CHEMICAL AND INFRARED SPECTROSCOPIC STUDIES OF FULVIC ACID FRACTIONS FROM A PODZOL

Infrared spectroscopy and chemical degradation indicated several fulvic acid fractions from an iron-humus podzol capable of complexing and translocating metals. Acidic polysaccharides, some of them resembling pectic acid, were isolated in appreciable quantities. These are able to bind metals through carboxyl groups, but peptide components present in the polysaccharide fraction may provide alternative metal complexing centres. The high yield of acid-extractable organic matter from the illuvial humus, together with its high content of carboxylic acid groups, make it likely that this fraction plays a major role in the translocation of metals. Phenolic compounds allegedly associated with this process were present in the fulvic acid solution in low amounts, and only in the extracts from the organic horizons.     

A COMPARISON OF THE SORPTION OF INORGANIC ORTHOPHOSPHATE AND INOSITOL HEXAPHOSPHATE BY SIX ACID SOILS

A comparison has been made of the sorption of inorganic orthophosphate and inositol hexaphosphate by six acidic surface soils from arable land in north-east Scotland. The sorption of inorganic P increased with increasing quantities added and tended towards a maximum, but was never complete. In contrast, the organic P was completely sorbed up to an added quantity which varied with the soil, and above this level the absolute sorption decreased, probably due to the formation of soluble complexes involving iron and aluminium. The sorption sites were apparently the same for the two P forms and, particularly at high levels of addition, the organic P depressed the sorption of inorganic P. Inorganic P did not depress the sorption-of organic P, which was preferentially adsorbed. The results help to explain the extreme stability of inositol hexaphosphate in these soils.     

Effect of stage of maturity and chop length on the chemical composition and utilization of formic acid-treated ryegrass and formic acid silage by sheep

Two areas of an early-heading perennial ryegrass cv. Cropper were harvested by either a precision-chop or a flail harvester at around 50% ear emergence (15 May 1978) and 14d later (29 May). Formic acid (85%) was applied at the rate of 2·2 litres t^-1. Mature crossbred wethers were used in a 2 × 2 factorial design to determine the effect of stage of maturity and method of harvesting (chop length) on the in vivo digestibilities of formic acid-treated grass in experiment 1 and formic acid silage in experiment 2. Apparent digestibility coefficients were determined at a fixed level of feeding for both grass and silage and at ad libitum access to feed for silage only. There were no significant differences in the concentrations of crude protein (CP), ether extract (EE), acid-detergent fibre (ADF) or acid-detergent lignin (ADL) in grass or silages of differing chop lengths but the later cut forages had significantly higher ADF and ADL concentrations and lower CP concentrations than the early-cut forages. The ADF and ADL concentrations were also higher in the silages than in the corresponding grasses. In general, the fermentation characteristics of precision-chopped silage were better than for the corresponding flail-cut silage but date of harvest was a more important determinant of quality and the late, flail-cut silage had the highest butyrate and ammonia N concentrations and the highest pH (411) of any treatment. There was a significantly higher intake of precision-chopped as compared with flail-cut silage with both the early-and the late-cut silage but there were no significant differences attributable to stage of maturity (i.e. date of harvest) or significant interaction between chop length and maturity. The slightly increased intake of early harvested, precision-chopped silage as compared with late precision-chopped silage was not significant. Dry matter digestibility (DMD) of the grass decreased at a rate of 0004 units d^-1 post 50% ear emergence. The results of experiment 2 indicated a decrease of 0·207 units d^-1 in silage fed at a similar level. The late-cut silage (DMD 0·292, mean of both harvesting treatments) thus had a significantly lower digestibility than the corresponding grass (mean DMD 0·247). Chop length had a variable influence on the DMD of both grass and silage fed at a fixed level but treatment differences were non-significant. However, a trend towards higher digestibility of flail-cut as compared with precision-chopped silage was apparent and this became statistically significant when the animals were allowed ad libitum access to feed. This may be a response to the generally lower intake of flail-cut silage.     

Water Analysis: A Systems Approach Incorporating Linear Programming

This paper reviews an interactive, policy-oriented simulation model and introduces the addition of a water module. This module enables policymakers to estimate and analyze those direct and indirect socioeconomic effects on a regional economy, occurring over time, which are attributable to regional water supply constraints and water allocation decisions. In addition, this paper presents a hear-programming-based approach which can guide the user in making water parameter adjustments for a chosen objective. An empirical demonstration of the procedure based on the Minnesota state economy illustrates its usefulness.     

