Long-term responses in the yield of Eastern Gamagrass [Tripsacum dactyloides (L.) L.] to nitrogen fertilizer under two harvest regimes in the United States

Eastern Gamagrass [ Tripsacum dactyloides (L.) L.] is a perennial C₄ grass with potentially high productivity. Intensive management through the application of nitrogen (N) fertilizer and frequency of cutting, however, may be required to maximize its potential for forage production. This study determined the long-term and residual responses of Eastern Gamagrass in terms of dry matter (DM) yield and tiller density to three annual application rates (0, 50 or 100 kg ha⁻¹) of a N-fertilizer solution applied by broadcasting or knife placement for 5 out of the 10 years of the study, and harvested using one-cut or two-cut regimes. Application of N-fertilizer increased total DM yield in the 5 years of N applications by 0·44 with the first increment of 50 kg N ha⁻¹, and by an additional 0·15 with the next increment of 50 kg N ha⁻¹. In the first year that directly followed N-fertilizer applications, DM yield was 0·175 higher than the no fertilizer treatment when 50 kg ha⁻¹ had been previously applied and a further 0·16 higher when 100 kg ha⁻¹ had been previously applied. Dry matter yields were greater from the one-cut than the two-cut regime only in years when no N-fertilizer was applied. Knife placement of N-fertilizer increased total DM yield only at 100 kg N ha⁻¹. Tiller densities were generally higher under the one-cut than the two-cut regime, particularly when N-fertilizer was broadcast. The application of N-fertilizer increased herbage production, especially when responses in the year subsequent to application are considered.     

The chemical composition, digestibility and energy value of fermented and urea-treated whole crop wheat harvested at three stages of maturity

The metabolizable energy (ME) content, digestibility in vivo and chemical composition of fermented and urea-treated whole crop wheat (WCW) forage harvested were measured at different maturities. Over 2 years, twenty-four wheat forages (cv. Slepjner, Hussar and Cadenza) were harvested at 376, 516 and 632 g dry matter (DM) kg⁻¹ in Year 1 and 341, 467 and 544 g DM kg⁻¹ in Year 2 (Cuts 1, 2 and 3 respectively). Forages were conserved in 200−-ι barrels with or without a formic acid-based additive and with urea in Cuts 2 and 3 (20 or 40 g kg⁻¹ DM). Chemical compositions, digestibility in vivo and energy losses in faeces, urine and methane were measured in wethers fed 12 g DM kg⁻¹ live weight. Respective ranges in pH, crude protein, water-soluble carbohydrates, starch and neutral detergent fibre plus amylase (NDFA) contents were 3·8–8·5, 89–394, 2–43, 23–424 and 306–655 g kg⁻¹ DM. ME content, digestible organic matter content (DOMD) and digestibilities of starch and NDFA ranged between 8·4 and 15·7 MJ kg⁻¹ DM, 558 and 708 g kg⁻¹ DM, 0·901 and 0·999 and 0·362 and 0·693 respectively. Predicted methane energy losses were poorly correlated with measured values ( r ² < 0·45) in both years, but this accounted for less than 0.1 MJ ME kg⁻¹ DM. Significant ( P < 0.05) effects of maturity on the ME/DOMD ratio were observed and ascribed to differences in the extent of fermentation. Therefore, treatment application and maturity exert considerable influence on the ME content of WCW.     

The productivity of four forage legumes sown alone and with each of five companion grasses

Four legumes—white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Europe—were established as pure-sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of 'intermediate' heading date. Two 'silage' crops and an 'aftermath grazing' crop were harvested in each of three successive years.
In the first harvest year, total herbage DM production of red clover ranged from 15·03 to 17·01 t ha^-1. White clover and lucerne swards produced considerably less at 7·12 to 11·01 t ha^-1. In the second harvest year, lucerne swards were the highest producing at 15·54 to 17·14 t ha^-1, while DM production from red clover and white clover swards ranged from 6·75 to 11·87 t ha^-1. Lucerne swards maintained their production superiority in the third year at 16·48 to 17·87 t ha^-1, while production from white clover swards ranged from 6·41 to 10·23 t ha^-1. However, red clover swards declined to 3·30 to 5·81 t ha ^-1; this above-average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were influenced in a similar manner to DM production.     

