Perennial Ryegrass-white Clover Research Articles

Effect of silage from ryegrass intercropped with winter or common vetch for grazing dairy cows in small-scale dairy systems in Mexico

The objective was to determine the effect of including silages of annual ryegrass (Lolium multiflorum) intercropped with winter vetch (Vicia villosa) (ARG-VV) or with common vetch (Vicia sativa) (ARG-VS) compared with maize silage (MS) on milk yield and milk composition of dairy cows grazing cultivated perennial ryegrass-white clover pastures with supplemented concentrate during the dry season. Six Holstein dairy cows with a mean yield of 19.0 kg/cow/day at the beginning of the experiment were randomly assigned to a 3 × 3 repeated Latin square. Treatments were: 8 h/day intensive grazing, 3.6 kg of dry matter (DM) per cow per day of concentrate plus MS, and ARG-VV or ARG-VS ad libitum at a stocking rate of 3.0 cows/ha for three experimental periods of 3 weeks each. Milk yield (MY) and milk composition, live weight and body condition score as well as silage and concentrate intakes were recorded during the third week of each experimental period, and pasture intake was estimated indirectly from utilised metabolisable energy. Economic analysis was obtained by preparing partial budgets. There were no statistical differences (P > 0.10) in MY, milk fat or protein content nor for live weight, but there was significant difference (P < 0.10) in body condition score. There were non-statistical differences in silage DM intake (P < 0.11); however, significant differences (P < 0.10) were obtained for estimated grazed herbage intake whilst no differences for total DM intake. Slightly higher economic returns (10%) were obtained with ARG-VS over MS, and this was 7% higher than ARG-VV. It is concluded that ARG-VS could be an option for complementing grazing for small-scale dairy production systems in the dry season as it is comparable to MS in animal performance and slightly better in economic terms.

Effect of offering concentrate supplement in late pregnancy, under conditions of unrestricted herbage, on the performance of multiple-bearing ewes and their lambs to weaning

The aim of the present study was to determine if offering ewes a commercial concentrate supplement under conditions of unrestricted perennial ryegrass–white clover herbage availability would increase newborn lamb heat production, colostrum intake and subsequent liveweight. Forty seven twin- and 43 triplet-bearing Romney composite ewes (1/2 Romney, 1/4 Finn, 1/4 Texel) were randomly allocated to either non-concentrate or concentrate treatment groups (twin non-concentrate, n = 24; twin concentrate, n = 23; triplet non-concentrate, n = 22; triplet concentrate, n = 21) from Day 79 of pregnancy. Concentrate-fed ewes were offered an increasing amount of concentrate sheep pellets from Day 79 until Day 90 of pregnancy, at which stage ewes were offered 400 g/day per ewe until they lambed. Pre- and post-grazing herbage masses did not differ (P &gt; 0.05) between non-concentrate (2162 ± 54 and 1704 ± 47 kg DM/ha) and concentrate (2135 ± 49 and 1771 ± 42 kg DM/ha) ewes. Ewe nutritional treatment had no effect (P &gt; 0.05) on ewe liveweight, body condition score, β-hydroxybutyate or non-esterified fatty acid concentrations in late pregnancy. Offering concentrates increased (P &lt; 0.05) the birthweight of triplet-born lambs (4.4 ± 0.1 v. 3.9 ± 0.1 kg for those born to concentrate and non-concentrate ewes, respectively) but had the opposite effect on twins (4.8 ± 0.1 v. 5.2 ± 0.1 kg, respectively). There was no difference (P &gt; 0.05) in maximal heat production, total heat production, rate to reach maximal heat production, and IgG concentrations at 24–36 h of age or liveweight and survival of lambs born to ewes offered concentrates or not. Twin-born lambs had greater (P &lt; 0.05) liveweight and total heat production and had higher (P &lt; 0.05) survival rates than triplet-born lambs. In conclusion, the results of the present study indicate that there are only minor beneficial effects from offering concentrate supplements to ewes in late pregnancy under conditions of unrestricted herbage availability and it is not a viable option for farmers to utilise.

