Availability to rhodesgrass (Chloris gayana) of nitrogen in tops and roots added to soil

¹⁵N-labelled Rhodesgrass material was prepared by growing plants in sand culture with labelled ammonium sulphate as their source of nitrogen. In a greenhouse experiment the labelled plant material in various physical configurations was added to an alluvial soil (fine sandy loam) from Samford with or without added mineral nitrogen. Two crops (six harvests) of Rhodesgrass were grown in the soil and the recovery of labelled nitrogen followed with time. Its partition at the end of the experiment was also determined.In general, after 16 months about one-third was recovered in the plant and two-thirds remained in the soil (plus any undecomposed added plant material). The only indication of volatile losses was a probable deficit of up to 10 per cent where litter (above-ground material) was placed on the soil surface.A higher nitrogen concentration in litter (1.3 per cent compared with 0.8 per cent) resulted in only a slight increase in labelled nitrogen recovery. Addition of mineral nitrogen (six doses of 50 kg N/ha) increased recovery from added litter material from 22 to 28 per cent and from added root material from 23 to 30 per cent.Grinding of added root material did not affect recovery. In the litter experiment, placing on the surface, incorporating in the top 2.5 cm of soil. and grinding and mixing with the soil resulted in final recoveries of 14, 28 and 32 per cent respectively.It is pointed out that caution must be exercised in extrapolation of results from laboratory and greenhouse studies to the field because many of the treatments used in the former are not analogous to field practices.     

The advantages and disadvantages of endoscopy

Endoscopy is generally a very safe and effective tool in the diagnosis and therapy of various gastrointestinal (GI) disorders, and must be used in conjunction with other diagnostic modalities. Endoscopy should not be a substitute for a complete work-up. There are many advantages of endoscopy, including minimal morbidity and mortality, and the sensitivity of this modality in the diagnosis of mucosal disorders of the GI tract. However, complications may occur, and there are limitations to endoscopy. This article will provide an overview of when to choose GI endoscopy and when other procedures might provide more information.     

Use of the partial farm budget technique to predict the economic impact of the flock management decision to use B-mode ultrasonographic pregnancy diagnosis

A computer spreadsheet was developed to predict the economic impact of a management decision to use B-mode ultrasonographic ovine pregnancy diagnosis. The spreadsheet design and spreadsheet cell formulas are provided. The program used the partial farm budget technique to calculate net return (NR) or cash flow changes that resulted from the decision to use ultrasonography. Using the program, either simple pregnancy diagnosis or pregnancy diagnosis with the ability to determine singleton or multiple pregnancies may be compared with no flock ultrasonographic pregnancy diagnosis. A wide range of user-selected regional variables are used to calculate the cash flow changes associated with the ultrasonography decisions. A variable may be altered through a range of values to conduct a sensitivity analysis of predicted NR. Example sensitivity analyses are included for flock conception rate, veterinary ultrasound fee, and the price of corn. Variables that influence the number of cull animals and the cost of ultrasonography have the greatest impact on predicted NR. Because the determination of singleton or multiple pregnancies is more time consuming, its economic practicality in comparison with simple pregnancy diagnosis is questionable. The value of feed saved by identifying and separately feeding ewes with singleton pregnancies is not offset by the increased ultrasonography cost.     

Virulence characteristics of a new race of the parasitic angiosperm,Striga gesnerioides,from southern Benin on cowpea (Vigna unguiculata)

An in vitro growth system was used to determine the virulence of two samples of Striga gesnerioides from Zakpota in southern Benin. Cowpea variety B301, previously considered resistant to all races of S. gesnerioides, was susceptible to both samples of the parasite. Two other cowpea varieties, 58–57 and IT81D-994, were totally resistant. Resistance in 58–57 was associated with a hypersensitive necrosis of infected roots, whilst IT81D-994 supported production of small S. gesnerioides tubercles with stems which failed to develop. Striga gesnerioides from southern Benin is the fourth race of the parasite to be identified, and the first with virulence on variety B301. The implications for breeding cowpeas with resistance to S. gesnerioides are discussed.Abbreviations IITA International Institute of Tropical Agriculture - LARS Long Ashton Research Station - SAFGRAD Semi-Arid Food Grain Research and Development     

Does Federal Aid to States Aid the States?

Using data from 1977 to 2009, we explore whether the agency issuing federal aid to states influences the rate of state economic growth. We find that agencies' housing poverty alleviation programs, such as the Department of Health and Human Services and the Department of Labor, have negative effects. The Department of Commerce and the Department of Interior have consistent positive effects, although this last effect is due to inordinately disproportionate spending in the state of Wyoming. Overall growth effects are relatively modest, suggesting that potential future cuts to federal discretionary spending may not be as damaging as feared.     

Relationships between agroforestry and community development according to practitioners

Post-adoption studies are relatively uncommon in the agroforestry literature. Thus little is known about progress and permanence following adoption. To better understand the relationship between agroforestry implementation and community development, seventy-seven practitioners in Cameroon with three or more years of experience were surveyed about the relationships between agroforestry and community development. Hypotheses were that they have observed differences in the association between agroforestry and community capitals. They were also surveyed about their satisfaction with agroforestry. Hypotheses were that satisfaction is high and negatively skewed when compared to community capitals measurements. Game play was used to collect responses. Friedman’s two-way non-parametric statistic was used to test for inter-item differences within the community capitals and satisfaction response sets. Shapiro–Wilk statistic was used to test for normality in both response sets and a bootstrap procedure and t-tests were used to test for differences in data skewness and kurtosis. Natural capital scored highest but did not differ significantly from built, human, and social capitals. Financial capital was significantly lower than natural capital, but not built, human, or social capitals. Political and cultural capitals were significantly lower compared to all others. Satisfaction was significantly higher when compared to community capitals, but the data were also negatively skewed suggesting capitals are a more representative and useful metric for researchers and technical assistance professionals focused on long-term practitioner support.     

Genetic analysis of flowering and maturity time in high latitude spring wheat

Due to the short growing season in the high northern latitudes, the development of early maturing spring wheat (Triticum aestivum L.) cultivars is important to avoid frost damage which can lower production and quality. We investigated earliness of flowering and maturity, and some associated agronomic traits, using a set of randomly selected high northern latitude adapted spring wheat cultivars (differing in maturity) and their F₁ and F₂ crosses made in a one-way diallel mating design. The parents, and their F₁ and F₂ crosses were evaluated under field conditions over 2 years. Anthesis and maturity times were controlled by both vernalization response and earliness per se genes, mainly acting additively. Non-additive genetic effects were more important in controlling grain fill duration, grain yield and plant height. Additive × additive epistatic effects were detected for all traits studied except time to anthesis. Segregation analyses of the F₂ populations for time to anthesis indicated the presence of different vernalization response genes. Molecular genetic analyses revealed the presence of Vrn-A1 and Vrn-B1 genes in the parental cultivars. Narrow-sense heritability was medium to high (60–86%) for anthesis and maturity times but low to medium (13–55%) for grain fill duration, plant height and grain yield. Selection for early flowering/maturity in early segregating generations would be expected to result in genetic improvement towards earliness in high latitude spring wheats. Incorporation of the vernalization responsive gene Vrn-B1 in combination with vernalization non-responsive gene Vrn-A1 into spring wheats would aid in the development of early maturing cultivars with high grain yield potential for the high latitude wheat growing regions of the northern hemisphere.