THE EFFECT OF THE TIME AND LEVEL OF INJECTION OF ANHYDROUS AMMONIA ON THE PRODUCTIVITY OF GRASSLAND

Four levels of nitrogen, 188, 285, 358 and 392 kgJ.ha (150, 225, 285 and 350 units/ac) supplied as anhydrous ammonia were injected on each of four occasions, 18 Dec, 5 Feb., 12 Mar. and 16 Apr. DM and CP yields were estimated at each of three harvests taken on 4 June, 19 July and 28 Sept Total DM yields showed only a 10% difference between the highest yielding injection date, 12 Mar., which yielded 12270 kg/ha (10946 Ib/ac) and the lowest, 16 Apr., which yielded 11169 kgJ.ha (9963 Ib/ac). Early injection of ammonia promoted growth during the late spring and later injections resulted in increased yields at the two later harvests. The responses per kg fertilizer N were 11.9 kg DM (10.8 lb/unit) and 3.6 kg CP (3–3 Ib/unit). It was concluded that ammonia should be applied to grassland before April and, preferably, during March, for maximum yields of DM and CP.     

THE USE OF THE IN VITRO TECHNIQUE IN THE DETERMINATION OF THE DIGESTIBILITY OF GRASS/LEGUME MIXTURES

The in vitro dry-matter digestibility was determined of two samples of Digitaria decumbens , one sample of Medicago sativa , and one sample of Trifolium repens and nine mixtures prepared from these samples.
When the results were compared with in vivo digestibilities the standard errors of the regressions for the three combinations of legume, grass and legume/grass mixtures were ±0.6, ±0.6 and ±1.5 percentage units, respectively.
It is considered that in vivo digestibility of mixtures of grasses and legumes can be estimated by the in vitro technique, provided that suitable grass and legume standards are included.     

THE USE OF THE FORAGE HARVESTER IN THE IMPROVEMENT OF ROUGH GRAZING

Considerable improvement has been achieved in rough grazings by fairly frequent close mowing with the forage harvester or flail mower, particularly when combined with manuring and surface seeding.
The implement has proved capable of tackling very tough vegetation and converting it into grazing swards of fair value and good botanical composition. Undesirable species have been largely eliminated by treatment over two growing seasons.
The method is believed to compare favourably in cost with sward renovation by cultivation or by herbicides.     

THE ROLE OF GREEN SOILING IN THE ECONOMY OF THE DAIRY FARM

With modern machinery and modem techniques of grass production, mechanical-or zero-grazing offers a means of utilizing the crop to perfection. Whether this results in enhanced profits depends largely upon the farm and the specific circumstances. It may, it may not. What is evident is that the health of the cows is not affected by an unnatural manner of summer feeding; the sward, per se, may be improved by the regular and uniform defoliation; and under conditions of intensive production and the vital need to use profitably every blade of grass, as for instance on small, highly-rented farms, the practice of zero-grazing merits the most careful consideration. It cannot lightly be dismissed as merely a new fad.     

光周期对马铃薯块茎形成的影响及对激素的调节

马铃薯出苗后接受１个月的每日８小时短日照处理并与当时自然光照长度进行比较，研究光照长度对块茎形成及内源激素②的影响，探讨块茎形成与激素水平的关系。结果表明：短日照处理使块茎形成显著提早，但使结薯数减少，植株茎叶生长受抑，块茎淀粉含量降低；短日照处理使叶片中ＡＢＡ含量提早增高，ＧＡ３含量提早减少，ＧＡ３与ＡＢＡ的比值提早显著降低．     

THE EFFECT OF TEMPERATURE IN THE MASS ON THE CHEMICAL COMPOSITION OF SILAGE

The effect of temperature on silage quality was investigated in a series of trials over a period of three years.
The results indicated that when conditions in the silage were favourable for the formation of lactic acid, either through treatment or because of the herbage itself, low temperatures in the mass had no adverse effect on silage quality.
Some results suggest that, with chopped or lacerated silage, low maximum temperatures are associated with better quality silage. The results, however, were not entirely consistent.
There appeared to be little or no advantage in allowing unchopped silage to heat to 100°F.     