The effects of autumn rotation length and cutting height on a perennial ryegrass-white clover sward

The effects of autumn rotation length and cutting height on a perennial ryegrass-white clover sward

Grazing behaviour of domestic ruminants according to flock type and subsequent vegetation changes on partially improved heathlands

The management of different livestock species may promote different vegetation dynamics that will affect subsequent animal performance and the sustainability of extensive grazing systems. The grazing behaviour of two livestock species (domestic cattle and sheep) under two different managements (monospecific or mixed with goats), and the subsequent vegetation changes were studied on mechanically cleared heathlands (Ulex gallii Planchon-Erica spp.), with one third of the total area improved with perennial ryegrass-white clover pasture (Lolium perenne L.-Trifolium repens L.). Results showed that animals in mixed herds spent more time grazing than in monospecific groups. Goats spent more proportional time grazing on shrubland (68%) compared to sheep (35%) and cattle (19%), which spent most of the time on the improved pasture. The diet composition estimates also confirmed that these two animal species basically selected herbaceous species (89-95%) whilst gorse was an important element of goats" diets (28%). Throughout the experiment, an increment of gorse cover, height and phytomass was observed, especially under single grazing; whereas dead matter and herbaceous covers decreased more under single than under mixed grazing. Besides, heather percentage and gorse height underwent a higher increase under cattle than under sheep grazing. On the improved areas the sward height was significantly higher with cattle, and the gorse sprouting was more controlled under sheep grazing treatments. It is concluded that the complementary grazing of goats can enhance the utilization of these heterogeneous plant resources, providing a more efficient way for both productive and environmental goals than single cattle or sheep grazing.

Effects of including chicory in perennial ryegrass–white clover leys on production and health in organic lambs

Two trials were conducted to examine the effect of chicory included in or as additional plots of the ryegrass–white clover pastures on growth, naturally acquired nematode infections and selectivity of chicory by lambs. In Experiment 1, 31 weaned Texel lambs (36 ± 7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover–chicory pastures (CHIC). In Experiment 2, 30 weaned Shropshire lambs (32 ± 7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover with access to small additional chicory plots, which corresponded to 3% (CHIC-LO) or 6% of the total grazing area (CHIC-HI). No consistent differences in live weight gain and nematode faecal egg counts were observed in lambs grazing the different pasture types. Sward height on the ryegrass–white clover–chicory pasture was higher than the ryegrass–white clover pasture in the period from the 21th August to October in Exp. 1 and in the period from July to mid August in Exp. 2. In Exp. 1 ewe lambs in CHIC performed better than ram lambs (197 ± 11 vs. 154 ± 13 g day − 1 ; P < 0.05 for ewe vs. ram lambs) whereas ram lambs performed best without chicory (190 ± 13 vs. 177 ± 11; P < 0.05 for ram vs. ewe lambs). The relative proportion of chicory eaten by lambs did not differ significantly from August to October and averaged 4.0%. Lambs showed a consistent aversion to chicory. It can be concluded that including chicory into a well-managed mixed sward of perennial ryegrass and white clover 1) improved herbage availability under conditions that are suboptimal for ryegrass/clover swards but 2) did not give consistent effects on growth performance or reduction of nematode infection levels of grazing lambs probably due to a low intake of chicory, as lambs avoided chicory in a mixed sward of high quality. The negative selection of chicory by lambs makes a strategic utilization of chicory's potential in a mixed sward difficult under relatively fertile soil conditions.

Effects of Stocking Rate and Heather Supplementation on Gastrointestinal Nematode Infections and Host Performance in Naturally-Infected Cashmere Goats

