Oat Densities Research Articles

Morphogenic characteristics of black oat and vetch under different densities

The objective of this study was to assess the morphogenic characteristics Avena strigosa and Vicia sativa plants cultivated in different sowing densities. The experiment was conducted in vases with farming soil. The experimental design involved randomized units, with four repetitions, consisting of a single vetch plant placed in the centre of each experimental unit and a variable number of oat plants (0, 1, 2, 3, 4, and 5) planted around the borders. The same procedure was also conducted with a single oat plant placed in the centre of the vase and a variable number of vetch plants (0, 1, 2, 3, 4, and 5) planted around the borders. The plants were grown for a total of 35 days. Morphogenic characteristics of the central plant were assessed at the time of transplantation as well as every 7 days. It was observed that the density increase in vetch plants did not significantly influence stem elongation, plant elongation, and leaf senescence rates of oat plants. However, higher densities did reduce the tiller appearance rate in oat plants. Increases in oat density caused significant impacts on the elongation rate and linear growth in the leaf senescence rate and reduced the number of ramifications in vetch plants. Higher density caused reduced leaf appearance and tiller rates while increasing phyllochron values. The results of this study indicate that increases in plant density trigger competition responses in both oat and vetch, which in turn negatively affect many of the assessed morphogenic characteristics for both species.

Harmonious impacts of allelopathic bacteria with chemical herbicides for sustainable production of wheat (<i>Triticum aestivum</i> L.) under wild oat (<i>Avena fatua</i> L.) infestation

Weeds are one of the major limiting factors for wheat production. So, a study was conducted to integrate allelopathic bacteria with reduced dose of chemical herbicide for sustainable wheat production in wild oat infestation. Cyanide-producing Pseudomonas strains were applied in four combinations with and without two chemical herbicides (Axial and Atlantis) at 25% and 50% recommended dose under axenic conditions. Results showed that C4 combination significantly reduced growth and development of wild oat under 50% Axial while increase wheat growth. Afterward, C4 combination and Axial herbicide were selected for field evaluation, where it reduced the weed density (82.1%), SPAD value (26.0%) and grain yield (88.2%) under 75% Axial, and relative wild oat density (70.9%), photosynthetic rate (26.6%) and transpiration rate (25.6%) under 50% Axial in wild oat. While C4 combination improved SPAD value (26.9%), shoot length (10.1%), tillering (33.3%), biological yield (32.7%), straw yield (24.4%), grain yield (46.8%), transpiration rate (9.6%) and stomatal conductance (14.7%) in wheat under 75% Axial. The increase in growth and yield of wheat was found at par with C4 under 50% and 75% Axial. Thus, it is concluded that allelopathic bacteria could be used with 50% Axial for sustainable wheat production under wild oat.

Using spatially-explicit plant competition models to optimise crop productivity in intercropped systems

Intercropping, by capitalizing on positive biodiversity–productivity relationships, represents a promising option to increase agricultural sustainability. However, the complexity and context-dependency of plant–plant interactions can make it challenging for farmers to find suitable crop combinations. Furthermore, intercropping is usually implemented with standard inter-row spacing and plant densities based on monoculture practices, which might not be the ideal configuration to maximize yield.Here we present a spatially-explicit yield analysis method based on plant ecological interaction models that allowed to optimize crop species combinations and spatial configurations for maximal yield in intercropped systems. We tested this method with three crop species, namely oat, lupine, and camelina. In a first step, field experiments in which crop density and adjacent crop type were varied provided us with indications on which species would compete more with each other. The results showed us that oat and camelina strongly competed with each other. In addition, the distance experiments allowed us to understand how the changes in yield associated with the presence of neighbors vary with distance. This allowed us to find the sets of parameters (identity of neighbors, sowing density, distances between individuals) that optimise intercrop yield (measured as Land Equivalent Ratio [LER]) for the three considered species. Specifically, we show that alternating rows of species led to higher LERs than a homogeneous species mixing, and that 3-species combinations are not necessarily more performant than the best 2-species combinations. In addition, we show that increasing the density of oat is generally beneficial for LER, while increasing the density of lupine is not.By modelling crop yield from simple and reproducible density and distance experiments, our results allow to optimize crop mixtures in terms of species combinations and spatial configurations, for maximal crop yield.

