Forage yield and quality of Leucaena leucocephala and Guazuma ulmifolia in mixed and pure fodder banks systems in Yucatan,Mexico

In tropical areas of Mexico, Leucaena leucocephala is widely used in silvopastoral systems. However, little information exists on other native woody species of high forage potential, such as Guazuma ulmifolia. The aim of this study was to evaluate the components of biomass, forage yield and quality, and availability of N in fodder banks of L. leucocephala, G. ulmifolia, and a mixture of both species during dry and rainy seasons, under sub-humid tropical conditions. The experimental unit was a 5 × 10 m plot, containing three rows with 2 m between rows; each row had 20 plant positions with 0.50 m between plants. Within each plant position there was either a single plant, in the case of pure-crop, or two plants, in the case of mixed of both species. A complete randomized block design with three repetitions was used. In both seasons, there were a significantly greater proportion of leaves in the G. ulmifolia fodder banks (71 %) and in mixed fodder banks (69 %) than in L. leucocephala fodder banks (64 %). Consequently, these systems had leaf-to-stem ratios of 2.4, 2.2 and 1.9, respectively. The forage yield of fodder banks was not influenced by season. The mixed fodder bank had greater forage yield (5.1 t DM ha^?1) than the L. leucocephala fodder bank (3.4 t DM ha^?1) in each season. Additionally, the mixed fodder bank accumulated more forage yield during the experimental period (10.2 t DM ha^?1 year^?1) than G. ulmifolia (9.0 t DM ha^?1 year^?1) or L. leucocephala (6.9 t DM ha^?1 year^?1). The concentrations of CP, C and C:N were not influenced by season. Forage NDF and ADF concentrations were greater in the rainy season (476 g kg^?1 DM) compared with the dry season (325 g kg^?1 DM). Mixed fodder banks had the greatest N yield (185.9 kg ha^?1) and consequently the greatest availability of N (371.8 kg N ha^?1 year^?1). We conclude that mixed fodder banks of L. leucocephala and G. ulmifolia are a better option for improving productivity and forage quality in comparison with pure fodder banks in Yucatan, Mexico.     

Occurrence and distribution of phthalate esters (PAEs) in wetland sediments

This study investigated the occurrence and distribution of 15 phthalate esters(PAEs) in sediments collected from Qixinghe wetlands, northeast China. Total concentration of PAEs in all sediments ranged from 128.41 to 502.79 μg kg~(-1), with the mean value of 284.61 μg kg~(-1).PAEs significantly differed among wetland types; the average PAEs concentration of surface sediments were as follows: Phragmites australis wetland(PAW, 419.87 ±73.61 μg kg~(-1)) [ Carex lasiocarpa wetland(CLW,304.18 ± 56.47 μg kg~(-1)) [ Deyeuxia angustifolia wetland(DAW, 129.78 ± 18.24 μg kg~(-1)). Dimethyl phthalate(DMP), diisobutyl phthalate, di-n-butyl phthalate, and di-(2-ethylhexyl) phthalate(DEHP) were found in all sediments,DEHP was the most abundant PAEs congeners with concentrations varying from 37.62 to 294.9 μg kg~(-1). DMP and DEHP exhibited relatively higher concentrations in CLW and PAW wetlands than in DAW, indicating that the different deoxidization and biodegradation conditions could have important implications for the distribution patterns of PAEs in wetland sediments. The variation of PAEs concentrations in horizontal and vertical sediments with wetland types could be attributed to the migration of contaminants by surface water, groundwater and atmospheric deposition. The occurrence and distribution of PAEs in wetlands also sμggests that contamination in natural ecosystems should not be overlooked.     

