Growth and nitrogen productivity of drip-irrigated winter wheat under different nitrogen fertigation strategies in the North China Plain

Excessive application of nitrogen (N) fertilizer is the main cause of N loss and poor use efficiency in winter wheat (Triticum aestivum L.) production in the North China Plain (NCP).  Drip fertigation is considered to be an effective method for improving N use efficiency and reducing losses, while the performance of drip fertigation in winter wheat is limited by poor N scheduling.  A two-year field experiment was conducted to evaluate the growth, development and yield of drip-fertigated winter wheat under different split urea (46% N, 240 kg ha^–1) applications.  The six treatments consisted of five fertigation N application scheduling programs and one slow-release fertilizer (SRF) application.  The five N scheduling treatments were N0–100 (0% at sowing and 100% at jointing/booting), N25–75 (25% at sowing and 75% at jointing and booting), N50–50 (50% at sowing and 50% at jointing/booting), N75–25 (75% at sowing and 25 at jointing/booting), and N100–0 (100% at sowing and 0% at jointing/booting).  The SRF (43% N, 240 kg ha^–1) was only used as fertilizer at sowing.  Split N application significantly (P<0.05) affected wheat grain yield, yield components, aboveground biomass (ABM), water use efficiency (WUE) and nitrogen partial factor productivity (NPFP).  The N50–50 and SRF treatments respectively had the highest yield (8.84 and 8.85 t ha^–1), ABM (20.67 and 20.83 t ha^–1), WUE (2.28 and 2.17 kg m^–3) and NPFP (36.82 and 36.88 kg kg^–1).  This work provided substantial evidence that urea-N applied in equal splits between basal and topdressing doses compete economically with the highly expensive SRF for fertilization of winter wheat crops.  Although the single-dose SRF could reduce labor costs involved with the traditional method of manual spreading, the drip fertigation system used in this study with the N50–50 treatment provides an option for farmers to maintain wheat production in the NCP.     

Monitoring land degradation in the semiarid tropics using an inferential approach: the Kabomo basin case study,Nigeria

Lack of baseline data on soil fertility status for most semiarid areas to a very large extent hampers the success of land degradation monitoring. However, this can be overcome by adopting an inferential approach which presupposes that soils of an area of uniform geologic, geomorphic and climatic characteristics differ mainly because of the uses to which they are put. On this basis, soil conditions of a long-standing vegetation community can be used to assess the extent of soil changes resulting from land-use practices, provided that both the vegetation community and the land-use plots are located in an area having the uniform environmental parameters noted above. This approach was adopted in the Kabomo area of Nigeria, a typical semiarid tropical ecosystem, to monitor the extent of soil degradation resulting from 20 years (1972–92) of arable farming, livestock ranching and legume grass farming. Using a systematic sampling procedure, topsoil (0–15 cm) and subsoil (20–30 cm) samples were collected from both the long-standing vegetation community plot (over 80 years old) which was chosen to serve as the control, and the three land-use plots. The collected samples were then analysed for texture, bulk density, water content, water stable aggregates greater than 0·50 mm, organic matter, pH, cation exchange capacity (CEC), total nitrogen, available phosphorus and exchangeable bases. The mean value of every property for each plot was then divided by the mean value of the same property for the control plot in order to assess the extent of change (i.e. extent of degradation) in the property. The Student's t-test was then used to assess the significance of such a change. The results obtained revealed that, in general, the mean values of the various soil properties, with the exception of sand and bulk density, have declined by between 3 per cent and 72 per cent, and in most cases the declines are statistically significant. Sand and bulk density, on the other hand, show some increases of between 6 per cent and 78 per cent, though only the increase in respect of the sand fractions are statistically significant. Similarly, it was observed that the extent of degradation was much greater under the arable land and least under the livestock ranching plot. The potential causes of these trends were discussed, while suggestions were offered on how best to utilize this approach in carrying out effective monitoring of land resources in the semiarid tropics. © 1997 John Wiley & Sons, Ltd.     