Influence of agro-landscape on the ecological sustainability of cover oats and perennial herbs phytocenoes

Biodiversity is the cornerstone of modern agro-phytocinology. Based on its records, the ecological sustainability of agricultural landscapes is predicted. The aim of the research was to study the influence of soils and the topography of the terminal moraine hill, as well as the age of phytocenoses, on the value of the coefficient of floristic similarity of oat communities with over-sowing of grasses (2019) and clover-and-timothy herbage of 1 year of use (2020). Monitoring of the botanical composition of phytocenoses was carried out on a transect – a field crossing slopes of different exposures and soils of varying degrees of swampiness, located at the agroecological station All-Russian Research Institute of Reclaimed Lands (VNIIMZ; Tver region, Russia). The standing density of oats, red clover, timothy grass, weed species, as well as other environmental parameters were taken into account on 30 systematically located land plots. It is shown that only a few plant species affect the Jaccard coefficient. The topography and soil features of the agricultural landscape, as well as the age of the plant community, have a significant impact on the stability and productivity of the agrocenosis. The main factor affecting the variability of the floristic similarity indicator is soil hydromorphism. An increase in the index of the floristic similarity coefficient is observed on all soils and slopes as the herbage matures. Productivity of grasses depends to the greatest extent on the nature of the interaction of the relief and soils – on the southern slope of the hill, a low hay yield was noted (on average, 5.34 t/ha), the minimum of which was observed on highly swampy soils (4.92 t/ha), on the northern slope, the yield of hay was higher (on average 6.57 t/ha), the minimum of which was noted on moderately swampy soils (6.26 t/ha). Based on the revealed patterns, it is possible to develop measures to adapt technologies for growing perennial grasses to the natural conditions of farms in the mode of adaptive landscape fodder production.

Quantifying compensation in crop mixtures and monocultures

Compensation can be defined as a process by which a system is able to regain its normal state in response to losing a part of its structure. From genes to individuals to communities, compensatory processes ensure functionality, stability and resilience. While there is a rich literature on compensation in natural and semi-natural communities, as well as for crop monocultures, quantification of compensation in the context of diversified agro-ecosystems, such as binary crop mixtures, has remained underdeveloped. We elaborate a method of quantifying compensation which is consistent across systems of only one component (monocultures) and two component-systems (mixtures). Using plant communities and their response to loss of plant density as an example, we apply this concept to a published data set on experimentally grown monocultures and mixtures of beans and oats. Against loss of plant density, oat and bean monocultures compensated 46 % and 33 % of grain yield, respectively. Compensation in the mixture was small (9%) when compensating loss of bean density, but larger (42 %) when bean density was fixed, compensating against loss of oat density. Remarkably, in the case of fixed bean density, the mixtures did not show a higher degree of compensation than the oats monoculture (i.e. where bean density is fixed at zero seeds). Further, we generalize this approach by characterizing four variables, the Contributor (which suffers the loss that needs to be compensated; e.g. plant density), the Reductor (which leads to a reduction in the Contributor; e.g. a mortality factor reducing plant density), the Outcome (which is the variable of interest that directly depends on the Contributor; e.g. grain mass per unit area), and the Compensator (which represents the variable responsible for the compensation, e.g. the grain mass per remaining plant) and summarize this as the ‘CROC’ model of compensation. We provide a framework for quantitative research on compensation in intercropping and other contexts, and its relationship to resilience and stability. The analysis of compensation in mixtures can help to develop the potential of diversification for improving multifunctional performance of agro-ecosystems, especially in response to biotic and abiotic stresses.

