Nutrient Loss

Ensuring acceptance of dedicated biomass feedstocks by landowners, agricultural communities, environmental and public interest groups, requires that the environmental benefits, concerns, and risks associated with their production be quantified. Establishment and management measures to benefit soil and water quality are being identified by ongoing research. Field studies are showing that nutrients are retained within the rooting zone of dedicated feedstocks, subsurface herbicide transport does not occur, and off-site chemical transport is minimal compared with traditional agricultural crops. The amounts and timing of fertilizer application were critical to minimizing off- site transport of nutrients. Maintaining soil cover decreased runoff, sediment losses, and nutrient transport compared with traditional agricultural crops. Conversion of traditional croplands to biomass and no-till crop production improved soil quality and soil carbon storage. Subsurface nutrient losses were less fr...

Addition of Lethalities is an traditional method to calculate the F value, received by a heated product. It requires time-temperature recordings of the coldest spot in the food product, preferably at small time intervals. Also a Lethality Table is needed of the correct reference temperature and the intended z value. This Excel document produces such a Lethality Table, for every chosen reference temperature, and for any z value, with temperature steps of 0.1 ⁰C. After a brief explanation of the equations behind a Lethality Table, two extensively worked examples show how to use such tables:
Example 1 calculates the received F value, and the microbial spoilage rate, of a sterilized packaged food; in Example 2 a Lethality Table is used to calculate the received F value, and the % nutrient or enzyme, retained in a liquid food, after pasteurization in a heat exchanger.
Using a Lethality Table to calculate the F value is, unfortunately, a very tedious activity.
Therefore both Worked Examples 1 and 2 also outline the application of two (down-loadable) Excel programs, e.g. F-SPOIL.xls and Build-Heat-Exchanger.xls, which much more rapidly calculate the received F value, the microbial spoilage rate, and the % nutrient retention in a heated food.

Current knowledge suggests that biochar can be applied to agricultural soils in order to boost crop yields and simultaneously sequester atmospheric carbon. Biochar could therefore have a role in ameliorating two of the major environmental problems facing humanity – climate change and food scarcity. Further benefits ascribed to biochar include reduced water demand (for irrigation), less downstream pollution and reduced emissions of greenhouse gases (eg NO2) from the soil. Evidence suggests that some of these effects are influenced by soil type. This ongoing PhD project is investigating the effect biochar has on a wide range of soil properties that influence productivity, in relation to soil type. Four distinct textural classes of soil widely found in eastern England (and surveyed in detail) are being compared, using four biochar treatment doses: 0, 0.1%, 0.5% and 2.5% w/w (equivalent to 0, 4, 20 and 100 t ha-1). Three types of experiment are being conducted: (1) Laboratory tests of soil hydrology, eg using Tempe cells; (2) Long-term outdoor pot trials with winter wheat; (3) Long-term farm field trials. Early results for pot trials to test available water capacity (AWC) show clear positive trends. It is expected that a great deal more data will have been obtained before presentation of the paper in September. The project will provide biochar data, which is lacking for this region, and extend our knowledge about the significance of soil type, which is also very scarce and fragmentary. By modelling and mapping the relative suitability of specific soils for amendment, according to various criteria, it is hoped that such information can pave the way for fine-tuning the strategic deployment of biochar. This methodology could be expanded and applied to other soils and other regions.

Time-temperature data, collected during pasteurization or sterilization of a food product, can be converted to the F-value (or F0-value), received by the heated product.
An F-value is an indication for the safety of the heated food, and for its shelflife.
In the past, calculation of the F-value from food time-temperature data, required tedious work with lethality tables. Excel computer program F-SPOIL.xls converts such time-temperature data (with equal time intervals) directly to lethality factors, and calculates the F-value, the microbial spoilage rate, or the % nutrient retention of the heated food.
4 Worked Examples, attached to the spreadsheet, step-by-step show how to use F-SPOIL.xls: both for liquid foods (Examples 1 and 2) and for solid foods (Examples 4A+B).
The time-temperature input of Worked Example 3 (“Validation”) was taken from a heating process in the literature. Both the lethality factors and the F-value, calculated by F-SPOIL.xls, were exactly equal to those in the literature, calculated with lethality tables. A brief explanation of the concept “lethality factor”, the equation how to calculate it, and a lethality factor example calculation, are included in Worked Example 3.

This Excel spreadsheet calculates the required sterilization time of canned solid foods, by applying Pham's (1987; 1990) formula method. The spreadsheet can also find the heat process value F of such foods.
Pham's original equations have been extended, to enable calculation of the microbial spoilage rate and of the nutrient retention. All equations used are listed in the calculation section of this spreadsheet.
Findings by Pham are compared and contrasted to those of C.R. Stumbo's heat processing model (1973): the calculated sterilization times Pt, heat process values F, microbial spoilage rates, and nutrient retention were found to be very similar.
Important differences between Pham and Stumbo, however, are: 1) Pham's equations were primarily developed for conduction-heating, solid canned foods; Stumbo's model can also be used for canned convection-heated, liquid products. 2) Pham developed equations for processes in which the heating (fh) and cooling (fc) rates can differ; Stumbo assumes equal heating and cooling rates: fh = fc.
Pham (1987) stated that some of his calculations have to be solved by trial and error. In this spreadsheet such iterations, indicated by pink cells, can easily be solved by Excel's tool Goal Seek. An instruction on how to use Goal Seek has been added.
Six worked examples are included, which may be of help in understanding the use of this spreadsheet. The worked examples are also applied for model validation, and to compare Pham's findings with Stumbo's results.

The sustainability of fast-growing tropical Eucalyptus plantations is of concern in a context of rising fertilizer costs, since large amounts of nutrients are removed with biomass every 6–7 years from highly weathered soils. A better understanding of the dynamics of tree ...

The mixed oak-pine ecosystems in the southern Appalachians are in decline because of a combination of drought and southern pine-beetle infestation. A commonly applied prescription for restoration of these degraded sites has been to fell all vegetation, allow it to dry, and conduct a site-preparation burn. However, there is little information on the mid- and long-term influences of this prescription

Se realizaron estudios a nivel preliminar en parcelas de erosión,
fundamentalmente, con la finalidad de caracterizar los factores
de la erosión hídrica que afectan a un suelo (Humic Dystrudept)
de la cuenca media del río Chama de los Andes venezolanos.
Particular atención fue puesta a los efectos de la erosión hídrica
en función de la cobertura proporcionada al suelo por dos cultivos
comunes de la región andina: papa (Solanum tuberosum L., var.
granola) y pasto kikuyo (Pennisetum clandestinum Hochst ex
Chiov). El período de investigación, dividido en cuatro etapas,
duró 103 días. Se procesó información meteorológica y de estudios
agrológicos, y se hicieron comparaciones entre mediciones en
campo y estimaciones de la pérdida de suelo mediante el modelo
USLE. En términos generales, los experimentos con parcelas de
erosión mostraron que la protección ejercida por la cobertura
vegetal depende marcadamente de su tipo, incrementando la
eficiencia de la protección con la evolución del cultivo a través de
sus etapas de desarrollo. Las pérdidas de materia orgánica y
nutrientes por arrastre en los sedimentos dependen marcadamente
del grado de protección ofrecido por la cobertura vegetal, perdiendo
peso el efecto de la agresividad de la lluvia; factor de mayor
importancia cuando se trata de suelo desnudo. Bajo las condiciones
de conducción de estos experimentos, los valores medidos en el
campo correspondieron muy aproximadamente con los estimados
a través de la Ecuación Universal de Pérdida de Suelo.