Low Rainfall Years Research Articles

Smallholder Farmer's Adaptability to Anthropogenic and Climate-Induced Variability in the Dhidhessa River Sub-basin, Ethiopia

Ethiopia depends on rain-fed agriculture with limited use of irrigation for agricultural production. More than 90% of the food supply in the country comes from low productivity rain-fed smallholder agriculture. Since the livelihoods of many farmers depend on rainfed agriculture, this paper investigates how smallholders adapt to climate variability. Dhidhessa sub-basin of the Blue Nile river basin is home to many vulnerable immigrant smallholders from other parts of Ethiopia. Our study focuses on this sub-basin to understand how crop production and patterns have depended on rainfall. Secondary data on land cover and croplands, the number of households growing crops, crop yields, crop prices and area covered by three major crops (teff, maize, and sorghum) are analyzed over a period 2000–2019 and interpreted in light of a primary household survey of 135 farmers in the basin. Results show that almost 40% of the basin is under crop cultivation, and the area under cultivation has been growing 8.6‰ per year. Irrespective of rainfall variability, the number of households practicing crop cultivation has also been growing over the years. This means that more farmers are moving into the basin to cultivate. Analysis reveals that adaptation strategies are at play. Farmer decisions to grow which crops are sensitive to rainfall and their expectations of crop prices resulting from rainfall variability. Their decisions and crop prices are endogenous to the smallholder sociohydrology of the basin, leading more farmers to grow Teff relative to other crops in years of lower rainfall. These decisions are due to the lower sensitivity of Teff prices to rainfall variability and farmers' expectations of higher Teff prices relative to other crops as rainfall decreases. Such behavior also induces climate resilience, enabling farmers to respond to climate variability rather than migrating out of the basin. Moreover, it allows more farmers to migrate in and engage in crop cultivation within the basin. Such an adaptive strategy based on past experiences offers a way forward to incorporating adaptation mechanisms in sociohydrological models to simulate and assess water futures for similar basins worldwide.

An assessment of water footprint for irrigated rice in Punjab


 Water scarcity has become one of the highest risks for environmental and economic security worldwide. The water footprint for rice production, i.e., the total volume of freshwater consumed to produce a unit quantity rice has been estimated for three different agroclimatic zones of Punjab for the years 2000 to 2017. The results revealed that effective rainfall (Peff) improved in later years due to a change in crop calendar,legally enforced by an Act prohibiting the transplanting of paddy before a specified date. During the period of study, minimum crop evapotranspiration (ETc) was 4645 and maximum was ETc of 9511 m3ha-1 during 2014 and 2011, respectively. The green water footprint (WFgreen) for rice varied from 646litreskg-1of rice during low rainfall years (2012) to 1149 litre kg-1 of rice during heavy rainfall (1192 mm) during 2011.Out of a total water footprint (WFtotal) of 2650 litre kg-1, the share of blue water footprint (WFblue) was higher 1804 litre kg-1 (68%), indicating a need to improve on-farm irrigation management to conserve water resources.

Spatial Appraisal of the Impacts of Drought on Agricultural Patterns in Karachi

This paper is aimed at studying the spatial changes in agricultural patterns practiced in the suburbs of Karachi, which is the most densely populated city of Pakistan with high food demands of the inhabitants. This study deals mainly with Physical factors primarily climatic indicators to observe and analyze the changes in the pattern of agricultural production and the types of crops in last 20-30 years. Variability of climate when coupled with anthropogenic factors play important role in the acceleration of problems for farmers. Trends of associated agricultural output observed in different years of high and low rainfall. This study has successfully demonstrated inquisitive approach by using published secondary data from governmental sources and ground verification in recent times. Temporal variation in biomass, was found dependent upon pattern of rainfall and temperature etc. Study reveals that there are clear signs of desertification and drought in the study area.