Long-term organic and conventional farming effects on nutrient density of oats

AbstractDeclining nutrient densities of crops in the past 50–70 years have been attributed to unsound agricultural practices and plant breeding focus on yield rather than quality. Few studies have quantified the soil and nutritional quality of grains in organic and conventional farms and reported results are scarce and inconsistent. The Rodale Institute's Farming Systems Trial (FST) was established in 1981 to quantify the effects of long-term organic and conventional grain cropping systems and tillage practices. A 2014 study to quantify effects on the nutrient density of oat grains was integrated into three systems within the long-term trial: organic manure-based (MNR), organic legume-based (LEG), and conventional synthetic input-based (CNV), split between tilled (T) and no-till (NT) practices. Oat grains with hulls removed were analyzed for minerals (n = 24), vitamins (n = 24), amino acids (n = 24) and proteins (n = 24), while soil samples to a depth of 10 cm were analyzed for elemental minerals, and total carbon (C), nitrogen (N) and sulfur (S). Organic systems increased six out ten soil minerals whose concentrations were influenced by cropping systems: aluminum (Al), iron (Fe), chromium (Cr), calcium (Ca), barium (B) and strontium (Sr). All essential amino acids were greater in oat grains under LEG systems compared with other systems except lysine, histidine and methionine. Both LEG systems also increased 12 out of 13 non-essential amino acids in oat grains. Total oat N, C and S required for amino acid synthesis tended to be greater in organic systems. Soil N, C and S were highly correlated with total oat amino acids under organic systems compared to CNV. Organic LEG had significantly greater vitamin B1 than MNR and CNV. These results suggest that nutrient concentrations of oat grains were greater in organic systems compared to CNV systems, and the increase could be partially explained by the long-term soil management differences between the systems.

Evaluation of panicle removal methods and crop topping applications as supplemental tools for wild oat (Avena fatua) management

AbstractIncreased frequency and occurrence of herbicide-resistant biotypes heightens the need for alternative wild oat management strategies. This study aimed to exploit the height differential between wild oat and crops by targeting wild oat between panicle emergence and seed shed timing. Two field studies were conducted either in Lacombe, AB, or Lacombe, AB and Saskatoon, SK, from 2015 to 2017. In the first study, we compared panicle removal methods: hand clipping, use of a hedge trimmer, and a selective herbicide crop topping application to a weedy check and an industry standard in-crop herbicide application in wheat. These treatments were tested early (at panicle emergence), late (at initiation of seed shed), or in combination at one location over 3 yr. In the second study, we investigated optimal timing of panicle removal via a hedge trimmer with weekly removals in comparison to a weedy check in wheat and lentil. This study was conducted at two locations, Lacombe, AB, and Saskatoon, SK, over 3 yr. Among all the tested methods, the early crop topping treatment consistently had the largest impact on wild oat density, dockage, seedbank, and subsequent year crop yield. The early (at panicle emergence) or combination of early and late (at initiation of seed shed) treatments tended to reduce wild oat populations the following season the most compared to the late treatments. Subsequent wild oat populations were not influenced by panicle removal timing, but only by crop and location interactions. Panicle removal timing did significantly affect wild oat dockage in the year of treatment, but no consistent optimal timing could be identified. However, the two studies together highlight additional questions to be investigated, as well as the opportunity to manage wild oat seedbank inputs at the panicle emergence stage of the wild oat lifecycle.

CARBON, NITROGEN, AND ORGANIC MATTER OF SOIL IN AN INTEGRATED CROP-LIVESTOCK SYSTEM

This study aimed to evaluate the effect of the integrated crop-livestock system on the contents and stocks of total organic carbon, total nitrogen, and soil organic matter. The experiment was carried out between April 2016 and February 2017, in a randomized block design in a strip-block scheme, with additional control treatment (fallow) and four repetitions. The treatments consisted of two densities of oat sowing (40 and 60 kg ha-1) in strips A and different grazing frequencies (without grazing - WG, one grazing - 1G, and two grazing - 2G) in strips B, besides fallow as a control treatment. The determinations of the contents of total organic carbon (TOC), total nitrogen (TN), and organic matter (SOM) were carried out in the soil layers of 0-5, 5-10, and 10-20 cm. Samplings were carried out after oat management, in the winter, and after soybean harvest, in the summer. The sowing density of black oats and the grazing frequencies were not able to promote changes in the total organic carbon and in the TOC stock, regardless of the time of evaluation. The use of 40 kg ha-1 of oat seeds would be recommended, as it does not promote changes in the increase in MOS, thus generating savings in the acquisition of seeds. The use of the lowest density of oat without grazing and one grazing promoted changes on the total nitrogen in the 5-10 cm layer after the removal of oats, when compared to the fallow, and it presented content similar to the management with two grazings.

