Net Requirements Research Articles

Minimization of deep percolation by a parabolic simulation model in a blocked end furrow irrigation method

AbstractSurface irrigation methods enable a lower cost of investment and energy requirements than pressurized systems if they are designed and managed properly. The aim of this investigation was to devise a new simulation model that would enable the determination of the optimum water application time and furrow length in a blocked end furrow system. The infiltration properties of the soil, net irrigation water requirement of the crop and inflow to the furrow constitute the main variables of this process. Deep percolation and the cross‐sectional area of the wetting pattern where the net irrigation water requirement of the crop is met along the furrow are the main components that were simulated interactively in the model. They were described as a function of time. The proposed model devised in this investigation was run for two different sample applications. While values of 93 and 94% water application efficiencies were obtained by running the USDA SCS method for the first and second sample applications, respectively, values of 92 and 94% were obtained, respectively, from the proposed model. These results indicate that the proposed model can be used in the design of a blocked end furrow system.

FAO-CROPWAT 8.0 Used for Analysis of Water Requirements and Irrigation Schedule in the Kutch Region of Gujarat

Abstract: Water is an important input for agriculture so this valuable resource is designed properly and deliverable. Reasonable information on evapotranspiration, crop water requirements, and net irrigation requirements is required for effective planning of this resource. To use optimum amount of water for crops and reduce irrigation quantity, some form of irrigation scheduling should be used by the farming community. Unscientific and injudicious application of groundwater in this region resulted in depletion of the groundwater table. To achieve effective utilization of the groundwater resources, there is a need to estimate the crop water requirement for different crops at different management levels to accomplish effective irrigation management. Crop water requirements of different crop in districts of Kutch was calculated using FAO CROPWAT 8.0 a computer simulation model. The simulation study was conducted with the objectives of determining irrigation water requirement and irrigation scheduling for some major crops. The Penman - Monteith method was used for evapotranspiration calculation in the model. The model predicted the daily, decadal as well as monthly crop water requirement at different growing stages of crops. Keywords: crop water requirement, irrigation scheduling, CROPWAT 8.0

Valuing sustainability Part 2: Australian valuers' perception of sustainability in valuation practice

PurposeThe research investigates valuers' understanding of the value of sustainability in property and its' consideration in valuation practice in Australia. This paper explores valuers' perceptions of the relationships between sustainability and market values, sustainability and valuation variables, and the value influence of industry sustainability certification schemes. Further, this paper tracks prevalence of certified buildings in Australian commercial markets and the evolution of valuers' knowledge of sustainability certifications used in Australia.Design/methodology/approachThis paper reports on the next rendition of a longitudinal study examining valuers’ practice in Australia. This research explores the evolution of Australian valuers' perception and knowledge of sustainability in valuation practice. The survey data has been periodically collected from practising valuers from 2007 to 2021. The survey questions investigate valuers' knowledge development, understanding, reporting and consideration of the relationship between sustainability and market value.FindingsThe results have identified the evolution of the influence of normative research on valuers' perceptions of the relationship between sustainability and value; with a clearer understanding emerging over time of where the value relationships are identified in valuation variables. Greater alignment between empirical Australian studies and valuers' perceptions of the influence of sustainability ratings on value, demonstrate the value connection for higher rated buildings under NABERS (energy rating) and Green Star. Whilst only 41% of the study's participants are including sustainability in their valuation reports, they include a higher level of commentary on building descriptions and initiatives, building ratings, and reporting of owner and tenant objectives, than in previous studies. Knowledge development relating to sustainability certification tool, NABERS was identified. This is likely linked to the introduction of mandatory disclosure legislation. This has also led to increased awareness and valuers' knowledge of the differences between the two key rating tools used in Australia.Research limitations/implicationsThe research has several limitations: firstly, recruitment of valuers and the number of valuers' responses has varied over time; secondly, due to collection methods respondents have a greater likelihood of having an interest in and knowledge of sustainability creating potential for positive bias; thirdly, respondents may have responded to the survey in different years, but due to anonymity there has been no ability to track this. The results provide insights into the Australian valuation profession but may not be fully representative of the profession overall in Australia.Practical implicationsThe broader agenda of net zero, climate change, mitigation and carbon requirements, whether driven by market forces or government legislation, are generating changes in property markets as investors' reconsider their positions and model the implications of carbon emissions on their bottom lines. Introductions of policy and legislation over time in the Australian context have led to changes in valuation practice and increasing consideration of energy efficiency and ratings in the valuation of assets. However, further guidance and research still is required in Australia to assist in the knowledge development of valuers, and their ability to consider the emerging effects of sustainability, net zero and other market driven objectives including legislation, and how these may affect or influence their evaluation of market evidence and thus property values.Originality/valueThe research has tracked valuers' understanding, knowledge, and consideration of sustainability and energy efficiency in valuation practice since 2007. In that time the research has found that, as the market has evolved and more rated buildings are built (or retrofitted), so too has valuers' knowledge and consideration in valuation practices evolved. Valuers are more engaged with industry rating tools such as NABERS. This suggests that the Australian mandatory disclosure policies have contributed to changes in the market, which are then interpreted by valuers and reflected in their perceptions and consideration of energy ratings in valuation practice.

