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Acidification is one of the recommended treatments to reduce NH3 emissions from animal slurry. Economically, the sulphuric acid is the most feasible agent to lower slurry pH. This study explains the impact of acidified slurry on soil and crop in a leaching trial. Pot experiments with ryegrass and cereal crops were used with 15 and 45 m3 ha−1 acidified slurry application. The effect of acidified slurry on ryegrass and maize yield was positive, increasing the yield by 40% and 20%, respectively, compared to unacidified slurry. There was a significant effect of acidified slurry on soil pH when large amount of acidified slurry (45 m3 ha−1) was used. Soil pH decreased by 0.1 units. The smaller amount of acidified slurry (15 m3 ha−1) had non-significant effect. Thus, for environmental protection purposes, it is necessary to ensure that the nutrient amounts applied with slurry, in particular easily soluble nitrogen and sulphur, correspond to the needs of the plants. Particular attention must be paid to Ca-poor soils. Sulphate ions are physically negatively absorbed in the soil, facilitating their availability in and leaching from the soil. With sulphate anions, an equivalent amount of Ca and Mg cations is always leached from the soil. [ABSTRACT FROM AUTHOR]

An incubation study with fresh, frozen, and dried clover and rye-grass shoots gathered in autumn was performed in the laboratory (43 days). The aim was to study inorganic and organic phosphorus (P) release from plant material during decomposition without soil. Plant materials (2 cm size) were mixed with small glass beads and placed in large syringes for consecutive water extractions on 7 occasions. Leachates were analysed for inorganic and total P. At the first leaching event, 8% of total crop P was released from fresh, 24% from frozen and 27% from dried plant material. During decomposition, both inorganic and organic P was released following first order kinetics, with grass releasing mostly inorganic P and clover mostly organic P. After 43 days, 42%–50% of total crop P from fresh, 49%–51% from frozen and 57%–69% from dried material was released, with significant differences between treatments. Using the results in calculations on field scale showed that P released from overwintering crops under cold climate conditions can amount to several kg P ha−1. Thus, senescence of overwintering aboveground biomass can be a significant source for P leaching from soils. [ABSTRACT FROM AUTHOR]

Phosphorus (P) solubility was studied in a sandy loam after the application of high and increasing application rates (40, 80 and 120 tonnes DM ha−1) of two composts and two biosolids (treated sewage sludge). In 7.5-L pots, the products were mixed into the soil (pH 6.2) and perennial ryegrass was sown. After two years, the soil was analysed forPAL, water-extractable P (Pw), pH and oxalate-extractable Al and Fe. In compost- and biosolids-amended soils,PALranged from 72 to 126% andPwfrom 53 to 169% of those measured in the unamended control. Due to high application rates, the products also had indirect effects on P solubility by elevating the pH or changing the P sorption capacity of the soil. The P sorption capacity of acidic soils was highly correlated toPAL(r2=0.75) andPwof the soil (r2=0.70). Despite highPALconcentrations in the original soil (150 mg kg−1DM), the highest application rates of the biosolids with high Al and Fe content were found to inhibit P supply to plants in the first months after application. [ABSTRACT FROM PUBLISHER]

The objective of this study was to investigate the impact of sewage sludge amendment (SSA), with the rates of 0, 30, 75, 150, and 300 t ha−1, on soil chemical properties and biomass, aboveground and root growth, and nitrogen and phosphorus uptake of ryegrass (Lolium perenneL.) seedling grown on a mudflat soil. Results showed that SSA modified the chemical properties of mudflat soil by decreasing soil salinity and pH, increasing soil organic matter, total and available N and P, and heavy metals. The biomass of root and aboveground parts of ryegrass showed increments with increasing SSA rates. Maximum increases of 5.6- and 1.3-fold in fresh weight of aboveground parts and root of ryegrass were observed at 300 t ha−1rate. Root grown at all SSA rates showed positive response to higher nutrient availability in the mudflat soil with increasing root average diameter and volume. The root length and surface area at 30 t ha−1SSA rate was significantly higher than those in other treatments. The sewage sludge amendment increased N and P content in both aboveground and root parts of ryegrass. Cd, Cr, Cu, Mn, Ni, and Zn accumulation in ryegrass was positively correlated with SSA rates. However, heavy metal concentrations in ryegrass did not exceed the safety standard for feed in China (GB 13078-1999), except for Cd at 300 t ha−1SSA rate. The study suggests that sewage sludge can be applied for mudflat soil amendment, which provides an innovative solution pertaining to new arable land resources and solid waste disposal. The optimum SSA rate is 150 t ha−1with maximum plant yield yet permissible metal accumulation. [ABSTRACT FROM PUBLISHER]

