The North China Plain suffers excessive application of nitrogen (N) and soil degradation. Recently, biochar has been promoted as an agricultural soil amendment to ameliorate soil quality, increase crop yield and mitigate greenhouse gas emissions. However, most proofs on the positive effects of biochar addition have been based on small plots or short-term field studies located in tropical or subtropical regions with defective soils. A long-term field experiment was designed with five N levels and two biochar rates to observe the changes in crop (winter wheat and summer maize) growth and soil chemical quality. Notably, crop yield was strongly dependent upon N application, with both wheat and maize yields increasing with N application. Biochar addition increased crop yield but not significantly, although the increase in grain yield was 0.96 t/ha in a rotation. Correlation analysis revealed that the optimal root-layer soil mineral N (Nmin) for crop production was around N120, especially with biochar addition. The effect of fertilization on soil chemical quality was mainly reflected in the increase in soil organic carbon (SOC), and the highest value was obtained at N60 whether or not biochar was applied. Overall, biochar addition did not appear to promote wheat and maize growth or increase the yield on calcareous alluvial soils in temperate regions, but significantly enhanced SOC content, especially at N60, which may play an important role in sustainable agricultural production.

The development of a community may rightly be said to be reflected in its meat requirements. Primitive peoples are quite satisfied as long as their bulk needs are met, irrespective of quality. This condition may fairly be said to be representative of most of Africa today. A more developed community demands meat of high quality from young and properly finished animals, and this is the I'equirement of the European and emergent African communities, a steadily rising demand which must be met from within the Continent if possible.

Deploying resistant cultivars is an economical and essential management method in controlling viral diseases, and there are several mutational resources for tobacco. In the present study, the inoculation of tobacco plants with tobacco viruses was performed in a greenhouse from 2011 to 2014 to identify mutants resistant to tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). The high-throughput screening included seeding uniformly, transplanting in seedbeds, inoculating by cloth brushes and reporting symptoms based on disease indices. A total of 4000 second generation segregating (M2) mutants of tobacco cultivar Zhongyan100 were screened. Seeds from highly resistant mutant M2 plants were selected and planted separately. The M3 were grown and mutational stability was measured. For TMV, ten highly resistant plants were selected in the M2 generation and the mutation rate was 0·012%. In the M3 generation, there were seven mutants with hereditary high resistance and, according to the results of real-time polymerase chain reaction, the N gene was detected in all seven M3. Two hereditary immune M4 mutants, one of which was a male sterile line, were identified and evaluated in the glasshouse and in the field. For CMV, seven highly resistant plants were selected from the M2 generation and the mutation rate was 0·009%. In the M3 generation, there was one mutant with hereditary high resistance. The results indicate that hereditary mutants may be identified in the M4 generation and back-crossed to wild-type Zhongyan100 to identify anti-viral genes.

Dairy cow systems based on grassland utilization are characterized by a variation of harvested forage quality from 1 year to another and a fluctuation of grass availability and quality during the pasture season. Consequently, the energy supplied by the diet – i.e., concentrates plus hay or silage in winter and grazing in summer, may not always match animal requirements. A modelling approach enables a representation of the complex relationships between the cow and pasture as they interact. A dynamic model of intake and milk production, focused on grassland utilization by the dairy cow, has been developed. The model operates in a deterministic fashion with a daily time step and is capable of dealing with a day-to-day variation in grass availability and quality at grazing as well as a constant feeding regime during the winter. The model has been built based on the theory that milk production is a result of (i) the energy requirements defined by the potential milk production and physiological status of dairy cows; (ii) the variation of energy supply by the diet; (iii) the ability of dairy cows to mobilize or store body reserves. The model was validated by comparing milk production predictions with experimental data (two groups of dairy cows in the winter time and one group at grazing). The model demonstrates a satisfactory range of accuracy (root-mean-square deviation equal to 1·8, 2·1 and 1·4 kg/cow/day). Model validations indicate that milk production predictions are sensitive to the diet offered (forage, grass and concentrate supply) and depend on dairy cow characteristics and their requirements (pMP). This model can be connected to a grass growth model in order to develop whole farm simulations.