Rehabilitation of degraded lands by means of fallowing in a semi-arid area of northern Nigeria

Land degradation in semi-arid regions of Nigeria is a very serious problem and therefore rehabilitation of degraded lands is essential. This article reports the results of an investigation which was carried out to assess the extent to which fallowing rehabilitates degraded lands in a semi-arid area in northern Nigeria. An inferential approach was used which involved side-by-side comparison of plots located within an area of uniform climatic, geologic and geomorphic characteristics, but which have been under fallow for different periods of time (2, 5, 10 or 15 years). Using a systematic sampling procedure, topsoil and subsoil samples were collected from each of the fallow plots and also from a plot under a plant community of well over 80 years of age which was chosen to serve as the control (fairly natural vegetation). The extent to which the land of each fallow plot had been rehabilitated could be assessed by comparison with the condition of the control plot. The samples were analysed for texture, bulk density, water-stable aggregates greater than 0.50 mm, moisture content, organic matter, pH, cation exchange capacity (CEC), total nitrogen, available phosphorus and exchangeable bases. An analysis of variance (ANOVA) technique was used to test for significant differences amongst the fallow plots, while Student's t-test was used to compare the mean values of the soil properties of the control with the same properties under each of the fallow plots. The results obtained varied considerably, but in general it was observed that there were decreases in the coarsening of soil texture and bulk density, but increases in other soil properties with increases in the length of the fallow period. However, the changes were generally found to be more significant under the older fallows (10 and 15 years) than under the newer fallows (2 and 5 years). The causes of these trends and their implication for sustainable land development in the area are discussed. It is concluded that for land rehabilitation to be effective in this area, either fallow times must be quite long, or ways of improving the soil's recuperative capacities under short-term fallow should be sought.     

The Effects of Plant Population Density on the Growth and Chemical Composition of Lablab purpureus Grown for Fodder Production in a Semi-Arid Region

Lablab purpureus was grown in two 6-month field experiments in the Savannah region of Africa, with high rainfall and hot temperatures in the first 2 months, followed by low rainfall and cool temperatures until harvesting in January. The experiments evaluated the effects of plant population density (PPD), using rows at 70-, 110- and 150-cm intervals, on the yield and nutritive value of the crop, and the effect of an interim harvest on response to PPD. Lablab yield ha⁻¹ was increased to a greater extent by an increase in PPD from 110 to 70 cm interrow spacing than by an increase from 150 to 110 cm, and yield plant⁻¹ decreased as PPD increased to a greater extent for double-harvested than for single-harvested plants. This suggested that high PPD in the early stages of growth is important to promote high crop yields in this environment, probably because it mitigates drought effects in autumn. The effects of PPD on herbage composition were small and suggested that plant maturity had not been greatly affected by density. It is concluded that the maintenance of plant cover in the early stages of growth is important for high yields in the Savannah region, which can be achieved by an interrow spacing of no more than 70 cm and avoidance of an interim harvest.     

Effects of dietary oil blend on fatty acid composition,oxidative stability and physicochemical properties of Longissimus thoracis et lumborum muscle in goats

This study examined the effects of dietary blend of 80% canola oil and 20% palm oil (BCPO) on the physicochemical properties, antioxidant status, oxidative stability and fatty acid composition of Longissimus thoracis et lumborum (LTL) muscle from goats during chill storage. Over a 14‐week feeding trial, 24 Boer bucks were randomly assigned to and supplemented with diets containing 0, 4 or 8% BCPO on a dry matter basis, slaughtered and the LTL was subjected to a 7 day chill storage. Neither diet nor post mortem ageing influenced (P > 0.05) antioxidant enzyme activities, chemical composition and cholesterol. Diet had no effect on the carbonyl content, free thiol content, water‐holding capacity, tenderness, pH and glycogen. Oil‐supplemented goats had higher (P < 0.05) C18:1 trans‐11, C18:3n‐3 and C20:5n‐3, carotenoid, tocopherol and redness, and lower thiobarbituric acid reactive substances values than the control goats. Post mortem ageing decreased (P < 0.05) shear force and oxidative stability of chevon. No significant (P > 0.05) changes were found in the proportion of individual fatty acids throughout storage. Total polyunsaturated fatty acids (PUFA) decreased while total saturated fatty acids increased as storage progressed. Dietary BCPO enhanced n‐3 PUFA without compromising the quality attributes of chevon.     

