Soil microbial properties of subalpine steppe soils at different grazing intensities in the Chinese Altai Mountains

Gefördert im Rahmen des Projekts DEA

The combined application of nitrogen and biochar reduced microbial carbon limitation in irrigated soils of West African urban horticulture

Gefördert durch den Publikationsfonds der Universität Kasse

The combined application of nitrogen and biochar reduced microbial carbon limitation in irrigated soils of West African urban horticulture

Abstract Background Intensive wastewater irrigated urban horticulture in sub-Saharan West Africa receives high nutrient inputs, which lead to large gaseous and leaching losses. The addition of biochar to the usually sandy soils may reduce these losses and improve the habitat conditions for soil microorganisms. Two similar experiments focused on crop yields and nutrient balances have been carried out over a 2-year period in semi-arid Ouagadougou, Burkina Faso, and in sub-humid Tamale, Ghana, representing to some extent different but typical locations in West Africa. Methods Biochar and N fertilization effects were measured on soil microbial biomass carbon (MBC), fungal ergosterol, and functional diversity, estimated by multi-substrate-induced respiration. It was additionally possible to study the effects of clean water irrigation on the respective microbial properties in Tamale soil. Results Sole biochar addition did not affect any soil chemical or soil biological properties analyzed. In contrast, biochar application with N fertilization increased the mean respiratory response of the 11 substrates added by 23% in the Ouagadougou soil and by 13% in the Tamale soil. N fertilization decreased soil pH in both cities by 1.1 units. However, a pH-H2O of 4.7 led to reduced MBC and ergosterol contents at Tamale. Also, the Shannon index of the respiratory response was positively correlated with the soil pH. Clean water irrigation decreased the ergosterol content and increased the respiratory response to organic acids. Conclusions Biochar addition with N fertilization improved habitat conditions for soil microorganisms. An N fertilizer-induced decline in soil pH < 5 should be avoided, as it decreased MBC and microbial functional diversity. Graphical Abstrac

Carbon use efficiency and microbial functional diversity in a temperate Luvisol and a tropical Nitisol after millet litter and N addition

Gefördert im Rahmen des Projekts DEA

Organic and inorganic fertilizer effect on soil CO2 flux, microbial biomass, and growth of Nigella sativa L.

Cattle manure has a high carbon/nitrogen ratio and may not decompose; therefore, full-dose application of urea fertilizer might improve biological properties by increasing manure decomposition. This study aimed to investigate the effect of combining cattle manure and urea fertilizer on soil CO2 flux, microbial biomass carbon, and dry matter accumulation during Nigella sativa L. (black cumin) growth under field conditions. The treatments were control, cattle manure, urea, different levels of split and full-dose integrated fertilizer. The results showed that integrated application of cattle manure and chemical fertilizer significantly increased microbial biomass carbon by 10%, soil organic carbon by 2.45%, total N by 3.27%, mineral N at the flowering stage by 7.57%, and CO2 flux by 9% over solitary urea application. Integrated application increased microbial biomass carbon by 10% over the solitary application and the full-dose application by 5% over the split application. The soil properties and growth parameters of N. sativa L. benefited more from the full-dose application than the split application of urea. Cattle manure combined with chemical fertilizer and the full-dose application of urea increased fertilizer efficiency and improved biological soil parameters and plant growth. This method decreased the cost of top dressing urea fertilizer and proved beneficial for the environment and medicinal plant health