An overlooked local resource: Shrub-intercropping for food production, drought resistance and ecosystem restoration in the Sahel

The Sahel is at the nexus of extreme ecological, socio-economic, and food security challenges where Green Revolution technologies have not been adopted and yields remain unchanged since the 1960s. Although the Parkland system where trees are maintained in cropped fields can have positive ecosystem outcomes, there is limited success for increasing yields at the landscape level. Here we report on a long-term study of inter-cropping with a local and overlooked evergreen shrub, Guiera senegalensis that offers a new approach to remediate degraded soils and increase crop productivity. A long-term factorial split-plot experiment of an optimized G. senegalensis intercropping system (~1500 shrubs ha−1 with coppiced residue additions to soils) compared to sole-cropping (as the main plot treatment) under four fertilizer treatments (0–1.5 times the recommended NPK rate) (as sub-plot treatment) was conducted relative to edaphic and agronomic performance of pearl millet (Pennisetum glaucum) and groundnut (Arachis hypogaea) in Senegal, West Africa. Contrary to conventional perspectives, G. senegalensis was non-competitive and indeed when coppiced there was a temporal offset of its fine root growth to the late rainy season when crop nutrient and water requirements are diminishing. The G. senegalensis intercropping system significantly increased crop yields, notably for millet where yields averaged across fertilizer treatments increased 126%. Importantly this system, over sole-cropping, maintained yields in low rainfall years which coincided with this system having significantly greater water use efficiency for both millet and groundnut. These responses were related to improved soil quality (increased particulate and total organic matter, and extractable nutrients). An important finding was that this system keeps surface soil temperatures below the critical 35 ℃, plant-physiological threshold during crop establishment which greatly improves crop emergence and early season growth. We conclude that this optimized shrub-intercropping system with its ability to produce abundant biomass (unpalatable to livestock) and unique ecological adaptation to coppicing, provides a logical approach for increasing food security and mitigating climate change. It is a local resource which subsistence farmers can directly utilize without external inputs or new infrastructure.

Improving economic water productivity to enhance resilience in canal irrigation systems: a pilot study of the Sina irrigation system in Maharashtra, India

Abstract This paper proposes scenarios to achieve more crop per drop and irrigation for all in water-scarce irrigation systems, with a particular reference to India. It uses economic water productivity (EWP) and water cost curve for EWP as tools to reallocate irrigation consumptive water use (CWU) and identify economically viable cropping patterns. Assessed in the water-scarce Sina irrigation system in Maharashtra, India, the method shows that drought-tolerant annual crops such as fruits and/or fodder should be the preferred option in irrigated cropping patterns. Cropping patterns with orchard or fodder as permanent fixtures will provide sustainable income in low rainfall years. Orchards in combination with other crops will increase EWP and value of output in moderate to good rainfall years. Governments should create an enabling environment for conjunctive water use and allocation of CWU to achieve a gradual shift to high-value annual/perennial crops as permanent fixtures in cropping patterns.

Converting from Seepage Irrigation to Plasticulture for Vegetable Production: A Case Study

This article is intended to provide information to producers and Extension agents that are interested in using drip irrigation for vegetable production. Cabbage production in Florida is dominated by the use of seepage or sub-irrigation. This system has traditionally been used because it is inexpensive to maintain and simple to use. Seepage irrigation works by damming tail water ditches, pumping water into open furrows, and effectively raising the water table to a depth accessible to the crop root system (For more information see EDIS Publication #HS1217). This type of irrigation practice is almost completely unique to Florida and is possible due to the persistence of a shallow, impermeable layer in the soil profile. This system can require vast quantities of water to be pumped from the aquifer in low-rainfall years. Plasticulture, or the use of drip irrigation and plastic mulch, has been proposed as an alternative production method for cabbage production in Florida.
 An on-farm demonstration was set up to provide a platform for collaboration between researchers, growers, and Extension professionals. The demonstration was located on Greene’s Farms in Bunnell, FL. The goal of the demonstration was to grow high-density cabbage populations using plasticulture side by side with seepage on a commercial farm. Fertilizer and irrigation management was closely matched between systems. The plasticulture system was designed to provide a small-scale installation of this technology for learning and commercial adaptation purposes. This small-scale system has great potential for encouraging adoption of this type of system with low risk to the grower.
 This article illustrates an innovative approach for converting from seepage irrigation to plasticulture and points out some options and challenges for growers considering a plasticulture system.

