1. A historical review of the dye adsorption method for the estimation of soil colloids is presented, and the method is criticised chiefly from the point of view of the isoelectric theory.

2. A procedure for the detection of hydrous alumina in soils is described, involving the demonstration of the isoelectrio point of hydrous alumina by means of preferential dye adsorption in suspensions of various pH values.

3. Satisfactory results were obtained with a mixture of acidic Biebrich Scarlet and basic Iodine Green. The former is adsorbed by hydrous alumina only on the acid side of its isoelectric point, and the latter only on the alkaline side.

4. The characteristics of an ideal dye for use in studies such as those described are tabulated.

5. The applicability of the mixture of dye-stuffs finally selected is demonstrated for a series of soils of varying basic ratio, and including examples of lateritic soils and clays.

A field trial was conducted during 1982–3 and 1983–4 on a loamy sand soil to study the effect of magnesium application to the soil and in foliar spray in relation to various levels of nitrogen on the growth and yield of wheat. Results indicate that wheat responde significantly to magnesium application only at the higher level of nitrogen. At the higher level of N (120 kg/ha), the response of wheat to magnesium application (10 kg/ha) to the soil and in foliar spray was 56 and 68 kg grain/kg Mg, respectively. However, the corresponding values at a low level of N (60 kg/ha) were only 14 and 15 kg grain/kg Mg. Magnesium at the higher level of N increased the chlorophyll content of leaves, leaf area index, interception of photosynthetically active radiation, number of ear-bearing tillers and number of grains per ear. The higher level of magnesium (20 kg/ha) did not result in extra beneficial effect compared with the lower level of Mg (10 kg/ha). Maximum interception of photosynthetically active radiation by the wheat canopy coincided with the attainment of maximum leaf area index and chlorophyll content of leaves at 90 days after sowing.

It was observed in a recently concluded study (O. O. BalogunandB. L. Fetuga, unpublished data) that methionine and palm-oil supplementation to a cassava flour-soya-bean meal diet encouraged satisfactory growth, efficiency of live-weight gain, nitrogen retention and carcass quality of weanling pigs. Our earlier reports (Balogun & Fetuga, 1981; Balogun, Fetuga & Oyenuga, 1982) also indicated that the muscles of pigs responded differently to dietary methionine and lysine and that the quantitative requirements of these amino acids for maximum development of the muscles were at variance with the methionine or lysine requirements for maximum growth performance and nitrogen retention.

The use of town stable manure enters so largely into the economy of farms, and especially market-gardens, situated within fairly easy distance of London or other large cities, that it is somewhat curious that but little information has been published in this country as to its chemical composition. In fact, with the exception of a couple of analyses made by myself as long ago as 1889, which were published at the time in the Mark Lane Express, and subsequently reprinted in Aikman's book on “Manures and Manuring,” I do not remember to have seen any analyses of London manure. The samples which were the subject of these analyses were collected from a very limited number of stables, some of which were littered with peat moss and others with straw, the object at the moment being to compare the manure produced with the two kinds of litter. I have more recently however made some fairly full analyses of two more representative samples of London manure, but before proceeding to give these it may be desirable to reprint in this place, for future reference, the old analyses just mentioned.

Applying coffee pulp biochar (BC) can be a complementary practice to the application of chemical fertilizers (CF) of crops; however, little evidence of its combined effects on coffee cultivation has been reported. A field trial was carried out during two evaluation years (2019 and 2020) to analyse the effect of the application of different BC doses (0, 4, 8 and 16 t/ha) in combination with four levels of fertilization (0, 33, 66 and 100% of the nutritional requirements) on physiological responses of 3-year-old coffee (Coffea arabica L. var. Castillo) trees. The results indicated that trees with 0 t/ha BC and 0% CF showed the lowest values in all the physiological variables studied (gs = 269.9 and 126.8 mmol/m2/s; Chl = 61.7 and 54.7 At-leaf readings; yield = 0.21 and 0.22 kg of dry parchment coffee (DPC)/tree for 2019 and 2020, respectively). Coffee trees treated with 8 t/ha BC and CF levels of 100% registered the highest results in gs (424.9 and 366.9 mmol/m2/s), Chl (71.1 and 69.8 At-leaf readings), yield (0.41 and 0.57 kg of DPC/tree) in 2019 and 2020, respectively. In conclusion, the application of BC from coffee pulp, especially at a dose of 8 t/ha, generates a positive effect on yield, gs, leaf nutrient concentration and Chl of coffee trees. The use of BC can be an alternative to complement the mineral nutrition of commercial coffee crops to help reduce the application of CF.

