With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of ...With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of nine plant species influence soil N availability,microbial biomass,andβ-glucosidase activity during soil fertility improvement.Significant differences in N concentration were found among the species,ranging from 12.2 g kg-1 in Zea mays to 39.2 g kg-1 in Baphia nitida.The C/N ratio was the highest in Z.mays(34.4),whereas lignin and polyphenol concentrations were the greatest in Acacia auriculiformis.The highest decomposition rate(0.251%per day)occurred in Tithonia diversifolia,and the lowest in A.auriculiformis,Albizia zygia,B.nitida,and Z.mays,with the half-lives of 28-56 d.Between 80%and 89%of N,P,K,Ca,and Mg were released from T.diversifolia in 7 d,compared with over 70%retention in A.auriculiformis,B.nitida,and Z.mays.The decomposition and nutrient release half-lives of Gliricidia sepium,Leucaena leucocephala,Azadirachta indica,and Senna spectabilis were less than 14 d.Soil mineral N,microbial biomass,andβ-glucosidase activity increased under all treatments,with T.diversifolia having the greatest effect.While N mineralization occurred in all of the species throughout the experiment,an initial N immobilization was recorded in the A.zy.gia,B.nitida,A.auriculiformis,and Z.mays treatments for up to 14 d.Decomposition and nutrient release rates,mineral N,soil microbial biomass,andβ-glucosidase activity were dependent on residue quality,and P and lignin levels,the lignin/N ratio,and the(lignin+polyphenol)/N ratio had the most significant effects(P≤0.05).展开更多
Agricultural activities that encourage slashing, burning and ploughing greatly affect the soil structure and soil organic matter on which soil water retention depends. In this study, we hypothesized that inclusion of ...Agricultural activities that encourage slashing, burning and ploughing greatly affect the soil structure and soil organic matter on which soil water retention depends. In this study, we hypothesized that inclusion of rotational leguminous tree species improves soil water retention in a semi-arid conservation agriculture system. In a study done in Kibwezi, semi-arid eastern Kenya, results showed that the amount of water retained in the different soil strata from plots with different tree species and tillage practices was highly significant (P = 0.032). Plots with planting basins and Gliricidia sepium and Faidherbia albida tree species retained more water in both the upper and lower strata. Plots with G. sepium tree species under planting basins and zero tillage under F. albida had significantly higher soil organic carbon levels than plots that were managed under ridges and ploughing (P = 0.002). On the other hand, bulk density in plots with planting basins and zero tillage and ridges ranged between 1.35 g/cm3 and 1.53 g/cm3. Conventional tillage plots had bulk density values of 1.65 g/cm3 and 1.72 g/cm3 in the upper and lower strata respectively. The time-dependent nature of rotational leguminous tree species on soil organic matter and soil water retention in the semi-arid conservation agriculture system highlights the importance of considering these species for improving organic carbon and water retention for improved crop production.展开更多
This study was carried out to assess the relationship of the status of nodulation(i.e., the number of nodules, their shape and size) in root and biomass production of plant growth parameters(i.e., number of leaves, ro...This study was carried out to assess the relationship of the status of nodulation(i.e., the number of nodules, their shape and size) in root and biomass production of plant growth parameters(i.e., number of leaves, root and shoot lengths, root biomass and shoot biomass) in Albizia saman and Leucaena leucocephala. The assessment started 60 days after seeding. The study revealed that nodulation response and biomass production in both species showed significant differences over time(p < 0.05) in all variables except in the root-shoot ratio(oven-dry) of L. leucocephala. The study also showed significant differences(p < 0.05) in nodule formation and biomass production at the end of the study period between the two species except in the number of nodules and leaves and the green root-shoot ratio. There were strong positive correlations between nodule formation and biomass production, i.e., the number of nodules and the age of plants, the number of nodules and leaves, as well as the number of nodules and biomass(root biomass and shoot biomass) in both species. The results obtained using principal component analysis(PCA) and correlation coefficients of the different characteristics of nodulation and biomass production were similar in both species. The PCA showed that shoot biomass(shoot green weight and shoot oven-dry weight) is positively correlated with PC1(with an eigenvalue of 7.50) and root length is positively correlated with PC2(with an eigenvalue of 0.19) in the case of A. saman. In the case of L. leucocephala, the PCA revealed that root biomass(root green weight and root oven-dry weight), shoot biomass and shoot length are also positively correlated with PC1, while nodule formation and the number of leaves are positively correlated with PC2(with an eigenvalue PC1 of 6.92 and PC2 of 0.49).展开更多
