THE DEVELOPMENT OF SURFACE SEEDING

The principles of surface seeding as they apply to conditions in the north of Scotland are described and are illustrated by results from trials. The types of land and vegetation most suited to exploitation by surface seeding are indicated, and the need to consider the improvement of rough grazings in relation to a farm as a whole is stressed.
Ploughing is not necessary but some seed bed preparation is desirable, except on ideal sites. Investigations show the importance of suitable seeds mixtures in association with adequate lime and fertilizer applications in both the establishment and maintenance of these swards. Reference is made to new techniques such as lime-coated seed and chemical pre-treatment.     

Rice seedling establishment as affected by cultivar,seed coating with calcium peroxide,sowing depth,and water level

Inconsistent seedling establishment is a constraint to the adoption of direct seeding of lowland rice (Oryza sativa L.) in the tropics. Rice cultivars with superior seedling establishment in flooded soil have been recently identified. The establishment of these tolerant cultivars was compared with a control cultivar with and without calcium peroxide-coated seed under various combinations of water level and sowing depth. Water level had little effect on seedling establishment when seed were sown on the soil surface, but establishment was reduced by raising the water level when seed were sown below the soil surface. Calcium peroxide-coated seed established better than the tolerant cultivars at 13- and 25-mm sowing depths, but their seedlings were shorter and less vigorous than those of tolerant cultivars. Tolerant cultivars and coated seed had longer mesocotyls than controls. Sowing tolerant cultivars beneath a flooded soil surface at less than 13 mm assists achievement of consistent seedling establishment in lowland rice production.     

THE ESTABLISHMENT OF GRASS AND FODDER CROPS AFTER SWARD DESTRUCTION BY HERBICIDES

A series of 9 experiments carried out on an alluvial soil at two levels of fertility during the period 1971–3 showed that cultivation of the mineral soil was unnecessary for the satisfactory germination, emergence and establishment of a wide range of forage crops. With small-seeded crops (grasses and clover) non-cultivation gave improved establish ment and early growth compared with crops from soil which had been disturbed. A second series of 6 experiments investigated the effects of surface plant material on the establishment of a smaller range of forage crops sown without cultivation. The presence of this mat or trash was associated with a reduction in establishment of seedlings, but not with subsequent growth of the plants that became established. Treatments which processed or partially removed the organic matter were associated with increased emergence. Crops with small seeds were more susceptible to the effects of organic matter than those with larger seeds.     

INTERACTIONS OF GRASS, CLOVER AND NURSE CROP IN THE SEEDING YEAR

Tall fescue S170 and Italian ryegrass S22, slow- and rapid-establishing grasses, respectively, were sown either with white clover or with a mixture of red and white clovers, with or without a companion- or cover-crop, and with or without nitrogen. Swards established without a cover-crop were grazed frequently or cut infrequently; swards undersown with the oat crop were grazed once in the autumn. In the year of sowing tall fescue/clover mixtures produced yields similar to those of Italian ryegrass/clover swards. Tall fescue proved sensitive to competition, even from red clover, during establishment and sowing under a cover-crop is therefore not recommended. The yield of red- and white-clover was increased when sown under a cover-crop and when cut infrequently, compared with frequent grazing by sheep. The growth of white clover was greatly reduced by adding red clover to the mixture, particularly under a cover-crop and when defoliation was infrequent, but red clover increased total yield. The effect of N applied to the seed-bed varied with the method of establishment. Cereal yield was reduced under dry conditions by undersowing with a mixture containing red clover.     

THE EFFECT OF SEED WEIGHT AND DEPTH OF SOWING ON THE EMERGENCE AND EARLY SEEDLING GROWTH OF PERENNIAL RYEGRASS (LOLIUM PERENNE)

Seed of S24 perennial ryegrass of two weight ranges, 0.9–2.1 and 2.5–3.6 mg, were sown in soil at depths of 1.25, 2.5, 5.0 and 7.5 cm. Seedling growth was studied during the 3 weeks following germination.
Seeds of both weight ranges germinated equally well at soil depths down to 7.5 cm. However, the number of shoots that emerged was reduced as the sowing depth increased. At similar depths of sowing, seedlings from the heavy seed were heavier and developed more leaves and tillers than those from light seed. Deeper sowing reduced seedling weight and the rate of leaf- and tiller-production. After emergence, the relative growth rates of the seedlings which grew from seed of both weight ranges were similar at those depths of sowing which permitted the highest proportion of emerged shoots to seeds sown. This indicates that the weight advantage gained by the seedlings that developed from heavy seed during their non-photosynthetic stage of growth was maintained, and was not increased by a greater relative growth rate after photosynthesis began.
The implications of the findings are discussed in relation to plant breeding, commercial seed production and sward establishment.     

