1. Sanders’ method of utilising previous crop records to correct experimental results by means of a linear regression is briefly described.

2. The method is applied to yield figures from rubber trees in Sumatra, and the precision of a dummy experiment is thereby increased nearly fourfold when the “preliminary” and “experimental” years are consecutive. When the “experimental” year is three years later than the “preliminary” year, the error variance of the adjusted yields is reduced to about a half.

3. It is concluded that not only has the method of correction been of value in the particular instance investigated, but that a uniformity trial utilised in this way should be of practical value in any major field experiments with rubber.

1. The nature of the replaceable base in a clay or soil exerts a profound effect on the physical properties. Clay-like properties are exhibited most strongly in the case of lithium, sodium, and magnesium.

2. The proportion of fine material in a soil (i.e. that which remains in suspension in a column 10 cm. high after 14 days) cannot be correlated with other physical properties. Thus a soil of which over 50 per cent, was dispersed to this extent was the least plastic of those examined.

3. A comparison of sodium, potassium, and calcium clays and soil showed that potassium resembles sodium in its chemical relationships as indicated by base exchange, but is very different from it in such physical properties as plasticity and permeability.

4. Using mixtures of one-half normal chlorides of two bases, calcium and potassium are absorbed in equivalent amount while the sodium absorbed is only one-sixth of the amount of either of the other two.

Global warming increases the risk of pests and weeds before wintering, and decreases the grain yield of winter wheat. Therefore, the sowing date should be delayed properly. But the variety of winter wheat that can adapt to late sowing remains unclear. Here, we selected two winter wheat cultivars and evaluated four sowing date treatments on 1 October (early sowing), 8 (normal sowing), 15 (late sowing) and 22 (latest sowing) over two wheat-growing seasons at the experimental Station of Shandong Agricultural University (35°96′N, 117°06′E), Daiyue District, Taian, Shandong, China. We examined the effects of sowing date on a few traits, and found that, compared with normal sowing, though spike number decreased, grain yield was maintained above 9300 kg/ha under late and latest sowing. The main reason was that the more accumulated N from jointing to anthesis resulted in a higher grain number per spike. The higher net photosynthetic rate after anthesis, through optimizing N distribution in the canopy and increasing Rubisco content of flag leaves, improved dry matter accumulation rate and contribution ratio of vegetative organs, ultimately, ensured consistent grain weight. The grain yield of high-tillering winter wheat cultivars decreased from 9370 to 8346 kg/ha. The main reason was that spike number, accumulated N from jointing to anthesis and net photosynthetic rate decreased significantly, which reduced the dry matter accumulation rate, and only satisfied less grains to achieve consistent grain weight. Therefore, low-tillering winter wheat cultivars are more adaptable to late sowing, and can reduce the harm of global warming.

The deposition of S in rainwater was measured at ten locations in central Kenya, monthly for 1 year (1977–8). Amounts deposited ranged from 1·58 to 3·81 (mean 2·47) kg S/ha. Concentrations ranged from 0·10 to 0·17 (mean 0·12) mg S/l rainwater. The washout factor (w) was 200 and the vertical deposition velocity (Vg) for dry deposition was 0·31 cm/sec. Two locations were affected by local anthropogenic emissions. The agricultural significance of these results is briefly discussed.

Seventy-seven adaptive research trials were conducted, with the participation of local farmers, on their fields during the 1993 and 1994 wet seasons (southwest monsoon seasons) in the warm subhumid tropical zone on the west coast of India. The objective of the trials was to compare the agronomic and economic benefits of an improved management consisting of placing urea briquettes containing diammonium phosphate (UB–DAP) by hand (56 kg N/ha and 14 kg P/ha) after controlled transplanting using a modified 20×20 cm hill spacing with two other practices: (i) the current management system, consisting of random transplanting and two split applications of prilled urea (PU) and a basal application of single superphosphate (SSP) and (ii) the farmers' traditional management practices, involving random transplanting and broadcasting of fertilizers. In spite of marked variations in rainfall distribution patterns during the 1993 and 1994 seasons, the improved management using UB–DAP increased grain yields by 2·14 t/ha (89%) in 1993 and 1·23 t/ha (45%) in 1994 over traditional management practices and by 1·56 t/ha (52%) in 1993 and 0·83 t/ha (27%) in 1994 over the current management system. These additional yields were obtained at a 28–36% lower plant population density (25 hills/m2v. 35–39 hills/m2). The use of a modified 20×20 cm spacing could reduce by up to 50% the labour normally required for the conventional placement of UB by hand about 1 week after transplanting using the standard 20×20 cm spacing (8–10 workdays/ha). The estimated value: cost ratios for the improved management ranged from 4·9 (1994) to 8·6 (1993) and increased further when the savings in seed input were considered. Stochastic dominance analysis of the yield data suggests that the improved management of UB–DAP could be risk-free and therefore would be preferred over the other two managements by rice farmers and policy makers.