Study of the nutritional requirements of sugar cane on a Jamaican estate necessitated simultaneous experimentation with five manurial factors: sulphate of ammonia, superphosphate, muriate of potash, bagasse, and filter press mud. By adopting a one-third replication of a 35 factorial scheme, each factor could be tested at single and double levels for comparison with the absence of the factor.

The structure and confounding system of the design adopted have been described and the method of computing the analysis of variance has been explained. Fractional replication introduces special problems of interpretation, and this experiment illustrates how they may be resolved. Each fertilizer clearly benefited the crop, and several interactions appeared; some ambiguity of meaning is an inevitable concomitant of fractional replication, so that care was needed in order to assign effects to the right causes. The most clearly marked effects were:

(i) Without phosphate, nitrogen failed to produce any response; where phosphatic manuring was adequate the crop responded well to nitrogen.

(ii) Superphosphate and filter press mud were practically interchangeable as sources of phosphate.

(iii) Bagasse appears to act as a source of potash; the interaction of responses is not very clearly established, but little extra response to artificial potash occurred when bagasse was given.

(iv) No evidence was obtained that the double level of any fertilizer was superior to the single.

There was also a suggestion of a reduced superphosphate response in the presence of bagasse.

If a recommendation on manuring were to be based on this experiment, it would be that a maximum of 3 cwt. sulphate of ammonia per acre be used with either 4 cwt. 18% superphosphate and 1 cwt. muriate of potash per acre or 10 tons filter press mud and 20 tons bagasse per acre. In reality, of course, no attempt ought to be made to determine a general manurial policy from results of a single year of experimentation on plant cane at one place.

The experiment should be regarded rather as typical of what can be done than as a complete investigation of manurial needs.

1. A preliminary study of the protein requirements of young steers of two breeds of African cattle has been described. These requirements were assessed by studying body weight changes of groups of animals fed for 140 days on rations varying in protein content.

2. There were only small differences between the breeds in their voluntary food intake while appetite seemed to be linearly related to protein content.

3. The two breeds were equally efficient in food and protein utilization.

4. Live-weight gain improved significantly as the protein content of the ration increased from 6 to 10%, but a further increase to 14% produced only a small subsequent improvement in growth.

5. Maintenance of weight was estimated to occur at a digestible protein intake of only 48% of that recommended by Brody (1945), while the required digestible protein for one pound daily gain was in agreement with the National Research Council (1950) standard.

An experiment was conducted to investigate the effects of planting pigeonpea in May, June or July at Mokwa and June or July at Shika and Kano, Nigeria at population densities of 18·5×103, 27·8×103, 55·5×103, 111×103, 222×103 and 444×103 plants/ha on dry matter (DM) and seed yields of cultivars Local, UQ50, 3D8103, 3D8104, 3D8111 and 3D8112 in the 1974/75 season. Planting in May had no above-ground DM yield advantage over planting in June at Mokwa. Planting in June gave higher yields than planting in July irrespective of site, except for the short, early maturing, soya-type cultivar 3D8103 at Shika. Cultivar responses to density were inconsistent between sites and also between dates at Shika and Kano. Cultivars Local, UQ50 and 3D8104 showed the highest DM yield at all sites. Leaf DM yield tended to decline as planting was delayed but was highest at densities of 111×103 or 222×103 plants/ha for May and June-planted cultivars Local, UQ50, 3D8104 and 3D8112, which showed potential as feed supplements for poultry. Reasons were advanced for the variability in pod yield responses to planting date and density between the different pigeonpea cultivars. Root DM yields were proportional to above-ground DM yield but, over all cultivars, root yield was unaffected by planting date at Shika.

