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N Balance (n + balance)
Selected AbstractsEstimation of net nitrogen flux between the atmosphere and a semi-natural grassland ecosystem in HungaryEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2010A. Machon The aim of this work is to estimate the net N balance (deposition , emission) between the atmosphere and a semi-arid, semi-natural grassland (Bugac station, Central Hungary, CarboEurope IP, NitroEurope IP level 3 site). Dry deposition of N compounds has been determined by the inferential method, based on continuous monitoring of NO2 gas and daily 24-hour concentration measurements of HNO3 vapour, NH3 gas, and NH4+ and NO3, particles, using dry deposition velocities from the literature, measured above surfaces with the same characteristics as Bugac station. The bi-directional flux of NH3 within the atmosphere and the canopy (excluding soil emission) has also been estimated by the inferential method. Wet deposition of nitrate and ammonium ions was calculated on the basis of daily precipitation sampling and concentration measurements of nitrate and ammonium ions. To estimate the soil-atmosphere exchange of different gaseous N forms (N2, NO, N2O, NH3), the DNDC model was used as validated by the chamber measurements of NO and N2O soil emission fluxes. Soil emissions of NO and N2O have been determined by dynamic and static soil chamber methods, respectively. The measurement and modelling activity covers a complete year. Using the measured and modelled data, the calculated N balance at Bugac station between August 2006 and July 2007 is estimated at ,8.8 kg N ha,1 year,1 (deposition) as a sum of the deposition and emission terms (,10.4 and 1.6 kg N ha,1 year,1, respectively). Due to the warm and dry weather during the examined period, wet fluxes were substantially lower than usual, which may also have altered the regular yearly course of dry deposition and emission. [source] Nitrogen balance and seasonal fluctuations in soil nitrogen contents in a corn (Zea mays L)-rye (Secale cereale L) rotation fieldGRASSLAND SCIENCE, Issue 1 2005Yuzo Kurokawa Abstract In a corn (Zea mays L)-rye (Secale cereale L) rotation field, the N output (plant uptake) and N input (crop residue and fertilizer applied) were measured for two years in order to evaluate the N balance in a forage production field. The soil was Low-humic Andosol (mesic Typic Hapludand). The disappearance of crop residues on both a dry matter and N basis, and the seasonal fluctuations of total, inorganic, and available soil N content in the field were investigated. The interaction between the nitrogen balance and the soil N contents are discussed. The total plant N uptake of the corn and rye exceeded the sum of the N input of the fertilizer applied and the N from crop residues, so the N balance of the corn-rye rotation had a negative value (two year average: ,8.4 gN m,2). After the gradual disappearance of crop residue on the dry matter basis, rapid disappearance on the N basis was observed. At the same time, the C/N ratio decreased to less than 20. The soil available (38.4,55.3 mg kg,1) and inorganic (21.5,45.2 mg kg,1) N had their lowest values in spring. After they increased in early summer, they decreased in late summer and increased in autumn. The total N (0.5,0.7%) gradually decreased during the experimental period. The results indicated that the soil-available N and inorganic N in the present study were highly dependent on the fertilizer-applied N. The relation among management practices, N input and soil available N contents are discussed. It is suggested that the negative N balance is one of the causes for a decrease in soil total N. [source] The use of endogenous nitrogen for microbial crude protein synthesis in the rumen of growing bullsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2000H. Kluth Summary The objective of this study was to quantify endogenous nitrogen (N) recycled for microbial protein synthesis in the rumen. Four growing bulls (Schwarzbuntes Milchrind; bodyweight: 240,310 kg) with duodenal T-shaped cannulas were fed diets containing four levels of crude protein content (200, 156, 102 and 63 g/kg dry matter, respectively). The diets were based on wheat, barley, tapioca meal, soybean extracted meal, dried beet pulp, meadow hay and straw. The diets had an energy level of 11.1, 10.9, 10.2 and 9.6 MJ metabolizable energy/kg dry matter. Faeces and urine were collected in four 7-day balance periods. Duodenal flow rate was estimated by TiO2, pelleted with grain, as a marker. The relationship between urine N excretion, the amount of microbial N reaching the duodenum, ruminal N balance and N retention were examined and the amount of endogenous N available for microbial protein synthesis without negative effects on the N retention was determined. It can be concluded that up to 16% of the microbial N supply could be covered by recycled