Journal of the Science of Food and Agriculture

doi: 10.1002/jsfa.2740310801pmid: N/A

Burns, Ian G.; Collier, Graham F.

doi: 10.1002/jsfa.2740310802pmid: N/A

A layer model for predicting the leaching of unadsorbed anions from unstructured soils has been extended to enable forecasts of the effects of rainfall on the redistribution and losses of weakly adsorbed ions, such as borate, to be made. The model is based on easily measured parameters including field capacity and the initial water and borate contents of each of the soil layers and calculates the redistribution of borate from the excess rainfall over evaporation. The partitioning of borate between the adsorbed and solution phases during leaching is calculated using a modified Langmuir isotherm equation. An advantage of the model is that it requires no specially fitted parameters which must be derived from separate leaching experiments. The model was tested against the results of published experiments on the leaching of borate from soil columns. Agreement with the experimental data was good and only marginally inferior to the agreement obtained using a more sophisticated model which required more detailed input information. The model was also used to forecast the amount of rainfall needed to reduce the concentration of borate in a sample of pulverised fuel ash (PFA) to a non‐toxic level. The results were consistent with the limited experimental data available. There was also reasonable agreement between the predictions of the model and the results of an experiment in which borate was leached from columns of PFA using a limited range of irrigation treatments.

Stone, David A.

doi: 10.1002/jsfa.2740310803pmid: N/A

Three coarse‐textured soils were amended with pulverised fuel ash and two similar fine‐particle materials, fluidised combustor ash and ground silica sand. Incorporation of the amendments to the Ap horizon of the soils increased available water retention by up to 70%. The additional water was mainly held at matric potentials between −0.05 and −1 bar. A concomitant increase in hydraulic conductivity and soil water diffusivity over the same potential range indicates, however, that the increase in water retention was at least partially offset by greater evaporation from the soil surface. This could explain the poor crop response to increases in available water capacity (AWC) reported in previous work and questions the importance placed on AWC in current soil productivity classification.

Stone, David A.; Rowse, Hugh R.

doi: 10.1002/jsfa.2740310804pmid: N/A

Emergence of cauliflower and radish seeds was increased by incorporation of pulverised fuel ash, and two similar fine‐particle amendments, fluidised combustor ash and ground silica sand, to two coarse‐textured soils. The effect was generally greatest on the coarsest soil and with the highest rates of amendment. From the known hydraulic properties of the treated and untreated soils, seed‐bed water conditions prevailing during the radish field experiment were simulated using a computer program to solve the flow equation for water movement in soil. Simulated soil water deficit and distribution of water loss within the profile agreed well with experimentally determined values. A laboratory experiment on water uptake by radish seeds showed little difference in uptake between seeds in treated and untreated soil at constant potential, despite large differences in water content and hydraulic conductivity. Sufficient water uptake for radicle emergence occurred within 6 h at potentials higher than −0.1 bar. The simulation indicated that potentials in the field did not fall below this level until at least 12 h after irrigation to field capacity. It was concluded that differences in the rate of seed water uptake did not produce the beneficial emergence effects recorded. The data suggest, however, that these are due to differences in water supply during the post‐imbibition pre‐emergence stage of seedling growth.

Stone, David A.

doi: 10.1002/jsfa.2740310805pmid: N/A

The incorporation of pulverised fuel ash and two similar fine‐particle amendments, fluidised combustor ash and ground silica sand, to the Ap horizon of coarse‐textured soils increased the available‐water capacity by up to 70% but had little effect on the yield of lettuce and cauliflower grown in the field. Plants grown on amended soils extracted more water from the surface horizon and less water from depth compared with extraction from unamended soil. As a result total water use by plants from amended and unamended soils was similar. This difference in distribution of water extraction, together with greater evaporation from the soil surface of amended soils, probably explains the poor crop responses to the fine particle amendments.

Hegsted, Maren; Linkswiler, Hellen M.

doi: 10.1002/jsfa.2740310806pmid: 7453147

The effects of saponin content, methionine content, and digestibility on the protein quality of alfalfa protein concentrates (APC) made from high and low saponin alfalfa were evaluated by chemical analyses and by rat bioassays. The protein quality of the APC both with and without added methionine were measured as protein efficiency ratios and as relative nutritive values (by a slope‐ratio assay). The low saponin APC had a higher crude protein content, a higher protein digestibility, a higher relative nutritive value, and higher protein efficiency ratios at all levels of added methionine than the high saponin APC. With the addition of 0.3% methionine the protein quality of the low saponin APC was as good as casein.

Martone, Celina B.; Crupkin, Marcos; Barassi, Carlos A.; Trucco, Raúl E.

doi: 10.1002/jsfa.2740310807pmid: N/A

A comparison of the Kjeldahl and Lowry methods for the determination of protein in fish meal has been made. The values obtained with the rapid colorimetric Lowry method, using extracts of total fish meal proteins, were lower than those obtained by the Kjeldahl method. For fish meal from different species the general factor 1.19±0.03 (confidence limit for P<0.01) may be used to convert protein values obtained by the Lowry method into protein values obtained by the Kjeldahl method.

Heaney, Robert K.; Fenwick, G. Roger

doi: 10.1002/jsfa.2740310808pmid: N/A

The glucosinolate content of 22 cultivars of Brussels sprout have been determined. The levels of total glucosinolates, determined by methods based on glucose release and gas chromatography, were substantially higher than those reported by other workers for cabbage and Chinese cabbage. The major glucosinolates in Brussels sprout leaf material were identified as gluconapin, progoitrin, sinigrin and glucobrassicin, with the latter two generally predominating. Detailed analysis of the material from five different growing sites has shown considerable variation in the total content but surprisingly little difference in the relative proportions of the individual glucosinolates within each cultivar. The glucosinolates of the corresponding seed material differ significantly from that in leaf; in particular glucobrassicin is found in trace amounts only, and glucoerucin, glucotropaeolin and neoglucobrassicin are all present, in addition to sinigrin, progoitrin and gluconapin.

Heaney, Robert K.; Fenwick, G. Roger

doi: 10.1002/jsfa.2740310809pmid: N/A

Quantitative differences in the relative glucosinolate content of Brussels sprouts have been used to assist differentiation between cultivars. The glucosinolate pattern of each individual cultivar, determined directly using gas chromatography, has been found to vary only slightly with growing site. Differing patterns of glucosinolates have been noted amongst the corresponding seeds, thus complementing the data obtained from the mature vegetable.

Cansfield, Peter E.; Marquardt, Ronald R.; Campbell, Lloyd D.

doi: 10.1002/jsfa.2740310810pmid: 7453148

Condensed proanthocyanidins were extracted from fababean hulls with water. The aqueous extract, after deproteinisation by freezing, thawing and acetone precipitation, was purified by chromatography using Sephadex LH20 gel and 95% ethanol developing solvent. Gradient chromatography of the purified condensed proanthocyanidins using 95% ethanol‐(50% v/v)acetone‐water with a Sephadex LH20 column yielded two peaks when the column effluent was monitored at 400 nm. Chromatographic behaviour before and after oxygen treatment indicated certain structural differences between fractions collected under the major peak. There were also considerable differences between the chromatographic properties of material collected from under the major peak and under the minor peak. Solvolysis experiments on the various fractions yielded differences in delphinidin: cyanidin and delphinidin: phlobaphene ratios. There were also differences in ‘tannin’ contents (determined by acidified vanillin methods) and all these differences confirmed that there were structural dissimilarities between the fractions. Tannin determinations made on the hulls of seven different cultivars of fababeans indicated condensed proanthocyanidin levels between 0–6%.