Zusammenstellung des im Jahre 1862 in den nachstehenden Revieren erlegten Wildes

Ohne Zusammenfassung     

Zur „Domestikation” des „Soilution-Earthworm”

Ohne Zusammenfassung     

Malarialage und Mückenbekämpfung in Montenegro

Ohne Zusammenfassung     

Haarlinge als Pelztierschmarotzer

Ohne Zusammenfassung Mit 5 Abbildungen     

Nitrogen release from different polymer-coated urea fertilizers in soil is affected by soil properties

The use of urea as nitrogen (N) fertilizer in agriculture needs to consider environmental, economic and resource conservation aspects because of low N-use efficiency (NUE). Polymer-coated urea (PCU) offers an effective way to improve the NUE of urea and to reduce its environmental trade-offs. However, we lack information on the impact of climate and soil properties on N release from PCU. Therefore, this study was performed to quantify the effects of soil texture, moisture and temperature on the release kinetics of N from PCU. We designed a test system for soil incubation experiments and investigated three fertilizers with different release patterns, five topsoils, three moisture levels and two temperatures over 48 days. We analysed the concentrations of inorganic N (${\mathrm{NH}}_4^{+}-\mathrm{N}$ and ${\mathrm{NO}}_3^{-}-\mathrm{N}$) in the soil and estimated N release rates using the unified Richards model. Soil texture did not change the N release patterns, but release rates varied significantly among the investigated soils. Changes in soil moisture for a given soil had no effect on N release from PCU and urea when fertilizers were incorporated into the soil at conditions supportive of crop growth. Lowering soil temperatures, however, decreased N release rates from PCU by 16%–49% but only in silt loam and not in sandy loam. We conclude that PCU improves the N residence time in soil, but predictions on N release from PCU must be adapted to the prevailing environmental conditions and cannot be generalized across differently textured soils.     

Does biochar contribute to close nutrient cycles of tree plantations on degraded Ultisols in the Ecuadorian Amazonia?

The use of biochar is expected to improve soil fertility and close nutrient cycles in degraded strongly weathered tropical soils. We, therefore, hypothesized that biochar amendment to tree plantations (a) increases nutrient fluxes with litterfall alone and with mineral fertilizer plus lime and (b) reduces N losses reflected by lower δ¹⁵N values of litterfall and soils than in unamended controls. We grew the native leguminous Schizolobium parahyba var. amazonicum (Ducke) Barneby and the exotic Gmelina arborea Roxb at two sites. We used a replicated full factorial split–split plot design of amendment of mineral fertilizer plus lime, 3 and 6 t ha⁻¹ biochar, and a control. We collected litterfall biweekly (2012–2013) and topsoil samples (0–0.25 m) in 2009 before tree planting, in 2011 and 2013. Fertilizer plus lime increased the mean annual concentrations of P, Ca and Zn in litterfall but decreased that of Mn. At the same time, fertilizer plus lime increased the annual fluxes of nutrients, Na and Al with litterfall. During the dry season, biochar decreased the N concentration in litterfall and the K flux with litterfall. During the rainy season, biochar increased the concentrations of Ca and Zn in litterfall and their fluxes with litterfall. Biochar did not influence the δ¹⁵N values of soil and litterfall after 51 months of tree growth. Fertilizer plus lime decreased the δ¹⁵N values of soil, because of the lower δ¹⁵N value of the used urea (−0.30‰) than the soil (4.5‰–7.8‰). Moreover, fertilizer plus lime increased the δ¹⁵N values of litterfall, possibly because of enhanced ¹⁴N leaching from the N-rich canopies. The amendment of up to 6 t ha⁻¹ biochar did not contribute to close nutrient cycles.