Efficient non-chemical weed control like flame weeding often requires repeated treatments. In weed control experiments the effect of each treatment may be estimated by removing and weighing the remaining weed biomass after the treatment, but the method influences the weed plants ability to regrow, and therefore it may influence the long-term effect of repeated treatments. Visual assessment of weed cover or image analysis do not affect the remaining parts of the weed plants after treatment, but the methods may have other disadvantages. In order to evaluate and compare three methods we measured changes in vegetation cover of perennial ryegrass after flaming by (1) a simple image analysis programme counting green pixels, (2) visual assessment of images and (3) by taking biomass samples. Plants were flame treated with eight different dosages (0, 20, 30, 35, 45, 60, 90 and 180 kg propane ha−1) and with various treatment frequency (2, 4, 6, 8 and 10 yearly treatments). Image analysis and visual assessment of images were easy methods to measure vegetation cover. The experiments showed that increasing dosages and frequent treatments resulted in increasing reduction of plant weight and vegetation cover. However, there were significant differences in the estimated effective doses (e.g., ED50 and ED90values) depending on assessment method and treatment frequency. One reason could be that image analysis and visual assessment did not affect the remaining weed parts after treatment and therefore gave a more realistic picture of the long-term effect of repeated treatments. Image analysis was most useful for assessing the effect of repeated treatments when weed cover was relatively low (below 40%) and when plots contained relatively much withered plant material. However, when weed cover is close to 100%, dry weight measurements reflected the effect of the treatment better. [ABSTRACT FROM PUBLISHER]

Crop production must continuously be adjusted according to economic return and fluctuating prices on inputs versus harvested plant products and calls for continuous revision of the crop rotation and flexible management systems. This study describes grass seed production of three different types, respectively, of perennial ryegrass (Lolium perenneL.) and red fescue (Festuca rubraL.) and their optimum number of growing seasons in terms of yield, selected yield components and economic gain. Three harvest years gave the maximum yield in the red fescue type with long stolons (cv. Pernille) and the highest number of fertile tillers in all three red fescue cultivars. Four harvest years gave the maximum yield for types with short stolons (cv. Suzette) and without stolons (cv. Tamara). The fifth year significantly reduced the yield compared to the highest obtained yield within each cultivar. The diploid amenity cv. Allegro and forage type cv. Borvi of perennial ryegrass can be harvested in five consecutive years without a significant yield reduction. The tetraploid type cv. Tivoli had the highest thousand seed weight and a significant yield decrease from the first to the second year of seed harvest and a continuous decline in seed yield is observed from the first to the fifth harvest year in this cultivar. Yet, when the economic incentive was calculated it was found that optimum harvest years cannot be determined by yield considerations alone. A combination of high grass seed price and low cereal price shows that red fescue can be grown up to four years and perennial ryegrass up to five years with high economic returns. [ABSTRACT FROM PUBLISHER]

This study examined whether the N release pattern during decomposition of plant materials used as green manures can be modified in the short term through mixing plant materials with different levels of easily degradable compounds. In a lysimeter study, white clover shoots were mixed with perennial ryegrass shoots or chicory roots. Leaching of clover N was decreased more by inclusion of chicory than by ryegrass. However, decreased leaching losses over the non-growing season did not lead to enhanced N uptake by the crop during the following growing season. [ABSTRACT FROM AUTHOR]

