Thursday, April 25, 2013

Students present research on soil temperatures, reindeer

Jennifer Lutze and Nathan Heeringa
Two seniors presented their theses April 19. Nathan Heeringa’s thesis was titled “The effects of terracing on soil quality of a Fairbanks area loess soil,” and Jennifer Lutze’s was “Performance and meat quality of reindeer (Rangifer tarandus tarandus) fed a cereal grain ration or wheatgrass haylage during the fall.”

Heeringa’s theory was that the challenge of Fairbanks’ short growing season could be somewhat alleviated by planting crops on south-facing terraces. The terrace offers an earlier thaw and higher solar radiation. It also can reduce soil erosion and increase soil moisture retention and soil microbial activity.

However, the negative possibilities include loss of organic matter, an altered soil structure and reduced aggregate stability.

His objectives were to determine whether soil disturbance caused by terracing increases or decreases the quality of a Fairbanks area loess soil in the short term and to provide benchmark data on changes to soil quality resulting from soil disturbance.

Heeringa took an inventory of native plants on his study area, then prepared six one-square-meter plots (three on the terrace and three on the undisturbed hillside). He took samples of soil cores and bulk density. He also examined a 10-centimeter-square surface organic layer.

He installed gypsum block, temperature data recorders and a rain gauge. Each week he removed vegetation within the plots. Soil samples were processed in preparation for lab testing of texture, pH and electrical conductivity. The bulk density was calculated.

Heeringa analyzed the carbon and nitrogen in the surface organic layer, the total carbon and nitrogen in the soil, the total inorganic nitrogen, as well as extractable phosphorus, potassium and micronutrients.

He learned that the terraced soil was warmer in May, June, July and August, but by September it switched and the terraced soil was cooler than the control plot. The ambient air temperature was significantly higher on the terrace than the hillside and the terrace soil held more moisture than hillside soil.

Disturbance neither increased nor decreased overall soil quality in the short term. Bulk density was the only significantly different physical characteristic. Nitrate was the only significantly different soil nutrient. Soil temperature and moisture proved variable.

Based on the results of this study, Heeringa recommends terracing south-facing slopes in interior Alaska and would recommend future study to collect data over multiple growing seasons and growing degree days.

Jennifer Lutze said reindeer meat is a good source of protein for Alaskans and is perceived as a healthier alternative to beef. Reindeer are currently being raised primarily on grain fed rations. Reindeer fed barley were shown to have a greater saturated fat content than range fed. If haylage is used the meat quality is closer to range fed but it was unknown how this affects animal performance or meat quality.

In her literature review, Lutze learned that human diets have changed dramatically, adding high amounts of saturated fats. Diets have changed as meat production has changed. Venison has lower lipid content than beef.

Pre-slaughter reserves of glycogen are influenced by the finishing diet in animals, Lutze noted. Ultimate pH values in reindeer are shown to reflect their nutritional status and physical condition. Meat that contains high ultimate pH values also tend to have a significantly shorter shelf life.

In her research, Lutze fed grain rations to seven control steers, while the seven treatment steers' diets were supplemented with wheatgrass haylage. Leftover grain feed was collected daily and haylage weekly. The animals had unrestricted access to water and mineral blocks.

The reindeer were weighed weekly at the same time of day then slaughtered and processed at Delta Meat and Sausage. Differences in the control and treatment groups’ ultimate pH values and carcass temperatures were found to be insignificant.

The total change in bodyweight by week and the difference in feed efficiency were shown to be significant. Lutze concluded that this type of feed regime is not likely to be cost efficient.

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