The aim of this study, performed on 62 adult dry cashmere goats grazing upland perennial ryegrass–white clover pastures and naturally infected with gastrointestinal nematodes , was to investigate the effects of stocking rate (SR: 24 vs. 38 goats · ha -1 ) and tannin-containing heather supplementation (H: Calluna vulgaris [L.] Hull, Erica spp.) vs. nonsupplementation on parasite burden, fecal egg counts (FEC), and live weight (LW) changes. Goats were randomly assigned to four treatments in a 2 × 2 factorial arrangement and grazed continuously from May to October. Six goats per treatment were slaughtered at the end of the grazing period, and adult worms in the abomasum and small and large intestines of each animal were recovered, counted, and identified. FEC was affected by SR ( P < 0.01) but not by H. However, the SR × H interaction was significant ( P < 0.05). FEC increased ( P < 0.001) along the grazing season in all treatments, and the SR × time interaction was significant ( P < 0.001). In general, mean total worm counts in abomasum and small intestine tended to be higher under high SR, although the differences were only significant ( P < 0.01) in Trichostrongylus spp. counts. In goats managed under the high SR, the mean of total Teladorsagia circumcincta counts was lower ( P < 0.01) in supplemented animals, but no differences were recorded for Trichostrongylus spp., Chabertia ovina , Oesophagostomum columbianum , and Trichuris ovis . The goats gained more LW ( P < 0.001) under low SR and when they were heather-supplemented. No significant SR × H interaction was found for LW change. In conclusion, high stocking rate increases the infectivity risk of pasture and the supplementation of grazing goats with heather contributing to improve animals' performance. Notwithstanding, the effect of heather availability on nematode FEC reduction could be highly dependent on the climatic conditions. Con el fin de estudiar el efecto de la carga animal (CA: 24 vs. 38 cabras/ha) y la suplementación con brezo (SB: Calluna vulgaris [L.] Hull, Erica spp.) vs. no brezo en las parasitosis por nematodos gastrointestinales del ganado caprino y su repercusión en las variaciones de peso, se manejaron 62 cabras cachemir adultas sin cría en pastoreo continuo de mayo a octubre en potreros de rye–grass y trébol blanco. Las cabras se distribuyeron en cuatro grupos según un diseño factorial 2 × 2. Al finalizar el pastoreo se sacrificaron seis cabras por tratamiento para contar el número de vermes en abomaso e intestino delgado y grueso, e identificarlos. El recuento fecal de huevos de nematodos fue afectado por la carga animal ( P < 0.01), pero no por la suplementacion; sin embargo se encontró una interacción significativa ( P < 0.05) entre CA × SB. La cantidad de huevos se incrementó ( P < 0.001) durante la estación de pastoreo en todos los tratamientos y la interacción CA × Tiempo resultó significativa ( P < 0.001). En general, el recuento de vermes en abomaso, intestino delgado y grueso tendió a ser mayor en los animales manejados en carga alta, aunque las diferencias fueron significativas ( P < 0.01) solo para Trichostrongylus spp. En carga alta, la media total de Teladorsagia circumcincta fue menor ( P < 0.01) en las cabras suplementadas, pero no se observaron diferencias para Trichostrongylus spp., Chabertia ovina , Oesophagostomum columbianum , y Trichuris ovis . Las ganancias de peso fueron mayores ( P < 0.001) en las cabras en carga baja y en las suplementadas, no observándose interacción CA × SB. En conclusión, en carga alta se observa un mayor riesgo de infección parasitaria, y la suplementación con brezo contribuye a mejorar las variaciones de peso de las cabras, aunque su efecto sobre los nematodos gastrointestinales podría depender de las condiciones climáticas.

Nitrogen uptake of a perennial ryegrass–white clover pasture following strategic nitrogen fertiliser application during the cool seasons in the Western Cape province, South Africa

The effect of four fertiliser nitrogen (N) levels (0, 50, 100 or 150 kg N ha−1) applied as a single dressing in either autumn (late April), early winter (early June), late winter (mid July), early spring (late August) or late spring (early October) on fertiliser N recovery by a perennial ryegrass–white clover pasture five weeks after fertiliser N application was investigated. Herbage N yield (kg N ha−1 uptake) was determined for the pasture from herbage N yield of the perennial ryegrass fraction and the clover fraction. Increased fertiliser N rate resulted in increased perennial ryegrass N yields. Perennial ryegrass N yields tend to be lowest during winter (early as well as late winter). Pasture N yield responses were similar to the perennial ryegrass N yields. Except in 2001, higher clover N yields (kg N ha−1) were recorded when no fertiliser N was applied compared to treatments that received fertiliser N. Clover N yields did not differ in the 50–150 kg N ha−1 range and would therefore not influence pasture N yield in that range. Although season of application influenced N yields the response pattern was not consistent among the years covered by the study. Calculating the apparent N recovery rate (difference between N removed in fertilised plots and control plots) can serve as an important tool to evaluate the efficiency achieved with fertiliser N application. More research is needed to develop N removal as a management tool to be used in strategic N fertilisation programmes.