Root Extraction Force Measurements for Sitka Spruce

Extraction force and displacement were measured on roots pulledhorizontally from the sides of a pit made in the soil afterremoval of the tree and the bulk of its root system. Measurementswere made on a brown earth and a deep peat, in 24- and 27- year-oldcrops respectively. The brown earth soil was drier and moredeeply rooted than the peat, but the root diameter at the pulledend, the length of root extracted and the root displacementat maximum extraction force were each similar on both soils.Extraction force was related to the root cross-sectional areaat the pulled end and regressions showed that roots requiredsignificantly more force for extraction on the peat than onthe brown earth. However, the difference was small, and anydifferences in tree stability between the two sites would haveto be explained by other features of the anchorage. Data arealso presented on effects of root morphology and depth on extractionforce.     

Interception of precipitation by pole-stage Sitka spruce and lodgepole pine and mature Sitka spruce at Kielder Forest, Northumberland

Interception loss was measured indirectly for 3 years in adjacentunthinned 25-year-old stands of Sitka spruce and lodgepole pineand for 2 years in a 63-year-old selectively thinned stand ofSitka spruce. For each stand measurements were made of grossprecipitation, throughfall and stemflow. Interception loss wasderived by subtracting the sum of throughfall and stemflow (netprecipitation) from gross precipitation. For the years 1977–78, 1978–79 and 1979–80,interception losses in the pole-stage Sitka spruce were 32,28 and 27 per cent of gross precipitation respectively whilethose in the lodgepole pine were 33, 29 and 26 per cent. For1979–80 and 1980–81 interception losses in the matureSitka spruce were 44 and 53 per cent of gross precipitation.The average interception loss was 29 per cent for both pole-stagecrops and 49 per cent for mature Sitka spruce. The proportions of net precipitation reaching the ground asstemflow and throughfall were 0.18 and 0.82 respectively forthe pole-stage Sitka spruce, 0.14 and 0.86 for the pole-stagelodepole pine and 0.02 and 0.98 for the mature Sitka spruce.     

Preference status does not indicate intrinsic quality differences in Drosophila pseudoobscura

The good genes hypothesis states that choosers prefer individuals of high intrinsic quality to individuals of lower intrinsic quality. Variation in longevity is thought to reflect, in part, intrinsic quality differences of individuals in addition to the costs of mating and reproduction. Here we report longevity variation of Drosophila pseudoobscura, a species in which previous experiments have demonstrated that individual mate preferences (pre-touching mate assessments) of females and males are associated with enhanced numbers of eclosed (adult) offspring and higher egg-to-adult survival (offspring viability). Using mate assessment arenas and protocols similar to those in a previous experiment that demonstrated fitness benefits to breeders and their offspring of mating with individuals they preferred, we tested the following predictions: (i) preferred discriminatees live longer than non-preferred discriminatees; (ii) males live longer than females; and (iii) virgins live longer than mated individuals. The experiment yielded 938 individuals for longevity analysis. Sex and mating status affected longevity: males lived longer than females, virgin females lived longer than mated females, but there were no differences in longevity for mated and virgin males. Non-preferred discriminatees of both sexes survived as long as preferred discriminatees, a result inconsistent with the prediction of the good genes hypothesis for mate preferences. To our knowledge, this is the first demonstration of the cost of reproduction for females in D. pseudoobscura and of longevity variation of preferred and non-preferred discriminatees.     

Rectal Hesection in the Dog A New Surgical Approach and the Evaluation of Its Effect on Fecal Continence

Thirteen healthy mixed breed dogs (6 female and 7 male) underwent rectal transection and resection of 0 to 6 cm using a dorsal approach. Rectoanal sphincter pressure studies were performed preoperatively and 6 weeks after surgery using a double balloon manometer device. Sphincter pressure profiles were altered in the 6 cm resection dogs. Clinical observations of defecation and degree of continence were made over a 10 week period postoperatively. The transection only and 4 cm resection dogs defecated normally. All dogs in the 6 cm resection group involving the peritoneal reflection were incontinent but retained some normal posturing behavior. Surgical complications included minor infection in two dogs, rectocutaneous fecal leakage in four dogs, breakdown of the anastomotic site in four dogs, and incontinence in all of the dogs that underwent 6 cm resections. Barium enemas were performed on the rectums postmortem to ascertain the degree of stricturing induced by the surgery. The index of stenosis measured did not correlate well with the extent of straining in each group. Histopathologic findings on dogs in the transection only and 4 cm resection groups without dehiscence showed mild granulomatous proctitis with normal myenteric plexi seen. Dogs suffering dehiscence had suppurative proctitis, necrosis, and obliteration of the myenteric plexi.