Ryegrass Clover Mixtures Research Articles

The Influence of Ozone on Net Ecosystem Production of a Ryegrass–Clover Mixture under Field Conditions

In order to understand the effect of phytotoxic tropospheric ozone (O3) on terrestrial vegetation, we quantified the impact of current O3 concentration ([O3]) on net ecosystem production (NEP) when compared to the conditions of the pre-industrial era. We compared and tested linear mixed-effects models based on [O3] and stomatal O3 flux (Fsto). The managed ryegrass–clover (Lolium perenne and Trifolium pratense) mixture was grown on arable land in the Czech Republic, Central Europe. Values of [O3] and Fsto were measured and calculated based on resistance analogy, respectively, while NEP was calculated from eddy covariance CO2 fluxes. We found the Fsto-based model more precise when compared to measured NEP. High Fsto was found even at low [O3], while broad summer maximum of [O3] was not necessarily followed by significant NEP decline, due to low soil water content leading to a low stomatal conductivity and Fsto. Comparing to low pre-industrial O3 conditions, current levels of O3 resulted in the reduction of cumulative NEP over the entire growing season, up to 29.7 and 13.5% when the [O3]-based and Fsto-based model was applied, respectively. During the growing season, an O3-induced reduction of NEP ranged between 13.1% in May and 26.2% in July when compared to pre-industrial Fsto levels. Looking to the future, high [O3] and Fsto may lead to the reduction of current NEP by approximately 13.3% on average during the growing season, but may increase by up to 61–86.6% in autumn, indicating further O3-induced acceleration of the senescence. These findings indicate the importance of Fsto and its inclusion into the models estimating O3 effects on terrestrial vegetation. The interaction between environmental factors and stomatal conductance is therefore discussed in detail.

Cadmium Uptake by Ryegrass and Ryegrass-Clover Mixtures under Different Liming Rates.

Cadmium accumulates in soils that receive repeated applications of Cd-rich superphosphate fertilizers. There is evidence that adding clovers to a crop solubilizes soil Cd, increasing the bioavailability of Cd. This can lead to high plant Cd concentrations. This research aimed to test whether liming-induced increases in pH in mixed crops of clovers and ryegrasses reduced forage Cd concentrations. A greenhouse pot trial applied lime at three rates (0, 1, and 2% of soil dry weight) to eight different plant treatments-four as monocultures (perennial ryegrass [ L.], Italian ryegrass [ Lam.], white clover [ L.], and red clover [ L.]) and four as ryegrass-clover mixtures (two plant types in each treatment)-in soil (initial soil pH = 5.1, initial soil Cd concentration = 1.31 mg kg) with added Cd (CdSO ∼ 1 mg kg). Adding lime increased soil pH in both mono- and mixed crops and, in most treatments, increased forage yields. However, the relationship between forage Cd and soil pH differed between plant treatments. In mono- and mixed crop treatments containing perennial ryegrass, adding lime increased the forage yield but did not increase the mass of Cd in the plants compared with the no-lime treatment. However, adding lime to treatments that included Italian ryegrass increased both the forage yield and the Cd compared with the no-lime treatment. The results show that a combination of certain plant species composition and lime rates can optimize forage yields without increasing forage Cd concentrations.

Process-based modelling to understand the impact of ryegrass diversity on production and leaching from grazed grass-clover dairy pastures

Ecological studies often suggest that natural grasslands with high species diversity will grow more biomass and leach less nitrogen (N). If this diversity effect also applies to fertilised and irrigated pastures with controlled removal of herbage, it might be exploited to design pastures that can assist the dairy industry to maintain production while reducing N leaching losses. The purpose of this study was to test whether pasture mixtures with a high functional diversity in ryegrass traits will confer on the system higher water- and N-use efficiency. The hypothesis was tested using a process-based model in which pasture mixtures were created with varying levels of diversity in ryegrass traits likely to affect pasture growth. Those traits were: the winter- or summer-dominance of growth, the ability of the plant to intercept radiation at low pasture mass, and rooting depth. Pasture production, leaching and water- and N-use efficiency were simulated for management typical of a dairy pasture. We found that the performance of the diverse ryegrass–clover mixtures was more strongly associated with the performance of the individual components than with the diversity across the components. Diverse pasture mixtures may confer other benefits, e.g. pest or disease resistance and pasture persistence. The testing here was within a selection of ryegrasses, and the greater possible diversity across species may produce different effects. However, these results suggest that highly performing pastures under fertilised and irrigated grazed conditions are best constructed by selecting components that perform well individually than by deliberately introducing diversity between components.