Effect of surface applied glycine betaine on herbage production and quality of perennial ryegrass - white clover pastures

Osmoprotectants have been reported to reduce the detrimental effects of various environmental stresses in many different plant species. However, there is little research available concerning pasture species. Two experiments were undertaken with the aim of quantifying the effect of surface applications of exogenous glycine betaine (GB) on herbage production and quality of perennial ryegrass (Lolium perenne L.)–white clover (Trifolium repens L.) pastures during periods of moisture stress and cold temperatures over 2 years. Pastures fertilised with GB were compared with unfertilised pastures and pastures fertilised with nitrogen (N). Rates of 0.5, 1.0 and 1.5 kg GB/ha.defoliation were applied in experiment 1 and 5 kg GB/ha.defoliation was applied in experiment 2. Surface applications of GB did not significantly affect herbage production relative to unfertilised pastures; herbage yields averaged 12 248 and 12 693 kg DM/ha over 11 months in experiment 1, and 7253 and 7177 kg DM/ha over 6 months during summer and autumn in experiment 2, for the unfertilised control and GB, respectively. During both experiments, herbage quality parameters were not affected by GB application, although the proportion of white clover in the sward between summer and winter during experiment 1 was greater (P &lt; 0.01) in plots treated with GB than in untreated plots. Application of N fertiliser increased (P &lt; 0.001) herbage production, but did not consistently affect herbage quality. The failure of surface applications of exogenous GB to improve the herbage production or quality of perennial ryegrass–white clover pastures suggests that it is not an appropriate method to enhance plant tolerance to environmental stress at the concentrations applied in these studies.

Effect of surface application of benzylaminopurine before and during water deficit on herbage production and quality

Insufficient water availability is one of the most serious environmental stresses for a plant and can be a major limitation to herbage production in many regions. Plant hormones, such as cytokinins, have been reported to reduce the detrimental effects of low water availability in many different plant species. However, there is little research available concerning the effect on pasture grasses. The aim of the present study was to quantify the effect of surface applications of 6-benzylaminopurine (BAP) before and during water deficit on herbage growth and quality of perennial ryegrass–white clover pastures. Pastures fertilised with BAP were compared with unfertilised pastures and pastures receiving nitrogen. Exogenous BAP application did not significantly affect herbage production or quality relative to unfertilised pastures. Nitrogen fertiliser increased total herbage production, but had little effect on herbage quality compared with BAP. The failure of surface applications of exogenous BAP to improve herbage production or quality suggests that it is not an appropriate method to enhance plant tolerance to water deficit at the concentration applied in this study.

Grazing behaviour and performance of lactating suckler cows, ewes and goats on partially improved heathlands

The foraging behaviour (grazing time and diet composition), live-weight (LW) changes and parasitic infection (faecal egg counts of gastrointestinal nematodes) of 12 beef cows, 84 ewes and 84 goats suckling their offspring, managed in mixed grazing on heathlands with 24% of improved pasture of perennial ryegrass-white clover, were studied during the years 2003 and 2006. The results showed that goats tended to graze for a longer time, and utilised significantly more heathland vegetation than cattle and sheep, including in their diet in an average of 0.39 herbaceous plants, 0.11 gorse and 0.51 heather over the grazing season, comparing with respective mean values of 0.85, 0.02 and 0.13 in cattle and sheep. Dietary overlap was higher between cattle and sheep (0.76) than between sheep and goats (0.53) or between cattle and goats (0.47). Despite the high performance of autumn-calving cows in spring, sheep had the best LW changes per livestock unit (LU) during the whole grazing season. Goats’ performance per LU was lower than in sheep but higher than in spring-calving cows. Regarding offspring production, lambs had higher LW gains per LU than calves and kids. Mean nematode eggs/g fresh faeces (epg) during the grazing season were higher in goats (91 epg) compared with sheep (34 epg) and cattle (14 epg), particularly from September to December. In conclusion, sheep performed best on these heathlands with improved pasture areas if the entire grazing season was considered, despite the good level of production in spring from autumn-calving cows. The results suggested the complementary use of goats in order to increase the effective utilisation of the available vegetation, achieving production levels similar to those from spring-calving cows. Therefore, mixed flocks of sheep and goats would be the most appropriate sustainable systems from the animal production and vegetation use points of view.

