Husbandry, working practices and field performance when using draught oxen in land preparation in Shambat, Nile Valley, Sudan

Little quantitative information is available on animal power in the Nile Valley in Sudan, despite that it is being used in the area for centuries and playing an important role in agriculture in the present day. A survey was conducted to assess draught oxen management and its association with field capacity and efficiency at the farm level and to identify potential areas for intervention. A sample of 50 farmers was selected for this purpose using the systematic random sampling technique. The main management parameters discussed were animal health, feeding, housing, work strategy and care for yoke and plough. The results showed that most of the farmers poorly manage their animals, and this was reflected in low working speeds and field efficiencies. The main dimensions of poor management were in veterinary care (78 % did not take their animals to the veterinary centre), feeding (66 % feed their animals shortly before work) and care for yoke (80 % did not follow daily care measures for their yokes) and plough (74 % did not follow plough care measure before and after work). Low working speeds (0.90–2.0 km/h) were recorded by the majority of the farmers (64 %). The majority of the farmers (70 %) recorded field capacities between 0.06 and 0.10 ha/h, while all of them worked at high field efficiencies of >86 %. The only parameter that significantly affected field capacity was the yoke-related wounds (p?=?0.019). Extension advice and capacity building in husbandry and working practices were identified as principal entry points for intervention.     

Thermal,spectroscopic, and flexural properties of anhydride modified cultivated <Emphasis Type="Italic">Acacia</Emphasis> spp.

The effects of chemical modification on the thermal stability of cultivated Acacia mangium and Acacia hybrid wood species were investigated. Evidence of modification was indicated by increase of weight and was confirmed by Fourier transform infrared analysis (FT-IR). The thermal stability measured by thermogravimetric analysis (TGA) increased after esterification with propionic and succinic anhydrides. Thermal stability of succinylated samples was found to be highest based on the values of on-set degradation temperatures, the temperatures at which 30, 50, and 70% degradation occurred. The observed higher thermal stability of the succinylated and propionylated Acacia wood samples when compared with unmodified wood was attributed to the reduction in hydrophilic nature of the wood due to esterification reaction.     

Possibilities to reduce rice straw-induced global warming potential of a sandy paddy soil by combining hydrological manipulations and urea-N fertilizations

Global warming potential (GWP) of sandy paddy soils may be reduced by trade-offs between N₂O, CH₄ and CO₂ emissions. Laboratory experiments using either rice straw (1% or 0.5%) or together with urea-N (25 or 50 mg N kg⁻¹ soil) at various levels of soil water were carried out for 30 days each, to test this assumption. Waterlogging combined with urea-N increased total N₂O emissions, with greater release upon rewaterlogging (7.4 mg N kg⁻¹ soil) than experienced by removing waterlogging only. Rice straw±urea-N either emitted small amounts of N₂O or resulted in negative values at all water levels, including saturated and aerobic. Total CH₄ fluxes declined with the decreased water levels and amount of rice straw (<193 mg C kg⁻¹ soil), and also for CO₂ with the latter (<1340 mg C kg⁻¹ soil), and rewaterlogging had little influence on both. N₂O under rewaterlogged and waterlogged±urea-N, CH₄ under waterlogged with rice straw, and CO₂ for the remainder were the major contributors to GWP. Results show that waterlogging following aerobic decomposition of rice straw (1%) with urea-N, applied either at the beginning or at the end of the aerobic conditions, could decrease GWP by 56-64% and 32-42% over the sole addition of rice straw (1% and 0.5%) under waterlogged and saturated conditions, respectively.     

Constituents of local plants. Part I. Chemical investigations on some cultivated Saudi Arabian plants

The 49 plant samples tested correspond to 19 family (Cactaceae to Vitaceae) exhibited a considerable variation with respect to their chemical composition which embraced the analysis of alkaloids leucoanthocyanidins, flavonoids, terpenes, steroles, cardiac glycosides, tannins, coumarins, steroid sapogenins, anthraquinones and phlobatannins.

---

Zusammenfassung Die Untersuchungen von 49 Pflanzen aus 19 Familien (von Cactaceae bis Vitaceae) ergaben beträchtliche Unterschiede in der chemischen Zusammensetzung.Untersucht wurde auf: Alkaloide, Leucoanthocyanidine, Flavonoide, Terpene, Sterole, Cardiac Glycoside, Tannine, Coumarine, Steroid Sapogenine, Anthraquinone und Phlobatannine.

