Soil faunal vs. fertilization effects on plant nutrition: results of a biocide experiment

Summary Intact cores of agricultural soil planted with Sorghum bicolor were treated with selective biocides or combinations of biocides to manipulate soil organisms. Half the replicates of each biocide treatment were also given N fertilizer. The plants were maintained in a greenhouse, where growth and nutrient content and soil-organism populations were monitored over 16 weeks.The plants responded strongly to fertilization, but showed weak and variable responses to the biocides, even though biocide treatments aimed at animal taxa effectively reduced their target groups. There were no strong interactions between faunal manipulations and fertilization, implying that there was little compensatory function of fauna in the absence of fertilizer. Conditions under which soil fauna are important in making mineral nutrients available to plants in the field need further investigation.     

Policy councils on food, nutrition and physical activity: the UK as a case study

International experience of Policy Councils on food and nutrition has developed over recent decades but they have not received the attention that is due to them. The 1992 International Conference on Nutrition recommended that governments create Food Policy Councils but few have been created. There has been more experience in local and sub-national policy councils, particularly in North America. Developing country experience of attempting to improve food policy integration stems from the 1970s. The UK's House of Commons' (Parliamentary) Health Committee, in its 2004 report on obesity, reviewed current policy determinants of the rise in obesity, concluding that national food and health policy lacked coherence, integration and effectiveness. To address this vacuum, it proposed the creation of a new 'Council of Nutrition and Physical Activity to improve co-ordination and inject independent thinking into strategy'. The case for creating such a Council in the UK is reviewed, as are possible organisational options, functions and remit. A Council could be created under the forthcoming Public Health Act. The purpose of the new Council would be to provide independent advice and strategic advice as well as monitor the linkages between policies on food, nutrition and physical activity, noting their environmental implications.     

Breast-feeding mothers can exercise: results of a cohort study

OBJECTIVES: To study the relationship between exercise by the mother and breast-feeding initiation and duration, and its effect on infant growth. DESIGN: A cohort study of mothers and infants, recruited at birth. Infant feeding methods were recorded in detail and breast-feeding was categorised as 'any' or 'full'. Exercise levels were categorised using the metabolic equivalent tasks approach based on details of physical activity recorded in questionnaires. SETTING: Perth, Western Australia. SUBJECTS: A total of 587 mothers were interviewed on seven occasions over a period of 12 months. RESULTS: There was no difference in the means of infant weight and length changes, indicating that exercise appeared to have no significant influence on infant growth up to 52 weeks after birth (P=0.236 and 0.974, respectively). The mother's level of exercise was not significantly associated with breast-feeding to 6 or 12 months. This applied to 'full' and 'any' categories of breast-feeding. CONCLUSION: Exercise does not affect breast-feeding outcomes at the usual levels of activity undertaken by mothers. Breast-feeding and exercise are important for maintaining and promoting health, and this study provides reassurance to health professionals wishing to encourage mothers to continue both behaviours.     

The CATCH Kids Club: a pilot after-school study for improving elementary students' nutrition and physical activity

BACKGROUND: Although many school-based diet and physical activity interventions have been designed and evaluated, relatively few have been tested for the after-school setting. After-school day-care programmes at either elementary schools or private locations provide a ready-made opportunity for health programmes that may be difficult to incorporate into an already-full school day. The purpose of this paper is to report on a pilot study of an after-school adaptation of the CATCH (Coordinated Approach To Child Health) elementary school programme called the CATCH Kids Club (CKC). METHODS: The CKC was pilot-tested and formatively evaluated in 16 Texas after-school programmes: eight in El Paso and eight in Austin (four intervention and four reference sites each). Evaluation consisted of direct observation of moderate to vigorous physical activity during play time, self-reported food intake and physical activity, and focus group interviews with after-school programme staff. RESULTS: Students responded well to the physical activity and snack components and were less interested in the five-module education component. Routine staff training was a key variable in achieving proper implementation; the ideal would be a full day with repeated follow-up model teaching visits. Staff turnover was a logistic issue, as was programme leader readiness and interest in conducting the programme. Strong and significant effects were observed for the physical activity but not for the education component. The results of the physical education component suggest it is feasible, effective and ready for larger-scale evaluation or dissemination.     

Determinants of nutrition improvement in a large-scale urban project: a follow-up study of children participating in the Senegal Community Nutrition Project

OBJECTIVE: To study individual determinants of differential benefit from the Senegal Community Nutrition Project (CNP) by monitoring improvement in children's weight-for-age index (WA) or underweight status (WA < -2 Z-scores) during participation. DESIGN: A follow-up study using the CNP child monitoring data. Linear general models compared variations in WA according to 14 factors describing the beneficiaries and CNP services. SETTING: Poor neighbourhoods of Diourbel, a large city in Senegal, West Africa. Over a 6-month period, the CNP provided underweight or nutritionally at-risk 6-35-month-old children with monthly growth monitoring and promotion and weekly food supplementation, provided that mothers attended weekly nutrition education sessions. SUBJECTS: All the children who participated in the first two years of the project (n=4084). RESULTS: Mean WA varied from -2.13 (standard deviation (SD) 0.82) to -1.58 (SD 0.81) Z-scores between recruitment and the end of the follow-up. The lower the child's initial WA, the greater was their increase in WA but the lower was the probability of recovery from underweight. Only 61% of underweight children recovered. Six months of CNP services may not be sufficient for catch-up growth of severely underweight children. The number of food supplement rations received was not a direct indicator of the probability of recovery. After adjustment for services received and initial WA, probability of recovery was lower in girls, in younger children, in twins and when mothers belonged to a specific ethnic group. CONCLUSIONS: Determinants of benefit from CNP differed from the risk factors for underweight. Identification of participants with a lower probability of recovery can help improve outcome. Moreover, an explanation for the lack of recovery could be that many underweight children are stunted but not necessarily wasted.     