Feeding strategies for small-scale dairy systems based on perennial (Lolium perenne) or annual (Lolium multiflorum) ryegrass in the central highlands of Mexico

Small-scale dairying is an option for campesinos in Mexico. The costs of feeding are high and strategies based on quality forages are a priority. The performance, agronomic variables and feeding costs were evaluated for dairy cows continuously grazing perennial ryegrass-white clover for 9 h/day (PRG) or fed cut herbage from annual ryegrass for 8 weeks followed by 9 h/day for 6 weeks on a tethered rotational grazing pattern (ARG). All cows received 3 kg/day of an 18% crude protein (CP) concentrate. A 14-week split-plot on-farm experiment was designed with 10 cows from two participating farmers, and 1.5 ha per strategy. Milk yield was recorded weekly and milk composition, live weight and body condition score were recorded every 14 days. Net herbage accumulation was greater for ARG (8222 kg organic matter (OM)/ha) than for PRG (5915 kg OM/ha) (p<0.05), with higher CP in PRG (p<0.05). Milk yield was 19 kg/cow per day for PRG and 15.9 kg/ cow per day for ARG (p>0.05). Over 14 weeks, PRG produced 1422 kg more milk. There were no differences for live weight or condition score (p>0.05), but linear regression shows a live weight gain of 0.200 kg/cow per day for PRG. Protein and fat content showed no differences (p>0.05), but milk fat content in PRG was below standard. ARG had 60% higher costs, and margins were 38% higher in PRG. ARG has a place in rain-fed fields. The results provide viable options for improving these systems that may be suitable in their socio-economic context and their social and personal objectives.

Anthelmintic and nutritional effects of heather supplementation on Cashmere goats grazing perennial ryegrass-white clover pastures1

To investigate anthelmintic and nutritional effects of heather supplementation in goats grazing perennial ryegrass-white clover pastures, 40 dry Cashmere goats were randomly assigned to 4 treatments in a 2 x 2 factorial arrangement: 2 grazing management treatments (supplementation with heather vs. nonsupplementation) and 2 anthelmintic treatments (treatment vs. nontreatment). Goats grazed continuously from May to September 2004. At the end of the grazing period, the number of dead goats due to gastrointestinal parasitism was 1 in the group supplemented with heather and dosed with anthelmintic, 4 in the group that received neither supplementation nor anthelmintic, and 0 in the other 2 groups. For goats that did not receive anthelmintic treatment, the percentage of heather in the diet was negatively correlated with fecal egg count in August (r = -0.59, P < 0.05) and September (r = -0.49, P < 0.1) and positively correlated (r = 0.54, P < 0.05) with BW changes during the grazing season. Therefore, the correlation coefficient between BW change and fecal egg count was negative (r = -0.62, P < 0.05). Rumen ammonia concentrations were always lower in supplemented goats (P < 0.05). However, VFA concentrations were greater in goats consuming heather (58.9 vs. 50.9 mmol/L), which suggests that ruminal fermentation was not adversely affected by consumption of tannins. Heather availability in the vegetation might represent a valuable opportunity and sustainable method to control gastrointestinal nematode infections in a goat production system based on grazing perennial ryegrass-white clover pastures.

Vegetation dynamics in Cantabrian heathlands associated with improved pasture areas under single or mixed grazing by sheep and goats