Alternative tactics in male African ground squirrels: the impact of variable rainfall on condition and physiology

Abstract Alternative reproductive tactics occur when conspecifics of the same sex use different behavioral processes to maximize reproductive success. Resource availability can have significant impacts on the proximate factors impacting the success and persistence of alternative tactics, such as an individual’s physiology, immunity, and body condition. Male Cape ground squirrels (Xerus inauris) display two alternative tactics, with some mature males dispersing from their natal groups and joining bands of nonrelated males (band males), whereas others do not disperse and remain philopatric in their natal groups past sexual maturation (natal males). Despite differences in metabolism, home ranges, and behavior, there is no difference in reproductive success between the two tactics, allowing us to test if rainfall (as a measure of primary productivity) influences body condition and physiological indices in tactics when fitness is equal. Over a period of 6 years, rainfall was positively related to body condition (mass–spine length residuals) in band males (N = 76), but not in natal males (N = 75). When we followed 18 males prior to and after dispersal, we also found a positive relationship between body condition and age following dispersal, but not prior to dispersal, and natal males maintained a better body condition in low rainfall years. During 2 years of low rainfall, band males (N = 39) had higher total ectoparasite abundance, and white blood cell differentials, implying they are less able to tolerate parasitic infection than natal males (N = 31). We found no difference in bacterial growth inhibition between tactics, suggesting that band and natal males both are equally resistant to parasites. The poorer body condition of band males during lower rainfall suggests they are less tolerant to parasites in these years. Dispersal during years of low rainfall thus may increase the costs to body condition and parasite infection, but the reproductive benefit of overlapping with more females may contribute to maintaining equal fitness between tactics.

Effect of Row Spacing and Seeding Rate on Russian Thistle (Salsola tragus) in Spring Barley and Spring Wheat.

Russian thistle (Salsola tragus L.) is a persistent post-harvest issue in the Pacific Northwest (PNW). Farmers need more integrated management strategies to control it. Russian thistle emergence, mortality, plant biomass, seed production, and crop yield were evaluated in spring wheat and spring barley planted in 18- or 36-cm row spacing and seeded at 73 or 140 kg ha−1 in Pendleton and Moro, Oregon, during 2018 and 2019. Russian thistle emergence was lower and mortality was higher in spring barley than in spring wheat. However, little to no effect of row spacing or seeding rate was observed on Russian thistle emergence or mortality. Russian thistle seed production and plant biomass followed crop productivity; higher crop yield produced higher Russian thistle biomass and seed production and lower crop yield produced lower weed biomass and seed production. Crop yield with Russian thistle pressure was improved in 2018 with 18-cm rows or by seeding at 140 kg ha−1 while no effect was observed in 2019. Increasing seeding rates or planting spring crops in narrow rows may be effective at increasing yield in low rainfall years of the PNW, such as in 2018. No effect may be observed in years with higher rainfall than normal, such as in 2019.

Water quality parameters and population characteristics for the Flinders Ranges Gudgeon

ABSTRACT The Flinders Ranges Gudgeon (Mogurnda clivicola) in South Australia, is restricted to permanent spring-fed pools of two creeks in the Northern Flinders Ranges. Consequently, the fish is classified as critically endangered. Regular monitoring of selected water chemistry and fish population characteristics has been conducted since 2018 by a “Friends of Parks” group in an ongoing project contributing to the conservation management for this endangered species. Mogurnda clivicola were abundant and healthy in Weetootla and Nepouie springs, with six or fewer fish displaying any skin lesions on each of the four sampling occasions of May and August 2019 and June and August 2020. Hence the fish populations were not adversely affected by the exceptionally low rainfall years of 2018 and 2019. Fish of less than 2 cm total length were present at each sampling time point, indicating that breeding can occur on an opportunistic basis rather than during a breeding season. Following a substantial flood during February 2020, a substantial breeding event resulted in large numbers of small fish and at Nepouie Spring. For pools that contained fish, the water quality parameters measured and their ranges were: conductivity 1141–13 800 µS/cm; dissolved oxygen concentration 1.9–12.0 mg/L; temperature 11.4–29°C; pH 7.1–8.8; [Ca++] 36–213 mg/L; [NO3-] 0.2–17.7 mg/L.

