Effects of Light and Nutrients on Tomato Plant Compensation for Herbivory by \u3ci\u3eManduca Sexta\u3c/i\u3e (Lepidoptera: Sphingidae)

This preliminary study examined how two resources (light and nutrients) influence the ability of tomato plants to show growth compensation for defoliation by the tobacco homworm (Manduca sexta). Growth rate and biomass of plants grown under high and low levels of light and nutrients, and exposed to 4 levels of defoliation by Manduca sexta were measured. Nutrients affected plant growth rate much more strongly than did light. Light and nutrients, however, each influenced how herbivory affected plant growth. Defoliation significantly decreased growth rate only under conditions of low light and high nutrients. Biomass, on the other hand. was low under all resource treatments except high levels of both light and nutrients, and defoliation significantly decreased biomass only under high levels of both resources. Thus, plants appeared to compensate for damage. in terms of biomass, only under conditions of either low light and/or low nutrients

Tools for managing manure nutrients

Manures are a valuable source of nutrients (and organic matter), and can be seen as a method of transferring nutrients around the farm (for homeproduced manures) or as a method of importing fertility (imported manures or composts). Good manure management offers a ‘win-win’ opportunity: benefits to soil fertility and benefits to the environment (less pollution). This paper describes two tools for manure nutrient planning: the use of look-up tables to assess nutrient content, and the development of a Decision Support Tool for describing nutrient transformations during manure management

Recovery of Agricultural Nutrients from Biorefineries

This review lays the foundation for why nutrient recovery must be a key consideration in design and operation of biorefineries and comprehensively reviews technologies that can be used to recover an array of nitrogen, phosphorus, and/or potassium-rich products of relevance to agricultural applications. Recovery of these products using combinations of physical, chemical, and biological operations will promote sustainability at biorefineries by converting low-value biomass (particularly waste material) into a portfolio of higher-value products. These products can include a natural partnering of traditional biorefinery outputs such as biofuels and chemicals together with nutrient-rich fertilizers. Nutrient recovery not only adds an additional marketable biorefinery product, but also avoids the negative consequences of eutrophication, and helps to close anthropogenic nutrient cycles, thereby providing an alternative to current unsustainable approaches to fertilizer production, which are energy-intensive and reliant on nonrenewable natural resource extraction

Analysis of Soil Nutrients and Organic Matter in organic and conventional Marine Shrimp ponds at Guaraíra Lagoon, Rio Grande do Norte State, Brazil

This study compares the soil nutrients from an intensive and semi-intensive and an organic marine shrimp farm located in Guaraíra Lagoon, Rio Grande do Norte State, Brazil. The organic system showed significant lower levels of organic matter and phosphorus when compared to the two conventional systems. The results indicate that the conventional systems release large amount of nutrients into the environment and the organic system is a sink of nutrients from the Guaraira Lagoon ecosystem

Utilising the concept of nutrients as a currency within organic farming system

This report was presented at the UK Organic Research 2002 Conference.Within organic systems, the successful management of nutrients at the field level is crucial for maximising production and minimising the environmental impacts. This requires that the farmer makes the best possible use of nutrients excreted by the grazing or housed livestock. In addition, the farmer must successfully manage the nutrients built-up in the ley phase of the crop rotation over the whole of the arable phase period. To analyse these complex flows, a nutrient budget model has been developed that describes the spatial and temporal flows within the organic farming system. The concept is analogous to treating nutrients as a currency where the flow of nutrients represents a cashflow. A spatial nutrient budget permits the analyses of the performance of the nutrient flows to be examined for the housing, manure, livestock, rotational land and permanent pasture to be analysed separately. This analysis will allow the farmer to better understand the weaknesses in the system, and hence take preventative measures

Repeatability and validity of a food frequency questionnaire in free-living older people in relation to cognitive function

