Typescript. / Bibliography: leaves [97]-105. / xiii, 105 l graphs, tables

Long term management of lodgepole pine depends, in part, on the nutrient capital of the site. Harvesting has been shown to increase the availability of nitrogen and other nutrients for a limited period of time. This increase, or nutrient flush, following cutting has been attributed to several factors including changes in organic matter quantity and quality, soil moisture and temperature regimes, and competition for nutrients. Knowledge of the duration and the magnitude of the nutrient flush would be valuable for management decisions. A consequence of lodgepole pine clearcuts was studied for soil nitrogen availability and microclimate. Mineral soil and forest floor samples were anaerobically incubated and analyzed for ammonium-nitrogen (ppm). The mineral soil showed a flush lasting about 12 years, peaking by year 8, while the forest floor material showed no trend. The size of the increase from year 2 to year 8 was about 52%. Temperature (air and soil), soil moisture, solar radiation, and precipitation data were collected, and a soil water budget was calculated using a simple water balance model. The average calculated soil water deficit was 119 mm, but this may have been an over-estimate. Windrowing following cutting may have depleted the site nitrogen reserve which in turn reduced the amount that was mineralized during incubation. The interaction between the soil temperature and moisture may have further limited nitrogen availability to the lodgepole pine trees. It is concluded that the dynamics of nitrogen availability following clearcutting are important for the establishment and growth of lodgepole pine. The summer moisture deficit appears to limit the nitrogen mineralization rate as well as seedling growth. / Forestry, Faculty of / Graduate

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Call number: LD2668 .T4 1960 Z57

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

A greenhouse experiment was conducted to study the effectiveness of Dwell, a nitrification inhibitor, on the efficiency of two fertilizers applied to three Arizona soils, Anthony sandy loam, Laveen loam, and Vinton loamy sand. Tomato plants Lycopersicum esculentum cultivar Row Pak were used as an index plant. These plants were grown in soil columns of 10 cm internal diameter and 50 cm in length, containing 4,500 g of soil. Two fertilizers, urea and ammonium sulfate (AS), were applied at two rates: 112 and 224 kg N/ha. The nitrification inhibitor Dwell was applied also at two rates: 0 and 1.27 kg/ha⁻¹ of active ingredient. The active ingredient in the chemical is 5- ethoxy -3- (trichloromethyl)-1, 2,4- thiadizole. Both fertilizers and Dwell were added to the soils using two methods: (1) uniform mixtures, in which the fertilizer and Dwell were mixed with the top 500 cm³ soil volume in the columns, and (2) banded fertilizers and Dwell, in which a soil paste, made by mixing 10 ml of 0.02% Dwell solution with the volume of 50 cm³ soil, was added to the required amount of the fertilizer to soil column about 7cm below the soil surface. This factorial designed experiment was arranged in a randomized complete block with three replications of each treatment. Plants were allowed to grow for 67 days after transplanting to the soil columns. At the end of the experiment, samples from two depths (0 to 18 cm and 18 5o 40 cm) were analyzed for NH₄, NO₃, and organic N. Dry matter yield and N content of plants were also determined. Results showed that Dwell was effective in improving N efficiency, as determined by yield and N content of plants, with all three soils and with both fertilizers. Higher yields were obtained when AS was used in all soils. Higher response to Dwell, but lower yields, were observed in urea treatments as compared to AS treatments. Dwell resulted in yield increase of 139 and 60% with urea in Vinton and Laveen soils, respectively, while with AS, the increases were 74 and 11%. The lowest response to Dwell occurred with the Anthony soil. Generally, higher yield was obtained when AS was thoroughly mixed and when urea was banded. Yield and N content in plants grown in these soils were in the following order: Laveen > Anthony > Vinton. Dwell was effective with both N rates, particularly with the high N rate of urea. Incubation studies showed that Dwell was effective in retarding nitrification for about 10 days. Accordingly, Dwell seems to have had no residual effect on soil nitrogen.