Agronomic performance and nutritive value of common and alternative grass and legume species in the Peruvian highlands

The agronomic performance and nutritive value of twelve annual and perennial grasses and legumes were analysed in order to define alternatives to local forages for dry-season feeding of ruminants in the Peruvian Andes. There were twelve species and two fertilizer treatments (no fertilizer and a N;P;K fertilizer mainly applied at sowing) in an experiment with a randomized complete block design with three replicates at each of two sites. Plant height, soil cover by forage and weed species, frost damage, dry matter (DM) yield and nutritive value of herbage were evaluated in 2005 and 2006. Among the annual species, Hordeum vulgare L. cv. UNA 80 and × Triticosecale Wittm. had the highest DM yields when fertilized (8226 and 6934 kg ha⁻¹ respectively). Without fertilizer the alternative cultivars had similar DM yields to that of the local forages. Cultivars of Avena sativa L. had lower concentrations of neutral-detergent fibre (NDF) (557 g kg⁻¹ DM) and higher concentrations of predicted net energy for lactation (5·86 MJ kg⁻¹ DM) than the other annual grass species (625 g kg⁻¹ DM and 5·01 MJ kg⁻¹ DM respectively), while the legumes were superior in concentrations of crude protein (277 g kg⁻¹ DM) and NDF (362 g kg⁻¹ DM). Considering the low agronomic performance of the perennial forages, a mixture of fertilized annual grasses and legumes appears the most appropriate approach to meeting the demand for forage of high nutritive value in the Peruvian highlands.     

A comparison of faba beans and peas as whole-crop forages

Faba beans and peas were compared as spring sown whole-crop forages in two trials at Lough-gall. No herbicide, insecticide or N fertilizer was used. Harvesting took place at the end of July. As pure stands, tic beans (cv. Blaze) yielded up to 10 t of dry matter (DM) ha⁻¹. Lower yields were obtained at lower seed rates, or with horse beans (cv. Stella Spring), broad beans (cv. Polar) or peas (cvs Minerva and Krupp). Tic and horse bean forage had a mean DM concentration of 166 g kg⁻¹, which was higher than those of broad bean and peas. Crude protein (CP) concentration at a mean of 159 g kg⁻¹ was similar in tic beans and peas. Faba beans mixed with cereals yielded less than beans alone, but peas with cereals yielded slightly more than peas alone. The inclusion of a cereal raised forage DM contents but lowered CP contents. Perennial ryegrass-white clover mixtures undersown in faba beans established well, but poorer swards were obtained in some of the pure pea stands which lodged severely. It is concluded that, as pure stands, tic beans have advantages over peas. Some of the disadvantages of peas can be overcome by growing a mixture of peas with cereals.     

Effect of stage of maturity of whole-crop barley on intake and liveweight gain by dairy steers differing in initial live weight

The effect of maturity at harvest of whole-crop barley for ensiling on intake and liveweight gain of dairy steers differing in initial live weight (LW) was evaluated in an experiment over two years. Light (104–120 kg) and heavy (402–419 kg) dairy steers were fed diets containing predominantly whole-crop barley silage harvested at the milk stage [dry matter (DM) content of 284 g kg⁻¹ and neutral-detergent fibre (NDF) concentration of 526 g kg⁻¹ DM] or the dough stage of maturity (DM content of 328 g kg⁻¹ and NDF concentration of 445 g kg⁻¹ DM) and supplemented with up to 1 kg of concentrate. Dry matter intake (g kg⁻¹ LW) was higher for whole-crop barley harvested at the dough stage than at the milk stage of maturity and the difference was greater in heavy than in light steers ( P <  0·001). Liveweight gain was higher and feed conversion ratio was lower for dough-stage compared with milk-stage silage ( P  <   0·05) but there was no interaction with size of steer. Whole-crop barley harvested at the dough stage of maturity promoted higher liveweight gains in dairy steers compared with whole-crop barley harvested at the milk stage due to a higher DM intake.     