Potential Antiviral Agents from Marine Fungi: An Overview

Biodiversity of the marine world is only partially subjected to detailed scientific scrutiny in comparison to terrestrial life. Life in the marine world depends heavily on marine fungi scavenging the oceans of lifeless plants and animals and entering them into the nutrient cycle by. Approximately 150 to 200 new compounds, including alkaloids, sesquiterpenes, polyketides, and aromatic compounds, are identified from marine fungi annually. In recent years, numerous investigations demonstrated the tremendous potential of marine fungi as a promising source to develop new antivirals against different important viruses, including herpes simplex viruses, the human immunodeficiency virus, and the influenza virus. Various genera of marine fungi such as Aspergillus, Penicillium, Cladosporium, and Fusarium were subjected to compound isolation and antiviral studies, which led to an illustration of the strong antiviral activity of a variety of marine fungi-derived compounds. The present review strives to summarize all available knowledge on active compounds isolated from marine fungi with antiviral activity.     

Chemical composition of seeds and oil of Xylopia aethiopica grown in Nigeria

The chemical composition and mineral constituents of Xylopia aethiopica, which is valued as a spice in Nigeria, were determined along with the physicochemical characteristics of the seed oil. The seeds had the following chemical compositions moisture (8.43 g/100 g), ash (5.89 g/100 g), crude lipid (9.58 g/100 g), crude protein (12.45 g/100 g) crude fiber (8.66 g/100 g) and carbohydrate (63.65 g/100 g). Calcium and potassium were the major minerals in the seed. The extracted lipid was examined for fatty acid composition. Linoleic (45.1 g/100 g) and oleic (26.5 g/100 g) acids were the predominant unsaturated fatty acids, while palmitic acid (18.0 g/100 g) was the major saturated acid. The iodine value of 97 g/100 g indicates that the seed oil is a non-drying type.     

The Effects of Sowing Date on the Growth and Nutritive Value of Lablab purpureus

In two similar experiments, Lablab purpureus was sown at different dates in July and August to evaluate the effects of sowing date on the yield and nutritive value of the plant and shed leaves. On each occasion, an interim harvest was performed on half of the plants sown at each date and the regrowth recorded. The interim harvest reduced the total yield, and in particular that of shed leaves. In one of the two experiments, late sowing resulted in a considerable reduction in yield, increased crude protein and reduced modified acid-detergent fibre concentrations. Ash concentrations were higher in plants sown later and their shed leaves. Sodium concentrations were inadequate for ruminants and, like phosphorus concentrations, tended to decrease with later sowing. However, both calcium and magnesium concentrations increased with later sowing and were sufficient for ruminant production. Potassium concentrations were high and were little affected by sowing date. It is concluded that both an interim harvest and late sowing are disadvantageous when lablab is grown for ruminant livestock, the former because of yield reduction and the latter because of yield reduction, increases in ash concentration and reductions in sodium and phosphorus concentrations.     

Lactation curves of friesian-bunaji crosses in NigeriaCourves de lactation de croisées frisonne-bunaji au NigeriaLaktationskurven von friesian-bunaji rinderkreuzungen in Nigeria

The validity of the gamma function to describe lactation curves of $\text{1}\text{2}$ and $\text{3}\text{4}$ bred Friesian-Bunaji crosses was investigated. The function explained 71% of the variation in yield in lactations which differed in duration, parity and season of calving. The effect of these variables on the components of the lactation curve was analysed by least-squares procedures. The goodness of fit of the function did not differ between classes of varying duration of lactation; short lactations, however, in addition to a lower persistence, also showed a low level of production. Lactation curves of first parity were flatter and also had a greatly reduced level of production compared to higher parities.Multiplying factors for estimating total lactation yield from part records were obtained from the fitted curves. The accuracy of prediction was greater when separate factors were used for each class of lactation length. The usefulness of part records in progeny testing is also discussed.