Cover crops can be used to reduce leaching and erosion, introduce variability into crop rotation and fix nitrogen (N) for use by the main crops, less is however known about effects on weeds. The effects on weed seed bank, weed growth and grain yield of 4 years of annual undersown clover and ryegrass alone and in combination, and one of the 4 years with clover or clover + grass as green manure, were studied in oat and spring wheat at two experimental sites in south-eastern Norway. These treatments were compared with no undersown crop (control) and with weed harrowing. In contrast to many results in the literature, the undersown clover in this study did not suppress annual weeds, but fertilized the weeds as well as the cereals. Undersown clover resulted in a statistically significant increase of grain yield at the two sites to 116% and 121% of control. During the 4-year period relative seed bank and density of emerged weed (dominated by Spergula arvensis) increased significantly about 4.5 and 10 times respectively in the undersown clover plots at Apelsvoll. At Kise both ryegrass alone and ryegrass mixed with clover significantly suppressed the weed biomass to 70% and 74% of control respectively. It is concluded that fertilization effects of undersown clover may have dominated and overriden the competitive effects. One whole-season clover green manure did not increase the mean yield, but resulted in a significant drop in seed bank size the following year, because of limited weed establishment in an established ley. Only a slight increase in average weed biomass was observed at one of the two experimental sites. The weed seed bank and the weed biomass were essentially kept at steady state during the experimental period in harrowed plots, but harrowing decreased grain yield significantly at both sites. [ABSTRACT FROM PUBLISHER]

Water-soluble carbohydrates and fibre fractions are important traits that influence forage utilization by the ruminant. Little is known about the quality variation among perennial ryegrass genotypes within the same maturity group or between near-isogenic diploids and tetraploids. The current study was carried out in the form of two experiments on two successive years (2006–2007) in three sites in Northern Germany. The main aim was to investigate the variation in nutritive value that could be attributed to differences in maturity among 20 intermediate heading perennial ryegrass genotypes or to differences in ploidy between near-isogenic diploids and tetraploids. Results of the first experiment revealed significant variation among the 20 tested genotypes in the investigated quality parameters that were consistent with the discovered variation in the maturity of the genotypes determined in terms of their Mean Stage by Count (MSC). In the second experiment, few but consistent significant differences were detected between near-isogenic diploids and tetraploids. The tetraploid derivatives had always significantly higher water-soluble carbohydrate content and lower neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) than their near-isogenic diploid parents. [ABSTRACT FROM PUBLISHER]

Changes in non-structural carbohydrates before and during winter are one of the major plant responses to winter stress. However, the observed pattern of changes is variable, not only between grass species but also between different experiments. This study examined the effect of developmental stage on carbohydrate reserves during winter in two grass species differing in winter hardiness. Timothy (Phleum pratense L.) and perennial ryegrass (Lolium perenne L.), sown early or late in the growing season, were sampled for total non-structural carbohydrates (TNC) in late October (end of main growing season), and then in late January, early March and late April. Quantitative and qualitative patterns of carbohydrate accumulation in crown segments were influenced both by plant genotype and developmental stage of the plants prior to winter. TNC increased from October to March, demonstrating considerable cell activity during winter, and declined to their lowest level in April. Sucrose proved to be the major reserve carbohydrate, followed by fructans. The highest content of TNC was found in the most winter-hardy cultivars, particularly in January and March. Early-sown plants accumulated higher levels of fructans than of sucrose, whereas late-sown plants mainly accumulated sucrose. These differences persisted during the winter. It can be concluded that the pattern of carbohydrate accumulation during winter differed between the two species studied and it was strongly affected by both cultivar and plant-developmental stage. [ABSTRACT FROM AUTHOR]

Festulolium (×Festulolium) is a cross between the two species fescue (Festuca L.) and ryegrass (Lolium L.) and is a promising forage and seed crop. To stimulate the production of Danish organic festulolium seeds a three-year field experiment was performed from 1999 to 2002 in a ryegrass-type festulolium, Paulita, and in a fescue-type festulolium, Hykor. The objectives were to examine the influence of row spacing (12, 24, and 36 cm) and seed rate (8, 12, or 16 kg ha-1) on plant establishment, development, and seed yield. Observations of autumn and spring in-row plant densities indicated satisfactory plant establishment in all combinations of seed rate and row spacing. The number of reproductive tillers was in the range from 800 to 2200 m-2 in Paulita and from 500 to 1300 m-2 in Hykor. Row spacing had an effect on the number of reproductive tillers and in both cultivars the highest number was achieved at 12-cm row spacing. Seed yields in the Italian ryegrass type averaged from 1050 to 1150 kg ha-1 and in the tall fescue type from 650 to 800 kg ha-1. Doubling row spacing from 12 to 24 cm had no effect on seed yield in Hykor, while a further increase of row spacing to 36 cm showed a decrease in seed yield. No effect of row spacing on seed yield was observed in Paulita. Neither of the two types was affected in seed yield by seed rate. The fact that row spacing in both types can be increased to 24 cm without having a concomitant negative effect on seed yield implies that mechanical weed control is an optional management technique. Therefore our results have important implications in/for organic grass-seed production. [ABSTRACT FROM AUTHOR]