Vegetation dynamics in partially improved heather-gorse shrublands were studied in a 3-year field experiment under single or mixed grazing of sheep and goats. The experimental plots comprised untreated heathland, mechanically cleared heathland and converted heathland to grassland (perennial ryegrass-white clover improved pasture, covering 33–50% of the total plot area). In the heathland and mechanically cleared areas, the accumulation of shrubs in terms of cover, height and phytomass was more controlled by goats than by sheep, with intermediate values for mixed treatments. The differences were mainly restricted to the gorse ( Ulex gallii), while the type of flock did not significantly affect heather species ( Ericaceae). Herbaceous species, chiefly grasses, increased more under goat than under sheep or mixed grazing. In the absence of grazing, the amount of phytomass accounted for 22 834 kg DM/ha in the heathland areas, with 73% heaths, compared to 11 654, 6764 and 8994 kg DM/ha under sheep, goat and mixed grazing, respectively. In the cleared areas the accumulation of phytomass without grazing reached 18 508 kg/DM ha, with 46% gorse, compared to 11 696, 6530 and 6902 kg DM/ha under sheep, goat and mixed grazing respectively. In the improved pasture areas, the cover and height of the flowerstems of perennial ryegrass ( Lolium perenne) were significantly lower under goat than under sheep grazing. After senescence, the rejected stems lead to increased percentages of dead matter in the pastures grazed only by sheep. White clover ( Trifolium repens) increased more during the first grazing season under goat than under sheep grazing. In the subsequent years, it increased in all treatments without significant differences. As consequence of the different sward composition, the nutritive quality of available pasture was higher under goat than under mixed and sheep grazing. Goats reduce the accumulation of woody phytomass in the heather-gorse shrublands, and maintain a better forage quality in the converted shrubland to grassland, thus enhancing the animal performance.

Effects of cutting frequency on plant production, N‐uptake and N2 fixation in above‐ and below‐ground plant biomass of perennial ryegrass–white clover swards

AbstractNitrogen (N), accumulating in stubble, stolons and roots, is an important component in N balances in perennial ryegrass–white clover swards, and the effects of cutting frequency on the biomass of above‐ and below‐harvest height were studied during two consecutive years. Total dry matter (DM) and total N production, and N2 fixation, were measured at two cutting frequencies imposed in the summers of two years either by cutting infrequently at monthly intervals to simulate mowing or by frequent cutting at weekly intervals to simulate grazing. Total DM production harvested was in the range of 3000–7000 kg DM ha−1 with lower DM production associated with the frequent cutting treatment, and it was significantly affected by the different weather conditions in the two years. The higher cutting frequency also reduced the biomass below harvest height but the different weather conditions between years had less effect on stubble and, in particular, biomass of roots. The biomass of roots of white clover was significantly lower than that of roots of perennial ryegrass and remained at a relatively constant level (200–500 kg DM ha−1) throughout the experiment, whereas the biomass of perennial ryegrass roots increased from 2400 kg DM ha−1 in the year of establishment to 10 200 kg DM ha−1 in the infrequent cutting treatment and 6650 kg DM ha−1 in the frequent cutting treatment by the end of the experiment, giving shoot:root ratios of 4·7–16·6 and 0·5–1·6 for white clover and perennial ryegrass respectively. Annual N2 fixation was in the range of 28–214 kg N ha−1, and the proportion of N fixed in stolons and roots was on average 0·28. However, as weather conditions affect the harvested DM production and the shoot:root ratio, care must be taken when estimating total N2 fixation based on an assumed or fixed shoot:root ratio.

Productivity and quality, competition and facilitation of chicory in ryegrass/legume-based pastures under various nitrogen supply levels

Traditional perennial ryegrass–white clover mixtures have limitations in combined productivity and quality that herbs like chicory may alleviate. This study examined the consequences on productivity and quality of as well as competition and facilitation after introducing chicory into varies ryegrass–legume-based pastures in a field study over three consecutive growing seasons. A cultivar of chicory, suitable for grazing, in pure stand was found to out-yield a pure stand ryegrass in terms of dry matter and nitrogen (N) accumulation but was found to yield similar to mixtures of chicory and ryegrass. The inclusion of chicory, increased N accumulation per area unit irrespective of associated leguminous species but had no effect ( P > 0.05) on the combined dry matter yield of these mixtures as compared to the chicory–ryegrass mixture. Chicory was not found to co-exist well with associated fodder legumes but it co-existed well with perennial ryegrass. Determined by a direct 15N plant labelling technique, chicory transferred little N to associated legumes and under moderate soil N conditions it almost out-competed the white clover whereas lucerne was able to withstand the competition with birdsfoot trefoil as intermediate. Chicory and ryegrass did exchange N amounting to less than 5% of the receiver plants’ N economy whereas the N transfer from the N-rich lucerne constituted 15% of the associated ryegrass’ N economy but less ( P < 0.05) of the chicory's N economy. These differences are ascribed to the species’ root morphology and root zonation. Chicory accumulated large amounts of calcium, potassium, sodium and zinc but significant less of magnesium and manganese, irrespective of the N supply. In the case of sodium it was a short-term effect whereas calcium and possibly also sulphur, copper and zinc accumulation increased over time. It is concluded that chicory may improve the management of intensive dairy farms with a large N surplus because of the increase in productivity per unit area and N uptake efficiency and add significant improvements of the quality of the forage.

