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Detailed measurements of herbage accumulation were made on a ‘Grasslands Nui’ perennial ryegrass (Lolium perenne)-dominant, ‘Grasslands Huia’ white clover (Trifolium repens) pasture under 4 late spring grazing intensities, based on residual leaf area index (LAI), and 2 grazing frequencies based on light interception. Lax grazing during late spring (residual LAI 0.9–3.0) resulted in rank stalky herbage, whereas hard grazing (residual LAI 0.1–0.9) resulted in more leafy herbage and higher ryegrass tiller density. For the 46 weeks of the experiment, 16.5 and 14.61 DM/ha accumulated with hard and lax spring grazing respectively. During autumn, delaying grazing until 2 weeks after 95% light interception markedly increased green herbage accumulation compared with grazing at 95% light interception, without significantly reducing ryegrass tiller density or white clover content. It is concluded that in spring, in contrast to other seasons, management of ryegrass-dominant pasture to control reproductive de...

Nitrogen at 0, 84, 168, 336, and 672 kg/ha was applied as liquid urea to a commercial maize cultivar (PX610) over three different growth stages. Plants were grown at a population of 96 900/ha and received continual trickle irrigation. Response was measured in terms of dry matter and nitrogen yields of the whole plant, leaf laminae, stem, cob, grain, husk, and roots. Overall yields of grain (11 000–14000 kg/ha) and total plant dry matter (24 000–29 000 kg/ha) at physiological maturity were high, but dry weight responses to different levels of nitrogen and times of application were not significant. Nitrogen content of the whole plant increased significantly with increasing nitrogen application rate. Dry matter and nitrogen concentration in the plant components changed in relation to changes in source-sink patterns as reproductive development began. Plants receiving 0 and 84 kg fertiliser N/ha showed classical nitrogen deficiency symptoms from late vegetative growth to maturity, but were the most ef...

Reproductive development, tillering, and herbage production were studied in mixed pastures containing ‘Grasslands Nui’ perennial ryegrass (Lolium perenne L.) and ‘Grasslands Huia’ white clover (Trifolium repens L.), which were rotationally grazed by sheep. The effects of interruption of ryegrass reproductive development during early culm elongation (TI) or 30% inflorescence emergence (T2), by either hard grazings (H; residual leaf area index (LAI) 0–0.7) or lax grazings (L; residual LAI 0.8–2.2) were compared. These grazing intensity treatments were continued until mid summer; and in late summer and autumn all pastures received the same grazing management. Culm elongation in an initial group of reproductive tillers, 2400/m2, started in October, and 30% inflorescence emergence occurred in mid November. During November and December a further 1000/m2 secondary reproductive tillers appeared. Few new reproductive tillers appeared after December. Vegetative ryegrass tiller density declined markedly dur...

The effect of sheep grazing on ryegrass aerial tiller development in mixed perennial ryegrass — white clover swards was studied in two experiments. Aerial tiller numbers were increased by lax grazing and reduced by hard grazing. Later interruption of reproductive development encouraged aerial tiller development. Aerial tillers made a minor contribution to herbage production and ryegrass tiller populations. It was concluded that aerial tillering contributed little to ryegrass persistence in mixed swards under the grazing systems used in this experiment, but that under different grazing or climatic conditions they could be more important.

An irrigated ‘Grasslands Nui’ perennial ryegrass (Lolium perenne L.) sward was mown during reproductive growth and subsequent vegetative summer growth using 6 cutting treatments. The treatments included combinations of stages of interruption of reproductive development and regrowth intervals. Tagged ryegrass tillers were used to measure tillering, tiller longevity, and tiller weight at different ages. Periods of rapid tillering in spring before culm elongation started, and after interruption of reproductive growth were observed. Interruption of reproductive development at inflorescence emergence increased tillering in the second period compared with other treatments. Later interruption of reproductive development reduced the number of pre-flowering tillers surviving into summer. Longevity of tillers tagged at the start of the experiment was greatest with early interruption of reproductive growth followed by infrequent cutting. Youngest tillers were smallest, and new tillers took 60–100 days after...