Interactions between nitrogen, phosphorus and potassium determine growth and N2-fixation in white clover and ryegrass leys

Variations in yield, N2 fixation and above-ground accumulation of nitrogen (N), phosphorus (P) and potassium (K) in white clover and ryegrass grown separately or in mixture were investigated under field conditions over two consecutive years at different supplies of N, P and/or K. Ryegrass-clover mixtures consistently out-yielded the pure stand clover and pure stand ryegrass in terms of dry matter. Improved N supply favoured ryegrass, and ryegrass in mixture with clover accumulated substantially higher amounts of N, P and K than ryegrass in pure stand. Conversely, the growth of white clover in mixture with grass was significantly depressed by N application, particularly when P and K were also applied. Plots of dry matter, N, P and K in white clover versus ryegrass in mixtures followed log-normal relations demonstrating the superior responsiveness of ryegrass to improved availability of N, P and/or K. Although competition for P and/or K reduced the N2 fixation rate in the mixture, the effect on the total above-ground N accumulation was insignificant. The proportions of P and K in the shoot dry matter of ryegrass in pure stand were only half of those of ryegrass in mixture with clover, while white clover co-cultivated with ryegrass had lower P concentration in dry matter, showing a P deprivation of clover growing in mixture with grass. Na was able to replace K under the competitive conditions in the mixture. In conclusion, the results show that growth and nutrient acquisition of clover and ryegrass interact in a complex manner involving competition, facilitation and complementarity.

Fate of 15N and 14C from labelled plant material: Recovery in perennial ryegrass–clover mixtures and in pore water of the sward

The belowground C and N dynamics leading to organic and inorganic N leaching from perennial ryegrass–clover mixtures are not well understood. Based on the hypothesis that four different plant materials would degrade differently, a 16 months field experiment was conducted to determine (i) the source strength of labelled plant residues in dissolved inorganic N (DIN) and dissolved organic N (DON) in pore water from the plough layer, and (ii) the plant uptake of organically bound N. Litterbags containing 14C- and 15N-labelled ryegrass or clover roots or leaves were inserted into the sward of a ryegrass–clover mixture in early spring. The fate of the released 14C and 15N was monitored in harvested biomass, roots, soil, and pore water percolating from the plough layer. No evidence of plant uptake of dual-labelled organic compounds from the dual-labelled residues could be observed. N in pore water from the plough layer during autumn and winter had a constant content of dissolved organic N (DON) and an increasing content of dissolved inorganic N (DIN). A positive correlation between aboveground clover biomass harvested in the growth season and total-N in pore water indicated that decaying roots from the living clover could be a major source of the 10 kg N ha −1 being lost with pore water during autumn and winter. The presence of 15N in pore water shifted from the DON fraction in autumn to the DIN fraction in late winter, with strong indications that 15N originated from the living ryegrass. However, 15N in pore water originating from plant residues only constituted 1.5% of the total dissolved N from the plough layer.

Palatability in sheep and in vitro nutritional value of dried and ensiled sainfoin (Onobrychis viciifolia) birdsfoot trefoil (Lotus corniculatus), and chicory (Cichorium intybus)

Three temperate forages, sainfoin, birdsfoot trefoil, and chicory, characterized by elevated contents of plant secondary compounds, were compared to a ryegrass-clover mixture (control) in dried (Experiment 1) and ensiled form (Experiment 2) in their palatability and nutritional value. Palatability was measured in adult wethers (n = 6) allowed to choose between the familiar control forage and one of the three test plants. Palatability index was calculated from differences in intake of control and test plants measured after given times. Generally at first contact, palatability of the unfamiliar plants was low. Lag time until palatability index approached or exceeded a value of 100 was 2 – 5 d, but could not be related to the content of condensed tannins. Sainfoin had a high palatability, the highest content of condensed tannins (77.4 ± 10.23 g/kg DM), a high content of duodenally utilisable crude protein (94.7 ± 16.87 g/100 g CP), and a high content of metabolizable energy (9.5 ± 0.38 MJ ME/kg DM), making this plant most promising for various purposes including anthelmintic action.