Improving maize production through nitrogen supply from ten rarely-used organic resources in Ghana

Where there is limited availability of conventional fertilizers, the use of organic materials is considered a viable alternative to increase the productive capacity of soils. Many potential plant residues remain underutilized due to limited research on their use as a nutrient source. In this study, the nitrogen supplying capabilities of ten rarely-used leaf biomass sources (Acacia auriculiformis, Baphia nitida, Albizia zygia, Azadirachta indica, Senna siamea, Senna spectabilis, Tithonia diversifolia, Gliricidia sepium, Leucaena leucocephala and Zea mays) were tested based on their nutrient content, N mineralization patterns and effect on maize yield (in comparison with inorganic fertilizer). N mineralization was studied in the laboratory using an incubation experiment. Field trials were also established using a randomized complete block design. Plant residues were applied at 5 t dry matter ha^?1 a week before planting maize while fertilizer was split-applied at 90 kg N ha^?1 on designated plots. From the results on plant residue chemistry, most of the plant residues recorded relatively high N concentration (≥24.9 g kg^?1) and low C/N ratio (≤20.1) although neither N content nor C/N ratio significantly (p > 0.05) affected their N mineralization patterns. Leaf biomass application of B. nitida, A. auriculiformis, A. zygia and maize stover resulted in an initial net N immobilization that lasted for 14 days. Application of all plant materials significantly increased the biological yield and N uptake of maize with G. sepium and T. diversifolia producing the greatest impact especially in the major rainy season. Relative to the control, total grain yield after four cropping seasons was comparable between inorganic fertilizer (9.2 t ha^?1), G. sepium (8.8 t ha^?1) and T. diversifolia (9.4 t ha^?1) treatments. The results on maize biological yield were significantly correlated with the effects of the treatments on N uptake. The findings suggest that in locations where inorganic fertilizers are limited, leaf biomass from G. sepium and T. diversifolia could offer the most suitable option in comparison with the other species used in this study.     

Effect of multipurpose tree species on soil fertility and CO2 efflux under hilly ecosystems of Northeast India

A 26 years old agroforestry plantation consisting of four multipurpose tree species (MPTs) (Michelia oblonga Wall, Parkia roxburghii G. Don, Alnus nepalensis D. Don, and Pinus kesiya Royle ex-Gordon) maintained at ICAR Research Complex, Umiam, Meghalaya, India were compared with a control plot (without tree plantation) for soil fertility status and CO₂ efflux. The presence of trees improved all the physico-chemical and microbial biomass parameters studied in this experiment. Relative to control, soils under MPTs showed significant increases of 17 % soil organic carbon, 26 % available nitrogen (AN), 28 % phosphorus (AP), 50 % potassium (AK), 65 % mean weight diameter (MWD) of aggregates, 21 % moisture and 34 % soil microbial biomass carbon (MBC) while reducing the mean bulk density (7 %). However, these parameters significantly differed among the tree species i.e., soils under A. nepalensis and M. oblonga had higher values of these attributes except bulk density, than under other species. Irrespective of treatments, the values of all these attributes were higher in surface soils while bulk density was highest in subsurface (60–75 cm). Cumulative CO₂ efflux under MPTs was significantly higher (15 %) and ranged from 1.71 g 100 g^?1 (M. oblonga) to 2.01 g 100 g^?1 (A. nepalensis) compared to control at 150 days of incubation. In all the treatments, increment in temperature increased the oxidation of soil organic matter, thereby increased the cumulative CO₂ efflux from soils. Of the tree species, with increment in temperature, A. nepalensis recorded more CO₂ efflux (2.50 g 100 g^?1) than other MPTs but the per cent increase was more in control plot. P. kesiya and A. nepalensis recorded highest activation energy (59.1 and 39 kJ mol^?1, respectively). Net organic carbon sequestered in soil was highest under A. nepalensis (25.7 g kg^?1) followed by M. oblonga (19.3 g kg^?1), whereas control showed the lowest values. Amount of net carbon stored in the soil had significant and positive correlation with MBC (r = 0.706**), MWD (r = 0.636*), and AN (r = 0.825**).     