Effect of the optimized regulated deficit irrigation methodology on quality, profitability and sustainability of barley in water scarce areas

A three-year experiment (2015–2017) was conducted under the semiarid conditions of the Hydrogeological Unit Eastern Mancha (HUEM) (Spain), using the optimized regulated deficit irrigation for a limited amount of irrigation water (ORDIL) methodology on barley. Five irrigation treatments were performed during the experiment: no deficit (ND), 100% (T100), 90% (T90), 80% (T80), and 70% (T70) of barley net typical irrigation requirements (2500 m3 ha-1) in the area. The aim was to determine the effect of ORDIL: 1) on the quality of grain and malt; 2) on the profitability and use of water at farm scale; and 3) on the profitability and sustainability of the HUEM. Despite using less water, ORDIL treatments showed no significant differences in grain quality with respect to ND, while T80 achieved the highest economic water productivity (average 0.17 € m-3). Thus, by using T80 instead of ND and increasing the irrigated area of barley on the farm by 14%, it is possible to save up to 31% of water with the same profitability. This amount of water could be used for more profitable crops, increasing the profitability of the farm. The use of ORDIL at basin scale, using T80 instead of ND and increasing the cultivated area by 9%, could have saved up to 55.9 hm3 over the 3 experimental years (16% of annual extractions in the HUEM). Supplying this water to more profitable crops, the profitability of the basin could have increased by up to 44.4 M€. In the case of saving this amount of groundwater, piezometric levels would have risen, decreasing the pumping costs and improving the environmental conditions in the area. Consequently, applying ORDIL in low-profit crops, such as barley, and in water scarce areas, could improve the profitability and/or the sustainability of agricultural systems, maintaining the production.

Valuing sustainability part 1: a review of sustainability consideration in valuation practice