In situ carbon and nitrogen dynamics in ryegrass–clover mixtures: Transfers, deposition and leaching

Carbon (C) and nitrogen (N) dynamics in a third production year ryegrass–clover mixture were investigated in the field. Cylinders (diameter 29.7 cm) were installed to depths of 20, 40 and 60 cm and equipped with suction cups to collect percolating pore water. Ryegrass and clover leaves were cross-labelled with 14C- and 15N-enriched urea and the fate of the two tracers was studied for 3 months during summer. Transfer of 14C occurred mainly from ryegrass to clover, whereas the largest transfer of 15N was in the opposite direction. The average transfer of N from clover was 40% (SE±3.1, n=9) of N in ryegrass, whereas the fraction of N in clover donated by ryegrass was 5% (±1.2, n=9). The amount of 14C transferred from ryegrass to clover was 1.7% (±0.1, n=9) of the 14C-activity in the total above-ground plant biomass found in the unlabelled clover and with a transfer from clover to ryegrass being 0.4% (±0.1, n=9). 15N-enriched compounds were not detected in percolating pore water, which may be caused by either dilution from irrigation or low availability of leachable N compounds. 14C was found solely as 14CO 2 in the pore water indicating that dissolved organic carbon (DOC) did not originate from fresh root deposits. Transfer of 14C between the two species in the mixed crop alongside with high transfer of 15N despite a large percolation of pore water indicates that part of the N transfer occurred in non-leachable N-forms. The amount of N transferred between the two species was found to depend on the ratio between dry matter accumulated in the donating and receiving species, the 14C-allocation within the receiving species and the root turnover rate in the soil.

Comparative productivity of irrigated short-term ryegrass (Lolium multiflorum) pasture receiving nitrogen, grown alone or in a mixture with white (Trifolium repens) and Persian (T. resupinatum) clovers

Dairy farms in subtropical Australia use irrigated, annually sown short-term ryegrass (Lolium multiflorum) or mixtures of short-term ryegrass and white (Trifolium repens) and Persian (shaftal) (T. resupinatum) clover during the winter–spring period in all-year-round milk production systems. A series of small plot cutting experiments was conducted in 3 dairying regions (tropical upland, north Queensland, and subtropical southeast Queensland and northern New South Wales) to determine the most effective rate and frequency of application of nitrogen (N) fertiliser. The experiments were not grazed, nor was harvested material returned to the plots, after sampling. Rates up to 100 kg N/ha.month (as urea or calcium ammonium nitrate) and up to 200 kg N/ha every 2 months (as urea) were applied to pure stands of ryegrass in 1991. In 1993 and 1994, urea, at rates up to 150 kg N/ha.month and to 200 kg N/ha every 2 months, was applied to pure stands of ryegrass; urea, at rates up to 50 kg N/ha.month, was also applied to ryegrass–clover mixtures. The results indicate that applications of 50–85 kg N/ha.month can be recommended for short-term ryegrass pastures throughout the subtropics and tropical uplands of eastern Australia, irrespective of soil type. At this rate, dry matter yields will reach about 90% of their potential, forage nitrogen concentration will be increased, there is minimal risk to stock from nitrate poisoning and there will be no substantial increase in soil N. The rate of N for ryegrass–clover pastures is slightly higher than for pure ryegrass but, at these rates, the clover component will be suppressed. However, increased ryegrass yields and higher forage nitrogen concentrations will compensate for the reduced clover component. At application rates up to 100 kg N/ha.month, build-up of NO3–-N and NH4+-N in soil was generally restricted to the surface layers (0–20 cm) of the soil, but there was a substantial increase throughout the soil profile at 150 kg N/ha.month. The build-up of NO3–-N and NH4+-N was greater and was found at lower rates on the lighter soil compared with heavy clays. Generally, most of the soil N was in the NO3–-N form and most was in the top 20 cm.

A delay model for the growth of ryegrass–clover mixtures: formulation and preliminary simulations

A model which describes the interaction of ryegrass and clover when grown together is proposed and analysed. The main biological feature of interest is the fixation of nitrogen by clover which is then subsequently used by ryegrass. In view of the difficulty of obtaining reliable data for the nitrogen level, this is modelled by a distributed differential-delay system. This enables a smaller set of variables and parameters to be used and the thresholds for sudden changes of outcomes with parameter values to be determined and related to the underlying biological processes. The dynamical system behaviour is extremely diverse, largely because of the effect of the distributed delay. Monocultures, coexisting mixtures, and limit cycle behaviour are possible long-term attracting outcomes. Numerical simulations of the model reveal that often two of these outcomes are possible for a given set of parameter values and which one is preferred depends on the initial conditions. The biological basis of the paper is proposed and then the model is analysed. Simulations and response outcomes are given for various values of the distributed delay. These indicate that this is a realistic model with an interpretable link to the underlying processes. The basis of the model is easily generalised to multiple-species models with seasonal variation or other externally-driven inputs.

