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11.
Sequestering C in biomass and soils in hybrid poplar plantations can help mitigate global climate change caused by the rising atmospheric CO2 concentration. However, the impact of the establishment of hybrid poplar plantations on C and N storage and dynamics is poorly understood. We studied the distribution and temporal changes of C and N in soil organic matter (SOM) density fractions in 2-, 5-, 11-, and 13-year-old (age as in 2006) hybrid poplar stands that form a chronosequence by sampling the plantations in both 2004 and 2006. Sodium polytungstate (SPT, density = 1.6 g mL- 1) was used to fractionate the soil into light (LF, density < 1.6 g mL- 1), occluded light (LFo, density < 1.6 g mL- 1) and heavy fractions (HF density > 1.6 g mL- 1). The results showed that C and N concentrations (g kg- 1 of fraction) in the SOM density fractions decreased in the order of LFo > LF > HF, while the C/N ratio was in the order of LF > LFo > HF. The amount of C and N stored in the LF, LFo and HF fractions and bulk soil in the top 10 cm of soil was: 149-504, 70-336, 1380-2876 and 1617-3776 g m- 2, respectively, for C, and 6-26, 3-20, 149-271 and 152-299 g m- 2, respectively, for N. From 2004 to 2006, C and N storage decreased in the LF and LFo fractions but increased in the HF fraction in the youngest stand. However, stand-age effects were likely muted by high inherent soil variability among the stands. Carbon storage in the light fraction was responsive in the short term to hybrid poplar plantation establishment. 相似文献
12.
Gebre Kahsa Tadel Yfter Kiros Aregay Teweldemedhn Tesfay Gebreselama Gebremariam Tikabo 《Tropical animal health and production》2020,52(1):41-52
Tropical Animal Health and Production - A farmer participatory approach was used to identify trait preferences and breeding practices for Afar goat population in Aba’ala district, Afar... 相似文献
13.
Tesfay Araya W. M. Cornelis J. Nyssen B. Govaerts H. Bauer Tewodros Gebreegziabher Tigist Oicha D. Raes K. D. Sayre Mitiku Haile J. Deckers 《Soil Use and Management》2011,27(3):404-414
The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for 3 yr (2005–2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5 × 19 m plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 m intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (P < 0.05) in CT followed by TER and DER+. Average soil losses of 5.2, 20.1 and 24.2 t/ha were recorded from DER+, TER and CT, respectively. Runoff was 46.3, 76.3 and 98.1 mm from DER+, TER and CT, respectively. Grain yield was significantly lower (P < 0.05) in DER+ under teff in 2006, probably due to the high sensitivity of teff to weeds. The yield of wheat in 2007 was significantly higher in DER+ followed by TER. The terwah system is recommended as a first measure for wider adoption to reduce runoff and soil loss and to increase crop yield. The long‐term goal is to achieve a derdero+ system, i.e. a permanent raised bed planting system along with the application of crop residues. 相似文献
14.
To explore the potential of trees and shrubs on farmlands on traditional systems in southern Ethiopia, mineralization of macronutrients and loss of organics from leaves of Cordia africana and Albizia gummifera were studied under shaded-coffee and agricultural land-uses during the dry season. Leaves in litterbags were incorporated at 15 cm depth in soil under both land uses and residues were recovered after 2, 4, 8, 12 and 16 weeks. Contents of macronutrients and organics in initial and recovered residues were measured. Single- or double-exponential decay or quadratic functions were fitted to describe patterns of decay or release of various leaf constituents. The two species differed significantly (P<0.05) with respect to contents of ash, N, P, K, cellulose (CEL), lignin (LG), total soluble polyphenols (PL), and condensed tannins (CT). Cordia had higher content of ash, K, P, CEL, LG and a higher C-to-N ratio while Albizia had higher contents of N, PL, CT and a higher C-to-P ratio. Albizia had significantly greater mass loss, N loss and release of CT than Cordia. N was immobilized for the first 4 weeks in most treatments. Across land uses and species, mass loss rates varied from −0.023 week−1 in Cordia to −0.034 week−1 in Albizia (R2>0.70). Higher rate of release of CT seems to have facilitated decomposition in Albizia despite higher initial PL and CT in the leaves of this species. There was no significant land-use effect on any of the variables considered. It was concluded that under drier conditions, tree cover might not affect decomposition, and that organic residues with high content of polyphenols, particularly condensed tannins could decompose faster than those with lower content. This suggests that indigenous tree species with high concentrations of tannins, supposedly considered to be of ‘poor quality’, might still be quite useful as an organic input for improving soil fertility and productivity in the tropics. 相似文献
15.
Mizan Tesfay Abraha Shimelis Hussein Mark Laing Kebebew Assefa 《Journal of Crop Science and Biotechnology》2017,20(5):379-386
The extent of genetic variation and heritability of a trait are among the major determinants of selection gains in plant breeding programs. The aim of this study was to determine the magnitude of genetic variation and inheritance of grain yield, and component traits of newly developed tef populations under moisture-stressed and non-stressed conditions for drought tolerance breeding. Seventeen crosses along with the parents were evaluated in the F2 generation under moisture-stressed and non-stressed conditions in northern Ethiopia during 2015 and 2016. There were marked genotypic and phenotypic variation among the crosses in the F2 generation for plant height, panicle length, peduncle length, number of productive tillers per plant, main shoot panicle seed weight, biomass yield, and grain yield under both test conditions, important for successful selection and genetic advancement. The families of DZ-Cr-387 x 207832 and DZ-Cr-387 x 222076 were high grain yielders with early maturity under both test conditions. 相似文献
16.
The experiment was conducted at Alamata Agricultural Research Center, Ethiopia using 20 Afar rams with an initial body weight
(BW) of 18.2 ± 1.76 (mean ± SD) kg. The objectives were to study the effect of supplementation with concentrate mix consisting
of wheat bran (WB), noug seed cake (NSC) and sesame seed cake (SSC) at the ratio of 2:1:1 on dry matter (DM) basis, respectively
on feed intake, digestibility, BW gain and carcass parameters of Afar rams fed tef (Eragrostis tef) straw basal diet. The experiment was arranged with four treatments and five replications in a randomized complete block
design. The treatments included feeding sole tef straw (T1, control), and daily supplementation with the concentrate mix offered
at 150 (T2, low), 250 (T3, medium) and 350 (T4, high) g DM per head. Total DM intake, crude protein (CP) digestibility, daily
BW gain (P < 0.001), DM and organic matter (OM) digestibility, and carcass parameters (P < 0.05) were higher in the supplemented
than in the control treatment. Intake of tef straw reduced as the level of supplementation increased, whereas the contrary
was true for CP intake. Performance in carcass parameters was better for the medium compared to the low level of concentrate
mix supplementation. Moreover, the medium level of supplementation did not substitute tef straw intake. Therefore, it is concluded
that the medium level of concentrate mix supplement maintained the utilization of the roughage feed and resulted in better
carcass parameters. 相似文献