This paper considers the sequence of seed development by measurement and observation of ehanges in seed moisture content, weight, colour, endosperm consistency, germination capacity and yield in perennial ryegrass Grasslands Ruanui, timothy Grasslands Kahu and a New Zealand strain of prairie grass (Bromus unioloides). Seed moisture content was high (60–70%) after anthesis and declined at different rates, depending on the species and the weather. Maximum seed dry weight (maturity) was reached approximately 30 days after peak anthesis in all species and was influenced by N application and grazing. Colour changes in the seedhead and endosperm solidification proved unsatisfactory as measures of maturity. Endosperm solidification was reached 4, 11 and 12 days before maximum seed dry weight in ryegrass, timothy and prairie grass, respectively. Seeds removed from the plant as little as 7, 10 and 4 days after anthesis in ryegrass, timothy, and prairie grass, respectively, germinated, provided that dormancy was broken; but they did not retain viability after 3 months storage. Maximum viability of ryegrass, timothy and prairie grass seed tested immediately after harvest occurred 30, 38 and 16 days after anthesis, compared with 17, 35 and 12 days, respeetively, when germination testing was delayed for 3 months. In ryegrass, grazing caused a significant increase in seed yield in the second year while N application alone did not significantly increase yield. In timothy, grazing and to a lesser extent N, were both detrimental to seed yield in the second year. Highest yields were obtained in treatments not receiving either grazing or N. In prairie grass, grazing depressed and N application increased yields in both years. In all species similar or increased yield could be obtained by mowing the crop at, or slightly prior to, seed maturity and allowing seed development and ripening to continue on the cut straw for up to 10 days. Using this technique higher seed yields were obtained in ryegrass and timothy than when seed was direct-harvested. In prairie grass similar yields were obtained whether the erop was direct-harvested or threshed following drying in the swath for 10 days. The use of ‘drying curves’ for the prediction of correct cutting time of seed crops is suggested for ryegrass, timothy and prairie grass.

Measurements were made of the influence of season and stocking rate on herbage mass, composition, and organic matter digestibility (OMD) and on the composition and OMD of the diet selected by grazing hoggets. A stocking rate of 36 hoggets per ha reduced the amount of stem and dead matter and increased the OMD of herbage on offer compared to 24 hoggets per ha. Herbage OMD declined from 60.7% to 54.7% over summer and increased from 56.7% to 72.1% in autumn. Herbage composition changes during 3-day grazing periods showed reductions of OMD, green leaf, ryegrass, and weeds, and increases in the proportion of dead matter. Diet samples from oesophageal fistulated sheep showed the selection of green leaf and the rejection of dead matter. Dead matter content of the diet was positively correlated with percentage composition of dead matter in the sward, and negatively correlated with the amount and percentage green leaf on offer. Diet OMD was positively correlated with percentage green leaf on offer and per...

The pattern of nitrogen distribution in field grown Lupinus albus, L. luteus, Pisum sativum, and Vicia faba which were sown in August or October, was measured. Although rates of N accumulation were similar, the start and duration of the rapid N accumulation phase differed between species. L. albus had the longest accumulation phase, which contributed to its superior seed protein yield. The data suggest that, in the field, timing of the initiation of the ‘self destruction‘ cycle in grain legumes is an important determinant of seed protein yield and can be initiated by the effects of water stress. The exception to this was P. sativum in which, at the early sowing, self shading may have been an important factor. It was concluded that early sowing was important to ensure maximum N accumulation and seed protein yield. Relatively small extension to the growth period by irrigation or reliable summer rain should achieve significant increases in seed protein yield.

1. In a grazing trial with sheep, cocksfoot, ryegrass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems, and also white clover.2. Live weights were recorded every 2-3 weeks, and wool production was estimated by clipping midside patches every month.3. Sheep on grass plus clover plots were significantly superior to sheep on grass plots in terms of live-weight gain, final live weight and clean-wool production.4. Sheep on ‘long’ pastures were significantly heavier than sheep on ‘short’ pastures for a month in the early part of the trial. Thereafter, differences in live weight were not significant.

1. In a grazing experiment with sheep, cocksfoot, rye-grass and tall fescue were grown with and without white clover, under ‘short’ and ‘long’ management systems.2. One sheep on each plot was fitted with an oesophageal fistula, from which herbage samples were collected at fortnightly intervals. The botanical composition of samples from the mixed swards was estimated by an optical point quadrat method. Samples were analysed for crude protein and cellulose, and digestibility was estimated in vitro.3. Treatment difference within the mixed swards were not significant in terms of botanical composition. The mean proportions selected were 73% grass, 9% clover and 18% dead matter. The proportion of clover selected did not differ significantly between sample collections.

