Composted shrub-prunings and other organic manures for smallholder farming systems in southern Rwanda

Organic manures are the primary source of crop nutrients in many African farming systems. The quantity of such materials that are available on farms and their quality are therefore important issues, especially in countries with limited land resources, such as Rwanda. In this study, different types of compost (including composted shrub-prunings) were compared with farmyard manure (FYM) and green manure (Calliandra calothyrsus) using beans (Phaseolus vulgaris) as test crops. The study confirmed the farmers’ general opinion that FYM has high manurial value for crop yields. Composts with P- and Ca-rich Tithonia diversifolia prunings were of similar quality as FYM or dung composts and had a higher fertilizer value than Calliandra ‘green manure’ (biomass transfer). However, the farmers’ perception of trees and shrubs as biomass and nutrient sources is still very low in Rwanda. This revised version was published online in August 2006 with corrections to the Cover Date.     

Decomposition of Erythrina poeppigiana leaves in 3-, 9-, and 18-year-old alleycropping systems in Costa Rica

Timing the application of organic residues and therefore the release of nutrients during decomposition may be critical to the growing crop in tropical alleycropping agroforestry systems. Field experiments were carried out in Turrialba, Costa Rica, to determine differences in Erythrina poeppigiana (Walp.) O.F. Cook leaf decomposition in 3, 9 and 18-year alleycropped agroforestry systems. Treatments consisted of mulch-only, and mulch plus Arachis pintoi Krapov. and W. Gregory var. CIAT 18347 in 3 and 9-year old alleycrops under no-till cultivation. The 18-year old site consisted of treatments with mulch-only and mulch plus chicken manure under disk plow cultivation. Litterbags, filled with E. poeppigiana leaves from 3, 9 and 18-year old trees, were placed on the soil surface and collected over a period of 84 days. Results showed no significant differences in the amount of plant residues remaining after 84 days in the 3-, 9-, and 18-year-old systems, or between the manure and mulch-only treatments. Comparing mulch-only treatments, leaves in the 18-year old system decomposed most rapidly which may be due to disk-plow cultivation practices where litterbags were in direct contact with the soil as opposed to the no-till system in the younger alleycrops.     

Soil fertility changes and response of maize and beans to green manures of leucaena,sesbania and pigeonpea

Three multipurpose tree species (MPTS)-leucaena (Leucaena leucocephala), sesbania (Sesbania sesban var. nubica) and pigeonpea (Cajanus cajan) were pruned at a height of 60 cm above the ground every two months, and resulting plant biomass was incorporated into the soil as green manure. For comparison, maize (Zea mays) stover was also incorporated into some plots, while some other plots were left fallow. Varying quantities of plant biomass which were incorporated into the soil over a period of 12 months caused large changes in major soil plant nutrients, and it substantially improved soil fertility. To test for improved soil fertility, test crops of maize and beans (Phaseolus vulgaris) were grown on the plots after six biomass incorporations of 4806, 13603, 16659 and 7793 kg. ha^–1yr^–1 for pigeonpea, sesbania leucaena and maize, respectively. Responses of the test crops indicated that sesbania and leucaena green manures improved maize stover, cobs and grain yields; and bean haulms and grain yields by 77.6% when compared to fallow plots. Residual effects of green manures still resulted in significant (P < 0.05) yield differences in the test cropin the third testing season. Economic significance of green manures in increasing food crop yields to small scale farmers is discussed.     

Effects of intercropping systems of trees with soybean on soil physicochemical properties in juvenile plantations

The intercropping system of tree with soybean in juvenile plantations, as a short-term practice, was applied at Lao Shan Experimental Station in Mao’er Shan Forest of Northeast Forestry University, Harbin, China. The larch (Larix gmelinii)/soybean (Glycine max.) and ash (Fraxinus mandshurica) intercropping systems were studied in the field to assess the effects of the intercropping on soil physicochemical properties. The results showed that soil physical properties were improved after soybean intercropping with larch and ash in one growing season. The soil bulk density in larch/soybean and ash/soybean systems was 1.112 g·cm⁻³ and 1.058 g·cm⁻³, respectively, which was lower than that in the pure larch or ash plantation without intercropping. The total soil porosity also increased after intercropping. The organic matter amount in larch/soybean system was 1.77 times higher than that in the pure larch plantation, and it was 1.09 times higher in ash/soybean system than that in the pure ash plantation. Contents of total nitrogen and hydrolyzable nitrogen in larch/soybean system were 4.2% and 53.0% higher than those in the pure larch stand. Total nitrogen and hydrolyzable nitrogen contents in ash/soybean system were 75.5% and 3.3% higher than those in the pure ash plantation. Total phosphorus content decreased after intercropping, while change of available phosphorus showed an increasing trend. Total potassium and available potassium contents in the larch/soybean system were 0.6% and 17.5% higher than those in the pure larch stand. Total potassium and available potassium contents in the ash/soybean system were 56.4% and 21.8% higher than those in the pure ash plantation. Biography: FAN A-nan (1972–), female, Ph. Doctor in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China.     