Seed yield was highest from the June sowing, cv. 3D8104 was the most productive and the optimum densities were 27·8×103 plants/ha for the larger-sized cultivars Local and UQ50, 55·5×103 plants/ha for the medium-sized cultivars 3D8104, 3D8111 and 3D8112, and 444×10 3 for cv. 3D8103. A complementary study over 13 years showed that the seed yield of intermediate and late maturing pigeonpeas was strongly and linearly related to total annual rainfall.

1. The fertility of three sterile bulls was restored by injections of human pregnancy urine extract (P.U.).

2. Cows which failed to exhibit oestrus were treated by injections of P.U. Three out of five cows responded within 24 hours to intravenous injections of 5 c.c. P.U. (2500 rat units) and one out of four to an injection of 3 c.c. P.U.

Two out of five cows responded immediately to a series of three intramuscular injections of 2 c.c. P.U. and one cow responded to a single intramuscular injection of 2 c.c. P.U. In addition four cows failed to respond immediately to four intramuscular injections of 2 c.c. P.U.

3. Evidence was obtained which shows that treatment with P.U. at the time of service increases the fertility of cows which show regular oestrus but nevertheless fail to conceive. It is believed that this condition is often due (a) to failure to ovulate, and (b) to deficiency of progesterone following ovulation.

We are grateful to Prof. R. Rae and Mr K. W. C. Campbell for their co-operation. Part of this work was carried out during the tenure by one of us (H.M.S.W.) of a Research Grant from the Ministry of Agriculture and Fisheries.

The object of the present communication is to collect together and compare the data obtained in the principal investigations which have been carried out in this country during the past five years into the variations in composition of the milk of the cow. The results of many of these experiments have been published only in annual reports or as special bulletins with limited and more or less exclusively local circulation.

Sesame (Sesamum indicum L.) is a crop of great antiquity which is widely grown in tropical and subtropical regions of Asia, Africa, South and North America and to some extent in Russia for edible oil and for animal feed purposes. The average yield in India is only about 235 kg/ha. Even under good management practices the seed yields usually remain poor and, therefore, commercial prospects of sesame production are not good.

Ferrous iron is oxidized and precipitated as iron ochre in field drains. In drainage waters taken from an ochre-producing site near Aberdeen, Scotland in 1987, iron deposition was inhibited by the addition of humic and fulvic acids, which form complexes with Fe(II). The inhibition was dependent on the concentrations of soluble humic materials and the proportion of Fe complexed. Iron deposition in the presence of humic substances is discussed in relation to the amount of the cation which is complexed and its oxidation state.

The carcass-weight increase of beef steers of various ages receiving fattening rations of different roughage: concentrate ratios was calculated by making use of the average dressing percentage of a control group slaughtered at the beginning of the experiment.

It is shown that, in terms of t.d.n./100 lb. carcass-weight increase, which is probably the more accurate measure of efficiency, the 2-year-olds were better feed converters than the calves. When the criterion was t.d.n./100 lb. live-weight increase the calves were superior. Ration B (1 concentrates: 1 roughage) was utilized most efficiently in terms of calculated carcass-weight increase, followed in a descending order by the high-concentrate ration C and the high-roughage ration (ration A).

The relationship of live-weight increase to carcass- weight increase as calculated is discussed. The proportion of live-weight gain laid down as carcass varied with age, growth rate and type of ration. This percentage variation ranged from 57% in slow-growing calves to 81% in fast-growing 3-year-olds. On the average, calves converted 61% of their live-weight gain into saleable carcass, the 2-year-olds 70·8% and the 3-year-olds 75·9%. The steers on the A (high roughage) ration converted 65·7% of live-weight gain into carcass, those on the C (high concentrate) ration 71·5% and those on the B (1 concentrate: 1 roughage) 69·2%. Reasons for these differences are discussed in terms of so-called differential growth.

The live weights and carcass weights of steers were plotted and the regression equation

where Yis carcass weight and X is live weight, was derived. The correlation coefficient r = 0·98 and the slope of the curve indicated that for an increase of 1% in the live weight of the steers, the carcass weight increased by 1·13%.