The relationship between vesicular-arbuscular mycorrhiza and lime: Associated effects on the growth and nutrition of brachiaria grass (Brachiaria decumbens)

Summary We studied the effects of limining on growth and nutrient concentrations of Brachiaria decumbens inoculated with five vesicular-arbuscular mycorrhizal (VAM) fungal assemblages which orginated from soils with different acidity. Liming increased plant growth when applied at rates up to 3 g kg^-1 soil and depressed growth at higher rates. Mycorrhizal plants grew better than non-mycorrhizal ones in unlimed soil and also liming rates of 4.5 and 6.0 g kg^-1 soil. The growth amelioration effects of VAM in highly acid or over-limed soils were related to nutrient uptake. VAM fungi isolated from an acidic soil exhibited a high symbiotic effectiveness and were better adapted to unlimed soil than those that originated from non-acidic soils. VAM root colonization, 90 days after planting, was little affected by liming. Fungal spore production and species compositions were highly affected by liming. A mixture of Glomus diaphanum and Glomus occultum predominated in unlimed soils inoculated with VAM assemblages isolated from non-acidic soils. In these fungal assemblages, an increased liming rate favored Glomus etunicatum over the other VAM fungi. Gigaspora margarita sporulated abundantly when introduced into unlimed soils, but rarely in limed soils. VAM appear to be crucial for the establishment of brachiaria pastures in the nutrient-deficient acidic soils of Central Brazil. It is suggested that liming may cause striking shifts in VAM populations which may, in turn, have a long-term impact on agricultural productivity in the tropics.     

Application of Hansch's model to guaianolide ester derivatives: a quantitative structure-activity relationship study

A quantitative structure-activity study to evaluate the effect of lipophilia/aqueous solubility on etiolated wheat coleoptiles elongation has been carried out with 34 guaianolides having different numbers of hydroxyl groups and ester side chains of variable length and structure: linear, branched, aromatic, and unsaturated. Compounds have been tested in a range of concentrations between 10 and 1000 microM. Data show a strong influence of lipophilia, expressed as logP values. Specially, data from alkylic side chain ester derivatives adjust to the mathematical model based on Hansch's transport theory; hence, a quantitative structure-activity relationships (QSAR) correlation with a high degree of reliance is provided. Moreover, all active compounds fit the Lipinski's rule of five. Also, the presence of additional hydroxyl groups and their derivatives in the basic skeleton does not affect the mode of action but greatly influences the activity, as they modify the transport through membranes and aqueous phases. Finally, a second hydroxyl group enhances differences of activity between alkylic side chain derivatives by increasing differences in van der Waals interactions.     

Field-scale study of the variability in pesticide biodegradation with soil depth and its relationship with soil characteristics

The extent of within-field spatial variability of pesticide degradation was characterised in topsoil and subsoil, using the compounds isoproturon, bentazone and mecoprop, which are major contaminants of groundwater and surface freshwater in Europe. Twenty topsoil samples from 0 to 15 cm depth and twenty subsoil samples from 50 to 60 cm depth were collected from a single agricultural field within a 160×90 grid. It was shown that degradation rates of all compounds declined with soil depth. Variability of pesticide degradation rates, pesticide sorption and formation of non-extractable pesticide residues was higher in subsoil relative to topsoil. Furthermore, in the subsoil, there was variation in large scale soil physicochemical composition, which did not occur in topsoil. The greater variability in pesticide degradation rates in subsoil relative to topsoil could be the result of a greater range of degradation kinetics, which could reflect greater spatial variability in the distribution and/or activities of pesticide metabolising communities.     

场次暴雨条件下濂水流域水沙关系探究

为探究场次暴雨条件下流域的水沙关系,该研究以赣南濂水流域为对象,基于1965—2020年的水文气象数据和土地利用数据,运用聚类分析、判别分析和Spearman相关分析等,在场次暴雨条件下,分析不同洪水类型、不同时段下的水沙特征及水沙关系,并对水沙滞回关系进行探究。结果表明：流域120场暴雨洪水划分为3种类型,发生频率由高到低依次为：Ⅲ型（短历时、小径流、低洪峰）、Ⅰ型（长历时、中径流、中洪峰）、Ⅱ型（中历时、大径流、高洪峰）。整个研究期划分的5个时段中,1996-2005年、2006-2020年的输沙特征值增幅较大,且单位径流的输沙能力大幅上升。不同洪水类型下的各水沙环路曲线比例差异较大;在不同时段下,逆时针型、“8”字型曲线分别在1996-2005年、2006-2020年的比例最高分别为4.30%、55.6%,这与流域内果园大面积开发导致的沙源位置及数量的改变有着密切关系。研究成果可为流域的水沙管理及调控提供科学依据。