DR Miller's interesting and important paper in the last number of this Journal (Vol. I. p. 377) raises several points in connexion with the long-continued action of rain on uncultivated and uncropped soils.

In recent investigations at this Institute, attempts have been made to devise for dairy cows a ration extremely low in magnesium to be used in fundamental studies of magnesium metabolism. All common farm roughages are moderately rich in magnesium, and wood pulp, which is low in this element, has been tested as a roughage for use in these experimental rations. American workers (Titus, 1926; Mead & Goss, 1935; Byers, Stanbus, Nelson, Brown, Davis & Gardiner, 1955; Matrone, Ramsey & Wise, 1957; Smith, McLaren, Anderson, Welch & Campbell, 1957; Ellis & Pfander, 1958; Williams, Musgrave, Schul & MacVicar, 1958) have previously used wood pulp as a substitute for roughage in the development of purified rations for cattle and sheep, and it was fed extensively as a substitute farm feedingstuff in Norway during the war years (1940–44)(Edin, Helleday & Nordfelt, 1941; Hvidsten, 1946). This note records some observations on the feeding of wood pulp, often as the sole roughage, to both dry and milking cows.

Two experiments at Wellesbourne studied the effects of cold treatments on the leaf and curd production characteristics of a range of annual and biennial varieties of cauliflowers.

Cold treatments delayed curd initiation and had a variable effect on the final number of leaves, but reduced the spread of curd initiation of plants which were 5 weeks old when cold-treated. The overall rate of leaf production and the final number of leaves generally increased with later-maturing varieties while initial rates of curd expansion generally declined.

The annual varieties produced a small number of leaves and fairly synchronously formed a curd which developed rapidly; the biennial varieties had a higher rate of leaf production after transplanting and then changed to the generative state over a more prolonged period, following which the curd developed slowly.

The difference between the bread wheat and feed wheat prices in the UK (the premium) is an important influence on behaviour throughout the entire grain chain. The aim of the present study was to quantify the influence of grain quality and other factors on interannual variation in the premium calculated as a proportion of the feed price. A hypothetical model of the UK wheat economy was devised, appropriate annual national data from 1982 to 2000 were collected for each component and multiple regression was used to develop a statistical model for the premium.

The statistical model included livestock numbers (calculated as pig equivalents), Hagberg falling number and wheat stocks, which together explained 0·80 of the interannual variation in the premium. A high premium was associated with high livestock numbers, low Hagberg falling number and low wheat stocks. These variables were included in the hypothetical model because: livestock numbers represent demand for feed wheat; Hagberg falling number is a quality criterion for purchase of bread wheat with a low value indicating poor quality and thus a smaller supply of bread wheat; wheat stocks are one of the sources of supply of wheat. It was concluded that of the 16 supply, demand or price variables in the hypothetical model the main variables associated with the premium from 1982 to 2000 were demand for feed wheat, quality of the wheat harvest and carry-over of wheat from the previous harvest.

The metabolism of nitrogen during incubation, at 28° C. for 184 days, of a soil treated with 1% by weight of five different bulky organic manures and 0·5% calcium carbonate was studied.

1. Ammonia and nitrite could not be detected at any sampling date with any treatment, hence nitrate levels in treated soils compared with that in the control soil indicated the extent of mineralization or fixation of nitrogen.