Growth and development of spring crops in competition with oat in the dryland Mediterranean climate of eastern Washington

AbstractWeed management during spring crop production in eastern Washington presents many challenges. Many spring crops are weak competitors with weeds. In May of 2010 and 2011, two spring crop trials were initiated near Pullman, WA, to compare the relative competitiveness of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), lentil (Lens culinaris Medik.), and pea (Pisum sativum L.) using cultivated oat (Avena sativa L.) as a surrogate for wild oat (Avena fatua L.) competition. The experiment was arranged as a split-block split-plot design with four replications. One set of main plots included three oat density treatments (0, 63, and 127 plants m−2), while a second set included each crop species. Crop species main plots were then split into subplots of two different seeding rates (recommended and doubled). Crop populations decreased as oat density increased and increased as crop seeding rate increased. As oat density increased, preharvest crop biomass decreased for all crops, while oat biomass and yield increased. Oat biomass and yield were greater in legume plots compared with cereal plots. Increasing oat density decreased yields for all crops, whereas doubling crop seeding rate increased yields for barley and wheat in 2010 and barley in 2011. Compared with legumes, cereals were taller, produced more biomass, and were more competitive with oat.

Competitive Interactions of Wild Oat (Avena fatua L.) with Quality and Yield of Wheat (Triticum aestivum L.)

ABSTRACT: Crop-weed competition and interactions are the focus of many researchers to make the weed management decision accurate and economical. Therefore, field studies were conducted in two consecutive years (2012-13 and 2013-14) at two different locations viz Peshawar (34.0167o N, 71.5833o E) and Chitral (35o50’46 N, 71o47’9 E) of Khyber Pakhtunkhwa (KPK) province, Pakistan. The aim of the studies was to determine the competitive ability of wild oat (Avena fatua L.) with wheat (Triticum aestivum L.) at two ecologically different locations and the possible effects on quantity and quality of wheat grains. In field studies, the experiment were laid out in randomized complete block design (additive design) with three replications in which the seed rate of wheat (var. Ata-Habib) was 125 kg ha-1 while wild oat was planted at 0, 5, 10, 15, 20, 25, 30, 35, and 40 plants m-2. Field data showed the effects of different wild oat densities during both the years were prominent by significantly decreasing the grain and biological yield-related variables of wheat. Wild oat density above 5 plants m-2 resulted in decreasing the wheat yield components. These results showed that wild oat started competition at initial stage of the wheat. All other yield related variables of wheat were decreased by the increasing density of wild oat, which is indicated that wild oat compete with wheat throughout the crop season. The grain yield losses in wheat ranged from 2-35% during year 1 and 1-21% during year 2 at wild oat density of 5-40 plants m-2. The quality variables of wheat grains showed protein content in wheat grains were decreased at higher density of wild oat. During year 2, the gluten content in Chitral was decreased with increasing density of wild oat. In light of the present studies, it is suggested that presence of wild oat decrease all eco-biological yield related variables of wheat.

Organic Matter Fractions and Carbon Management Index in Oxisol Under Integrated Agricultural Production Systems

This work aimed to evaluate the oxidizable and chemical fractions of organic matter and the carbon management index in different integrated agricultural production systems, hay production and native forest areas in an Oxisol. Nine areas with different management systems were evaluated being six managements of the combination between different oat density (40 and 60 kg ha-1) and grazing frequencies (0, 1 and 2) in autumn-winter and soybean succession in spring-summer, one with natural reseeding ryegrass and forage turnip in autumn-winter and soybean succession in spring-summer and two reference areas. In each soil management systems were collected soil samples composite in the 0-5, 5-10 and 10-20 cm layers and determined the Total Organic Carbon (TOC), humic substances (Fulvic Acids - FA, Humic Acids - HA and humin - HUM), the carbon in the oxidizable fractions (F1, F2, F3 and F4) and Carbon Management Index (CMI). Were observed that chemical, oxidizable fractions and CMI, do not have significant differences between with the various managements each other. For TOC, HA, HUM, F1, F3, F4 and CMI, the managements did not differ from the reference areas indicating maintenance of soil carbon.