---

Résumé Des 49 échantillons des plantes appartenant aux 19 espèces (Cactaceae à Vitaceae) ont été examinées. Il y a des différences considérables concernant leur composition chimique, ici spécialement les analyses des alkaloids, leucoanthocyanidins, flavonoids, terpenes, sterols, cardiac glycosides, tannins, coumarins, steroid sapogenins, anthraquinones et phlobatannins.

     

Chemical composition and nutritional quality ofCleome dolichostyla seeds

Seeds ofCleome dolichostyla were analysed for proximate composition, mineral element contents and amino acid composition, in-vitro protein digestibility (IVPD) and calculated protein efficiency ratio (C-PER). The seeds (dry basis) were rich in oil (32.1%), protein (24.6%) and fiber (17.8%) content. The contents of various mineral elements mg/100 g) were: Ca=1970, P=493, Mg=127, Na=35, K=465, Fe=71.97, Zn=2.25, Cu=0.44 and Mn=1.45. Aspartic acid, glutamic acid, glycine, arginine and histidine were the major amino acids inC. dolichostyla seed protein accounting for half of the total amino acids. Lysine was the most limiting essential amino acid (FAO/WHO, 1973 reference pattern) with a chemical score of 45 for the protein. The IVPD of cleome seed protein was 72.2% and C-PER was 1.08 relative to the IVPD and C-PER values of 90.0% and 2.50 for the Animal Nutrition Research Council casein.     

Nutritional quality of pearl millet flour and bread

Market samples of pearl millet flour and bread from Saudi Arabia were analysed for chemical composition and nutritional quality. Pearl millet flour contained, on a dry weight basis, 17.4% protein, 6.3% fat, 2.8% fiber and 2.2% ash. Lysine was the most limiting essential amino acid with a chemical score of 53 (FAO/WHO, 1973). Linoleic acid (44.8%), oleic acid (23.2%) and palmitic acid (22.3%) were the dominant fatty acids in millet oil followed by stearic acid (4.0%) and linolenic acid (2.9%). The invitro protein digestibility (IVPD) of millet flour was 75.6% and the calculated protein efficiency ratio (C-PER) was 1.38 in comparison to ANRC casein values of 90% and 2.50, respectively. Baking at 300°C for 15 min had only little effect on the proximate and fatty acid composition of the bread but decreased the arginine, cystine and lysine contents by 31.3%, 15.8% and 13.8%, respectively. The IVPD was not affected but the C-PER decreased by 18% on baking.     

Genetic gains in two selection phases of a wheat-breeding programme

Genetic gain in field crops is usually estimated as the collective contribution of several breeding programmes. Critical to an individual breeder, however, is the genetic gain realized within a single programme. Our objective was to quantify per-annum genetic gains from 1969 to 1993 within two successive phases of experimental line testing in the wheat (Triticum aestivum L.) breeding programme of the Oklahoma Agricultural Experiment Station. Data for grain yield (Phases I and II), volume weight and heading date (Phase II) were analysed according to the procedure developed by St. Martin and McBlain (1991). Genetic gains for grain yield were indistinguishable between phases, averaging 4.6 ± 1.1 and 4.2 ± 1.3% of the control mean across the 24-year period. Genetic gain for volume weight averaged only 0.2% of the check mean, reflecting lower selection pressure for that trait compared to grain yield. Inconsistent genetic gains in heading date reflect a preference for a window of desirable heading dates rather than difficulties in selecting uni-directionally for maturity. The absence of a decline in genetic gain in recent years indicates that future improvement in grain yield is likely; however, increased attention must be given to volume weight to maintain US domestic and export standards for hard winter wheat. The statistical procedure was useful in monitoring long-term trends in genetic gains and identifying gaps in programme efficiency.     