Efficacy of diatomaceous earth formulations against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) in Kersting’s groundnut (Macrotyloma geocarpum Harms): influence of dosage rate and relative humidity

The pulse beetle, Callosobruchus maculatus F. is a key pest to stored Kersting’s groundnut, Macrotyloma geocarpum Harms. There are many reports evaluating various diatomaceous earths (DEs) against stored product pests, but there is limited information on the efficacy of these materials against C. maculatus and none on Kerstings groundnut. Laboratory experiments were conducted to evaluate the efficacy of the DEs, Diatomenerde, Probe-A, Fossil shield, and Damol-D1 against C. maculatus in seeds of M. geocarpum. Each DE was applied at 0.50, 1.00, 1.50, and 2.00 g kg^?1, and each treatment infested with newly emerged C. maculatus in petri dishes. The set up was maintained at 50 and 80 % RH regimes at ambient temperature. Data were collected on adult mortality (at 24 h, 48 h, 7 days, and 14 days), oviposition, and progeny emergence of the beetles, and their effects on weight loss and viability of seeds. Probe-A proved the most effective against the beetle, followed by Damol-D1 and Fossil shield. Adult mortality increased progressively with the increasing dosage of DE and exposure time. Seeds treated at 2.00 or 1.50 g kg^?1 recorded significantly lower number of eggs and F1 emergence compared with the lower dosages in all DEs. Increased DE concentration consistently decreased seed weight loss due to low beetle infestation, but there was no significant effect on seed viability. DEs were more effective at 50 % RH than at 80 % RH. Probe-A or Damol-D1 applied at 1.50 or 2.00 g kg^?1 at 50 % RH is a viable alternative for preventing C. maculatus infestation in stored Kersting’s groundnut.     

Millwood honeylocust trees: seedpod nutritive value and yield characteristics

The Millwood (MW) cultivar of the honeylocust (Gleditsia triacanthos L.) tree has gained particular interest for silvopasture systems due to the production of edible, high-sugar seedpods that livestock may consume after pod drop. Two studies were conducted within an active sheep and honeylocust silvopasture to (1) estimate nutritional variability of seedpods among MW trees, and to (2) determine seedpod yields and seasonal production variation of MW trees. Seedpods were harvested from each pod-bearing MW in October 2008 and 2009, just prior to pod drop. Nutritional characteristics such as detergent fibers, crude protein, in vitro digestibility, and sugar concentrations were determined for fractionated husk and seed components. Further, MW fodder yields were estimated in 2008, 2009, and 2010 through field measurements and tree yield classification. Both ground husks and seeds were low in fiber (273 and 132 g kg^?1 neutral detergent fiber, respectively) and highly digestible (787 and 963 g kg^?1, respectively). Seed husk sugar concentrations averaged 223 g kg^?1. Based on the nutritive fractions assayed, whole ground MW seedpods grown in Virginia have a nutritional profile comparable to that of ground whole-ear dent corn (Zea mays L.) or oat (Avena sativa L.) grain. Nearly all MW trees displayed some form of alternate-bearing pattern. Average dry matter yields of pod-bearing trees were 15.8, 4.8, and 14.7 kg tree^?1 in 2008, 2009, and 2010, respectively. Pod yield and quality indicate MW honeylocust trees have good potential as fodder-bearing trees in temperate silvopasture systems.     

Optimal seed water content and storage temperature for preservation of Populus nigra L. germplasm

Context

Black poplar (Populus nigra L.) is an alluvial forest tree species whose genetic pool is decreasing in Europe. Poplar trees produce short-lived seeds that do not store well.

Aim

The feasibility of seed storage in conventional and cryogenic conditions after their desiccation from water content (WC) of 0.15 to 0.07 g H₂O g^?1 dry mass (g g^?1) was investigated.

Methods

Seed germinability was evaluated (seeds with a radicle and green cotyledons were counted) after storage of seeds for a period of 3 to 24 months at different temperatures: 20°, 10°, 3°, ?3°, ?10°, ?20° or ?196°C.

Results

Seeds desiccated to a 0.07 g g^?1 WC can be stored successfully at ?10 °C and ?20 °C for at least 2 years. A significant decrease in germination was observed only after 12 months of seed storage (WC 0.15 g g^?1) at temperatures above 0 °C. We demonstrated that both fresh (0.15 g g^?1 WC) and desiccated (0.07 g g^?1 WC) seeds can be preserved at ?196 °C for at least 2 years.

Conclusions

Seed storage temperature and time of storage were statistically significant factors affecting seed storability. The presented data provide a foundation for the successful gene banking of P. nigra seeds.     