Grass Species and Cultivar Effects on Establishment of Grass–White Clover Mixtures

Grasses may differ in their compatibility with white clover (Trifolium repens L.) during establishment. We conducted greenhouse and field experiments to evaluate the compatibility of early‐ and late‐maturing cultivars of perennial ryegrass (Lolium perenne L.) and orchardgrass (Dactylis glomerata L.) with ‘Will’ white clover during establishment. Monocultures and binary mixtures of each cultivar with white clover were established from seed in pots in two greenhouse studies. After an initial harvest at 6 wk of growth, plants were harvested every 2 or 4 wk at a 4‐ or 8‐cm height for 8 wk. The same monocultures and mixtures were planted in field plots and harvested twice at 4 or 8 cm after an 11‐wk establishment period. White clover produced more (P < 0.05) stolon + leaf mass and clover proportion of herbage yield was greater when grown with early‐maturing than with late‐maturing grass cultivars in the field and greenhouse. This indicates that early‐maturity grasses were more compatible with white clover. Individual perennial ryegrass plants had about twice as many tillers per plant (P < 0.01) and yielded 24% more (P < 0.01) dry matter than orchardgrass in mixture with clover. Perennial ryegrass–clover mixtures yielded 20% more herbage and had 40% more tillers per unit area than orchardgrass–clover in the field. Clover plants in monoculture were heavier and more complex in structure than plants in mixture in both field and greenhouse. We conclude that maturity of grass cultivars has an effect on white clover establishment and that early‐maturing cultivars of perennial ryegrass or orchardgrass are more compatible with Will white clover during the establishment phase.

Tissue Turnover Within Grass-Clover Mixed Swards Grazed by Sheep. Methodology for Calculating Growth, Senescence and Intake Fluxes

1. A sustainable, low-input land use might be achieved by the use of grazed grass-legume mixtures. However, maintaining the species balance has proven to be difficult, especially as grazing provides differential defoliation and regrowth. Since changes in the sward botanical composition can be ascribed to species differences in growth, senescence or intake, a method that yields independent estimates of these three fluxes for both components of a grazed grass-legume mixture is needed. 2. The objective of this paper is to present and assess such a detailed tissue turnover method based on non-destructive measurements of individually marked population units. This method was applied during two spring and summer growing seasons to a ryegrass-clover mixture continuously or rotationally grazed by sheep and is assessed using these experimental results. 3. Defoliation was measured on grazed population units (i.e. grass tillers; elongated and axillary shoot growing points of clover). To calculate the growth rate of defoliated leaves, a sample of ungrazed leaves of each defoliation status (with or without previous defoliation) was used. Additionally, for clover, a sample of ungrazed leaves of each 'botanical number' was also required. The mean extension rates of leaves that underwent defoliation during an observed period, and of leaves that did not, was not significantly different during the preceding period. 4. The estimates of the mixture growth flux varied by less than 10 and 17% when the mean values of the gravimetric coefficients and of the density of the population units, respectively, were increased by one standard deviation. The net recruitment of new population units led to an underestimation of the growth flux by 8 and 5% with grass and clover, respectively. 5. The method was partially validated, by comparing independent estimates of the mean dry-weight of the population units, based either on tissue turnover or on destructive measurements. For vegetative tillers and elongated clover growing points, both estimates were highly correlated with no significant bias. 6. Although this method is labour intensive, it yields reliable estimates of the growth, intake and senescence fluxes, at three different levels (square metre, population unit and plant part). Hence, a better understanding of the impacts of herbivory on the grass-legume balance in a grazed mixture can be gained.