endogenous N, but N retention should not be decreased by more than 1.5 residual standard deviations of maximal N retention. [source] Effects of high potassium chloride supplementation on water intake, urine volume and nitrogen balance in miceANIMAL SCIENCE JOURNAL, Issue 1 2010Iori MURAI ABSTRACT Sixteen ICR male mice were assigned to a control diet group or a KCl diet group in metabolic cages to clarify the effects of KCl supplementation on water intake, urine volume and N balance, and 5% of KCl was supplemented in KCl diets for 4 or 8 weeks. Bodyweight of KCl supplemented mice was significantly higher than that of control mice from 24 to 28 days after treatment. Feed intake, water intake and urine volume of KCl supplemented mice were significantly higher than those of control mice, and the increased water intake and urine volume in KCl supplemented mice were 4.49 and 4.15 g, respectively. Urinary N, K and Cl excretion were significantly higher in KCl supplemented mice. Although N retention was not significantly different between control and KCl supplemented mice, N retention in KCl supplemented mice tended to be lower. Serum creatinine concentration at 8 weeks after treatment was lower in KCl supplemented mice. Histological alteration using hematoxylin-eosin and Sirius red staining was not found in the kidney of each mouse at 4 and 8 weeks after treatment. These results suggest that high KCl supplementation increases water intake, urine volume and urinary N excretion in mice. [source] Effect of supplementation of garlic powder on rumen ecology and digestibility of nutrients in ruminantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2008Metha Wanapat Abstract BACKGROUND: The present study investigated the effect of garlic powder (GAP) supplementation on rumen fermentation pattern, nutrient digestibility and intake in ruminants fed on straw as a roughage source. RESULTS: Dry matter intake and apparent digestibility of nutrients were similar among treatments. The apparent digestibility of crude protein tended to be higher in cattle supplemented with GAP compared to those fed without GAP (P = 0.08). Ruminal populations of protozoa and bacteria were decreased, as influenced by GAP supplementation. Ruminal pH and NH3 -N were similar among treatments, while blood urea nitrogen tended to be decreased (P < 0.05). Total volatile fatty acids (VFAs) were not affected by GAP supplementation but individual VFAs were significantly different (P < 0.05), especially C3; meanwhile, C2:C3 ratio was reduced by GAP supplementation (P < 0.05). In addition, N balances were significantly increased as level of GAP supplementation increased and was highest at 120 g d,1 GAP. CONCLUSION: Results of this study suggest that feeding of GAP at 80 g d,1 with urea-treated rice straw could enhance ruminal propionate production and thus lower C2:C3 ratio, decreasing the protozoal population, as well as increasing N retention and absorption in ruminants. Copyright © 2008 Society of Chemical Industry [source] Cropping strategies, soil fertility investment and land management practices by smallholder farmers in communal and resettlement areas in ZimbabweLAND DEGRADATION AND DEVELOPMENT, Issue 5 2009J. G. Cobo Abstract Three smallholder villages located in typical communal (from 1948), old (1987) and new (2002) resettlement areas, on loamy sand, sandy loam and clay soils, respectively, were selected to explore differences on natural resource management and land productivity. Focus group discussions and surveys were carried out with farmers. Additionally, farmers in three wealth classes per village were chosen for a detailed assessment of their main production systems. Maize grain yields (t,ha,1) in the communal (1·5,4·0) and new resettlement areas (1·9,4·3) were similar but significantly higher than in the old resettlement area (0·9,2·7), despite lower soil quality in the communal area. Nutrient input use was the main factor controlling maize productivity in the three areas (R2,=,59,83%), while soil quality accounted for up to 12%. Partial N balances (kg,ha,1,yr,1) were significantly lower in the new resettlement (,9·1 to +14·3) and old resettlement (+7·4 to +9·6) than in the communal area (+2·1 to +59·6) due to lower nutrient applications. Averaged P balances were usually negative. Consistently, maize yields, nutrient applications and partial N balances were higher in the high wealth class than in poorer classes. This study found that most farmers in the new resettlement area were exploiting the inherent soil nutrient stocks more than farmers in the other two areas. We argue that effective policies supporting an efficient fertilizer distribution and improved soil management practices, with clearer rights to land, are necessary to avoid future land degradation and to improve food security in Zimbabwe, particularly in the resettlement areas. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||