Nitrous oxide production by nitrification and denitrification in soil aggregates as affected by O2 concentration

Nitrous oxide emitted by soils can be produced either by denitrification in anoxic conditions or by nitrification in presence of O₂. The relative importance of the two processes, particularly under varied partial pressures of O₂, is not always known. This paper focuses on the influence of O₂ concentration on N₂O production by nitrification and denitrification in an arable Orthic Luvisol. Soil aggregates (2-3 mm size), water unsaturated, received 116 mg N kg⁻¹ as ammonium sulphate labelled with ¹⁵N and were incubated during 14 days at different O₂ partial pressures: 0, 0.35, 0.76, 1.5, 4.3 and 20.4 kPa. A ¹⁵N tracing technique was used to quantify nitrification and denitrification rates. ¹⁵N₂O and ¹⁵N₂ were measured. Oxygen pressure appeared to strongly influence both nitrification and denitrification rates and also N₂O emissions. Nitrification rates were reduced by a factor of 6-9 when O₂ decreased from 20.4 to 0.35 kPa. They were highly correlated with O₂ consumption rates. Denitrification mainly occurred in complete anoxic conditions. The proportion of N₂O emitted by denitrification was estimated by two independent methods: one based on ¹⁵N tracing using isotope composition of NH₄, NO₃ and N₂O, the other based on the measurement of the ¹⁵N₂O:¹⁵N₂ ratio. The two methods gave close results. The highest N₂O emissions were obtained under complete anoxic conditions and were due to denitrification. However, N₂O emissions almost as important were obtained at day 14 with 1.5 kPa O₂ pressure, and they were due to nitrification. Nitrification was the main source of N₂O at O₂ concentrations greater than 0.35 kPa. The amounts of N₂O-N emitted by nitrification were linearly related to the amounts of N nitrified, but the slope of the regression was highly dependent on O₂ concentration: it varied from 0.16 to 1.48% when O₂ concentration was reduced from 20.4 to 0.76 kPa. Emissions of N₂O by nitrification may then be quite significant if nitrification occurs at a reduced O₂ concentration.     

CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations

Emission of N₂O and CH₄ oxidation rates were measured from soils of contrasting (30-75%) water-filled pore space (WFPS). Oxidation rates of ¹³C-CH₄ were determined after application of 10 μl ¹³C-CH₄ l⁻¹ (10 at. % excess ¹³C) to soil headspace and comparisons made with estimates from changes in net CH₄ emission in these treatments and under ambient CH₄ where no ¹³C-CH₄ had been applied. We found a significant effect of soil WFPS on ¹³C-CH₄ oxidation rates and evidence for oxidation of 2.2 μg ¹³C-CH₄ d⁻¹ occurring in the 75% WFPS soil, which may have been either aerobic oxidation occurring in aerobic microsites in this soil or anaerobic CH₄ oxidation. The lowest ¹³C-CH₄ oxidation rate was measured in the 30% WFPS soil and was attributed to inhibition of methanotroph activity in this dry soil. However, oxidation was lowest in the wetter soils when estimated from changes in concentration of ¹²⁺¹³C-CH₄. Thus, both methanogenesis and CH₄ oxidation may have been occurring simultaneously in these wet soils, indicating the advantage of using a stable isotope approach to determine oxidation rates. Application of ¹³C-CH₄ at 10 μl ¹³C-CH₄ l⁻¹ resulted in more rapid oxidation than under ambient CH₄ conditions, suggesting CH₄ oxidation in this soil was substrate limited, particularly in the wetter soils. Application of and (80 mg N kg soil⁻¹; 9.9 at.% excess ¹⁵N) to different replicates enabled determination of the respective contributions of nitrification and denitrification to N₂O emissions. The highest N₂O emission (119 μg ¹⁴⁺¹⁵N-N₂O kg soil⁻¹ over 72 h) was measured from the 75% WFPS soil and was mostly produced during denitrification (18.1 μg ¹⁵N-N₂O kg soil⁻¹; 90% of ¹⁵N-N₂O from this treatment). Strong negative correlations between ¹⁴⁺¹⁵N-N₂O emissions, denitrified ¹⁵N-N₂O emissions and ¹³C-CH₄ concentrations (r=−0.93 to −0.95, N₂O; r=−0.87 to −0.95, denitrified ¹⁵N-N₂O; P<0.05) suggest a close relationship between CH₄ oxidation and denitrification in our soil, the nature of which requires further investigation.