A study was made to determine the effects of grazing to a height of 1 in. when the swards reached heights of 3 and 9 in. on the dry matter production, LAI, tillering and rate of leaf production of new and old tillers in the spring–summer and autumn–winter seasons of 3 pasture species growing in association with white and red clovers. In both seasons the herbage yield under 9–1 management was higher than that under 3–1 and was significantly greater in the spring-summer season. Differences in DM production between cocksfoot, tall fescue and Ariki ryegrass failed to reach significance. Light utilization under the 2 management systems was considered to be inefficient. In the autumn-winter period there was a linear relationship between the LAI and DM production in all treatments. The rate of leaf production per tiller was significantly higher in cocksfoot than in ryegrass and tall fescue in both seasons. New tillers had a significantly higher rate of leaf production than old tillers in the spring-summer period, but not in autumn-winter. The numbers of grass tillers and rooted nodes of clover were significantly higher under 3–1 than under 9–1 and were influenced by season.

1. The rate of clean wool production, carcass apparisal and reticulo-ruminal development of grazing sheep were used to evaluate differences in pasture quality. Perennial ryegrass, cocksfoot and tall fescue pastures were assessed as pure stands and also white clover.

1. An experiment was conducted in which lambs grazed on pastures of cocksfoot, ryegrass and tall fescue grown with and without white clover, as well as on pastures of pure white clover.

A study was made of the effects of gangmowing, grazing, and combinations of the two on the productivity, botanical composition, nitrogen status, and animal consumption of a pasture, and on the earthworm population under the pasture. Gangmowing increased pasture production, particularly in the summer, by encouraging greater clover growth. The nitrogen contents of both grass and clover were also increased. Grazing plus gangmowing resulted in greater pasture consumption than from grazing alone. Numbers and weights of earthworms under the gangmown pastures were much higher than under the pasture only grazed.

The eifect of 1 ft-diameter (0.30 m) dung patches on the yield and botanical composition of a dairy pasture was followed in two randomized-block experiments. Experimental plots consisted of 3 concentric rings round each dung patch of diameter 2 ft (0.61 m), called R2; 3 ft (0.91 m), called R3; and 4 ft (1.22 m), called R4. They were sequentially harvested. In the first experiment described there was a significant increase in the total yield of grass species, predominantly ryegrasses, around each dung patch. This increase was first evident in R2 but spread progressively outward and was still detectable in R4. Plant material, particularly clover components, decayed rapidly beneath the dung patches. Leaving a dung patch on the pasture for 15 days kiUed 75% of the grass tillers and the rooted nodes of clover stolons; thus causing a significant reduction in pasture regrowth from the patch area when the dung patch was removed. The second experiment included three defoliation treatments, viz. 1. Cut regularly to 1 in. (2.54 cm) in all three rings; 2. Cut to 21/2 in. (6.35 cm) in R2 and 1 in. (2.54 cm) in R3 and R4; 3. Control undefoliated. In all three treatments there was a significant increase throughout the experiment in total yield of grasses around the dung patchy. The increase was confined to R2, but was still evident after 14 weeks. The greatest cumulative yield during tbe period of the experiment came from around the dung patches receiving the most intensively defoliated treatment.

The results of experiments undertaken in England and New Zealand are reported. Under highly productive pasture a significant correlation was found between pasture production and earthworm numbers and weights. This relationship was not evident until the pastures were more than 3 years old. On pastures of similar total dry-matter production there was a significant correlation between yield of clover and numbers and weights of earthworms. The return of dung by the grazing animal increased earthworm numbers and weights, and the application of nitrogenous fertilizer had a similar but less marked effect. The earthworm population was not demonstrably related to the macro-organic-maller content of the pastures. The grazing of grass-clover pastures was not essential for an increase in earthworm populations to occur. Allolohophora species (mainly A. caliginosa) were dominant under pure grass swards, whereas Lumhricus species (mainly L. rubellus) were dominant under grass/clover swards.