RESEEDING AND SURFACE TREATMENT-A COMPARISON OF TWO METHODS OF IMPROVING HILL GRAZINGS

Two methods of improving hill land for sheep grazing have been compared on a Festuca/Agrostis pasture in mid-Wales. Ploughing and reseeding, following a pioneer crop, resulted in an excellent sward which remained productive at the end of the 8-year trial period. Surface seeding with light cultivation gave only a fair establishment of white clover, but no sown grass, during the same period. The production and financial results point to the superiority of the former technique where conditions are suitable and where increased grass production can be met by increased sheep stocking. Any worthwhile method must produce real improvement to the herbage.     

EFFECTS OF METHOD OF ESTABLISHMENT ON TALL FESCUE AND ITALIAN RYEGRASS MIXTURES IN THE FOLLOWING YEAR

Tall fescue and Italian ryegrass mixtures react differently to management in the year of sowing. The decrease in yield of tall fescue and the increase in growth of red clover, caused by the use of a cover crop, was still evident in the following year. In both the spring grazing and total yield of the first harvest year, the Italian ryegrass/ white clover mixture was better than the tall fescue/white clover mixture when a cover crop was used. The reverse trend was recorded when the grass plus clover was sown without the cereal. In general, the addition of red clover to the tall fescue/ white clover, or Italian ryegrass/white clover mixture, increased the yield, but the magnitude of the increase was modified by management during establishment. The increase in total herbage yield and the reduction of white clover growth due to nitrogen application were both related to management in the year of sowing. Consideration should thus be given to method of establishment in the assessment of herbage seeds mixtures.     

THE YIELD AND COMPOSITION OF LUCERNE, GRASS AND CLOVER UNDER DIEEERENT SYSTEMS OE MANAGEMENT

The yields of two varieties of lucerne sown alone and in associalion with each of three grasses were compared with similar red clover/grass mixtures over the period 1953–56 under two levels of nitrogenous and potassic fertilizers and two cutting treatments. The main object of the experiment was to gain a wider knowledge of the productivity and chemical composition of lucerne sown alone, and in mixtures, under relatively high rainfall conditions.
The highest production was obtained from Du Puits and its mixtures, which exceeded Grimm and S 123 red clover mixtures. The yields of the lucerne/grass mixtures were not significantly better than those of the pure sown lucerne. Under the most favourable conditions for lucerne, Du Puits eliminated practically all the sown grasses, viz., S 23 ryegrass, S 51 timothy and S 215 meadow fescue.
The application of nitrogen encouraged the growth of the grasses, often at the expense of the legume, especially the slower growing Grimm and S 123. The effect on Du Puits was less marked, but in no case was there a stibstantial increase in actual legume yield. Increasing the level of potassium, although not immediately affecting the yield, proved beneficial to lucerne survival in the later years. The protein yield from the best lucerne plots was found to be double that from pure grass swards heavily fertilized with nitrogen.
Three cuts of lucerne in the first two harvest years had a disastrous effecl on the carry-over of lucerne from the second to the third year. Both varieties of lucerne and their mixtures behaved in a similar fashion, although S 123 red clover appeared to be indifferent to these conditions. It is suggested that the cause of this was the unfavourable weather experienced in 1954.     

A DISCUSSION ON THE INFLUENCE OF RELATIVE MOISTURE AVAILABILITY ON THE SWARDS RESULTING FROM STANDARD GRASS SEEDS MIXTURES

Results are given of analyses made over a three-year period, 1955–57, on swards produced from a standard seeds mixture sown under a wide range of ecological conditions. The results are related lo available moisture on the different soils in the areas examined.     

THE EFFECT OF SHEEP URINE ON THE GERIMINATION AND EARLY ESTABLISHMENT OF A COMMON WEED GRASS

Sowings of annual meadow grass ( Poa annua ) were made in pots of soil which had been treated with sheep urine, with urine diluted × 50, or with water as a control. The treatments were applied before, at, and after sowing.
Urine, whether applied at sowing time, or eleven days before or after, significantly reduced the germination or establishment of the weed grass.
Diluted urine tended to reduce the number of established seedlings when applied at or shortly after sowing.
In a subsidiary experiment the number of viable seeds in soil taken from pastures which had received no urine for four years were compared with those from soil under pastures receiving urine. The difference was not significant.     

