Forty soils from top layer (0-20 cm) were sampled in different regions of China and Kjeldahl, HF-Kjeldahl and double treatment methods were used to determine total N, total N plus fixed ammonium, and total N and the r...Forty soils from top layer (0-20 cm) were sampled in different regions of China and Kjeldahl, HF-Kjeldahl and double treatment methods were used to determine total N, total N plus fixed ammonium, and total N and the residual fixed ammonium left in soil after determination of total N, respectively, to evaluate if Kjeldahl’s method could include the fixed N by soil minerals. The fixed N by soil minerals was measured by Silva-Bremner procedure to make comparison. Results showed that total N determined by Kjeldahl’s method averaged 1.622 g kg-1, while that by HF- Kjeldahl’s method 1.633 g kg-1, and that by double procedure 1.666 g kg-1. Obviously results obtained by the last two methods, particularly the double treatment method, were higher than Kjeldahl’s, showing that Kjeldahl’s method could not or not fully release N fixed by 2:1 minerals in soil, and therefore the determined results would not be the true “total N” for soils that contained large amount of the fixed N. The mineral fixedN averaged 166 mg kg-1, accounting for 10.1% of the total N while the residual fixed N amounted to 30.4 mg kg-1, equivalent to 1.9% of the total N or 18.3% of the total fixed N. The residual fixed N was correlated neither to organic matter nor to total N, but closely related to the total fixed N with a correlation coefficient of 0.598 (n=40), showing that the fixed N was the sole source of the residues. Soils having high residues of the fixed N were just those containing high fixed N, and soils containing high fixed N were just those containing high amount of 2:1 minerals. As a result, Kjeldahl’s method could not give a true value of the total N for such soils. However, for those containing small or little amount of 2:1 minerals, there was no significant difference in results measured by these methods.展开更多
Protein is essential for the growth and maintenance of the body. They play a crucial role in different biological processes. This study focuses on comparing the protein contents of local rice grown in the Senegal Rive...Protein is essential for the growth and maintenance of the body. They play a crucial role in different biological processes. This study focuses on comparing the protein contents of local rice grown in the Senegal River valley and rice imported from Asia. The objective is to evaluate the importance of the protein nutritional value of local rice compared to imported rice. Protein contents were determined using the Kjeldahl method. The results of the protein assays show that local rice varieties such as Sahel 108 and Sahel 134 grown in the Thilène basins had protein percentages comparable to those of imported rice. The protein percentages were 15.19% ± 0.91% for the Sahel 108 variety and 16.62% ± 0.01% for the Sahel 134 variety compared to 15.8% ± 0.01% on average for imported rice. Thus from the point of view of protein content, local rice has a nutritional value identical to that of imported rice which it can validly replace. It is important in Senegal to encourage local production, which would make it possible to reduce imports on the one hand and to make quality rice available to the local Senegalese market on the other. Sahel varieties with high protein contents deserve large-scale development to meet the country’s protein needs.展开更多
基金the National Natural Sci。ence Foundation of China(30230230,30070429 , 40201028)
文摘Forty soils from top layer (0-20 cm) were sampled in different regions of China and Kjeldahl, HF-Kjeldahl and double treatment methods were used to determine total N, total N plus fixed ammonium, and total N and the residual fixed ammonium left in soil after determination of total N, respectively, to evaluate if Kjeldahl’s method could include the fixed N by soil minerals. The fixed N by soil minerals was measured by Silva-Bremner procedure to make comparison. Results showed that total N determined by Kjeldahl’s method averaged 1.622 g kg-1, while that by HF- Kjeldahl’s method 1.633 g kg-1, and that by double procedure 1.666 g kg-1. Obviously results obtained by the last two methods, particularly the double treatment method, were higher than Kjeldahl’s, showing that Kjeldahl’s method could not or not fully release N fixed by 2:1 minerals in soil, and therefore the determined results would not be the true “total N” for soils that contained large amount of the fixed N. The mineral fixedN averaged 166 mg kg-1, accounting for 10.1% of the total N while the residual fixed N amounted to 30.4 mg kg-1, equivalent to 1.9% of the total N or 18.3% of the total fixed N. The residual fixed N was correlated neither to organic matter nor to total N, but closely related to the total fixed N with a correlation coefficient of 0.598 (n=40), showing that the fixed N was the sole source of the residues. Soils having high residues of the fixed N were just those containing high fixed N, and soils containing high fixed N were just those containing high amount of 2:1 minerals. As a result, Kjeldahl’s method could not give a true value of the total N for such soils. However, for those containing small or little amount of 2:1 minerals, there was no significant difference in results measured by these methods.
文摘Protein is essential for the growth and maintenance of the body. They play a crucial role in different biological processes. This study focuses on comparing the protein contents of local rice grown in the Senegal River valley and rice imported from Asia. The objective is to evaluate the importance of the protein nutritional value of local rice compared to imported rice. Protein contents were determined using the Kjeldahl method. The results of the protein assays show that local rice varieties such as Sahel 108 and Sahel 134 grown in the Thilène basins had protein percentages comparable to those of imported rice. The protein percentages were 15.19% ± 0.91% for the Sahel 108 variety and 16.62% ± 0.01% for the Sahel 134 variety compared to 15.8% ± 0.01% on average for imported rice. Thus from the point of view of protein content, local rice has a nutritional value identical to that of imported rice which it can validly replace. It is important in Senegal to encourage local production, which would make it possible to reduce imports on the one hand and to make quality rice available to the local Senegalese market on the other. Sahel varieties with high protein contents deserve large-scale development to meet the country’s protein needs.