The effects of strategic nitrogen fertiliser application during the cool season on perennial ryegrass-white clover pastures in the Western Cape Province 4. Selected nutritive characteristics and mineral content

The influence of a single application of fertiliser N (0, 50, 100 and 150 kg N ha−1) applied in either autumn, early winter, late winter, early spring or late spring on selected nutritive and mineral parameters of a perennial ryegrass-white clover pasture was investigated over a three-year period. Responses were measured over one regrowth cycle five weeks after the application of N treatments. A sample of the plant material harvested was separated into grass and clover fractions. Dry matter (DM), crude protein (CP), in vitro organic matter digestibility (IVOMD), phosphorus (P) and calcium (Ca) content were determined for each sample. Winter applications of fertiliser N, in combination with the higher N rates, resulted in higher ryegrass CP contents. Clover CP content was decreased (P=0.05) with spring (early and late) applications, but fertiliser N rate did not appear to affect clover CP content. The highest IVOMD values for both ryegrass and clover were recorded in winter. Increased fertiliser N rate resulted in lower DM contents with the lowest DM produced during winter, while the highest DM contents were produced where no fertiliser N was applied in spring. P content was significantly influenced by season of application and fertiliser N rate in ryegrass and only by season of application in clover. The highest mineral concentrations were found in winter. The rate and season of fertiliser N application as used in this study did not negatively affect pasture mineral content and quality, but care must be taken to protect the grazing animal from the potential negative effects of high forage N contents on animal health.

The effects of strategic nitrogen fertiliser application during the cool season on perennial ryegrass-white clover pastures in the Western Cape Province 2. Dry matter production

The response of an irrigated perennial ryegrass-white clover pasture to fertiliser nitrogen application rates of 0, 50, 100 and 150 kg N ha−1 applied in either autumn, early winter, late winter, early spring or late spring was investigated over a three-year period. Primary dry matter production (PDM) and residual dry matter production (RDM) were recorded five and ten weeks after fertiliser N application, respectively. PDM responses were determined mainly by fertiliser N application rate. On average the highest PDM was obtained following N applications in spring and lowest when N was applied in early winter. Although RDM production generally also increased with increasing fertiliser N rates, responses were much smaller than those recorded for PDM and were affected by the season of fertiliser N application. The highest RDM was obtained when N was applied in autumn and winter while application in spring had no, or even a negative effect, on RDM. Total dry matter production (PDM+RDM) increased (P<0.05) with increasing N application rates. Except for the 0 kg N ha−1 treatment in 2002, which recorded lower DM yields compared to fertilised plots, total annual dry matter production of the pasture was not affected by N fertiliser application rate. Nitrogen application can therefore be used to improve dry matter production during a short predetermined period. Although the 150 kg N ha−1 applied in early and late spring generally gave the best results in terms of PDM, the 50 kg N ha−1 application treatments resulted in a more efficient conversion of N applied to additional DM produced.

The effects of strategic nitrogen fertiliser application during the cool season on perennial ryegrass-white clover pastures in the Western Cape Province 3. Clover content

The influence of a single application of fertiliser N (0, 50, 100 and 150 kg N ha−1) applied in either autumn, early winter, late winter, early spring or late spring on the grass-clover balance in a perennial ryegrass-white clover pasture was studied over a three-year period. Responses were measured over two regrowth cycles five and ten weeks after the application of N treatments. Increased fertiliser N rates of up to 100 kg N ha−1 resulted in increasingly lower clover percentages. No differences in clover content were recorded between the 100 and 150 kg N ha−1 application rates five weeks after fertiliser N application. The effect of season of application was inconsistent due mainly to different initial clover contents and differences in environmental conditions amongst years. Partial recovery of clover content was noted at the second regrowth cycle but not to the same levels as at the 0 kg ha−1 treatment combinations. Fertiliser N did not reduce (P>0.05) total clover DM production (kg clover ha−1) over 10 weeks when applied in autumn and early winter. Clover DM yields were, however, reduced (P=0.05) when fertiliser N was applied during early and late spring, excluding 50 kg N ha−1 applied during early spring 2000. The application of 50 kg N ha−1 during the relatively normal rainfall years in 2000 and 2002 did not cause the clover content to drop below 30 %. The application of 150 kg N ha−1 resulted in numerous treatment combinations where the clover percentage was less than 30 %, the recommended minimum for the pasture to benefit from the clover component.