Does relative time of emergence affect stand composition and yield in a grass–legume mixture? Kura clover (Trifolium ambiguum)–meadow bromegrass (Bromus biebersteinii) and Kura clover–orchardgrass (Dactylis glomerata) mixtures

Establishing Kura clover (Trifolium ambiguum) in mixtures with grass species is challenging, because slow growth of clover seedlings results in low competitive ability. This study examined establishment success by altering time of seeding of the grass component to reduce competition with Kura clover seedlings. Two trials, one of Kura clover–meadow bromegrass (Bromus biebersteinii) and the other Kura clover–orchardgrass (Dactylis glomerata) mixtures were planted in Edmonton, Alberta. Grasses were seeded at the same time as the clover, or introduced when the clover reached one true leaf or three true leaves, in the autumn of the planting year or the following spring. Species composition varied significantly between treatments. When sown at the same time, Kura clover contributed 31 and 14% of yield in the establishment year when sown with meadow bromegrass and orchard grass, respectively. Delaying grass sowing until Kura clover had one or three leaves gave a higher percentage of Kura clover compared with planting at the same time. Autumn and spring grass sowing resulted in stands of 78 and 80% clover with meadow bromegrass, and 74 and 67% clover with orchardgrass. Altering the competitive advantage of the grass species to produce a more balanced mixture was successfully achieved by delaying seeding of the grass relative to Kura clover. A long interval before introducing the grass (autumn or following spring), was not successful as established Kura clover seedlings have an increased competitive ability.     

Nitrogen studies in Lolium perenne grown for seed. II. Timing of nitrogen application

The effects of applying nitrogen at different growth stages to S24 and S23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1971 to 1976. These varieties of ryegrass were found to be insensitive to timing of nitrogen application from apex initiation to the stage when ears first emerged. However, if nitrogen application was delayed until about 30% or more of the ears had emerged, yields were lower compared with earlier applications, this effect being significant when nitrogen was delayed until 70–80% ear emergence because of a decrease in both numbers of fertile tillers and number of seeds per unit area. No advantages were found for splitting nitrogen applications between apex initiation and ear emergence.     

A DISCUSSION ON THE INFLUENCE OE RELATIVE MOISTURE AVAILABILITY ON THE SWARDS RESULTING FROM STANDARD GRASS SEEDS MIXTURES

Results are given of analyses made at the beginning of the second and third harvest years, 1956 and 1957, of swards produced from a standard seeds mixture sown under a wide range of ecological conditions.     

THE RENOVATION OF DOWNLAND PERMANENT PASTURE II.

An experiment, A, involving dates and methods of application of 2,4-D (amine) as a preliminary treatment in the renovation of a poor downland permanent pasture, followed by surface cultivations and sowing of S.24 perennial ryegrass and S.100 white clover, was carried out at Hurley between 1953 and 1955.
In spite of initial differences in the establishment of S.24 and S.100, pre-treatment with herbicide had no effect upon the cover of sown and unsown perennial ryegrass and white clover two years later. At this date, perennial ryegrass contributed one-quarter and one-eighth, and white clover one-third and one-quarter, to the total cover of renovated and unrenovated plots respectively.
The increase in dry-matter yield resulting from renovation was approximately 10 per cent. This was considered small in relation to the estimated improvement in yield brought about by grazing management and manuring in the course of the trial.
In experiment B, plots receiving herbicide were given differential management and manurial treatments after spraying in an attempt to control the ingress of undesirable creeping grasses. The results indicated that this ingress could be checked by close grazing soon after spraying.     