Identifying suitable temperate grass species and cultural practices for herbage production in the mountain regions of North Vietnam

In North Vietnam, during winter, shortage of herbage constrains the profitability of dairy farming. The first objective of this study was to evaluate the potential of alternative temperate (C₃) forage species, namely common oat ( Avena sativa L.), lop-sided oat ( Avena strigosa Schreb.), Italian ryegrass ( Lolium multiflorum L.) and a commercial forage mixture (Avex), to address the shortage of herbage during winter in the mountain regions of North Vietnam. The second objective was to measure the effects of cultural practices (sowing rate, harvest interval and irrigation level) on yield of dry matter (DM), chemical composition, digestibility of DM and metabolizable energy (ME) concentration of herbage from the best adapted C₃ species previously tested (lop-sided oat). Four experiments were conducted. Oat species proved to be the best adapted species and produced the highest annual yield of herbage (7600 kg DM ha⁻¹) with a high nutritive value. Yields of DM of lop-sided oat were not affected by sowing rate of seed but increased as the length of harvest intervals increased from 30 to 45 and 60 d ( P  <   0·001). Crude protein concentration, digestibility of DM and ME concentration decreased as the harvest interval increased ( P  <   0·01). Irrigation increased the yields of DM of lop-sided oats by 1·3 ( P  <   0·05) but had no effect on the nutritive value of herbage. It is concluded that both common oat and lop-sided oat are suitable species to provide herbage in the winter for the mountain regions of North Vietnam.     

WHOLE-CROP VICIA FABA FOR CONSERVATION. A COMPARISON BETWEEN WINTER-, HORSE-, TICK-, AND BROAD-BEAN CULTIVARS

A trial containing cultivars of Vicia faba var. equina, minor and major was harvested as a whole-crop in 1971. The aim was to estahlish the DM yield obtainahle from a selection of spring-hean cultivars and evaluate this in relation to previously reported yields from winter heans. DM yields ranged from 48 to 86 hkg/ha over the three cutting dates. Significant differences were found hetween cv. in digesdhiUty, the range being 54 to 71%, and one hroad-hean cv. was shown to have a high digestihility at all cuts. Crude-protein contents of 13 to 19% were recorded. Percentage DM rose from 16 to 18% at the first cut to 23 to 45% at the third, hroad-hean cv. rising more slowly than horse- and dck-hean cv. Spring-bean cv. had a lower DM yield than winter cv. Horse hean was superior to tick bean in DM yield, percentage DM, and D-value. Broad-bean cv. proved difficult to dry and therefore may be more suitable for ensilage than dehydradon.     

Silage and milk production: a comparison between long, chopped and ground hays as supplements to silage of high digestibility

Grass silage made in May from S24 perennial ryegrass had a DM concentration of 262 g kg^-1 and an in vitro D-value of 0·698, and was given ad libitum to twelve Ayrshire cows in a 16-week feeding experiment. In addition supplements of hay with a mean in vitro D-value of 0·603 were offered in one of three forms—long, chopped (12·1 mm) or ground (0·80 modulus of fineness) and cubed—and of concentrates given at either 2 or 4 kg per 10 kg milk. Hay averaged 18·2% of total forage DM intake with mean daily intakes of 1·28, 1·22 and 2·26 kg DM per cow in the long, short and ground forms respectively. The highest daily intakes of forage, i.e. silage plus hay, occurred on the ground hay treatments, with values of 10·24 and 9·25 kg DM per cow on the 2 and 4 kg concentrate treatments respectively. The mean daily milk yields were 18·2,18·2 and 19·2 kg per cow on the long, short and ground hay treatments respectively but the increase in yield with the ground hay was only significant at the low level of concentrate intake. The hay treatments had small and non-significant effects on milk composition. It is concluded that ground hay was superior to either long or chopped hay as a supplement for silage, but the small advantages depended on the level of concentrate intake.     

Agronomic factors affecting the yield and quality of forage maize in Ireland: effect of sowing date and plastic film treatment

The objectives of these studies were to examine the effects of sowing date and plastic film on the yield and quality of forage maize ( Zea mays L.) in Ireland, a marginal maize-growing area. In 1989–95, comparisons were made of maize sown through clear plastic film (PP treatment), and maize sown in the conventional manner without plastic (NP treatment), in terms of dry-matter (DM) yield and quality (cob, grain and starch contents). The PP treatment significantly increased DM yields in five years, with a mean yield increase of 3·10 t ha⁻¹. Whole-plant DM content increased (significant in four years) by a mean of 0·15; cob content increased (significant in five years) by a mean of 0·32; grain content increased (significant in all of the three years examined) by 0·75; and starch content increased from 236 to 318 g kg⁻¹ DM ( P  < 0·01) in 1995 where the plastic film treatment was used. Organic matter digestibility values were similar for both treatments in 1995. Sowing date in the April-May period had no consistent effect on DM yields, but early sowings did increase cob (significant, except in 1994), grain (significant in one (1995) of the two years tested) and starch ( P  < 0·05) contents (only tested in 1995). Sowing on 11 April 1995 through perforated plastic gave lower yields than the NP treatment sown on the same date, due to severe frost damage in early May.     