To gain information about how widening of the row distance influences seed yields in first-year perennial ryegrass, experiments with four row distances in three types of perennial ryegrass were conducted at the University of Aarhus, Faculty of Agricultural Sciences. Perennial ryegrass was undersown at 12-, 24-, 36-, or 48-cm row distance in a cover crop of spring barley. The seeding rate in perennial ryegrass was 6 kg seeds ha-1 regardless of row distance. Although increasing the row distance from 12 to 48 cm had a negative effect on the yield component number of reproductive tillers, the yield was not affected in the first-year seed production in three perennial ryegrass cultivars. Regardless of row distance the seed rate was 6 kg ha-1 and hence in-row plant density in autumn and spring was higher at 48 compared with 12 cm; however, in all three cultivars the highest number of reproductive tillers was recorded at 12-cm row distance. Row distance affected seed yields of only the diploid amenity cultivar 'Allegro', where a row distance of 48 cm reduced the seed yield compared with 12- and 24-cm row distance. When data from the three cultivars were merged there was a positive correlation between the seed yield and seed weight (r=0.72***), whereas the correlation between seed yield and the number of reproductive tillers was negatively correlated (r= - 0.49***). This may reflect choice of cultivars in the experiment with the tetraploid forage cultivar 'Tivoli' having the lowest number of reproductive tillers, highest seed weight, and highest seed yield, and the diploid amenity cultivar 'Allegro' having the highest number of reproductive tillers, lowest seed weight, and the lowest seed yield. When the three cultivars were merged, there was a positive and highly significant correlation between seed weight and seed yield (r=0.72***). In contrast, there was no correlation between seed weight and seed yield when data were analysed for the individual cultivars. This suggests a cultivar-dependent relationship between seed weight and seed yield and furthermore between number of reproductive tillers and seed yield. [ABSTRACT FROM AUTHOR]

Establishment methods have proven to be of major importance for grass-seed production. The objective of this research was to test the effect of different sowing techniques on plant establishment and the subsequent seed yield. Perennial ryegrass (Lolium perenne L.) is used as the model grass due to its large importance in Danish agriculture. In a three-year trial six different methods of under-sowing of perennial ryegrass in a spring barley cover crop were employed. Perennial ryegrass was either sown directly at different depths within the spring barley (Hordeum vulgare L.) rows or placed 2, 6, or 12 cm from the spring barley rows. Results of dry-matter yield indicate that the best establishment of the grass occurred when placing the grass 6 or 12 cm from the cover-crop row, and this is of importance in less vigorous grasses. Overall, no seed-yield difference has been observed for perennial ryegrass when placing the grass 2, 6, or 12 cm from the cover-crop row. Placement of the ryegrass seed crop 6 cm from the cereal row showed that a significant yield increase of 34-71 kg ha-1 can be obtained compared with sowing in the cereal row. [ABSTRACT FROM AUTHOR]

The aim of the present investigation was to study the effect of white clover (var. Milka and Donna), red clover (var. Fanny) and ryegrass (var. Tove) undersown in winter wheat on a succeeding oat crop. Under the climatic conditions prevailing in Sweden, growing a catch crop after winter cereals is of particular interest because the latter are usually followed by a spring sown crop, leaving the ground bare during autumn and winter. Field trials were carried out during three growing seasons in an integrated farming system and for one year in an organic farming system. Competition from the dense wheat crop in the integrated farming system had a negative effect on the undersown species, and at harvest of the wheat they showed quite poor growth in all three years, with nitrogen contents under 5 kg ha-1. No significant yield increase was measured without added nitrogen when the averages for all three years were calculated. On average, the grain yields were improved by 750 kg ha-1 (14% moisture content) for the treatments with undersown clover for all three years when 90 kg N ha-1 were added. The experiment within the organic system showed a different pattern with a better development of the undersown clover species, with nitrogen contents approximately 25 kg ha-1 and an improvement in oat grain yield, from around 2000 kg ha-1 for the control to almost 3500 kg ha -1 with clover undersown the previous year. [ABSTRACT FROM AUTHOR]