The selenium concentration of cereal grain and herbage from 131 farms in England and Wales was, in general, low: the proportions of samples with values below 0·03 mg/kg D.M. were 60% for grain (primarily barley, from 96 farms) and 39% for conserved herbage (primarily hay, from 131 farms). Values for fresh herbage from 12 farms were similar to those for conserved herbage. There were no significant differences in selenium concentration among herbage species. For all samples, those from the Cambridge area contained more selenium than those from other parts of England and Wales.

The present communication is intended as a contribution to the study of the capacity of soils to retain moisture in equilibrium with the atmosphere. The experimental material with which it deals consists in part of the analytical data obtained in the investigation of one hundred soils of the county of Dorset, which has been carried out for the County Council, and in part of a series of determinations made for the purpose of elucidating this problem.

Individual muscles, individual bones and fat depots from the non-carcass parts (head, foreshanks and tail) of 40 steers (chilled carcass weight 142–174 kg) were studied in an attempt to predict carcass composition more accurately than in an earlier study where the crude non-carcass parts, head, tongue, foreshanks and hindshanks were used.

The technique did not improve the accuracy of prediction of muscle or bone. Carcass fat, which was calculated by difference in the earlier study, was predicted more accurately using intermandibular fat weight (requiring 3–4 min to obtain) plus fat thickness at the 12th rib. However, the accuracy of this prediction (carcass fatness range 14·0–33·6%, residual standard deviation 1·98%) was no greater than that using chilled side weight plus fat thickness at the 12th rib.

Careful dissection and trimming of anatomical entities from the non-carcass parts therefore offered a slight advantage only in the prediction of carcass components over existing techniques.

Substitution of hot side weight for chilled side weight, and sacral crest fat thickness for fat thickness at the 12th rib did not lead to a loss in the accuracy of prediction of muscle, bone or fat.

Seeds from individual heads of wild safflower (Carihamus oxyacantha Bieb.) plants collected from five locations were used in this study. Locations were situated on a roughly east-west transect passing through Shiraz, Iran. The western locations were cooler with higher annual rainfall than the eastern sites. Wild safflower plants of different locations produced about an average of 150 heads per plant, but only 60% of them contained seeds. Frequency distributions constructed for number of seeds per head, germination percentage, and seedling length showed trends of change in the skewness of the distribution for the latter two characteristics parallel to the environmental selective pressure, i.e. the skewness was towards the left for eastern locations but it gradually moved to the right for western ones. Striking amounts of polymorphism were also observed for these characters. A very high proportion of total variance was concerned with differences between heads of the same plant for number of seeds, germination ercentage, and seedling length. Very little variability was found among plants of the same ecotype.

Estimates of dry matter intake reported by Barlow el al. in this journal in 1988 appeared low for grazing beef cows during early lactation. Further estimates for 144 crossbred and Hereford cows at Grafton, NSW, support the contention that the previous estimates for early lactation were biased downward. This appears to have been simply a scale effect as rankings of pastures and cow genotypes remained unchanged, although the magnitude of differences did alter.

Nine experiments in the East of Scotland were completed in the years 1966, 1967 and 1968 to test the response of potatoes grown for ware to five levels of a 15½–15½–21 fertilizer applied at rates of 0, 4, 8, 12, 16 and 20 cwt per acre.

1. Mean yield of ware tubers increased up to the highest fertilizer level.

2. Mean yield of small tubers increased only up to the 8 cwt per acre level and then declined.

3. Dry matter content of ware tubers decreased with increasing levels of fertilizer.

4. Increasing fertilizer levels lowered soil pH. At one site this was associated with a significant reduction of common scab on the tubers.

The main findings of the present trials may be. summarized as follows:

(1) When ‘mineralized’, cooked potatoes are fed as the bulky supplemental food in the Lehmann system of pig-feeding, and the basal meal allowance is restricted to 3 lb. per head per day, bacon pigs are able to make as good progress, in respect both of rate of live-weight increase and economy of food conversion, and at every stage from 60 to 200 lb. live weight, as they would if kept on a diet composed wholly of balanced meal. In the present trials, pigs of about 200 lb. live weight were able to consume 15–17 lb. of cooked potatoes per day in addition to the daily allowance of 3 lb. of meal. It required, on an average, about 1030 lb. of cooked potatoes and 311 lb. of balanced meal per pig to fatten the animals from 60 to 200 lb. live weight. The cooked potatoes, when assessed on the air-dry standard of 13 % moisture, were able to replace the balanced meal on a lb. for lb. basis without detriment to the progress of the pigs, and the average saving of meal thus made possible amounted to about 225 lb. per pig, or 38·2 % of the total meal consumed per pig on the control, all-meal diet.

(2) Cooked potatoes should be introduced into the ration gradually and the allowance should be scaled according to live weight in the manner adopted in the present trials. When the amount to be fed is large, it is best to feed ‘mineralized’, cooked potatoes only during the morning and to place the basal meal in the trough towards the end of the afternoon.

