Italian ryegrass (Lolium multiflorum) growth response to water and nitrogen

At present, and more so in the future, irrigated agriculture will take place under water scarcity. Owing to the global expansion of irrigated areas and the limited availability of irrigation water, there is a need to optimize water production and use efficiency (WUE). In South Africa, annual ryegrass (Lolium multiflorum) is one of the most widely grown cool season pasture species under irrigation. It is mainly used in dairy farming enterprises. Shortages of water and nitrogen can, however, be limiting factors for the production of this pasture. By using appropriate irrigation and nitrogen management tools, water and nitrogen productivity of the pasture can be improved. The objective of this study was, therefore, to determine the effects of different water levels in combination with different N fertiliser applications on the growth rate and dry matter production, quality, water use and water use efficiency of annual ryegrass. For two seasons, the trial was conducted under a rain shelter on the Hatfield Experimental Farm of the University of Pretoria. Higher frequency of irrigation coupled with high nitrogen application significantly improved the dry matter yield. Canopy size influenced the LAI and FI which in turn affects the yield. The study showed that the treatments that were irrigated twice weekly and top-dressed with 60 kg N ha-1 after each cut consumed the most water, and this resulted in the production of higher yield, maintenance of the largest leaf area index and higher interception of the incoming solar radiation. The increase in these parameters may be due to the sufficient water and nitrogen fertiliser that induces rapid cell elongation as a result of higher water potential, higher turgor pressure and higher photosynthetic processes. As hypothesized, the decrease in the frequency of water application resulted in an increase in the DMC, digestibility, ME and CP values. Nitrogen application had an effect on the WU, as less water was used in the treatments that received no nitrogen. Highest KC value recorded was in the optimal range and this indicates that the treatments were not over-irrigated. As the irrigation interval increased, more water was depleted from the soil profile. Depletion rates increased as the season progressed but generally it was minimal in the frequently irrigated treatments. Increase in WUE was achieved by reducing the frequency of irrigation from twice a week to once a week without causing significant yield loss. A possible reason for the increase in the WUE by reducing the irrigation frequency could be ascribed in part to reduced evaporation from the soil resulting from the lower wetting frequency of the deficit irrigation treatments. Within the same irrigation frequency, higher WUE was achieved by alleviating a limiting factor, N fertiliser, in this case, through increases in dry matter production. The highest WUE was achieved by irrigating once every two weeks. However, in some treatments, the WUE was not improved with the reduction in the frequency of irrigation as the water saved was overshadowed by yield loss. In summary, it can be said that the hypotheses that pasture production will be positively associated with soil moisture content, water stress can improve the quality of the pasture, N fertiliser will increase the DM response to soil moisture content and WUE will increase by alleviating a limiting factor, N fertiliser in this case were accepted. A logical extension of this work would be to do the trial in an open field to analyze the effect of irrigation and nitrogen fertilization on the growth, yield and quality of the pasture and then extrapolate the results to other sites and soil types using models.Dissertation (MSc(Agric))--University of Pretoria, 2011.Plant Production and Soil Scienceunrestricte

Investigations of Physico-Chemical Parameters and its Pollution Implications of Elala River, Mekelle, Tigray, Ethiopia