Seeding densities of the oat crop and the amount of grazing on the physical property and soil carbon

The objective of this study was to evaluate the effect of two sowing densities of oat crop, managed in an integrated crop-livestock system (ICLS), or the use of fallow during the winter period, on the soil physical properties, total carbon and soil carbon stock, in two years. A split-plot in a randomized block design, with additional treatment was used. It was found that the number of grazing in the year 2014 adversely affected the values of macroporosity and microporosity in the layer 0-0.05 m, besides the microporosity in the 0.1-0.2 m layer. The total porosity in the 0.1-0.2 m layer was positively influenced by the sowing density of oats only in the year 2014. The soil penetrometer resistance (SPR) had changes after winter 2015, at 0-0.05 m due to the number of grazing. During 2014, there were no changes in the total carbon and carbon storage of the soil. In 2015, the amount of grazing used, negatively affected the total carbon in layers 0-0.05 and 0.1-0.2 m. However, it positively affected the storage of carbon in soil in the layer 0.05-0.1 m. The adoption of the lower density of the oat crop with realization of a grazing tends to improve the physical properties, total carbon and soil carbon stocks.

Balancing Objectives in an Organic Oat Rotation Year: Implications of Planting Date and Crop Density

Core Ideas Yield, test weight, and returns over seed cost were greatest at early planting dates. Early planting optimized forage establishment and weed suppression in one site‐year. Increasing oat density increased yield in one site‐year, and test weight overall. Target oat density had no effect on returns over seed cost. Oat (Avena sativa L.) is an important component of organic row crop rotations in the Upper Midwest. Our goal was to determine the effects of planting date and crop density on oat grain yield and yield components, test weight, straw yield, underseeded alfalfa and ambient weed biomass, and returns over seed cost. We conducted an experiment on certified organic farmland on an agricultural experiment station near Boone, IA, USA, over 2 yr. A randomized complete block split‐plot design was used to test effects of planting date (6, 17, and 28 Apr. 2015, 22 Mar. 2016, 4 and 15 Apr. 2016) as whole plot and target crop density (161, 236, 312, and 386 plants m–2) as subplot. Planting date had the greatest effect on response variables. Yields decreased by 33 and 9%, respectively, over 2015 and 2016 planting periods. Delayed planting decreased test weight in both site‐years. Alfalfa biomass decreased and weed biomass increased (as a function of delayed planting) in 2016, but had no effect in 2015. Increasing oat density had a positive linear effect on grain yield and test weight, and no effect on alfalfa biomass in both site‐years. Increasing oat density had a negative effect on weed biomass in 2016 and no effect in 2015. Returns over seed cost did not differ among our density treatments in both site‐years. Our results highlight potential no‐cost improvements that can be made to organic oat management to improve grain yield and quality, without negatively impacting forage establishment or weed suppression.

Altering the competitiveness of tame oat (Avena sativa L.) versus wild oat (Avena fatua L.) with phosphorus and seeding rate

Currently, no in-crop herbicide is registered to control wild oat (Avena fatua L.) in tame oat (Avena sativa L.). Wild oat must be controlled in tame oat using other agronomic practices. The objective of this research was to determine if side-banded phosphorus (P) in combination with seeding rate would increase the competitiveness of tame oat with wild oat, increasing yield and quality. An experiment was conducted from 2003–2005 at Indian Head, SK. The experimental design was a strip-plot design with four replications. The strips were low and high wild oat density. A two-way factorial, seeding rate (150, 250, 350, and 450 plants m−2), and P rate (0, 15, and 30 kg P2O5 ha−1) were seeded across the strips. Phosphorus affected seed density, grain yield, oat biomass, and wild oat fecundity. Seeding rate affected most of the measured variables and interacted with wild oat and year. The application of P increased the competiveness of oat by increasing crop biomass by 7.6% and grain yield by 3.4% and decreasing wild oat seed from 1.26% to 0.76% in the harvested grain. Wild oat decreased grain yield by 23% in 2003, 4.4% in 2004, and 11% in 2005. Increasing the seeding rate increased grain yield by 5% when wild oat was present. Wild oat did not interfere with the uptake of side-banded P. Producers need to use both P fertilization and higher seeding rates to improve the competitiveness of tame oat and the management of wild oat in tame oat.