Production of Protein Feed from Chicken Manure with Double Strains of Bacteria by Solid State Fermentation

Protein feed are produced from the mixtures of chicken manure and wheat bran with the aspergillus oryzae and geotrichum candidum by solid state fermentation., at the same time, nitrogen source (urea) was added to the culture in the course of the fermentation.The contents of protein and amino nitrogen in the chicken manure feed reach 20.70% and 19.74% and the amino nitrogen in culture change from 56.89% to 95.36%. The feed is very tasty and can replace partial formula feed. The result of feeding pig showed that the average daily gain is increased by 10.83% compared with the control group.     

Long-term effects of fertilisation regime on earthworm abundance in a semi-natural grassland area

Environmental protection organisations involved in farmland-bird conservation promote the use of organic fertilisers, especially farmyard manure, to enhance the availability of earthworms, which are an important prey for farmland-birds. We studied changes in earthworm numbers in a field experiment on a semi-natural grassland with three different types of fertilisation; no fertilisation (NF), and application of slurry manure (SM) or farmyard manure (FM). Samples were taken in April, yearly from 1982 to 1990 and in 2005. On average, the SM treatment had a lower (29%) earthworm abundance and a higher mean individual body weight than the FM and NF treatments. No statistically significant differences were observed between the FM and NF treatment. In 2005, earthworm abundance did not differ between the SM and NF treatment. The yearly variation in earthworm numbers and biomass was high, and significantly related to winter coldness. Colder winters resulted in lower earthworm abundances in the next spring. Especially the number of endogeic earthworms varied with winter coldness. The large variation between years stresses the need to be careful with the interpretation of short-term field experiments, or comparisons between areas based on single sampling events.     

Wood-inhabiting fungi in stems of Fraxinus excelsior in declining ash stands of northern Lithuania,with particular reference to Armillaria cepistipes

Abstract

Stem bases of 210 Fraxinus excelsior trees of three different health categories were sampled by the means of an increment borer in declining ash stands in northern Lithuania. From this number, 15 sound-looking, 132 declining and 63 dead trees from three discrete plots yielded 352 isolates, representing 75 fungal species. In addition, mycelial fans and rhizomorphs typical of Armillaria spp. from 205 and 20 trees, respectively, were sampled and subjected to fungal isolations. Species richness was similar in trees from each health category, but community structures differed, indicating that species composition of wood-inhabiting fungi in stems changes along with the changes in tree health condition. Armillaria cepistipes was the most common species (86 isolates from 210 wood samples, or 41.0%), isolated more frequently and consistently than any other potential tree pathogen. It also showed abundant occurrence on a majority of trees in the form of mycelial fans and rhizomorphs, from which 64 and 14 isolates of the fungus were obtained, respectively. The population structure of A. cepistipes revealed the presence of 53–93 genets per hectare, some of which extended up to 30–55?m.     

Carbon‐mineralization kinetics in an organically managed Cambic Arenosol amended with organic fertilizers

The dynamics of C mineralization in an organically managed Cambic Arenosol amended with hen manure, a stabilized compost (compost), and three different combinations of both fertilizers (varying from a 1:100 to a 1:10 ratio) were studied during an incubation experiment to estimate the potential of such combinations to preserve/restore soil C content relative to single applications. A strong increase of the CO₂‐C emissions relative to the unamended soil (control) was observed after soil application of all five organic‐fertilizer treatments. A significantly higher amount of applied C was lost in hen‐manure treatment (648 mg CO₂‐C [g C applied]^–1) when compared to compost (159 mg CO₂‐C [g C applied]^–1) or to the three combined treatments (176–195 mg CO₂‐C [g C applied]^–1). The first‐order exponential model and the double exponential model were used to fit the C‐mineralization data in the treatments considered. Results showed that mixing “small” amounts of hen manure with compost did not affect the total amount of potentially mineralizable C, but significantly increased the mineralization rate constant. Clearly, combinations of both fertilizers promoted an initial faster mineralization of the organic matter, and consequently a faster release of nutrients, without affecting the total amount of C sequestered in soil.     

Oxidation capability of modified fly ash based adsorbent for mercury in coal-fired flue gas

Fly ash based adsorbent is dipping modified by NaCl or NaBr solution and the purpose is to improve their oxidation capability. Adsorption experiments of vapor-phase elemental mercury are performed in a laboratory-scale fixed-bed reactor. Physical properties of the adsorbent before and after modification are measured and the influences of the solution concentration and flue gas temperature on mercury oxidation rate are studied. The results show that when NaBr solution concentration is 5%, the mercury oxidation rate can reach 79.43%. The saturation adsorption quantity of absorbent 5%-NaBr is 1 700 ng/g and the service life is about 480 hours. Flue gas temperature played an important role in mercury oxidation and the best temperature ranged from 100 to 200 ℃.