Degree Name

Master of Science (MS)

Semester of Degree Completion

1980

Thesis Director

Roger Darding

Abstract

Laboratory experiments were conducted to determine the effect of "N-Serve" (DOW) on the availability of urea nitrogen and the subsequent greening effect on perennial ryegrass (Lolium perenne L.) seedlings as compared to the availability of nitrogen and subsequent greening from a controlled release ureaformaldehyde fertilizer. A low organic matter sandy loam soil and a high organic matter clay loam soil were used in this study. Soil treatments of urea and ureaformaldehyde fertilizers were applied and incorporated at concentrations of 0, 25, 38, and 50 ppm-N. N-Serve at concentrations of 0.25, 0.50, and 1.0 ppm active ingredient were applied and incorporated with the three highest urea concentrations in all possible combinations. Two hundred grams of soil were placed in styrofoam cups. For each soil, there were six trials corresponding to incubation periods of 0, 2, 3, 4, 5, and 6 weeks. All treatments were replicated three times per each trial. Soil water was maintained at field capacity (by weight) throughout the experiment. All cups were incubated in a room which had an average temperature of 80°F, a light intensity of 400 ft-c at table top, and a 16-hour photoperiod. At the end of each incubation period, the soils were sampled for ammonia and nitrate nitrogen. At the same time, twenty seeds of L. perenne L. were planted in the soil. Seedlings were grown for seventeen days and then excised at the soil surface and analyzed for total chlorophyll. Control of nitrification was obtained in both soils by the use of N-Serve at 0.50 and 1.0 ppm. Maintenance of NH3-N was longest in the clay loam soil at 1.0 ppm N-Serve. The increased persistence of NH3-N in the clay loam soil was attributed to the decrease in volatilization of N-Serve by adsorption to the organic matter and by the bonding of ammonium nitrogen to the clay fraction of the soil. Chlorophyll content of the ryegrass plants was increased in all treatments for both soils during the period of time in which ammonium nitrogen was most prevalent. Urea in conjunction with N-Serve promoted the highest concentrations of chlorophyll by prolonging the availability of ammonium nitrogen. The ammonium released from the ureaformaldehyde treatments nitrified rapidly and did not enhance chlorophyll synthesis in the ryegrass seedlings.

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