GrazingFutures: learnings from a contemporary collaborative extension program in rangeland communities of western Queensland, Australia

Producer reliance on drought subsidies instead of proactive planning and timely destocking in low rainfall years has prompted Queensland government investment in promoting business and drought resilience. GrazingFutures (AU$6 million budget, 2016–2022) is an extension project focussed on enhancing business management skills of extensive livestock producers in western Queensland, Australia. The region’s rangelands are in productivity decline, span 1 million km2 and are managed by graziers operating more than 2400 livestock businesses (beef, sheep and goats). The Queensland Department of Agriculture and Fisheries delivers GrazingFutures as a component of the Drought and Climate Adaptation Program, in partnership with regional natural resource management groups and other public and private organisations. Project delivery emphasised upskilling multi-agency staff and livestock producers to promote practice change within three whole of business themes: (1) grazing land management; (2) animal production; and (3) people-business. Three independent surveys (2018, 2019, 2020) indicated positive practice change was occurring in grazing businesses as a consequence of the project. Graziers instigated management changes even under major environmental challenges including extended drought (2013–2020), an extreme flood event in 2019 and the COVID-19 pandemic in 2020. This paper details the rationale, progress against the objectives, challenges and future direction of the GrazingFutures extension project.

Soil Management Systems to Overcome Multiple Constraints for Dryland Crops on Deep Sands in a Water Limited Environment on the South Coast of Western Australia

Deep sands on the south coast sandplain of Western Australia (WA) have multiple soil constraints including water repellence, high soil strength, low nutrient levels and subsoil acidity. The aim of the study was to test contrasting methods of managing water repellence and to assess their impacts on one or more soil constraints to crop production. These methods included seeding tyne design (knife point, winged points, paired row), soil wetting agent addition, strategic inversion tillage (rotary spading, mouldboard ploughing to 0.35 m) and clay-rich subsoil addition (170 t ha−1 with incorporation by spading to 0.20 or 0.35 m). Limesand (2 t ha−1) was applied as a split plot treatment prior to tillage. Cumulative crop yields were increased by 2.1–2.6 t ha−1 over five years by the strategic deep tillage and clay application treatments compared to the control. Water repellence was reduced by the inversion ploughing and subsoil clay addition treatments only. The effect of water repellence on crop establishment was expressed only in low rainfall years (Decile < 4) and mitigated by the paired row, wetting agent, spader and clay-amended treatments. In all years, plant numbers were adequate to achieve yield potential regardless of treatment. Soil K and plant tissue K and B were increased where clay had been applied. Inversion tillage reduced soil pH, organic carbon (OC) and macro nutrients in the 0–0.1 m layer although in most years there was no significant decline in plant tissue macro nutrient levels. Soil strength was reduced as a result of the inversion tillage to a depth of 0.35 m. However, the alleviation of soil strength and the crop yield responses diminished with time due to re-compaction. No crop response to the applied lime was found over five years at this site since the soil pHCaCl2 exceeded 4.7 within the root zone. In terms of soil constraints, we conclude that compaction was the dominant constraint at this site followed by water repellence and K deficiency.