Establishment and production of common sainfoin (Onobrychis viciifolia Scop.) in the UK. 1. Effects of sowing date and autumn management on establishment and yield

The effects of sowing date and autumn management of sainfoin ( Onobrychis viciifolia Scop.) were investigated over 3 years in the UK. Replicated plots were sown between April and September in 2003 and 2004. Autumn management treatments were early and late cutting carried out in the establishment year and in subsequent years. Dry matter (DM) yields were measured over 3 years. One harvest was taken from April to July sowings in the establishment year and three harvests in each of the following years. DM yields from sowings in April and May were 2·8 and 3·3 t DM ha⁻¹, respectively, in the establishment year, which were higher ( P  <   0·001) than from sowings in June and July. Sowings from April to July yielded 10·9–12·5 t DM ha⁻¹ in the first full-harvest year, and 9·5–11·5 t DM ha⁻¹ in the following year. Sowings in August and September only gave 5 t DM ha⁻¹ year⁻¹. Early-autumn cutting of an established sward reduced yields of sainfoin at the second harvest in the first and second full-harvest years. Sowing in May had the lowest proportion of weed species (0·06) in the establishment year, and sowing in July had the highest (0·53). Crude protein concentration increased as the seasons progressed from 149·8 to 230·1 g kg⁻¹ DM.     

Morphological development and forage quality changes in crimson clover (Trifolium incarnatum L.)

The development of efficient forage management and utilization is facilitated by a knowledge of the changes in nutritive value and patterns of dry matter (DM) distribution within plants. The objectives of this experiment were to determine the patterns of DM accumulation and the change in nutritive value during maturation of crimson clover ( Trifolium incarnatum L.), a cool-season annual forage legume adapted to mild winter areas and acid soils. Crimson clover was established on a Dystric Eurocrept soil with pH 5·4 in Galicia, north-western Spain, during three consecutive years (1990–92). Shoot samples were taken at approximately biweekly intervals in the spring and summer after autumn sowing, and were separated into stems, leaves and seed pods. DM accumulation, crude protein (CP) and acid-detergent fibre (ADF) concentrations and in vitro organic matter digestibility (IVOMD) were determined for each plant part at each stage. Average annual DM production at initial flowering was 4·2 t ha^–1, whereas the CP and ADF concentrations and IVOMD values were 134 g kg^–1 DM, 302 g kg^–1 DM and 0·720 respectively. The nutritive value declined with age, coinciding with a reduction in leaf:stem ratio (from 0·53 at the vegetative stage to 0·13 at the ripe seed stage). This decline was more rapid than that reported for other legumes, possibly because of the low leaf:stem ratio of crimson clover. However, as it is used in the Atlantic coastal areas of north-western Spain, where it is harvested around initial flowering, it can provide forage of good quality.     

Response to late season nitrogen of upland swards in Wales

During 1984 and 1985, trials at sixteen sites throughout Wales measured the yield response in upland swards from applying 40 and 80 kg N ha⁻¹ at three dates, 20 August, 4 September and 18 September. All sites were between 230 m and 345 m above sea level. Grass yields were measured by cutting plots during October and November.
Nitrogen increased the herbage dry-matter (DM) yield at all sites in both years. The yield response per kg N applied varied between sites. Mean yield response for the two years declined from 16·2 kg DM kg N⁻¹ with 40 kg N ha⁻¹ applied on 20 August to 8·9 kg DM kg N⁻¹ with 80 kg N ha⁻¹ applied on 18 September. In general there was a decline in response to N with increased rate and delay in time of application. The results indicate that responses above an optimum of 9 kg DM kg N⁻¹ can be obtained well into September. A general rule that 1 kg N can be economically applied per 4 summed day degrees air temperature >6 °C remaining in the autumn up to 30 November is suggested.
Delay in application and increasing N rate increased crude protein in the herbage but had only small effects on modified acid detergent (MAD) fibre and sugar. Generally, grass quality was good. Sward density assessed during the spring after nitrogen had been applied appeared to have been unaffected by the treatments.     