基金fully funded by the International Foundation for Science (IFS) in Stockholmsupported by the West Africa Regional Program of the CGIAR Research Program on Climate Change, Agriculture, and Food Security (CCAFS) in Bamako, Mali
文摘With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of nine plant species influence soil N availability,microbial biomass,andβ-glucosidase activity during soil fertility improvement.Significant differences in N concentration were found among the species,ranging from 12.2 g kg-1 in Zea mays to 39.2 g kg-1 in Baphia nitida.The C/N ratio was the highest in Z.mays(34.4),whereas lignin and polyphenol concentrations were the greatest in Acacia auriculiformis.The highest decomposition rate(0.251%per day)occurred in Tithonia diversifolia,and the lowest in A.auriculiformis,Albizia zygia,B.nitida,and Z.mays,with the half-lives of 28-56 d.Between 80%and 89%of N,P,K,Ca,and Mg were released from T.diversifolia in 7 d,compared with over 70%retention in A.auriculiformis,B.nitida,and Z.mays.The decomposition and nutrient release half-lives of Gliricidia sepium,Leucaena leucocephala,Azadirachta indica,and Senna spectabilis were less than 14 d.Soil mineral N,microbial biomass,andβ-glucosidase activity increased under all treatments,with T.diversifolia having the greatest effect.While N mineralization occurred in all of the species throughout the experiment,an initial N immobilization was recorded in the A.zy.gia,B.nitida,A.auriculiformis,and Z.mays treatments for up to 14 d.Decomposition and nutrient release rates,mineral N,soil microbial biomass,andβ-glucosidase activity were dependent on residue quality,and P and lignin levels,the lignin/N ratio,and the(lignin+polyphenol)/N ratio had the most significant effects(P≤0.05).
文摘Agricultural activities that encourage slashing, burning and ploughing greatly affect the soil structure and soil organic matter on which soil water retention depends. In this study, we hypothesized that inclusion of rotational leguminous tree species improves soil water retention in a semi-arid conservation agriculture system. In a study done in Kibwezi, semi-arid eastern Kenya, results showed that the amount of water retained in the different soil strata from plots with different tree species and tillage practices was highly significant (P = 0.032). Plots with planting basins and Gliricidia sepium and Faidherbia albida tree species retained more water in both the upper and lower strata. Plots with G. sepium tree species under planting basins and zero tillage under F. albida had significantly higher soil organic carbon levels than plots that were managed under ridges and ploughing (P = 0.002). On the other hand, bulk density in plots with planting basins and zero tillage and ridges ranged between 1.35 g/cm3 and 1.53 g/cm3. Conventional tillage plots had bulk density values of 1.65 g/cm3 and 1.72 g/cm3 in the upper and lower strata respectively. The time-dependent nature of rotational leguminous tree species on soil organic matter and soil water retention in the semi-arid conservation agriculture system highlights the importance of considering these species for improving organic carbon and water retention for improved crop production.
文摘This study was carried out to assess the relationship of the status of nodulation(i.e., the number of nodules, their shape and size) in root and biomass production of plant growth parameters(i.e., number of leaves, root and shoot lengths, root biomass and shoot biomass) in Albizia saman and Leucaena leucocephala. The assessment started 60 days after seeding. The study revealed that nodulation response and biomass production in both species showed significant differences over time(p < 0.05) in all variables except in the root-shoot ratio(oven-dry) of L. leucocephala. The study also showed significant differences(p < 0.05) in nodule formation and biomass production at the end of the study period between the two species except in the number of nodules and leaves and the green root-shoot ratio. There were strong positive correlations between nodule formation and biomass production, i.e., the number of nodules and the age of plants, the number of nodules and leaves, as well as the number of nodules and biomass(root biomass and shoot biomass) in both species. The results obtained using principal component analysis(PCA) and correlation coefficients of the different characteristics of nodulation and biomass production were similar in both species. The PCA showed that shoot biomass(shoot green weight and shoot oven-dry weight) is positively correlated with PC1(with an eigenvalue of 7.50) and root length is positively correlated with PC2(with an eigenvalue of 0.19) in the case of A. saman. In the case of L. leucocephala, the PCA revealed that root biomass(root green weight and root oven-dry weight), shoot biomass and shoot length are also positively correlated with PC1, while nodule formation and the number of leaves are positively correlated with PC2(with an eigenvalue PC1 of 6.92 and PC2 of 0.49).