菜用大豆荚皮性状与产量形成的关系

利用菜用大豆的四个杂交组合,对其荚皮性状即荚皮的长、宽、表面积以及荚皮的内膜层、革质层等性状进行试验观察,并分别与子粒、产量进行相关分析.荚皮的长、宽、表面积、荚皮内膜层、荚皮革质层与产量有极显著正相关,荚皮表面积与产量的相关系数达0.6795**,内膜层鲜重与产量的相关系数和通径分析均达到0.8433**.革质层与子粒的相关性较大,百荚革质层的鲜重、风干重与百粒重的相关系数达0.6681**、0.6112**,荚皮厚与子粒鲜、干重及产量均呈极小不显著的正负相关(-0.0706～0.2810).在育种工作中应重视荚皮的表面积、内膜层和革质层等对产量和产品质量的影响.     

THE EFFECT ON THE SOIL OF THE COMPONENTS AND MANAGEMENT OF A LEY

The effect of four grasses, and four methods of utilizing the herbage, on the root weight, the proportion of organic matter in the soil and the water-stability of the soil aggregates was measured over a period of three years. The grass species in the sward had a greater effect upon the measurements than had the methods of management. Of the grass species, Lolium perenne produced the greatest root weight and highest percentage of organic matter in the soil.     

THE SIGNIFICANCE OF VIRUS DISEASES FOR THE PRODUCTIVITY OF GRASSLAND

The effect of cocksfoot streak virus (CSV) on Dactylis glomerata L. and barley yellowdwarf virus (BYDV) on Lolium perenne L. was investigated under both single-plant and simulated-sward conditions. The effect of cocksfoot mottle (CFMV) was examined on single plants. CFMV was lethal, and in conditions of inter-plant competition CSV was semi-lethal and BYDV was non-lethal. When the virus was lethal, a considerable lag-phase was observed between mortality and complete compensation in yield. When the virus was non-lethal, plant growth was restricted, either horizontally (CSV) or vertically (BYDV). In mixed, healthy and infected plant populations healthy individuals compensated only for reductions in lateral growth.
CSV infection transformed plants of a pasture variety into 'hay' types and BYDV infection transformed plants of a hay variety into 'pasture' types. CSV increased the plant's aggressiveness in hay conditions, but reduced its ability to withstand frequent defoliation. Conversely, BYDV increased the plant's aggressiveness in pasture conditions, but reduced it in hay conditions. Compensation from healthy plants occurred only in CSV-infected swards subjected to frequent defoliation. Some possible reasons for the absence of compensation in other treatments are discussed.     

THE EFFECT OF THE GRAZING ANIMAL ON THE N STATUS OF GRASS SWARDS

Thirty-one sets of N yield data were considered, taken from seven experiments grazed by sheep. N yield could be explained in terms of fertilizer N rate, an estimate of soil N and an interaction between the two. Fertilizer N increased grass N yield more on grazed swards than on cut swards, and this effect was greatest on soils with high available soil-N. It is concluded that N recircula-tion can be substantial on heavily-stocked swards receiving high rates of fertilizer N, so increasing the efficiency of fertilizer as a source of N in these conditions.     

THE EFFECT OF DALAPON ON THE SPECIES OF HILL GRASSLAND

The effect of dalapon is described on pastures of Agrostis/Festuca, Festuca ovinal Deschampsia flexuosa and related Nardus- or Molinia -rich hill grasslands. The results are discussed in relation to the technique of surface sowing and the choice of vegetation types suitable for treatment.     

THE AUTOMATIC RECORDING OF THE GRAZING BEHAVIOUR OF DAIRY COWS

A technique for the automatic recording of the grazing behaviour of dairy cows was investigated, using ‘Vibracorders’ which transmit grazing movement via a pendulum and stylus to a 24 h recording chart. The total labour input was 2 h/day for 6 cows, which gave 144 h of results. In 2 months, 3312 h of recording were obtained. Total grazing time per cow in 24 h was 559 min. on a rigid rotational system of grazing and 638 min. on a system of set stocking. Grazing time was significantly and negatively related to the yield of available herbage DM. It is concluded that if the Vibracorders are sealed and fitted correctly, they are simple, reliable and accurate instruments for automatically measuring the grazing behaviour of dairy cows.     

