effect on weed cover, while having minimal effect on crop performance. Rotary hoeing also had a direct negative effect on weed cover, but a corresponding negative effect on crop performance resulted in a diminished total effect on weeds. Results demonstrate the complex interactions that define the relative abundance of weeds faced by organic growers, but, generally, factors that enhanced crop competitiveness provided the most effective weed management.

Integrated weed management in maize-based intercropping systems

Field experiments were conducted to study the effect of intercropping and integrated weed management practices on weeds experiment was conducted at Agricultural College and Research Institute, Madurai (Tamil Nadu) during winter 2013. The experiment was laid out in a split plot design and replicated thrice. The main plots were assigned with three cropping systems, viz. maize, maize + blackgram, maize + cowpea and six weed management practices, Application of pendimethalin at 0.75 kg/ha followed by one rotary hoeing on 35 DAS recorded the highest weed control efficiency (85.9) and reduced weed populations and weed dry matter production at 60 DAS. The maize + cowpea system resulted increased plant height, LAI and dry matter production of maize at 30, 60 and 90 DAS respectively. Application of pendimethalin at 0.75 kg/ha followed by one rotary hoeing on 35 DAS resulted in the highest grain and straw yield of maize 6.05 and 18.15 t/ha, respectively.

Developing an Integrated Weed Management System for Herbicide-Resistant Weeds Using Lentil (Lens culinaris) as a Model Crop

The escalating evolution of weed species resistant to acetolactase synthase (ALS)-inhibitor herbicides makes alternative weed control strategies necessary for field crops that are dependent on this herbicide group. A fully integrated strategy that combined increased crop seeding rates (2X or 4X recommended), mechanical weed control with a minimum-tillage rotary hoe, and reduced-rate non–ALS inhibitor herbicides was compared with herbicides, rotary hoe, and seeding rates alone as a method of controlling ALS inhibitor–tolerant Indian mustard as a model weed. The full-rate herbicide treatment had the lowest weed biomass (98% reduction) and the highest yield of all treatments in 3 of 4 site-years, regardless of seeding rate. The fully integrated treatment at the 4X seeding rate had weed suppression rates equal to the full herbicide treatment at the recommended seeding rate. The fully integrated and reduced-rate herbicide treatments at the 4X seeding rate reduced weed biomass by 89% and 83%, respectively, compared with the control at the recommended seeding rate. The rotary hoe treatment alone resulted in poor weed control (≤38%), even at the highest seeding rate. Fully integrated and reduced-rate herbicide treatments at 2X and 4X seeding rates had yields equal to those of the full herbicide treatment at the recommended seeding rate. Partially or fully integrated weed control strategies that combine increased crop seeding rates and reduced-rate non–ALS inhibitor herbicides, with or without the use of a rotary hoe, can control weeds resistant to ALS-inhibitor herbicides, while maintaining crop yields similar to those achieved with full-rate herbicides. However, combining increased seeding rate, reduced-rate herbicides, and mechanical rotary hoe treatment into a fully integrated strategy maximized weed control, while reducing reliance on and selection pressure against any single weed control tactic.