Several methods of expressing ‘efficiency of the fattening’ were applied to the data and the results are discussed. The methods were unanimous in selecting the steers on the B ration as the most efficient followed by those on ration C and the poorest were those on the A ration. Methods based on live-weight increase showed the calves, but those based on carcass-weight increase the 2-yearolds, as the most efficient. Results obtained by applying the Efficiency Quotient and Efficiency Index suggested that the older animals wero the more efficient. They differed from all other methods since these indicated that efficiency declined with age.

Efficiency values calculated by different formulae vary and no efficiency index has yet been evolved that will embrace all the variable factors which may have an influence on the efficiency of growth and fattening.

1. The structure of the cattle population (4 June returns), as well as of cattle sales to the Ministry of Food, have been illustrated.

2. The trends in cattle production show the definite changes from that of the traditional storestock rearing to that of milk selling.

3. A considerable part (38·2%) of the total graded animals slaughtered for beef are the ‘wastage’ animals from the breeding and dairying herds.

4. Reference has also been made to the high proportion of ungraded cows (36·7% of the total cows) purchased by the Ministry. The ungraded cattle, however, are only 17% of the total sales. On the other hand, the ungraded ‘wastage’ cattle contribute 90% of the total ungraded cattle.

5. More heifers than steers were sold for slaughter, and it has been shown that the average live weight of the graded steers is nearly 224 lb. heavier than that of the heifers.

1. Data for the composition and digestibility of certain by-products of the ryegrass seed cleaning industry are presented in amplification of data already published.

2. It is shown that the ‘hairgrass’ fraction of ryegrass seed cleanings has a starch equivalent somewhat superior to that of pure ryegrass seed or oats, and that this may be ascribed in all probability to its content of ratstail fescue seed.

3. It is shown that the ‘flatweed’ fraction, consisting chiefly of buttercup seed, has a starch equivalent, on a dry-matter basis, about three-quarters that of oats or pure ryegrass seed, and that it is, in spite of a relatively high content of digestible oil, among the least valuable constituents of the cleanings, apart from dust, straw and other worthless material.

4. Commercial Yorkshire fog seed is shown to have a feeding value comparable to that of pure perennial ryegrass seed.

5. Some data are presented regarding the inorganic constituents of ryegrass seed and ryegrass seed by-products.

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.

An experiment to measure the effects of cold conditions upon heat production in young sambar (Cervus unicolor) and red deer (Cervus elaphus) was conducted during winter 1994, at Massey University, Palmerston North, New Zealand (NZ), using four young animals of each species. Animals were fed a pelleted concentrated diet (total N 29g/kg DM; 11·9MJ metabolizable energy (ME)/kg DM) at approximately maintenance ME intake (MEI). Hair coat characteristics were measured on samples cut from a patch on the mid-side of the body. Pairs of animals (one sambar and one red deer) were confined in two open circuit calorimetry chambers (one deer in each chamber) for 18-day periods, and oxygen consumption was measured at 20 and 5 °C, with and without simulated wind (6 km/h). Heat production was calculated as 20·5 MJ/1 oxygen consumed.

Hair coats of sambar deer were less deep, lighter in weight (g/m2) and contained a lower proportion of undercoat than those of red deer. Fibre length of both guard hairs and undercoat were shorter in sambar deer than in red deer, whilst fibre diameter of both guard hairs and undercoat was greater in sambar deer. Heat production (HP) at 20 °C was lower in sambar than in red deer (P <0·05; 0·46 v. 0·48-0·53 MJ/kgW0·75 per day). Increases in HP from 20 to 5 °C and from 20 °C to 5 °C W (i.e. with wind effect) were greater in sambar than in red deer (P < 0·01; 34 v. 16% and 44 v. 20%, respectively). Calculated lower critical temperatures (LCT) were higher for sambar than for red deer (P < 0·10) both in the absence (0 km/h; 11·6 v. 8·9 °C) and in the presence of wind (6 km/h; 140 v. 11·1 °C). Under field conditions, young sambar deer are likely to require more shelter and better feeding during cold weather than do red deer.