Some effect fluid-sowing, pre-germination, irrigation and soil covering on the establishment and growth of seedlings of white clover slot-seeded into permanent pasture

Seeds of white clover ( Trifolium repens ) were sown alone or in fluid, or pre-germinated in fluid on to the soil surface of slots cut in an old Agrostis/Festuca sward. Seeds were left uncovered or covered with a thin layer of soil and irrigated from the outset or after 14 days delay.
With irrigation from the outset, seedlings established soonest from pre-germinated seeds but final percentage establishment ranged only from 50 to 63% for the three states of seed. With delayed Irrigation, however, few pre-germinated s1 survived and although germination of dry seed was delayed, final percentage establishment was unaffected. Soil covering increased establishment slightly. The number of leaves per seedling was greatest with pre-germination and early irrigation and least with pre-germination and delayed irrigation. Delayed irrigation also decreased the number of leaves per seedling for seedlings grown from dry seed.
The effects of early irrigation persisted so that at 84 days it significantly increased total yield of clover from all three states of seed, on average threefold, but much more from pre-germinated than from dry seed. Soil covering greatly increased yield, especially where irrigation had been applied from the outset. The interaction of early irrigation and soil covering was even more pronounced for stolon weights, and stolon growth of Individual seedlings appeared to benefit more from soil covering than from early irrigation.
The results showed the importance of early seedling emergence, but no advantages of fluid sowing per se. They also indicated large overall beneficial effects of early irrigation and its additive interaction with soil covering.     

Effects of rates and times of application of starter dressings of nitrogen fertilizer to surface sown perennial ryegrass-white clover on hill peat

The effects on clover and grass growth of five levels of ammonium nitrogen (NH₄-N) applied before sowing, at sowing and after nodule initiation have been investigated. A pot experiment in which S184 white clover was grown in a peat soil showed that NH₄-N up to 688 mg N per pot (approx. equivalent to a field rate of 120 kg ha^-1 N) applied before sowing and at sowing did not affect clover growth. N-fixing activity (C₂H₂-reduction), on the other hand, was reduced progressively up to the highest level (688 mg N per pot). Application after nodule initiation increased growth relative to the zero-N treatment at all levels of application. Maximum growth and N fixation occurred at 516 mg N per pot where the DM yield was 70% higher than in the absence of added N. A field trial in which S184 clover and S24 perennial ryegrass were surface sown on to a peat soil showed an increase in grass and clover growth in the first year in response to 120 kg ha^-1 N applied at sowing. Grass growth alone was increased at 120 kg ha ^-1 N applied 40 d before sowing. Lower rates of application before sowing and at sowing did not affect clover or grass growth. The effect of the delayed application of NH₄-N on legume growth was less marked than that in the pot experiment, 90 kg ha^-1 N stimulating clover growth by 40% in the first year. The effect was however different from that in the pot experiment, in that, whilst 30kg ha^-1 N increased N fixation relative to the zero-N treatment, plants exposed to higher levels showed a depression in N-fixing capacity. N-fixation was correlated with nodule numbers in the delayed NH₄-N application, the closest correlation being with the number of multilobed nodules which was highest at 30 kg ha^-1 N and lowest at 120 kg ha^-1 N. It is suggested that circumstances exist when the use of a relatively low starter N dressing (20–60 kg ha^-1 N) at sowing would not increase clover or grass growth in the early stages of the establishment of a hill reseed. Under such circumstances higher rates of application (100 kg ha ^-1 N), preferably delayed until the seedlings are in a position to take up the nitrogen rapidly, would have the greatest effect.     

A COMPARISON OF THE HERBAGE YIELD OF ITALIAN RYEGRASS AND TALL FESCUE MIXTURES IN THE SECOND AND THIRD YEAR AFTER SOWING

The annual yield of tall fescue was higher than that of Italian ryegrass in the third year after sowing, but the total yield of herbage from grass plus clover swards was similar.
In both the second and third year after sowing, the yield of herbage in the spring grazing was higher when fescue was used as the sown grass. The method of establishment of both tall fescue and Italian ryegrass affected the total and seasonal yield in the second and third year after sowing, but the magnitude of these effects was not nearly as marked as it was earlier in the life of the leys. In the second year after sowing, swards of both Italian ryegrass and tall fescue had a higher yield of total herbage and of white clover, and a lower ingress of unsown species, when established without a cover crop and grazed frequently in the year of sowing.
The inclusion of red clover did not increase total yield of DM in the second and third year after sowing, and it slightly decreased the yield of the tall fescue mixture in the third year following sowing when N was applied. S170 tall fescue was readily grazed by sheep in spring and autumn.
The apparent recovery of applied N varied with the mixture sown, and the management given during establishment.     