Effects of irrigation, N fertilizer, cutting frequency and pesticides on ryegrass, ryegrass–clover mixtures, clover and lucerne grown on heavy and light land

SummaryThe effects of irrigation, nitrogen fertilizer, cutting three or six times per year and a combined pesticide treatment that included aldicarb, phorate, benomyl and methiocarb on ryegrass (Lolium perenne) cv. S.23, either alone or in mixtures with white clover (Trifolium repens) cvs S.I00 or Blanca, and on lucerne (Medicago sativa) cv. Vertus grown on a silty clay–loam at Rothamsted and a sandy loam at Woburn were studied in 1977–81.Benefits from irrigation were greater for six-cut than three-cut swards, with pesticides than without, for ryegrass with clover S. 100 than ryegrass with Blanca and at Woburnthan at Rothamsted. Lucerne did not benefit.Responses of ryegrass to fertilizer N were best fitted by the model y = a + b/1+cx+dx2; and those of ryegrass–clover by the model y = a+bx (where y = yield, x = amount of N; a, b, c and d are constants). Without N, yields of ryegrass–Blanca clover mixtures considerably exceeded those of ryegrass–S.100. The former gave yields equivalent to those of ryegrass given 270 kg N/ha at Rothamsted and 330 kg N/ha at Woburn.Lucerne without irrigation, N or pesticides gave yields in excess of all other unirrigated crops, even when these received pesticides and maximum N. Yields from three cuts of ryegrass greatly exceeded those from six cuts but yields of ryegrass–Blanca were greater from the six-cut regime.Pesticides substantially improved the yields of ryegrass and clover, whether grown separately or mixed, but not those of lucerne. Pesticides not only controlled pests and diseases but also increased the incidence of vesicular–arbuscular mycorrhizas. The relative magnitude of yields of the different swards at the two sites differed, depending on treatment with irrigation, N fertilizer and pesticides. Differences between sites were removed or reversed by appropriate combinations of treatments.Ryegrass–Blanca given no N fertilizer and cut six times removed 300 kg N/ha, an amount that was increased by irrigation and decreased by less frequent cutting; ryegrass–S.100 clover contained less N. Removals of P and K. often exceeded 35 and 300 kg/ha, respectively, each year. Herbage containing Blanca clover had much more Ca than that containing S.100 but at comparable yields all swards contained similar amounts of Mg.

Influence of dissimilarities in temporal and spatial N-uptake patterns on15N-based estimates of fixation and transfer of N in ryegrass-clover mixtures

The temporal N-uptake patterns of white clover (Trifolium repens L.) mixed with perennial ryegrass (Lolium perenne L.) and of red clover (Trifolium pratense L.) mixed with Italian ryegrass (Lolium multiflorum Lam.) were determined in successive harvests of herbage within the growth cycles of a ley established near Zurich (Switzerland). Rooting patterns were examined by injecting15N-fertilizer at soil depths ranging from 10 to 40 cm. The results were analyzed to determine the effect of variations in time and depth of N-uptake on the15N-based measurement of N from symbiosis (Nsym) and N from transfer (Ntrans).

Plant root distribution and water use patterns of some pasture and crop species

Abstract During a summer of lower-than-average rainfall, yield, root distribution, and soil moisture tension were measured for perennial ryegrass, white clover, ryegrass-clover mixture, cocksfoot, wheat, maize, and lucerne growng on a deep free-draining soil. In all species most roots occurred in the top 20 cm of soil, root numbers decreasing down to 100 cm, with smaller variable numbers at the maximum depth sampled. Cocksfoot and perennial ryegrass had the highest root numbers in the top 40 cm, cocksfoot roots continuing to be more numerous to 140 cm. The effective depth of the soil exploited for water by all species except lucerne was approximately 130 cm. Lucerne extracted water from at least 210 cm. Lucerne, maize, and cocksfoot produced at least twice as much dry matter as ryegrass and white clover, both of which had stopped growing by the final harvest. Maize which was not sown until late spring did not begin to deplete the soil water until the pasture species had used much of that which was available. Lucerne depleted the soil water uniformly at all levels of the profile to 150 cm, whereas all other plots showed depletion first near the surface and only later at greater depths This could be significant in maintaining nutrient availability under drying conditions.

Root Development of Field Crops. J. E. Weaver

Previous articleNext article FreeCurrent LiteratureRoot Development of Field Crops. J. E. Weaver W. CrockerW. Crocker Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 82, Number 2Oct., 1926 Article DOIhttps://doi.org/10.1086/333652 Views: 1 Citations: 1Citations are reported from Crossref Journal History This article was published in the Botanical Gazette (1876-1991), which is continued by International Journal of Plant Sciences (1992-present). PDF download Crossref reports the following articles citing this article:Ebrahim Benyas, Jennifer Owens, Salome Seyedalikhani, Brett Robinson Cadmium Uptake by Ryegrass and Ryegrass–Clover Mixtures under Different Liming Rates, Journal of Environmental Quality 47, no.55 (Sep 2018): 1249–1257.https://doi.org/10.2134/jeq2018.01.0015