Biomass production and chemical composition of Moringa oleifera under different planting densities and levels of nitrogen fertilization

The effect of different planting densities (100,000 and 167,000 plants ha^?1) and levels of nitrogen fertilization (0, 261, 521, and 782 kg N ha^?1 year^?1) on biomass production and chemical composition of Moringa oleifera was studied in a split-plot design with four randomized complete blocks over 2 years with eight cuts year^?1 at the National Agrarian University farm in Managua, Nicaragua (12°09′30.65″N, 86°10′06.32″W, altitude 50 m above sea level). Density 167,000 plants ha^?1 produced significantly higher total dry matter yield (TDMY) and fine fraction yield (FFDM), 21.2 and 19.2 ton ha^?1 respectively, compared with 11.6 and 11 ton ha^?1 for 100,000 plants ha^?1. Growth rate in 167,000 plants ha^?1 was higher than in 100,000 plants ha^?1 (0.06 compared with 0.03 ton ha^?1 day^?1). Average plant height was 119 cm irrespective of planting density. Fertilization at the 521 and 782 kg N ha^?1 year^?1 levels produced the highest TDMY and FFDM in both years of the study and along all cuts. The interaction between cut and year was significant, with the highest TDMY and FFDM during the rainy season in the second year. Chemical composition of fractions showed no significant differences between planting densities. Significantly higher crude protein content was found in the coarse fraction at fertilizer levels 521 and 782 kg N ha^?1 year^?1 (87.9 and 93.7 g kg^?1 DM) compared with lower levels. The results indicate that Moringa can maintain up to 27 ton ha^?1 dry matter yield under dry tropical forest conditions over time at a planting density of 167,000 plants ha^?1 if the soil is regularly supplied with N at a level of approximately 521 kg ha year^?1 in conditions where phosphorus and potassium are not limiting.     

Quantifying biological nitrogen fixation of agroforestry shrub species using 15N dilution techniques under greenhouse conditions

Some land-use systems in Saskatchewan, Canada include the nitrogen-fixing trees buffaloberry (Shepherdia argentea Nutt.), caragana (Caragana arborescens Lam.) and sea buckthorn (Hippophae rhamnoides L.). These species provide various ecological functions such as ameliorating soil moisture, light and temperature but little work has been done quantifying biological nitrogen fixation by these species. Greenhouse experiments were conducted to quantify N₂-fixation using the ¹⁵N natural abundance and the ¹⁵N dilution methods. Buffaloberry failed to form nodules in all but one of the four replicates in the natural abundance experiment. Using the ¹⁵N dilution method, the percentage of N derived from atmosphere (%Ndfa) in the shoot of buffaloberry averaged 64 %. For caragana, the mean  %Ndfa was 59 and 65 % and seabuckthorn was 70 and 73 % measured using the natural abundance and dilution methods, respectively. Because of large variability in biomass production between plants grown in the natural abundance experiment and the dilution experiment, the amounts of N₂ fixed also were very variable. Buffaloberry fixed an average of 0.89 g N m^?2; the average for caragana ranged from 1.14 to 4.12 g N m^?2 and seabuckthorn ranged from 0.85 to 3.77 g N m^?2 in the natural abundance and dilution experiments, respectively. This corresponds to 16 kg N ha^?1 year^?1 for buffaloberry; an average of 15–73 kg N ha^?1 year^?1 in caragana and 11–67 kg N ha^?1 year^?1 in seabuckthorn. The substantial amounts of N₂ fixed by these species indicate that they have the potential to contribute to the overall N balance in land-use systems in which they are included.     

Performance of Zebu Steers Grazing on Western Tanzania Native Forages Supplemented with <Emphasis Type="Italic">Leucaena Leucocephala</Emphasis> Leaf Meal