Cattle slurry as a source of nutrients for red clover: herbage production and clover contribution

An established sward of red clover cv. Hungaropoly sown pure received approx. 30 kg P ha^-1 and 200 kg K ha^-1 each year for 3 successive years. The P and K were applied either as cattle slurry, inorganic fertilizer or combinations of these. Treatments were applied either in spring or after the first harvest. There were a total of six treatments and these were harvested three times each year. The average yields of total herbage DM over all the treatments in the first, second and third years were 15·2, 14·2 and 14·2 t ha^-1 respectively and the various treatments had no significant effect on the overall yields.
Treatments had a significnt effect on red clover DM yields and percentage red clover in one harvest in each of the first 2 years and all three in the third year. Yields of red clover were lower and grass higher in treatments receiving cattle slurry only. On this treatment there was a total yield of 23·2 t ha^-1 red clover DM in the 3 years compared with 30·2 t ha^-1 on the inorganic fertilizer treatments. However, by applying P and K fertilizer in the spring, followed by cattle slurry after the first harvest, it was possible to maintain a high proportion of red clover in the sward and to produce yields of red clover DM similar to those on the inorganic fertilizer treatments.     

A study of the nutritive value of white clover (Trifolium repens L.) in relation to different stages of phenological maturity in the primary growth phase in spring

This paper reports the effects of onset of phenological maturity on the nutritive value of white clover ( Trifolium repens L.). The study comprised (i) examination of an extensive data set on nutritive value and (ii) investigation of the constituents of nutritive value, in vivo feeding value, protein degradability and metabolizable protein content of white clover harvested at three stages of maturity (early-flowering, full-flowering, ripe seed stages) during the primary growth phase in spring in Australia. The data set on nutritive value showed a consistent pattern of high nutritive value during cool season months, progressive decline through spring and uniformly lower nutritive value over summer. Results from laboratory determinations, in sacco degradability studies and a digestibility trial on white clover harvested at early-flowering, full-flowering and ripe seed stages were consistent with results from the data set on nutritive value. Onset of maturity during the primary growth phase in spring was accompanied by large changes in nutritive value: neutral-detergent fibre (NDF) increased from 184 to 301 g kg⁻¹ dry matter (DM), nitrogen (N) declined from 36 to 20 g kg⁻¹ DM, in vitro digestibility declined from 0·74 to 0·65 and metabolizable protein content declined from 144 to 67 g kg⁻¹ DM from early-flowering to ripe seed stage. These nutritive value changes were accompanied by a decline of in vivo digestibility at the rate of 0·0032 d⁻¹ and an 0·2 reduction in voluntary intake.     

Barley/pea mixtures as cover crops for grass re-seeds

Substantial annual fluctuations in the performance of arable silage mixtures, comprising Minerva forage pea and Goldmarker barley, were observed from ten annual sowings between 1977 and 1986, Total dry matter (DM) yield varied between 2·5 and 11·5 t ha⁻¹. Dry matter content also ranged widely from 10·3% to 20·0% and there was a large variation in the proportion of peas in the DM (0·44 to 0·90). Almost 80% of this yield variation was due to the fluctuation in pea performance and over 60% of all yield variation was related to the variation in sunshine hours and air temperature.
In 1983 and 1984 differences in seed rate of between 20 and 140 kg ha⁻¹ of Minerva and 80 and 160 kg ha⁻¹ of Goldmarker influenced the forage composition at harvest, with the pea component capable of outgrowing and suppressing the other species when sown at over 80 kg ha⁻¹. Very high yields of peas were associated with increasing stress on the undersown grass re-seed and were considered undesirable.
It was concluded that sowing rates of between 120 and 160 kg ha⁻¹ for barley and a maximum of 60 kg ha⁻¹ for peas would, in most years, provide the best compromise between attaining good arable silage yields and avoiding excessive dangers of damage of undersown grass re-seeds.     