THE MACHAIR GRASSLANDS OF THE HEBRIDES

The utilization of Scottish hill-land potential is severely limited by inadequate wintering facilities resulting from a low proportion of inbye land to hill-land. The machair lands of the Uists, in the Outer Hebrides, however, provide a more suitable ratio, which is not commonly found in the Highlands of Scotland.
Investigations into the grassland problems of the Hebrides were intensified in 1955; and some of the data obtained from trials are given here, as are suggestions for improving the production and utilization of grass in these areas. The climate, soil, and agricultural system all interact to provide conditions which are rarely seen elsewhere.     

THE EFFECT OF DEFOLIATION ON THE SEED-PRODUCING CAPACITY OF BRED VARIETIES OF GRASSES

Leafy grass varieties S24 perennial ryegrass, S26 cocksfoot, S215 meadow fescue and S51 timothy were cut in October and at various growth stages in spring; S53 meadow fescue was grazed at similar periods. Sub-plots were given different applications of N. The control plots had similar manurial treatments but were not defoliated. The seed yield of S24 following October cutting was significantly lower than the control in the first harvest year and significantly higher in the second; the mean yields over 2 years, as a result of cutting at this stage and before ear formation in March, were very similar to those of the control treatment. The mean yields from 3 harvest years for S26, S215 and S51 were generally improved by cutting in October and before ear formation, but cutting after ear formation reduced the number of heads and the seed yields. Extra N applied in conjunction with the defoliation had no significant effect on the number of seed heads or on seed yield. Double grazing of S53 in Sept. and Dec. reduced significantly its seed production in both harvest years. Application of N in spring gave a greater response than a similar application in autumn.     

THE EFFECT OF NITROGENOUS FERTILIZER ON THE RATE OF GROWTH OF ITALIAN RYEGRASS

This paper describes the rate of growth of Italian ryegrass in the spring, measured by recording DM yield at weekly intervals up to 10 weeks. There were 3 levels of applied N: 25, 75 aud 125 lhJac (28, S4 and 140 kgJha). Rate of growth declined after the sixth week at all 3 levels of N. Grass receiving 25 Ib N produced 5000 Ib DMJac (5600 kgJha) in 10 weeks, that receiving 75 lb N 6800 Ib (7700 kgJha) and that receiving 125 lb N 7100 lb (8000 kgJha). The DM content of herbage fell after the first week and subsequently increased steadily up to 10 weeks; the fall was least marked and the rate of increase most rapid at tbe lowest level of N. In vitro digestibility (measured in one year only) was much affected by stage of growth and little affected by level of N.     

THE EFFECT OF METHOD OF SOWING ON THE ESTABLISHMENT OF GRASS SEED CROPS

Methods used by growers to establish seed crops of perennial ryegrass, cocksfoot, timothy and meadow fescue have been examined. While satisfactory establishments were obtained by sowing perennial ryegrass broadcast, cocksfoot, timothy and meadow fescue should be sown in rows, especially if they are to be sown under a cover crop.     

THE EFFECT OF NITROGENOUS FERTILIZER ON THE RATE OF GROWTH OF ITALIAN RYEGRASS

In an experiment described earlier (13), the N content of Italian ryegrass in spring reached a high value one or two weeks after applying N and then fell quickly at first and then more slowly. After 10 weeks average N content (in DM) was 0.6% from an application of 25 lh N/ac (28 kg/ha), 0.9% from 75 lb N (84 kg/ha), and 12% from 125 lb N (140 kgJha). Nitrate-N content fell more abruptly and tben remained fairly constant. Percentage nitrate–N (in DM) fell below 0.10% during the second week after an application of 25 lb NJac, during the third week after 75 lb N, and during the fifth week after recciriag 125 lb N. The yield of N increased during the first 5 or 6 weeks, remained fairly constant for 3–5 weeks, and then hegan to fall. During the ninth and tenth weeks, the crop lost an average of 9 lb N/ac per week (10 kg/ha) after an application of 75 Ib N/ac and 12 lb N/ac per week (13 kg/ha) after 125 Ib N.     

营养液对马铃薯微型薯数量及产量的影响

为探索营养液的成分及浇灌次数对微型薯的数量及产量的影响,设计了3种营养液成分A_1,A_2,A_3和3种浇灌次数B_1(两天浇1次),B_2(4天浇1次),B_3(6天浇1次)。研究结果是:选择A_2营养液,每4天浇1次或6天浇1次就可达到低成本、省工、省力、薯块数量多、产量高、大中薯率高的优质脱毒微型薯。