Nitrogen mineralization from cattle manure, filter-mud, factor ASH and nitrogen uptake by maize (Zea mays) in a glasshouse experiment
1996
Amolol, R.A(University of Nairobi, Department of Soil Science, Nairobi, Kenya) | Karanja, N.N(Tropical soil Biologv and Fertility, UNESCO ROSTA, Nairobi) | Plan, C.A(Tropical soil Biologv and Fertility, UNESCO ROSTA, Nairobi)
A study was conducted to improve nitrogen release ability from filtermud(FM) through reduced curing time. Chemical analysis of filtermud, cattle manure, factory ash and soil samples were carried out.Laboratory incubation experiments using filtermud alone or in mixtures at various ratios with factory ash and mineral nitrogen was conducted for a period of 12 weeks. Cattle manure and factory ash (alone or in combination with mineral nitrogen) were included to make 15 treatments. Miwani FM was found to be strongly acidic (pH 4/3) and relatively with less lignin . conteht cqmpared to that from Muhorom and Chemelil. In terms of nitrogen release Miwani FM was superior to that from Chemelil and Muhoroni, as it released 53% of nitrogen (available) after 12 weeks. Regression analysis of nitrogen release showed that there was a negative linear relationship ~ith the following; % lignin content (1' = -0.99),lignin to nitrogen ratio (1' = -0.93) and carbon to nitrogen ratio (1'=0.85), hence lignin was the predominant factor controlling the nitrogen release from these organic materials. A maize crop was grown for 9 weeks in pots containing soils with FM from Miwani mixed with or without mineral nitrogen at the following rates; 0, 7.5, 15,30 and 45 tha-I, soil mixed with 100 kg N ha-I was included giving a total of six treatments. FM at 45 tha-I amended with mineral nitrogen at the rate of 9 kg N per ton of PM gave significantly (P:5:0.05)) higher dry matter (19g/pot) and nitrogen uptake (13%) than the rest of the treatments. Therefore, for an inherently low ferti] such as Cambisol addition of 45tha-I amended with mineral nitrogen at 9 ] (calcium ammonium nitrate) per ton would be required to improve the fer and hence nutrient availability. Field need to be conducted, since the resull were laboratory based.
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