The effects of strategic nitrogen fertiliser application during the cool season on perennial ryegrass-white clover pastures in the Western Cape Province 1. Soil nitrogen dynamics

The dynamics of soil inorganic-N in reaction to a single, strategic application of fertiliser N were studied during the period 2000 to 2002 in an Oakleaf soil with a clay content increasing from 10 to 30.8% with depth. Soil inorganic-N was monitored to a soil depth of 500 mm (0–100, 200–300 and 400–500 mm layers) over a seven-week period (7, 21 and 49 days) following the application of 0, 50 and 150 kg N ha−1 in the form of LAN (28) applied as a one-off application to a perennial ryegrass-white clover pasture during five different seasons (autumn, early winter, late winter, early spring or late spring). Inorganic-N content increased from 2000 to 2002 possibly as a result of biological N fixation by the clover. The application of 50 kg N ha−1 did not result in significant differences in inorganic-N content compared to the 0 kg N ha−1 treatments during almost the entire study and can therefore be regarded as a low risk treatment with regard to environmental pollution. The increasing effect of 150 kg N ha−1 on inorganic-N lasted for at least 3 weeks in the 0–100 mm layer and 7 weeks in the 200–300 mm layer, with the highest inorganic-N content measured in autumn and early winter during years of average rainfall (2000 and 2002). Leaching of fertiliser N within one week after application to the 400–500 mm soil layers during 2000 and 2001 emphasised the possible negative effect of application rates exceeding the absorption capacity of the pasture. Nitrogen application rates exceeding the N absorption capacity of the pasture may therefore result in reduced nitrogen response efficiencies (kg additional dry matter per kg N) and inorganic-N contamination of natural resources especially in winter when the inorganic N-uptake capacity of the pasture is low as a result of low pasture productivity.

Comparison of biomass production and biological nitrogen fixation of multi-species pastures (mixed herb leys) with perennial ryegrass-white clover pasture with and without irrigation in Canterbury, New Zealand

Abstract Legume-based pastures in Australasia are predominantly perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). These pastures have disadvantages such as limitations in the production and persistence of white clover and ryegrass in drought prone regions. With the increasing interest in organic agriculture, more complex pasture mixtures are seen as an alternative to the standard ryegrass-white clover (RWC) pasture. Although anecdotal evidence exists to support the benefits of alternative pastures, there is insufficient scientific evidence to support or refute these claims. The present study was conducted to compare three different alternative multi-species (mixed herb leys) (MSP) pastures with the standard RWC pasture with and without irrigation, in terms of biomass and biological nitrogen fixation (BNF) over a period of 1 year under field conditions in Canterbury, New Zealand. Isotopic dilution technique involving field 15N-microplots were used to measure BNF. Irrigation doubled dry matter yields (DMY) of all pastures compared with those under dryland. There was no significant difference between DMY of all pastures under dryland. However, under irrigation, MSP pastures out-yield RWC pasture in total and legume DMY. Red clover MSP produced significantly lower DMY than the comprehensive or lucerne MSP treatment, probably due to the ability of lucerne in extracting water from deeper soil depth. Seasonal changes in plant composition varied according to the species sown, soil moisture status and temperature. Total and seasonal amounts of N2 fixed followed the same trend as the DMY and were related to the DMY of legumes. On average, about 26–34 kg N was fixed per tonne of legume DMY, showing a uniformity across all pastures. Overall, based on the present results of 1-year study, the MSP pastures tend to result in higher DMY, BNF and legume growth compared with that of the RWC pasture, provided irrigation is available. With increased BNF, these irrigated MSP pastures may provide high quality feed to grazing animals.