Information is lacking on the potential of leguminous fodder trees such as Leucaena leucocephala as a feed resource to supplement the native forages in traditional grazing management systems in the tropics. Two studies were conducted (1) to assess traditional fodder banks’ forage nutritive potential on animal production, and (2) to investigate the effect of Leucaena leucocephala leaf meal (LLM) supplementation on growth of steers grazing standing hay basal forages in the dry season. The traditional forages had low nutritive values indicated by low mean crude protein (CP) of 23 g kg⁻¹ dry matter (DM), and high fibre contents of 717, 546 and 153 g kg⁻¹ DM for neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL), respectively. The forages were poorly degraded in sacco and had low metabolisable energy (ME) (4.2–4.6 MJ kg⁻¹ DM). Mean washing losses A, slowly degradable DM fraction, B, potential degradability, (A+B) and mean 48 h DM degradability (DMD) of grazing land forages were 70, 471, 541 and 326 g kg⁻¹ DM, respectively. In the supplementation study, 16 growing steers (160.8±0.24 kg) were randomly allocated into four groups, in a completely randomized design. Four LLM treatment diets (T1, T2, T3 and T4), with four levels: 0, 0.4, 0.6 and 0.8 kg DM for control, low, medium and high LLM levels, respectively, were randomly allocated to the animals in the four groups for 70 days (d). LLM supplementation (p<0.05) improved mean weight gain from −0.30 to 0.26 kg steer⁻¹ d⁻¹, for T1 and T4, respectively. Steers on T4 gained (p<0.05) more weight compared to the animals in T1 and T2, though there was no (p>0.05) difference in weight gains between animals on T3 and T4 (0.14 vs. 0.26 kg steer⁻¹ d⁻¹, respectively). Standing hay basal forages alone could not sustain animal productivity during dry seasons unless corrected for protein. Higher levels of LLM supplementation prevented weight losses and improved the performance of grazing steers, a management practice thought appropriate to low income pastoralists in semiarid western Tanzania.     

Variation in vegetation composition,biomass production,and carbon storage in ridge top forests of high mountains of Garhwal Himalaya

Abstract

The present study was aimed to anticipate how forest composition, regeneration, biomass production, and carbon storage vary in the ridge top forests of the high mountains of Garhwal Himalaya. For this purpose five major forest types—(a) Pinus wallichiana, (b) Quercus semecarpifolia, (c) Cedrus deodara, (d) Abies spectabilis, and (e) Betula utilis mixed forests—were selected on different ridge tops in the Bhagirathi Catchment Area of the Uttarkashi District of Garhwal Himalaya. The highest species richness (10 species) and stand density (804 ± 184.5 stems ha^?1) were recorded in Abies spectabilis forests, whereas lowest species richness (4 species) and species density (428 ± 144.7 stems ha^?1) were found in Quercus semecarpifolia forests. The total basal cover (TBC) values were maximum (91.1 ± 24.4 m² ha^?1) in Cedrus deodara forests and minimum (26.5 ± 11.7 m² ha^?1) in Pinus wallichiana forests. The highest total biomass density (TBD) (464.2 ± 152.5 Mg ha^?1) and total carbon density (TCD; 208.9 ± 68.6 Mg C ha^?1) values were recorded for Cedrus deodara forests; however, lowest TBD (283.4 ± 74.8 Mg ha^?1) and TCD (127.5 ± 33.7 Mg C ha^?1) values for Quercus semecarpifolia forests. Our study suggests that Abies spectabilis-dominated forests should be encouraged for biodiversity enrichment and reducing carbon emissions on ridge top forests of high mountains.     

Arbuscular mycorrhizal association of indigenous agroforestry tree species and their infective potential with maize in the rift valley, Ethiopia

Tree species in agroforestry are important source of inoculum for companion agricultural crops. Agroforestry trees can serve as a source of Arbuscular mycorrhiza (AM) inoculants to intercropped annuals. We studied spore abundance, root colonization of Albizia gummifera (J.F. Gmel.) and Croton macrostachyus (Hochst Ex Del.) trees and their effect on colonization of maize. Soil and root samples were collected from field standing trees from under and outside the canopy of trees and maize crops in the main rainy season. The number of spore count was significantly higher under the canopy of A. gummifera (791/100 g of dry soil) and C. macrostachyus (877/100 g of dry soil) trees than outside the canopy (547 and 588/100 g of dry soil, respectively). The level of root colonization of C. macrostachyus (45 %) was higher than A. gummifera (41 %). Root colonization of maize crops grown under the canopy of A. gummifera and C. macrostachyus trees was significantly higher than outside the canopy (P < 0.001). Maize seedlings grown on non-sterilized soils collected under and outside the canopy of A. gummifera and C. macrostachyus trees recorded higher root colonization, plant height, shoot and root dry weight than grown on sterilized soils (P < 0.001). The percentage of AM colonized roots of Zea mays seedlings was significantly positively correlated with the number of spore counts for field soils. The rhizospheres of indigenous agroforestry perennial species are important source of inoculum for annuals. The integration of perennials and annuals in an agroforestry system enhances the maintenance of soil quality in the tropics.     