2. A good straw compost (carbon/nitrogen ratio, C/N, 20·6) was the only material which showed mineralization of nitrogen over practically the whole of the incubation period.

3. Rotted farmyard manure (C/N 15–6) caused a small, whilst fresh grass (C/N 22·6), caused a fair amount of nitrogen fixation in the early stages, but there was a small overall mineralization of nitrogen by the final sampling.

4. A poor straw compost (C/N 42·5) and straw (C/N 147·0) both caused considerable fixation of nitrogen in the early stages. With continuing incubation the bulk of the nitrogen fixed by the poor compost, but only a small portion of that fixed by the straw, was released.

Three experiments have investigated the effect of the timing of control of infestations of volunteer barley (Hordeum vulgare), Stellaria media and Galium aparine on the growth and yield of winter oilseed rape (Brassica napus). Although the experiments used conventional herbicides to achieve the different timings of control, the work was done in the context of the commercialization of herbicide-tolerant oilseed rape, where treatments could be applied at any time from autumn to spring. In the three seasons studied, oilseed rape growth was particularly vigorous in the autumn and, as a consequence, the competitive impact of the weeds was lower than anticipated. Untreated volunteer barley and G. aparine reduced yields in one and two experiments, respectively. However, in all experiments volunteer barley reduced crop growth in winter and spring severely, even though January treatments prevented yield loss in these vigorous crops. Delayed control of this weed would not be advisable if the weed was particularly dense or the crop less vigorous. In contrast, the G. aparine had no effect on crop growth and was only really apparent in the crop in late summer, so delaying treatment until even March would not put yields at risk. In one year, S. media markedly reduced crop growth in late winter but in the second experiment this did not occur. Consequently, as with the G. aparine, delayed autumn control would be unlikely to jeopardize yields. Thus, if herbicide-tolerant crops are commercialized in Europe, there will be flexibility in timing of application of herbicides to control broad-leaved weeds in winter rape but there would be a risk of yield loss from delayed control of volunteer cereals.

In a glasshouse study, the pattern of flower and pod production at the various flowering nodes of Phaseolus vulgaris (cv. 344) was mapped out. Soft X-radiation techniques were also used to study the development of retained and abscissed pods at the various nodes while varying levels of flower or pod removal were used to study the modification to pod development at each flowering node following organ removal.

The period of flower opening over the whole plant spanned an average of 12 days and 90% of the pods retained to maturity were formed from flowers opened within 4 days of anthesis. The terminal inflorescence produced most of the flowers on the plant (25%), but nodes 2 and 3 developed the bulk (50%) of the pods retained. Only 30% of the open flowers on the plant formed pods that were retained to maturity.

Pod elongation was initially very rapid in the pods to be retained, following successful fertilization, with the latter period of pod growth devoted almost entirely to seedfilling. A slow growth rate characterizes the development of abscission in Phaseolus pods and the number of seeds per pod is determined later in pod growth.

Flower or pod removal prolonged flowering and led to longer leaf retention and more branches on the main stem. The number of mature pods was lower on the treated plants and the more severe the removal the larger were these treatment effects. Plants compensated for fewer pods by having more seeds per pod but these were not enough to prevent significant depression of seed dry weight per plant by the most severe removals. Flower or pod removal led to a shift of emphasis in pod production by the plant from nodes 2 and 3 to other areas of the plant where natural wastage of flower and young pods is high.

Resistance to bean common mosaic virus in the cultivars Seafarer and Aurora from the U.S.A. is controlled by the dominant gene I originally found in the cv. Corbett Refugee.

Experiments are described in which the ‘once-used’ soils left over from previous culture experiments were employed as aggregates in the growth of vegetables. It was demonstrated that sand with full nutrients was superior to ‘once-used’ soil with water only, but that ‘once-used’ soil supplied with the full quota of soluble nitrogen was superior to the sand with full nutrients. The root of the cabbage in sand was an exception, and a possible explanation was that sand as aggregate favoured true root formation, while soil favoured the formation of tops. The ‘once-used’ soil in these experiments deteriorated in physical propertes owing to the conditions of the experiment, which included the use of nitrogen as sodium nitrate, possibly owing to the tendency to the formation of sodium clay; it is argued that a judicious choice of fertilizers and/or the use of flocculating electrolytes should overcome such tendencies.