Water budget components estimation for a mature citrus orchard of southern China based on HYDRUS-1D model

Minimizing the adverse impacts of soil erosion and seasonal drought are critical to sustain production for citrus orchards on red soil slopes in Southern China. Investigation of water budget between water supply and crop water demand is important to develop specific soil and water conservation measures to effectively utilize rainwater and irrigation in dry season. In this study, the surface runoff and soil water content at depths of 10 cm,20 cm, 30 cm, 40 cm, 60 cm, and 100 cm in the soil were monitored, and HYDRUS-1D model was employed to estimate the evapotranspiration and deep percolation at a mature citrus orchard in southern China. The results show that the annual effective rainfall in citrus orchards in the study area during 2010–2015 was 560.8–1071.2 mm, with an average of 812.4 mm. The average effective rainfall from April to September was more than 70 mm per month, and the total amount accounted for 66.63 % of the annual effective rainfall. Deep percolation could account for 18.85 %–65.65 % of the effective rainfall, which was the main factor affecting the effective rainfall. The water demand of citrus was 645.4–994.9 mm, with an average of 843.2 mm. The average water demand of 6 years from May to August was over 90 mm per month, accounting for 55.34 % of the whole growth period, which was the key period of citrus water demand. Seasonal water deficit may occur in both high and low rainfall years in the study area, and the frequency and degree of water shortage are prominent from July to October. According to a water demand analysis, surface runoff collected by rainwater harvesting for irrigation can satisfy the water shortage for citrus during the fruit growth period. Measures to reduce deep percolation should also be considered to increase the effective rainfall for sloping citrus orchards.

Different levels of rainfall and trampling change the reproductive strategy of Kobresia humilis in the Qinghai-Tibet Plateau

The sedge Kobresia humilis (C.A. Mey. ex Trautv.) Serg. is the dominant plant in the alpine meadows of China’s Qinghai-Tibet Plateau, which has experienced substantial grassland degradation due to reduced rainfall and overgrazing. In this study we sought to determine the reproductive strategy of K. humilis under three levels of rainfall and seven levels of trampling by Tibetan sheep and yaks with a two year simulation trial on the Plateau. With a reduction in rainfall and an increase in trampling intensity, there was a decrease in sexual reproduction indices, plant height and single leaf number. The highest rainfall promoted sexual reproduction, whereas average rainfall was conducive to vegetative reproduction, and the lowest rainfall inhibited reproduction. The reproductive strategy of K. humilis could be judged according to the average rainfall from July to August. Notably, after two years of low rainfall and a heavy trampling treatment, K. humilis produced more seeds with smaller size. The rainfall presented a two-way regulation function in the trampling effect on K. humilis reproductive characteristics.

Effect of tillage and irrigation interactions on soil water dynamics, root growth and water use efficiency of wheat in the indo-gangetic plain

Field experiment was undertaken during the rabi seasons of 2015–16 and 2016–17 to study the effect of tillage and irrigation interaction on soil water dynamics, root growth, yield and water use efficiency (WUE) of wheat in a maize-wheat rotation in a sandy loam soil. The treatments comprised of three levels of tillage as main plot [Conventional tillage (CT), Deep tillage at the interval of two years (DT) and No tillage with maize residue @ 5 t ha−1 (NT)] and three levels of irrigation as sub-plot [I1: 1 irrigation (CRI), I2: 3 Irrigations (CRI, Tillering, Flowering) and I3: 5 Irrigations (CRI, Tillering, Jointing, Flowering, Milk)] were evaluated in a split plot design. Results showed that no tillage with residue (NT) treatment maintained higher soil moisture content in the surface layer (0–15 cm) than that of conventional tillage (CT) and deep tillage (DT) but in lower layers (45–120 cm), soil moisture content under DT was higher than that of NT and CT. Profile moisture storage at 0–120 cm soil depth was the highest under DT followed by NT and CT, respectively. In both the years, seasonal evapo-transpiration under DT was higher than that of CT, followed by NT. The root length density (RLD) under DT was significantly higher than that of NT and CT by 12.5 and 40.7 per cent, respectively at 0–15 cm soil depth. The RLD increased significantly with increasing irrigation level at 0–15 cm soil depth. Grain yield of wheat during high rainfall year (2016–17) was higher than that of low rainfall year (2015–16) by 39.2 per cent due to higher water availability, lower maximum air temperature and more bright sunshine hours received during that period. In both the years, there was no significant difference among tillage treatments with respect to grain yield of wheat but it increased significantly with irrigation. However, during the year 2015–16, there was no significant difference in the grain yield due to I2 and I3 whereas during the year 2016–17, there was no significant difference in the grain yield between I1 and I2 irrigation levels. There was no significant difference among tillage treatments with respect to WUE of wheat in year 2015–16 but during 2016–17, WUE of wheat under DT was significantly higher than NT. During the year 2015–16, WUE of wheat decreased with the increase in irrigation levels but during the year 2016–17, there was no significant difference among the irrigation treatments with respect to WUE of wheat.