Development and application of a capillary electrophoresis method for the determination of ellagic acid in E. globulus wood and in filtrates from E. globulus kraft pulp

A capillary zone electrophoresis (CZE) method for simple and rapid determination of ellagic acid (EA) in Eucalyptus globulus wood and in the filtrate from unbleached kraft pulp has been developed. This is the first application of CZE for the detection of EA in industrial streams from cellulosic pulp production. The EA determinations in wood extractives and in pulp filtrates were succeeded only after sample acidification. This new CZE analytical procedure allowed reliable determinations of EA in E. globulus wood (1.1 ± 0.6 g kg^?1 of dry wood) and in the filtrates from unbleached kraft pulp (98 ± 0.7 mg L^?1). Gas chromatography–mass spectrometry was used as a reference method for the quantification of EA in industrial samples.     

Earthworm population and microbial activity temporal dynamics in a Caspian Hyrcanian mixed forest

Few studies have analyzed how tree species within a mixed natural forest affect the dynamics of soil chemical properties and soil biological activity. This study examines seasonal changes in earthworm populations and microbial respiration under several forest species (Carpinus betulus, Ulmus minor, Pterocarya fraxinifolia, Alnus glutinosa, Populus caspica and Quercus castaneifolia) in a temperate mixed forest situated in northern Iran. Soil samplings were taken under six individual tree species (n = 5) in April, June, August and October (a total of 30 trees each month) to examine seasonal variability in soil chemical properties and soil biological activity. Earthworm density/biomass varied seasonally but not significantly between tree species. Maximum values were found in spring (10.04 m^?2/16.06 mg m^?2) and autumn (9.7 m^?2/16.98 mg m^?2) and minimum in the summer (0.43 m^?2/1.26 mg m^?2). Soil microbial respiration did not differ between tree species and showed similar temporal trends in all soils under different tree species. In contrast to earthworm activity, maximum microbial activity was measured in summer (0.44 mg CO₂–C g soil^?1 day^?1) and minimum in winter (0.24 mg CO₂–C g soil^?1 day^?1). This study shows that although tree species affected soil chemical properties (pH, organic C, total N content of mineral soils), earthworm density/biomass and microbial respiration are not affected by tree species but are controlled by tree activity and climate with strong seasonal dynamics in this temperate forest.     

Sapling biomass allometry and carbon content in five afforestation species on marginal farmland in semi-arid Benin

Allometric equations are routinely used in the estimation of biomass stocks for carbon accounting within forest ecosystems. However, generic equations may not reflect the growth trajectories of afforestation species that are introduced to degraded farmland characterized by water and nutrient limitations. Using sequential measurements of the height, basal diameter, and above- and belowground biomass of juvenile trees, we developed allometric equations for five woody species (Moringa oleifera Lam., Leucaena leucocephala Lam., Jatropha curcas L., Anacardium occidentale L. and Parkia biglobosa Jacq.) subjected to a gradient of water and nutrient availability in an afforestation trial on degraded cropland in the semi-arid zone of Benin, West Africa. For three of the species studied, the allometric relationships between basal diameter and biomass components (i.e. leaves, stems and roots) were described best by a simple power-law model (R² > 0.93). The incorporation of species-specific height–diameter relationships and total height as additional predictors in the power-law function also produced reasonable estimates of biomass. Fifteen months after planting, roots accounted for 10–58% of the total biomass while the root-to-shoot ratio ranged between 0.16 and 0.73. The total biomass of the saplings ranged between 1.4 and 10.3 Mg ha^?1, yielding 0.6–4.3 Mg C ha^?1, far exceeding the biomass in the traditional fallow system. The rate of stem carbon sequestration measured ca. 0.62 Mg C ha^?1 year^?1. Overall, the allometric equations developed in this study are generally useful for assessing the standing shoot and root biomass of the five afforestation species during the juvenile growth stage and can help in reporting and verifying carbon stocks in young forests.     

