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An investigation of the pH, organic matter content, total nitrogen, and cation exchange properties of the soil of the l8-year-old rotation plots at Chatham, Virginia, was carried out. Individual soil samples were taken of each of the 36 sub-plots which compose the experiment. After the chemical analyses were completed, the data obtained was analyzed statistically. As a result of this investigation, the following conclusions are presented: 1. Application of ground limestone which resulted in increased crop yields also tended to increasae organic matter and cation exchange capacity. 2. The lower soil reaction of the unlimed plots seemed to be more effective in retaining a larger percentage of the total dry matter produced as soil organic matter. 3. A significant positive correlation waa found between soil organic matter and cation exchange capacity. 4. There seemed to be no significant correlation between fertilizer treatments, crop yields, and carbon-nitrogen ratio. 5. Applications of different amounts of superphosphate and their combinations with muriate of potash and muriate of potash and nitrate of soda apparently has had no effect on the amount ot exchangeable calcium, magnesium, and hydrogen present. 6. Exchangeable potassium seemed unaffected by fertilizers not containing potassium, but showed a marked increase on the plots receiving potassium in a mixture. 7. Applications of ground limestone have resulted in large increases of exchageable calcium and magnesium, increases in exchangeable potassium and marked decreases in exchangeable hydrogen and pH values. Percentage base saturation was also greatly increased by pound limestone applications. / M.S.

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Increasing levels of nitrate (NO3-) in groundwater have become a major environmental and health concern. In situations where NO3-concentrations in the soil-water system pose an environmental hazard, water table management may be a desirable practice to reduce such pollution. Careful management of N applications is also believed to reduce NO3- levels. / A field experiment was conducted in 1996 and 1997 at St. Emmanuel, Quebec, about 30 km South-West of Macdonald Campus of McGill University, to investigate the effect of water table management (WTM) and N fertilizer combinations on potentially leachable NO3- and denitrification rates in the top soil layer (0--0.15 m). The field was planted with monocrop corn (Zea mays. L) in both years. Treatments consisted of a factorial combination of two water table managements, free drainage (FD) and subirrigation (SI) (about 1.0 m and 0.6 m, respectively, below the soil surface) and two N fertilizer rates, 200 kg ha-1 (N200) and 120 kg ha-1 (N120). / Water table management had a significant effect on reducing NO3 - concentrations in the soil profile. Subirrigation treatment reduced NO3- in the top soil layer by 41% and 15% in 1996 and 1997, respectively. Similarly, NO3 - levels were 50% and 20% lower in N120 compared to N200 treatment. / Climatic conditions (rainfall and temperature) played a large role in regulating denitrification rates. Due to drier and cooler conditions in 1997, denitrification rates were lower compared to 1996, leaving more NO3 - in the soil profile. Following harvest, this high NO 3- concentration may be subject to leaching.

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No description available.

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No description available.