Objectives: To determine the repeatability and validity of a self-administered, 175-item food frequency questionnaire (FFQ) in free-living older people and to assess whether these are influenced by cognitive function. Participants and setting: 189 free-living people aged 64-80y were recruited from participants in a previous study. Design: To assess repeatability, 102 (52M, 50F) participants completed the FFQ on two occasions three months apart. To assess validity, another 87 participants (44 M, 43 F) completed the FFQ and a four-day weighed diet record three months later. 25 nutrients were studied. Results: For repeatability, Spearman rank correlation coefficients were above 0.35 (p<0.05) for all nutrients. Cohen’s weighted Kappa was above 0.4 for all nutrients except starch, riboflavin, retinol, β-carotene, and calcium. There were no substantial differences in correlation coefficients between sub-groups divided by short-term memory test score. There was no clear pattern for correlation coefficients in sub-groups divided by executive function test score. For validity, the Spearman rank correlation coefficients were above 0.2 (p<0.05) for all nutrients except fat, mono-unsaturated fatty acids, niacin equivalents and vitamin D, and Cohen’s weighted kappa was above 0.4 for alcohol and was above 0.2 for 13 other nutrients. Participants in the lowest-score groups of short-term memory and executive function had the lowest median Spearman correlation coefficient. Conclusions: The FFQ had reasonable repeatability and validity in ranking nutrient intakes in this population though the results varied between nutrients. Poor short-term memory or executive function may affect FFQ validity in ranking nutrient intakes

Demand for Nutrients: The Household Production Approach

This study uses the household production theory to study the demand for nutrients, i.e., households purchase a combination of food items from the market and produce the needed nutrients from these food items. By following the traditional household production approach, shadow prices for nutrients in food consumption are calculated. The cost function that generates the shadow prices appears plausible in terms of its elasticities of substitution and factor demand. After obtaining the calculated shadow prices of nutrients, the nutrient demand functions are estimated. Results show that the own-price elasticity of demand for nutrient is inelastic, whereas the expenditure elasticities indicate that nutrients are normal goods. Crossprice elasticities show that there appears to be complementarity in the demand for nutrients. This seems a logical result.nutrient, household production theory, demand, Demand and Price Analysis,

Effects of Potassium Source and Secondary Nutrients on Potato Yield and Quality in Southcentral Alaska.

Calcium (Ca), magnesium (Mg), and sulfur (S) are required for the growth and development of all higher plants. They are commonly referred to as secondary nutrients because they are less often limiting to plant growth than the primary nutrients nitrogen (N), phosphorus (P), and potassium (K), although secondary nutrients are as critical for crop growth and development as the primary nutrients. There is limited information available concerning secondary nutrient requirements of potatoes grown in southcentral Alaska. Laughlin (1966) conducted studies between 1961 and 1963 comparing potassium chloride (KCl) and potassium sulfate (K2SO4) as potassium sources for Green Mountain potatoes, and determined the effects of varying rates of magnesium sulfate (MgSO4) and K2SO4 on Kennebec potatoes. Since these studies were conducted without irrigation and at production levels about one-half those obtained by top producers in the Matanuska Valley today, it was considered appropriate to expand upon the previous work using current production practices. Potassium was supplied as KCl and K2 SO4 to explore the need for additional S under local potato production conditions and to determine the effects of the chloride (Cl) and sulfate (SO4) anions on production and quality of potato tubers. In addition, Mg and Ca were added to determine whether the background levels of these nutrients were adequate for optimum production

Pathways for Nutrient Loss to Water; Slurry and Fertilizer Spreading

End of project reportThere are almost 150,000 farms in Ireland and these contribute substantial quantities of N and P to inland and coastal waters. Some of these nutrients are carried from wet soils by overland flow and by leaching from dry soils. Farm practice can reduce the loss from farms by judicious management of nutrients. Improvements are required to diminish export of nutrients without impairing operations on the farm. Literature regarding nutrient loss from agriculture was reviewed in this project and maps were prepared to predict best slurry spreading times around Ireland. Two further maps were prepared to show slurry storage requirement on farms