Bushfires in Australia: a serious health emergency under climate change

Bushfires in Australia: a serious health emergency under climate change

Testing and Application of the AquaCrop Model for Wheat Production Under Different Field Management Conditions in South-Eastern Australia

A field experiment involving two spring wheat varieties (EGA Gregory and Livingston) was conducted for 2 years (2013 and 2014), late sown in the first year and early sown in the second year, under two soil water regimes (rainfed and supplemental irrigation) at Wagga Wagga, Australia. The FAO’s AquaCrop model version 4.0 was calibrated and validated for crop canopy cover, dry aboveground biomass, soil water content and grain yield. The root-mean-square error (RMSE) for grain yield and dry aboveground biomass was 0.293 and 2.2 t ha−1, respectively. The RMSE for the rootzone soil water content was 25 mm. The validated model was used to analyse the effect of in-season and off-season conditions on grain yield and water productivity. Grain yield and water productivity decreased (50% for Gregory and 43% for Livingston) with the delay in sowing date. Applying four irrigations to the mid-May sown wheat resulted in a higher (6.5, 5.7 and 5.2 t ha−1, respectively, at 80% exceedance probability) yield relative to the mid-April and mid-June sowing dates. Applying supplemental irrigation both in September and October resulted in a better yield (6.7 vs. 6.0 t ha−1) and water productivity than applying irrigation only in October. The effect of off-season managements such as mulch and pre-irrigation on yield is 68% higher in low-rainfall years that that of in the wet years.

How to make more from exposure data? An integrated machine learning pipeline to predict pathogen exposure.

Predicting infectious disease dynamics is a central challenge in disease ecology. Models that can assess which individuals are most at risk of being exposed to a pathogen not only provide valuable insights into disease transmission and dynamics but can also guide management interventions. Constructing such models for wild animal populations, however, is particularly challenging; often only serological data are available on a subset of individuals and nonlinear relationships between variables are common. Here we provide a guide to the latest advances in statistical machine learning to construct pathogen-risk models that automatically incorporate complex nonlinear relationships with minimal statistical assumptions from ecological data with missing data. Our approach compares multiple machine learning algorithms in a unified environment to find the model with the best predictive performance and uses game theory to better interpret results. We apply this framework on two major pathogens that infect African lions: canine distemper virus (CDV) and feline parvovirus. Our modelling approach provided enhanced predictive performance compared to more traditional approaches, as well as new insights into disease risks in a wild population. We were able to efficiently capture and visualize strong nonlinear patterns, as well as model complex interactions between variables in shaping exposure risk from CDV and feline parvovirus. For example, we found that lions were more likely to be exposed to CDV at a young age but only in low rainfall years. When combined with our data calibration approach, our framework helped us to answer questions about risk of pathogen exposure that are difficult to address with previous methods. Our framework not only has the potential to aid in predicting disease risk in animal populations, but also can be used to build robust predictive models suitable for other ecological applications such as modelling species distribution or diversity patterns.