PurposeThe research investigates valuers' understanding of the value of sustainability in property and its consideration in valuation practice. The paper explores the extant research that has examined valuers' perceptions of the relationships between sustainability and market values, sustainability measurement, value relationships and the standards and guidelines released industry bodies.Design/methodology/approachThis paper, part 1 of 2, reports the current state of play of valuation research in the consideration of sustainability in valuation practice and the role of industry bodies in the guidance regarding sustainability consideration in valuation. The second paper provides the next rendition of a longitudinal study examining valuation practice in Australia.FindingsThe paper provides an overview of the evolution of the consideration of sustainability in property over the past two decades. Providing insights of how the property sector, its markets and valuation professionals have responded to answering the questions of: what is the value of sustainability? Whilst earlier publications both industry and academic publications alike focussed on the normative aspects of how sustainability should affect value, more recent research starts to ascertain the implications of sustainability on property values. Despite industry bodies providing information, education, guidelines and standards, it would seem that valuers in their practice are still grappling with the challenges of understanding the rapidly evolving area of sustainability, environmental, social and governance and climate risks in valuations.Research limitations/implicationsThe paper does not present as an authority on all research that has been conducted to date, it provides an overview of the evolving nature of both academic research and industry consideration of sustainability, particularly in a valuation context. This provides the background for Part 2.Practical implicationsThe broader agenda of net zero, climate change, mitigation and carbon requirements, whether driven by market forces or government legislation, are generating substantial changes in property markets, as investors reconsider their positions and model the implications of carbon emissions on their bottom lines. Government policies appear to have a considerable influence over market behaviours, which filters through to stakeholder decision-making. However, despite government policies, clear market signalling and industry body guidance on valuing sustainability, the content and depth of sustainability consideration in valuation are still limited.Originality/valueThe paper provides an overview of the last decade of research into the value of sustainability and the evolving nature of information and guidance for valuers to identify, evaluate and consider sustainability in valuation.

Simulating employment and fiscal effects of public investment in high-quality universal childcare in the UK

This paper simulates the likely fiscal and employment effects of a vast public annual investment programme of free universal high-quality early childhood education and care (ECEC) services in the UK. It examines the extent to which it would pay for itself fiscally for different scenarios of pay increases. Investing in high-quality universal ECEC benefits all children by improving their life chances, especially for those living in lower income families. It also generates larger employment effects than other more typical investment policies such as construction projects and fosters gender equality in employment: not only it provides many high-quality jobs for women, it also allows many mothers to improve their lifetime earnings prospects by freeing up their childcare constraints. This in turn has beneficial fiscal revenue effects for the government. Estimations of annual public expenditure for a system of highly qualified and well-paid childcare staff with low child-to-staff ratios are performed, with universal coverage for all pre-school children aged 6 months to 4.5 years. Labour demand and matching supply effects are also simulated using input–output methods, for different take-up rates of the programme. A microsimulation tool is used to calculate increases in household income and tax liabilities and decreases in social security benefits spending. This results in a net annual funding requirement of between 28 and 39% of the gross investment. Two funding methods are then explored: raising taxation in a progressive way and recouping the cost over time from persistent mothers’ increased earnings. The former would entail a net additional contribution by the richest 20% of households of at most 0.4% of their income; the latter would require 21 to 31 years to offset the programme on average, which is within a typical working life-course following a first child’s birth, of 35 years.

CO2 Capture from IGCC by Low-Temperature Synthesis Gas Separation

Capture conditions for CO2 vary substantially between industrial point sources. Depending on CO2 fraction and pressure level, different capture technologies will be required for cost- and energy-efficient decarbonisation. For decarbonisation of shifted synthesis gas from coal gasification, several studies have identified low-temperature CO2 capture by condensation and phase separation as an energy- and cost-efficient option. In the present work, a process design is proposed for low-temperature CO2 capture from an Integrated Gasification Combined Cycle (IGCC) power plant. Steady-state simulations were carried out and the performance of the overall process, as well as major process components, were investigated. For the baseline capture unit layout, delivering high-pressure CO2 at 150 bar, the net specific power requirement was estimated to 273 kJe/kgCO2, and an 85% CO2 capture ratio was obtained. The impact of 12 different process parameters was studied in a sensitivity analysis, the results of which show that compressor and expander efficiencies, as well as synthesis gas separation temperature, have the highest impact on power requirements. Modifying the process to producing cold liquid CO2 for ship transport resulted in 16% increase in net power requirements and is well suited for capturing CO2 for ship transport.