The effects of supplying the fertilizer nitrogen (N) as a recommended quantity of ammonium nitrate or as a commonly used dose of poultry manure on yield of sugarbeet infected with Beet mild yellowing virus (BMYV) or Beet yellows virus (BYV) were studied in field experiments at IACR-Broom's Barn in 1990, 1991 and 1992. Three N fertilizer treatments comprising Zero (N0), standard rate of 110 kg N/ha (N1) and poultry manure equivalent to c. 300 kg/ha of available N (N2) were applied to plots which were uninoculated or were subsequently inoculated with either BMYV or BYV. Averaged over virus treatments, N1 increased sugar yields by 23% relative to N0: there was no further increase when N2 was applied. When averaged over N treatments, early virus yellows infection reduced the sugar yields by 23%. Generally there was no significant interaction between N supply and virus infection. There was no evidence that the large N supply could reduce the yield effect of virus yellows infection, as had previously been thought. Crops infected from late July produced similar yields to uninoculated controls. The main effect of virus yellows was to reduce the efficiency of radiation conversion even when account was taken of the light intercepted by yellow foliage. Whilst the N2 treatment helped to maintain a green leaf cover throughout the season on virus yellows infected crops, it had no effect on virus replication. Beet processing quality was impaired by increasing the N supply and by virus infection, but again there were generally no significant interactions between infection and N rate.

This group, which is concerned with the applications of mathematics to agricultural science, was formed in 1970 and has since met at approximately yearly intervals in London for one-day meetings. The fortieth meeting of the group, chaired by Dr John Thornley of Henley-on-Thames, UK and the Centre for Nutrition Modelling, University of Guelph, Canada, was held in the Kohn Centre at the Royal Society, 6 Carlton House Terrace, London on Friday, 11 April 2008 when the following papers were read.

Sugar beet bolting in the root crop was studied during nine growing seasons, under the extreme climatic conditions in which the autumn-sown crop grows in Southern Spain.

Bolting is positively correlated with the number of days with minimum air temperatures ranging from 2 to 8 °C or with the number of days with mean temperatures between 8 °C and 13 °C.

The occurrence of bolting is also affected by rainfall distribution in so far as it determines the date of seedling emergence.

This study sought to determine whether increases in live weight (LW) of steers implanted with Compudose 200®, a growth promotant that contains 17β-oestradiol, arose in part from increases in resistance of those steers to cattle ticks and gastro-intestinal nematodes (worms) to which the steers were exposed while they were growing. Half of a group of interbred Hereford × Shorthorn (HS) and interbred Brahman × HS (BX) steers was implanted with Compudose 200 on two occasions 200 days apart. Half of each of the implanted and nonimplanted groups in each breed was treated every 3 weeks to control cattle ticks and worms. All animals grazed together and were regularly monitored for parasite burdens and LW changes. Both breeds responded positively to Compudose 200, to which BX responded most, and to treatment to control parasites. Resistance to either ticks or worms was unaffected by the presence of the implant so that, within each breed, increases in LW gain in response to the implant were similar regardless of parasite control. Thus the increases in LW gain resulting from the use of Compudose 200 arose directly from the action of the implant on metabolism, not indirectly through any effect on resistance to parasites.

It was aimed to simultaneously study standardized ileal digestible (SID) tryptophan (Trp) and lysine (Lys) for gilts. A digestibility assay was previously conducted to determine the SID amino acid in the basal diet (low levels of SID Trp and Lys). Sixty-four gilts (15.04 ± 1.44 kg) were allotted to 16 diets in a 4 × 4 factorial arrangement (1.55, 1.85, 2.15 and 2.45 g/kg SID Trp and 9.72, 11.12, 12.52 and 13.92 g/kg SID Lys) with four replicates per treatment. Performance, longissimus muscle (LM), backfat thickness (BF) and blood variables were evaluated. An interaction was observed for G:F, and by response surface model, the optimum Trp level was achieved at 2.15 g/kg (0.159 g/MJ of ME). A quadratic effect of Trp was observed on body weight (BW) and average daily gain (ADG); the daily feed intake increased linearly as Trp increased. The optimum Trp levels of 2.25 and 2.24 g/kg were estimated for BW and ADG, respectively. The BF increased with increasing levels of Trp. There was a quadratic and linear effect of Trp and Lys, respectively, on the LM, in which the optimum Trp level was determined as 2.05 g/kg in the diet. Plasma urea nitrogen decreased as Trp and Lys levels increased. Using estimates provided by response surface, maximized G:F ratio was obtained at 2.15 g SID Trp/kg of diet and at least 13.92 g SID Lys/kg of diet is necessary to optimize the G:F for 15–30 kg gilts, providing a Trp:Lys ratio of 15.4:100.