The purpose of the study was to assess the water quality parameters of Elala River found in Mekelle, Tigray, Ethiopia. Four sampling sites were chosen spatially along the water course to reflect a consideration of all possible activities that are capable of affecting the quality of the river water. The water samples were collected monthly for three consecutive months (March to May, 2014) at the four sampling sites. In order to understand the characteristics of Elala River, principal component analysis (PCA) was utilized using 22 water quality parameters: water temperature, electrical conductivity, turbidity, pH, total solids, total suspended solids, total dissolved solids, total alkalinity, total hardness, calcium, magnesium, chloride, sulfate, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen, total nitrogen, dissolved oxygen, biological oxygen demand, chemical oxygen demand, orthophosphate and total phosphorus. Among the 22 studied water quality parameters: electrical conductivity (904.11 to 2156.11 μS/cm), turbidity (21.07 to 34.99 NTU), total dissolved solids (700.22 to 1328.22 mg/L), total alkalinity (131.85 to 267.26 mg/L), total hardness (198.67 to 478.67 mg/L), chloride (47.32 to 259.43 mg/L), calcium (65.13 to 146.99 mg/L), chemical oxygen demand (16.02 to 32.53 mg/L), sulphate (271.82 to 384.07 mg/L), nitrate-nitrogen (6.82 to 62.38 mg/L), orthophosphate (0.03 to 0.14 mg/L) and total phosphorus (0.04 to 0.19 mg/L) were above the prescribed limit of WHO guidelines for drinking purposes, while all analyzed water quality parameters fall within the FAO standard limit for irrigation purposes. The water is thus not potable for domestic purposes without some forms of physical and chemical treatment while it is useful for agricultural purposes.Keywords: Elala River, Water quality, Correlation Matrix, Principal Component Analysis, Mekelle, Ethiopia

Tobacco use among Eritrean health professionals : a final scientific report

The prevalence of smoking among health professionals, especially among male physicians (17%), is a cause for concern given their role as public health leaders. Cessation programmes in the heath care setting and training on cessation techniques was non-existent but the desire to quit among tobacco users was high. Efforts to strengthen tobacco control in Eritrea would include securing the ratification of the WHO Framework Convention on Tobacco Control to guide ongoing efforts to reduce the prevalence of tobacco use and exposure to second hand smoke. Cessation programmes should be incorporated as a key component of the primary heath care setting

Long-term landscape changes in relation to rainfall variability and natural resources management in the northern Ethiopian highlands

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Forage yield and quality response of annual ryegrass (Lolium multiflorum) to different water and nitrogen levels

Water and nitrogen shortages in annual ryegrass (Lolium multiflorum) production can be improved by using proper irrigation and nitrogen scheduling methods. The aim of this research was to analyse the effect of water and nitrogen application on dry matter production and forage quality of annual ryegrass. Treatments consisted of three irrigation levels, scheduling application to field capacity once every two weeks (W1), once a week (W2) or twice a week (W3), and three nitrogen (N) levels, top-dressing after each harvest at a rate of 0 (N1), 30 (N2) or 60 (N3) kg N h−1 cycle−1. Yield increased as a function of the amount of water and nitrogen fertiliser applied. The dry matter (DM) content, in vitro organic matter digestibility (IVOMD), crude protein (CP) and metabolisable energy (ME) were higher in the treatments being irrigated once every two weeks. These results conclude that higher irrigation coupled with high N application significantly improved the dry matter yield, while water stress, to some extent, did improve the quality of the pasture by increasing the DM content, IVOMD, CP and ME values.Water Research Commission (Project 1650 ‘Guidelines for irrigation management in pasture production’).http://www.tandfonline.com/loi/tarf202016-04-30hb201

Performance of simple irrigation scheduling calendars based on average weather data for annual ryegrass

Poor irrigation management in pastures can lead to yield and quality reduction as well as loss of income through extra pumping and leaching of nitrate fertiliser. A number of irrigation scheduling techniques of varying levels of sophistication have been developed over the years to address limited irrigation water availability and maximise productivity. Despite this, the adoption of irrigation scheduling tools by farmers remains low. The objective of this study was to assess the use of simple irrigation scheduling calendars based on average weather data to improve irrigation management in ryegrass. The calibrated Soil Water Balance (SWB) model was used to generate simple irrigation calendars and assess effectiveness for different scenarios by mechanistically simulating water dynamics and pasture growth. Scheduling irrigation using the calendars gave similar irrigation applications, water losses and yields compared to a more scientific real-time scheduling (in response to soil water depletion by the crop). While site-specific irrigation scheduling calendars can easily be generated by consultants and irrigators, even simpler monthly estimates of average daily water use can also be useful. Application of calendars by farmers is encouraged to improve water and nutrient use efficiency of irrigated pastures, if real-time irrigation scheduling is not employed.Water Research Commission.Project 1650http://www.tandfonline.com/loi/tarf20hb201