EFFECTS OF WILD OAT (AVENA FATUA L.)DENSITY ON WHEAT (TRITICUM EASTIVUM L.). YIELD AND YIELD COMPONENTS

The experiment was conducted under field condition at Jimma University, College of Agricultures and Veterinary Medicine (JUCAVM) to determine the effect of various wild oats (Avevafatua L.) densities on yield and yield components of Wheat (Triticumeastivum L.). The experiment design used was the randomized complete block design and each of the experimental treatment was replicated three times. A Wheat cultivar, Digalu was grown with (0, 20, 40, 60 and 80) Wild Oat densities as a treatment. Data were recorded on wheat plant height, number of tillers, fresh weight and dry weight. The result revealed that various Wild Oats densities statistically (p≤0.05) affected plant height, number of tillers, fresh weight and dry weight. The maximum values of all the parameters were recorded in the (0) Wild Oat density as well as from Wild Oats density (20). Whereas, the minimum values of these parameters were recorded where (80) wild oats densities were present. From the study it could be concluded that Wheat yield and yield components were greatly affected by Wild Oat densities. Judicious control measures for wild oats are recommended to be adopted that can control Wild Oats in Wheat crop to reduce the crop losses due to this noxious weed.

Diverse Rotations and Optimal Cultural Practices Control Wild Oat (Avena fatua)

In western Canada, more money is spent on wild oat herbicides than on any other weed species, and wild oat resistance to herbicides is the most widespread resistance issue. A direct-seeded field experiment was conducted from 2010 to 2014 at eight Canadian sites to determine crop life cycle, crop species, crop seeding rate, crop usage, and herbicide rate combination effects on wild oat management and canola yield. Combining 2× seeding rates of early-cut barley silage with 2× seeding rates of winter cereals and excluding wild oat herbicides for 3 of 5 yr (2011 to 2013) often led to similar wild oat density, aboveground wild oat biomass, wild oat seed density in the soil, and canola yield as a repeated canola–wheat rotation under a full wild oat herbicide rate regime. Wild oat was similarly well managed after 3 yr of perennial alfalfa without wild oat herbicides. Forgoing wild oat herbicides in only 2 of 5 yr from exclusively summer annual crop rotations resulted in higher wild oat density, biomass, and seed banks. Management systems that effectively combine diverse and optimal cultural practices against weeds, and limit herbicide use, reduce selection pressure for weed resistance to herbicides and prolong the utility of threatened herbicide tools.

Effects of cultivar and grazing initiation date on fall-grown oat for replacement dairy heifers

Fall-grown oat has shown promise for extending the grazing season in Wisconsin, but the optimum date for initiating grazing has not been evaluated. Our objectives for this project were (1) to assess the pasture productivity and nutritive value of 2 oat cultivars [Ogle and ForagePlus (OG and FP, respectively)] with late-September (EG) or mid-October (LG) grazing initiation dates; and (2) to evaluate growth performance by heifers grazing these oat forages compared with heifers reared in confinement (CON). A total of 160 gravid Holstein heifers (80 heifers/yr) were assigned to 10 research groups (8 heifers/group). Mean initial body weight was 509±40.5 kg in 2013 and 517±30.2 kg in 2014. Heifer groups were assigned to specific pastures arranged as a 2×2 factorial of oat cultivars and grazing initiation dates. Grazing heifer groups were allowed to strip-graze oat pastures for 6 h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Main effects of oat cultivar and sampling date interacted for forage characteristics in 2013, but not in 2014. During 2013, oat forage mass increased until early November before declining in response to freezing weather conditions, thereby exhibiting linear and quadratic effects of sampling date, regardless of oat cultivar. Similar trends over time were observed in 2014. For 2013, the maximum forage mass was 5,329 and 5,046 kg/ha for FP and OG, respectively, whereas the mean maximum forage mass for 2014 was 4,806 kg/ha. ForagePlus did not reach the boot stage of growth during either year of the trial; OG matured more rapidly, reaching the late-heading stage during 2013, but exhibited only minor maturity differences from FP in 2014. For 2013, average daily gain for CON did not differ from grazing heifer groups (overall mean=0.63 kg/d); however, average daily gain from FP was greater than OG (0.68 vs. 0.57 kg/d), and greater from EG compared with LG (0.82 vs. 0.43 kg/d). For 2013, advantages in average daily gain for heifers grazing FP pastures were likely related to the greater energy density of FP oat throughout the fall that reached a maximum of 68.8% total digestible nutrients on November 27 compared with only 63.7% for OG on October 10. During 2014, average daily gain from CON exceeded all grazing heifer groups (0.81 vs. 0.57 kg/d), and average daily gain from EG again exceeded LG (0.70 vs. 0.44 kg/d). These results suggest that delaying grazing until mid-October will consistently suppress heifer growth performance, particularly if rapidly maturing cultivars are used.