The productivity and response to inorganic fertilizers of species-rich wetland hay meadows on the Somerset Moors: the effect of nitrogen, phosphorus and potassium on herbage production

The effects of fertilizer nitrogen (N), phosphorus (P) and potassium (K) on herbage production were investigated in herb-rich hay meadows in Somerset, UK. Swards were cut after 1 July each year, followed by one or two aftermath cuts. Dry-matter (DM) yield at cutting, metabolizable energy (ME) production and recovery of N, P and K were measured over 4 years.
Total annual DM production increased from 4·7t ha⁻¹ without fertilizers to 10·5t ha⁻¹ with 200 kg N, 75 kg P and 200 kg K ha⁻¹ per year, and ME output from 38·8 GJ ha⁻¹ to 92·5 GJ ha⁻¹. Applying moderate replacement rates of P and K without N increased annual DM and N yields by 43% and 36% respectively, but N response was modest unless high rates of P and K were used. Annual ME output and recovery of N, P and K were all significantly increased by taking an additional, earlier cut for silage, even though DM yield was unaffected.
The results suggest that potential output of these meadows is similar to that of a wide range of less diverse permanent pastures. Data from this and a concurrent experiment will help to estimate the financial implications of fertilizer and cutting date restrictions within Sites of Special Scientific Interest and the wider Environmentally Sensitive Areas.     

Effect of rainfall and temperature on yield of Vicia sativa under rainfed Mediterranean conditions

The productivity of Vicia sativa grown in rotation with barley under rainfed Mediterranean conditions was examined at two locations over several years (eighteen location × year situations). Rainfall during the growing season ranged from 200 to 500 mm. Vetch relied on indigenous rhizobia for nodulation and N fixation while for phosphorus it was fertilized with 20kgPha⁻¹. Harvesting took place at the beginning of pod formation. The dry matter (DM) yield reached 6·6t ha⁻¹ and the N offtake 215 kg ha⁻¹. The highest yields were obtained when rainfall exceeded the 350 mm level. The N concentration of the forage was not influenced by rainfall or by the productivity of the plants. Yield of DM was related to the number of days of ground frost in January but not in February and March. Monthly minimum and maximum temperature was not related to the DM yield. The combination of monthly rainfall and temperature explained over 95% of the variation in yield.     

Effect of fertilizer nitrogen rate and timing on herbage production and nitrogen use efficiency for first-cut silage

Eight field-plot experiments were carried out on established grassland swards between 1984 and 1988 to examine the effects of date and rate of application of calcium ammonium nitrate (CAN) on herbage dry matter (DM) yield and apparent efficiency of nitrogen (N) use at first-cut silage.
CAN application significantly increased ( P <0 ·001) the mean yields of herbage and N uptakes by herbage in all experiments. Herbage yields were similar ( P > 0·05) with N rates of 100 kg ha⁻¹, 125 kg ha⁻¹ or 150 kg ha⁻¹ in five experiments but in the other three there were increases above 100 kg ha⁻¹. Date of N application had a significant effect on DM yield in three experiments; this effect was inconsistent for both single and split dressings. Lower production was associated with reduced uptake of N, a trend that primarily reflected lower DM yields and not wide herbage N content variation.
It is concluded that selection of the date on which to apply fertilizer N in early spring to obtain optimum herbage yields at first-cut silage often required little precision. The use of fertilizer N rates >100 kg ha⁻¹ should be questioned where there are likely to be appreciable quantities of available N derived from non-fertilizer sources.     

The effect of harvesting system on nutrient losses during silage making. 1. Field losses

An experiment was carried out during 1982 in which the effects of three differing harvesting systems on the field losses occurring during the conservation of grass as silage were examined. The treatments were either (a) harvesting herbage directly by means of a flail harvester (unwilted flail, UF), or (b) pre-cu ing of herbage with a rotary drum mower and lifting using a precision-chop forage harvester with wilting (WP) and without wilting (UP). Herbage was harvested on 26 May, 21 July and 7 September 1982. The mean yields of herbage produced from plots harvested by the three systems were not significantly different, with dry ma er (DM) yields of 12470, 12300 and 12230 kg ha^-1 for the UF, UP and WP treatments respectively. However, field losses with the UP and WP treatments were greater than with the UF treatment (P<0·01). As a result the yields of herbage ensiled with the UP and WP treatments, 11690 and 11320 kg DM ha^-1 respectively, were significantly lower than with the UF treatment, 12710 kg DM ha^-1 (P <0·05). Wilting of first cut herbage for a period of 72 h resulted in a significant reduction (P<0·05) in digestible organic ma er (DOM) concentration (determined in vitro), whereas small increases in DOM concentration were observed following wilting of second and third harvest material.
It is concluded that, even under favourable weather conditions, both pre-cutting and wilting of herbage prior to harvesting can result in considerable losses of nutrients in the field.