Fodder production responses to pruning height and fodder quality of some trees and shrubs in a forest-savanna transition zone in southwestern Nigeria

Seasonal fodder production responses of five shrubs (Centrosema arenarium, Desmodium strigillosum, Desmodium velutinum, Phyllodium pulchellum, and Tadehagi triquetrum)and five trees (Albizia gummifera, Berlinia grandiflora, Albizia niopoides, Bauhinia monandra, and Inga edulis) to pruning heights ranging from 15 to 75 cm were evaluated during the main-wet, minor-wet, and dry seasons of 1993 and 1994 in the forest-savanna transition zone of West Africa. Fodder from the main-wet season was analysed for nitrogen (N) and phosphorus (P), and dry matter degradation characteristics after 6, 12, 24, 48, 72 and 96 h of incubation in rumen-fistulated N'Dama steers. In the minor-wet season, fodder production of all species increased in response to increasing pruning height with the exception of P. pulchellum and A. gummifera. Highest fodder production was attained at a pruning height of 45 cm for the Desmodium species, 50 cm for P. pulchellum, and 75 cm for the rest of the species. Concentrations of N and P varied significantly among the species; for N the ranges were 28.7–38.8 g kg^–1 (shrubs) and 25.3–44.5 g kg^–1 (trees), while for P the ranges were 3.26–7.04 g mg^–1 (shrubs) and 3.58–6.76 g mg^–1 (trees). Dry matter degradation characteristics differed significantly among shrubs and trees; ranges for shrubs were: soluble fraction (a), 128–185; degradable fraction (b), 664–703; potential degradability (PD), 793–857, as g kg^–1; rate of degradation (c), 0.0241–0.0308 as % h^–1 while for trees ranges were: (a), 139–160; (b), 651–826; (PD), 824–970, as g kg^–1; (c), 0.0143–0.0227 as % h^–1. Based on fodder production and quality, C. arenarium, D. strigillosum, D. velutinum, B. monandra, I. edulis, and A. niopoides were the most promising species for the development of animal agroforestry technologies in the west African forest-savanna transition zone and similar environments in the tropics.This revised version was published online in November 2005 with corrections to the Cover Date.     

Insecticidal activity of thiamethoxam against the bamboo powder post beetle <Emphasis Type="Italic">Dinoderus minutus</Emphasis> Fabr. (Coleoptera: Bostrichidae)

Thiamethoxam (ACTARA^® 25WG) was evaluated for its insecticidal activities against the bamboo powder post beetle Dinoderus minutus Fabricius (Coleoptera: Bostrichidae). The study showed that thiamethoxam had contact toxicity against D. minutus. Based on dose-mortality responses, LC₅₀ values for thiamethoxam against D. minutus ranged from 1.74 to 7.94 μg ml^?1. Laboratory and field exposure tests showed that thiamethoxam at concentration of atleast 10 μg ml^?1 may have anti-oviposition or anti-feeding effects on D. minutus and can protect post harvest Bambusa vulgaris Schrad. culms against the infestation of this bamboo boring beetle.     