Response of wild oat weeds to the mechanical methods and application time of control under EL-Bayda condition in Libya

Field experiment were carried out during the two growing seasons (2007-08 and 2008-09) at the experiment station of Crop Science Department, Faculty of Agriculture, University of Omar Al-Mukhtar, El-Bayda, Libya to study the response of time of application and Mechanical control methods of wild oat (Avenafatua L.). The results revealed that, the wild oat density reduced by 76.54 and 85.63% because of soil solarization compared to unweeded and the best time reduced the weed density were before leveling in two seasons. Wild oats heights were reduced due to soloarization as a method of weed control by 64.38 and 75.77% compared to unweeded in both seasons respectively, and solarization before soil leveling gave the smallest height. Wild oat dry matter reduced by soil surface and before soil leveling by 68.88 and 86.46% compared to unweeded in both seasons respectively.

Impact of process conditions on the density and durability of wheat, oat, canola, and barley straw briquettes

The present study is to understand the impact of process conditions on the quality attributes of wheat oat, barley, and canola straw briquettes. Analysis of variance indicated that briquette moisture content and initial density immediately after compaction and final density after 2 weeks of storage are strong functions of feedstock moisture content and compression pressure, whereas durability rating is influenced by die temperature and feedstock moisture content. Briquettes produced at a low feedstock moisture content of 9 % (w.b.) yielded maximum densities >700 kg/m3 for wheat, oat, canola, and barley straws. Lower feedstock moisture content of 110 °C and compression pressure >10 MPa minimized the briquette moisture content and maximized densities and durability rating based on surface plots observations. Optimal process conditions indicated that a low feedstock moisture content of about 9 % (w.b.), high die temperature of 120–130 °C, medium-to-large hammer mill screen sizes of about 24 to 31.75 mm, and low to high compression pressures of 7.5 to 12.5 MPa minimized briquette moisture content to 700 kg/m3. Durability rating >90 % is achievable at higher die temperatures of >123 °C, lower to medium feedstock moisture contents of 9 to 12 % (w.b.), low to high compression pressures of 7.5 to 12.5 MPa, and large hammer mill screen size of 31.75 mm, except for canola where a lower compression pressure of 7.5 to 8.5 MPa and a smaller hammer mill screen size of 19 mm for oat maximized the durability rating values.

Suppression of Annual Weeds in Pea and Cereal Intercrops

Experiments were constructed to investigate effects of pea [Pisum sativum L. (Partim)] and spring cereal intercrops on annual weed suppression and grain yield in an organic farming system. Pea, spring wheat (Triticum aestivum L. emend. Fiori et Paol.), barley (Hordeum vulgare L.), oat (Avena sativa L.), and triticale (× Triticosecale Wittm.) were sown as sole crops and as intercrops at a 50:50 proportion of grain legume and spring cereal seeds relative to sole crop rates. The density of wheat, oat, and triticale sole crops was significantly higher compared with intercrops with pea. All investigated intercrops were significantly denser than the sole pea crop. Low height was observed in pea and barley sole crops and intercrops. Mostly weed number and mass were not significantly different between sole cereal and intercrops. Crop density was more effected by suppression than weed height. Where crops were sparser, increases in weed density and mass corresponded to a significant decline in grain yield. In the pea–cereal intercrop, where pea accounted for 20.3 to 35.2% of the total plant number, cereals exhibited the greatest weed suppression ability, productive stem number and height being the main factors responsible for this.