The implications of land preparation, crop establishment method and weed management on rice yield variation in the rice-wheat system in the Indo-Gangetic plains

The implications of adopting alternative seeding methods for rice and wheat establishment were examined at three geographically separate sites in the rice-wheat system of the Indo-Gangetic plains, across northern India. Rice yields in cultivated plots, established by either wet or dry seeding methods, were evaluated in comparison to yields from zero-tillage plots and under conventional transplanting methods. In the same trials, the effects of crop establishment methods in wheat were assessed both on wheat yields and rice yields. Rice crop establishment methods markedly influenced the emerging weed flora and attainable yields were measured in relation to intensity of weed management. Over four years, average rice grain yields in the absence of weed competition were greatest (6.56 t ha⁻¹) under wet seeding (sowing pre-germinated rice seed on puddled soil), and similar to those from transplanted rice (6.17 t ha⁻¹) into puddled soil, and dry seeded rice after dry soil tillage (6.15 t ha⁻¹). Lowest yields were observed from dry seeded rice sown without tillage (5.44 t ha⁻¹). Rice yield losses due to uncontrolled weed growth were least in transplanted rice (12%) but otherwise large (c. 85%) where rice had been sown to dry cultivated fields or to puddled soil, rising to 98% in dry seeded rice sown without soil tillage. Weed competition reduced multiple rice yield components, and weed biomass in wet seeded rice was six-fold greater that in rice transplanted into puddled soil and twice as much again in dry seeded rice sown either after dry tillage or without tillage. Wheat grain yields were significantly higher from crops sown into tilled soil (3.89 t ha⁻¹) than those sown without tillage (3.51 t ha⁻¹), and also were elevated (5% on average) where the soil had been dry cultivated in preparation for the previous rice crops rather than puddled. The method of wheat cultivation did not influence rice yield. Soil infiltration rates in the wheat season were least where the land had been puddled for rice (1.52 mm h⁻¹), and greater where the soil had been dry-tilled (2.63 mm h⁻¹) and greatest after zero-tillage (3.54 mm h⁻¹).These studies demonstrated at research managed sites across a wide geographic area, and on farmers’ fields, that yields of dry seeded rice sown after dry cultivation of soil were broadly comparable with those of transplanted rice, providing weed competition was absent. These results support the proposition that direct seeding of rice could provide an alternative to the conventional practice of transplanting, and help address rising costs and threats to sustainability in the rice-wheat rotation. Further, analysis of patterns of long-term rainfall data indicated that farmers reliant on monsoon rainfall could prepare fields for dry direct seeded rice some 30 days before they could prepare fields for either transplanting or seeding with pre-germinated seed. Dry, direct seeding of rice contributes a valuable component of an adaptive strategy to address monsoonal variability that also may advance the time of wheat establishment and yield. Whilst the results illustrate the robustness, feasibility and significant potential of direct seeded rice, they also highlight the critical nature of effective weed control in successful implementation of direct seeding systems for rice.     

THE EFFECT OF POTASSIUM ON ESTABLISHMENT AND SEEDLING VIGOUR

A permanent pasture was ploughed, 5 rates of potassium were incorporated in the seed-bed and a timothy/white-clover seed mixture was sown direct without a companion crop. Plant counts were taken during the fourth week of establishment. The highest rate of potash increased the size and number of timothy/white-clover plants considerably, without altering the timothy/white-clover ratio. Half the plots were cut once during the seeding year and the other half twice. Increasing rates of K increased dry-matter yields, particularly on the plots cut 7 weeks after sowing. Botanical analysis in the following year showed that, under both cutting systems, increasing rates of K tended to increase the proportion of white clover and decrease that of unsown species.     

FERTILE TILLER PRODUCTION AND SEED YIELD IN MEADOW FESCUE (FESTUCA PRATENSIS L.)

The seed-producing capacity of two varieties of meadow fescue, S215 and S53, sown at three different spacings, was compared. One level of nitrogen was applied on three different dates in the spring. Tiller counts were made periodically during the growth of the crop. Fertile-tiller production was found to be related to vegetative growth.
The varieties differed not only in yield, but also in growth dynamics. A larger percentage of overwintering shoots became fertile in the hay variety, than in the pasture variety.
Drill spacings had significant effects on plant establishment and on vegetative-and fertile-tiller numbers. In both years N applied in March gave the highest production of fertile tillers. Date of N application did not produce marked trends in yield. The influence of spacing and date of N application on the number and density of spikelets indicated that the plant adjusted itself to environmental factors. Thus spikelet numbers were reduced in early heads with narrower drill spacing and with late applications of N. Head emergence was earlier in narrow drills, but time of N application in the spring did not produce significant differences in this respect.