Long-term monitoring of crab Cardisoma guanhumi (Decapoda: Gecarcinidae) captures in Jobos Bay Estuary, Puerto Rico

Abstract: The densities of the land crab Cardisoma guanhumi has been dropping for the past decades, as a result numerous management strategies, laws and regulations throughout the tropics have been developed to reduce population declines. The reasons for declines include: overfishing, habitat degradation and loss, and continued capture in Natural Protected Areas (NPA). In Puerto Rico, an admistrative order of 1999, regulates a closed season, prohibits the captures of crabs through the year from NPA and has a legal size for capture (64 mm). The goal of this research was to monitor spatial-temporal dynamics of captures for C. guanhumi after the implementation of the admistrative order. Crabs captured from thirty-one hunters in six communities surrounding the Jobos Bay Estuary (JBE) in south east Puerto Rico was studied over a period of 15 years, 2004 through 2018. The size (carapace width and length), sex and color were documented for 1531 crabs. There was significant difference in crab size through time and space. The smallest crabs with captured in the west of JBE and in the year 2004, while the largest crabs were captured in the west and in 2013. As expected smaller hunting areas had smaller crabs due to higher hunting pressure. Further, there was significant difference in crab color by size, smaller crabs were orange, intermediate size was brown and larger crabs were blue. Color of crab can therefore be used to determine legal limit. From 2009 to 2018 three percent of hunters captured crabs smaller than the legal-size limit. Although there was no significant relationship between climate (temperature, rainfall) and crab size, smaller crabs were captured in 2013-2016 during years of lower rainfall. Also, crab size increase from 2004 until 2013 coincided with mangrove recovery in the JBE. The laws and management strategies in Puerto Rico for the protection of crabs by size and prohibition in NPA, is not enough. Therefore, the impact of climate variability, sea level rise and anthropogenic pressures on crab habitat, therefore, warrants further investigation.

DOĞU KARADENİZ HAVZASI HİDROELEKTRİK ENERJİ DURUMUNUN İNCELENMESİ

In this study; firstly, it was put forward Turkey's hydroelectric development status, then the hydroelectric power status of Eastern Black Sea Basin were investigated. Hydropower installed capacity in Turkey reached 26.681 MW by the year 2016. This value corresponds to 34% of total installed power. In terms of energy production; the share of hydroelectric power in total energy is around 25%, but it drops below 20% especially in drought and low rainfall years. The hydroelectric potential of the Eastern Black Sea Basin is 10,944 GWh per year. The portion corresponding to approximately 79.6% (8,706 GWh/year) of this value as of 2017 belongs to the HPPs in operation. Energy generated the hydroelectric power plants in operation correspond to approximately 18.8% of the total hydropower production in Turkey (58,218 GWh/year) as of 2017. The provinces having the largest hydroelectric potential in the basin were Giresun (32%), Trabzon (26%) and Rize (18.5%), respectively. Hydroelectric energy projects have a great importance for the Turkish energy sector and economy. For this reason, development studies and investments in the hydropower sector should be supported and put into operation immediately.

Between-year variation in the effects of phosphorus deficiency in breeder cows grazing tropical pastures in northern Australia

Breeder herd productivity can be severely reduced by dietary phosphorus (P) deficiency. The performance of small groups of P-deficient (Pdefic) or P-supplemented (Psupp) breeder cows was studied over 5 annual cycles while grazing C4 grass-Stylosanthes pastures at a site in the seasonally dry tropics of northern Australia. Soils contained c. 4 ppm of bicarbonate extractable P. Plasma inorganic P concentrations (PIP) during the wet season indicated that the Pdefic cows were deficient in P in 4 years and marginal in one year. Annual liveweight (LW) changes ranged widely between annual cycles from −71 to +13 kg in Pdefic cows and from +4 to +44 kg/head in Psupp cows. The LW responses to increased dietary P ranged from −9 to +115 kg, were greatest in years when LW losses by the Pdefic cows were greatest, and were associated with low-rainfall years. LW gains of calves suckling Psupp cows (mean 0.86 kg/d) tended to be higher (range 0.01–0.17 kg/d; mean 0.09 kg/d) than those of calves suckling Pdefic cows, but were significantly (P = 0.03) higher in only one year. Reconception appeared to be higher in Psupp than Pdefic cows during the 2 years of lower rainfall. Overall, the results indicated that responses to P supplementation by breeders grazing P-deficient pastures can vary widely between years. Therefore, the response in any one year may not reliably indicate responses in the longer term.