Soil carbon stocks in planted woodlots and Ngitili systems in Shinyanga,Tanzania

Our understanding of the processes influencing the storage and dynamics of carbon (C) in soils under semi-arid agroforestry systems in Sub-Saharan Africa (SSA) is limited. This study evaluated soil C pools in woodlot species of Albizia lebbeck (L.) Benth., Leucaena leucocephala (Lam.) de Wit, Melia azedarach (L.), and Gmelina arborea Roxb.; and in farmland and Ngitili, a traditional silvopastoral system in northwestern Tanzania. Soil organic carbon (SOC) was analyzed in the whole soil to 1 m depth and to 0.4 m in macroaggregates (2000–250 μm), microaggregates (250–53 μm), and silt and clay-sized aggregates (<53 μm) to provide information of C dynamics and stabilization in various land uses. Synchrotron-based C K-edge x-ray absorption near-edge structure (XANES) spectroscopy was also used to study the influence of these land use systems on the soil organic matter (SOM) chemistry to understand the mechanisms of soil C changes. Whole soil C stocks in woodlots (43–67 Mg C ha^?1) were similar to those in the reserved Ngitili systems (50–59 Mg C ha^?1), indicating the ability of the planted woodlots on degraded lands to restore SOC levels similar to the natural woodlands. SOC in the woodlots were found to be associated more with the micro and silt-and clay-sized aggregates than with macroaggregates, reflecting higher stability of SOC in the woodlot systems. The continuous addition of litter in the woodlots preserved recalcitrant aromatic C compounds in the silt and clay-sized aggregates as revealed by the XANES C K-edge spectra. Therefore establishment of woodlots in semi-arid regions in Tanzania appear to make significant contributions to the long-term SOC stabilization in soil fractions.     

Coarse woody debris of Fagus sylvatica produced a quantitative organic carbon imprint in an andic soil

Coarse woody debris (CWD) is involved in important forest ecosystem functions and processes, e.g., habitat provision, water retention, and organic matter decomposition. However, a quantitative, CWD-produced soil organic carbon (SOC) imprint has not yet been detected, possibly due to lack of free adsorption sites on soil minerals. To circumvent this potential constraint, we selected plots with and without CWD in a beech (Fagus sylvatica L.) primeval forest in the West Carpathian volcanic range (Slovakia). Local andic soil contains abundant allophane and amorphous Fe-compounds as important SOC binding agents. The C concentration in the fine earth of sampled soils was determined by the dry combustion method. We established that organic carbon concentration decreased with depth from 0.20 kg kg^?1 (0.0–0.3 m) to 0.11 kg kg^?1 (0.3–0.5 m) in soil with CWD and from 0.13 kg kg^?1 (0.0–0.3 m) to 0.07 kg kg^?1 (0.3–0.5 m) in soil without CWD. The respective average differences in soil organic carbon concentration (0.07 kg kg^?1) and stock (15.84 kg m^?2) between the two series of plots within the upper 0.3 m were significant according to the t test (P < 0.05 or P < 0.01, respectively). Also, corresponding differences within the 0.3–0.5 m layer (0.04 kg kg^?1 and 5.51 kg m^?2) were significant (P < 0.05, P < 0.001). Our results represent the first indication that CWD-produced SOC imprint may reach deeper than just a few centimeters in soils featuring high adsorption capacity, such as Andosols.     

A comparison of cold tolerance and biomass production in Leucaena leucocephala L. pulverulenta and L. retusa

Expansion of leucaena into temperate regions of the world will require additional tolerance to freezing stress. Leucaena leucocephala may be the most widely tested woody legume in the last 15 years. Leucaena pulverulenta and Leucaena retusa are two species with more cold tolerance than L. leucocephala. A screening trial with 38 accessions of L. pulverulenta, 26 of L. leucocephala, and 1 of L. retusa was begun in 1983 at Kingsville, Texas where freezing temperatures may occur every year. A biomass production trial using L. leucocephala (K-8) was planted in 1982 to evaluate the biomass production of this widely used strain under semi-arid conditions with minimum fertilizer inputs and no irrigation. Biomass estimations were made with regression equations that predicted weight from log₁₀ basal stem diameter measurements. The trees in both trials were harvested after a − 12°C freeze in December 1983 killed all trees except L. retusa to ground level. Less severe freezes in 1984–1985 of − 7°C and − 9°C killed all L. leucocephala to ground level whereas less than 2% of the L. pulverulenta were killed to ground level, thus demonstrating the difference in cold tolerance between these two species. Dry wood production in the screening trial of the L. leucocephala after 10 months' coppice growth ranged from 654 to 3602 g dry biomass per tree and that of the L. pulverulenta during the same period ranged from 437 to 2505 g dry biomass per tree. Dry wood productivity of L. leucocephala (K-8) 1-year coppice growth ranged from 1.4 t ha⁻¹ on a poorly drained soil to 10 t ha⁻¹ on a moderately drained soil.