The effect of seed protein content on grain yield has been studied in varieties of spring barley, oats and wheat grown under differing cultural conditions. Grain yield was affected by seed protein content in one experiment where very low yields were attained, but the effects were inconsistent. No effect was observed in two other experiments made in a glasshouse and the field. In a growth-room experiment, seed with high protein content produced more vigorous seedlings than low-protein seed; these differences were accentuated by increasing seedling age at very low nutrient levels, but decreased with seedling age at normal nutrient levels. It is concluded from the results that variations in seed protein content are unlikely to have a significant effect on yield under practical conditions.

Labelling using the stable 15 isotope of nitrogen allows a close monitoring of the fate of the fertilizer applied to arable crops. Because 15N data give direct estimates of nitrogen transformation rates, they also provide more stringent tests for N models than those based on bulk inorganic N dynamics. They may therefore point at flaws in models that had previously gone unnoticed, especially if 15N was monitored on short time steps which capture even rapid processes like nitrification.

Here we tested the simple, process-based model SUNDIAL on two such data sets obtained in Northern France under winter wheat and winter rape crops receiving various doses and forms of fertilizer N. In both experiments, microplots (≈ 1 m2 in size) within larger blocks were dressed with 2·0 atom-% enriched labelled 15N, as urea, or ammonium-nitrate as NH+4–15NO3 or 15NH+4–H–NO3. Replicate micro-plots were subsequently sampled on four occasions after fertilizer application, and 15N enrichment was monitored in plant roots and tops, and at several depths in the soil in inorganic and organic forms.

Comparison between observed and simulated data showed that, shortly after application, SUNDIAL either underestimated (rapeseed) or overestimated (wheat) the rates of crop uptake. Also, the gradual incorporation of 15N into soil organic matter was too quick in autumn and too slow in spring under the rapeseed crop. The simulation of the rapid depletion of the labelled soil inorganic N pool was correct under wheat, whereas under rape, SUNDIAL predicted an accumulation of nitrate which was not observed.

After a longer time interval (1–2 months), the simulated and observed amounts of fertilizer-derived N in the crop and in the soil became more comparable. However, SUNDIAL only accounted for part of the unrecovered labelled N. Additional measurements indicated that denitrification and ammonia volatilization were responsible for most of the losses, with discrepancies occurring because SUNDIAL failed to volatilize ammonia after fertilizer spreading. The other major source of error lay in the simulation of crop demand for nitrogen, which may be improved based on sounder eco-physiological concepts, such as that of a regulation of plant uptake by shoot biomass.

Studies of leaf area estimate of some oil crops were made using planimeter measurement, punch borer and length × width × factor. The extent of sample variation depended on the variety in each of these methods; the last two methods were found to be simple, precise and less time consuming.

Statistical experiments were made to ascertain the effect of variations in applied soluble phosphate on the growth of Milan Strap-leaved Purple Top Turnips in a light gravel soil already containing sufficient available phosphate, and in a fen soil possessing an inadequate supply of available phosphate, as aggregates for growth.

No adverse effect on yield, calculated as fresh or dry matter of tops, roots, or whole plants, was suffered in either soil at any of the stages of growth considered at the highest concentrations of soluble phosphate, unlike the behaviour of this turnip when grown in a pure sand containing no clays or humates, where there was a narrow optimum range of phosphorus at a low concentration. The gravel soil occupied an intermediate position, however, between sand with its low optimum range of soluble phosphorus, and fen soil, where positive response to increasing concentrations of soluble phosphorus approached the ‘normal’, and thus there was a range of phosphorus at low concentration tending to a maximum yield followed generally by a greater numerical yield at the highest concentrations of phosphorus.

At the seedling stage in gravel soil variation in applied phosphate had absolutely no statistical effect on yield, moisture content of tops, roots and whole plants, and the ratios, for fresh or dry matter, Top/Root, Root/(Whole plant) and (Whole plant)/ Top.