A series of 240 thin-layer drying runs carried out in 1988 and 1989 at the Scottish Centre of Agricultural Engineering were analysed to find out which factors influenced the rate of drying of grass mixtures. The grass used in the experiments was cut by hand, by a mower without conditioner or by a mower with conditioner. The experiments covered a range of air conditions from 16·0 to 40·4 °C temperature and 24·4 to 82·8% relative humidity. By fitting curves to the experimental data it was shown that the drying curves could be simulated by a two-parameter, exponential equation. Analysis of the data showed that the experimental results could be adequately represented by holding one of the parameters fixed and fitting the curves with only one parameter varying. The variable parameter, called the drying coefficient, was dependent on harvesting method and related to drying air temperature, initial moisture content and ratio of leaf area to stem area. A regression equation relating the drying coefficient to these variables for conditioned and unconditioned grass is presented.

Predictions from the regression equations indicated that the temperature of the drying air had a major effect on the drying coefficient. Both the initial moisture content of the samples and ratio of leaf to stem had a smaller influence on the coefficient over their likely range.

The experiments of Briggs & Shantz led them to conclude that the “wilting coefficient” is a soil “constant” which is (a) independent of the kind of plant used as indicator, (b) independent of the conditions under which the plant was grown, and (c) directly related to several other soil constants.

Subsequent research as well as an examination of their own results has shown that (c) is untrue, while (a) and (b) are substantially correct for hygrophytes and mesophytes. Earlier writers have been led to wrong conclusions regarding (a) and (b) through assuming (c) to be correct and through disregarding the particular nature of “permanent wilting” as defined by Briggs & Shantz.

The fact that considerable variation is to be found between the osmotic pressure found in different plants, in different parts of the same plant and in the same part under different conditions is not at variance with conclusions (a) and (b) when properly understood.

An important factor making for the substantial constancy of the “wilting coefficient” for a given soil is the extreme steepness of the curve connecting suction pressure and soil moisture content, in consequence of which differences of suction pressure of unquestionable significance from the standpoint of plant physiology give rise to differences in soil moisture content that are too small to be detected.

Maize grain production in Nigeria is the collective effort of several growers individually cropping small areas. In these farms, maize stands are at suboptimal densities, soil fertility is low and crop loss from pests is high. Consequently, grain yields are characteristically low. By planting maize at closer spacing than the current standard, 90 x 25 cm, Fayemi (1963), Chinwuba (1967), and Okigbo (1972) were able to raise grain yield. However, the effect on pest population in Nigeria of increasing host plant density has received little research attention. Cromartie (1975) showed that host plant density and arrangement affect insect population dynamics. Other reports by Ficht (1932), Finch & Skinner (1976), Ralph (1977), Zepp & Keaster (1977), Adesiyun (1978) and Mayse (1978) indicate differential insect colonization, establishment and damage on host plants sown at different densities.

Metabolism trials were conducted with sheep to study the effects of conservation of herbage as silage, frozen or artificially dried grass upon the magnesium and calcium availabilities in the conserved products.

When the diet was changed, approximately isomagnesaemically, from hay and barley to each of the conserved products, there was a highly significant (P < 0·001) decrease in the plasma magnesium concentration. However, the plasma magnesium concentrations of the ewes eating the artificially dried grass were significantly lower (P < 0·05) than the corresponding values when they ate the frozen grass or silage. No changes were seen in the plasma calcium concentrations.

The apparent availability of magnesium in the silage was significantly higher (P < 0·05) than that in the frozen and artificially dried grasses. Also, the apparent availability of magnesium and calcium was lower in the dried grass than in the other two products, whilst the retention of both magnesium and calcium was significantly lower (P < 0–05) when the dried grass was eaten as compared with the frozen grass and silage. The percentage urinary loss of magnesium was greatest on the silage and least on the dried-grass diet.

It was concluded that artificially drying grass caused a reduction in magnesium availability.