Sensitivity of Irrigation Water Requirement to Climate Change in Arid and Semi-Arid Regions towards Sustainable Management of Water Resources

This study aimed to assess the spatiotemporal sensitivity of the net irrigation water requirement (NIWR) to changes in climate, for sixteen crops widely cultivated in four irrigation projects located in arid and semi-arid regions of Iraq. Using LARS-WG and five GCMs, the minimum and maximum temperature and precipitation were projected for three periods from 2021–2080 with 20-year steps (P1, P2, and P3) under representative concentration pathways (RCPs) 2.6, 4.5, and 8.5. Weather data available for a reference period from 1990–2019 in four representatives’ meteorological stations were used. The climate variables and other required data were inserted into the CROPWAT 8 NIWR tool. Findings revealed that the increase in the NIWR for the considered crops due to climate change falls in the range 0.1–42.4%, 1.8–44.5%, 1.2–25.1%, and 0.7–14.7% for the North Jazeera Irrigation Project (NJIP), Kirkuk Irrigation Project (KRIP), Upper Khalis Irrigation Project (UKIP), and Dalmaj Irri-gation Project (DLIP), respectively. Barley is more susceptible to changes in climate, whereas maize, potato, soybean, and millet are found to withstand changes in climate better than others. The novel outcomes of this study support optimal spatiotemporal allocation of irrigation water requirement and the sustainable management of water resources in a changing climate in arid and semi-arid regions.

The Effect of Different Probability Levels in Estimating the Net Water Requirement of Rice in the Northern Provinces of Iran

The Effect of Different Probability Levels in Estimating the Net Water Requirement of Rice in the Northern Provinces of Iran

Effect of the optimized regulated deficit irrigation methodology on water use in garlic

The continuing decline in water availability for agricultural uses and increased energy costs have made it necessary to improve water productivity in crops. The optimized regulated deficit irrigation (ORDI) methodology was developed to maximize the yield of annual crops under water-scarce conditions, either by reaching a specific deficit target or distributing a limited volume of irrigation water throughout the growing season (ORDIL). The objective of this study was, for a limited amount of available irrigation water, to determine the effect of ORDIL methodology on yield, agronomic and irrigation water productivity and water footprint of a purple garlic cultivar crop under semi-arid conditions. To this end, five irrigation treatments were evaluated from 2015 to 2017 on an experimental farm located in semi-arid conditions (Albacete, Spain): no deficit (ND), and four with different volumes of available irrigation water, corresponding to 100% (T100), 90% (T90), 80% (T80), and 70% (T70) of garlic net irrigation requirements for the weather conditions of the intermediate typical meteorological year (2750 m3 ha-1). Yield decreased with increasing deficit, being up to 25% less for T70 compared with ND. However, the T70 ORDIL treatment attained the greatest average irrigation water productivity (5.30, 4.32 and 2.53 kg m-3 for 2015, 2016 and 2017, respectively) and the lowest average water footprint (349, 416 and 631 m3 Mg-1), while ND exhibited the greatest total water footprint in the process (18%, 14% and 4% greater than T70).

Climate-Induced Perspective Variations in Irrigation Schedules and Design Water Requirements for the Rice–Wheat System

Conceptualizing the implications of climate change for crop evapotranspiration (ETc) and subsequent net irrigation water requirement (NIWR) is critical to sustaining Pakistan’s agriculture and food security. In this article, future ETc, NIWR, and design water requirements (DWR) were projected for the rice–wheat system of Punjab, Pakistan. Consistently increasing temperatures signify an impending hotter transition in the future thermal regime, accompanied by a substantial increase in monsoon rainfall. Future climate warming accelerated ETc and NIWR, which were compensated by 2–5 and 1–2 additional irrigations during the rice and wheat seasons, respectively. Future rice and wheat required 13–18 and 2–5 irrigations per season, respectively. Effective rainfall increments did not compensate for the warming-driven higher ETc and NIWR because of uneven and erratic rainfall distribution. Rainfall occurrence and the duration of peak irrigation demand were mismatched, resulting in surplus rainwater availability during the future rice season. The results suggest that DWR for 5- and 10-year return period droughts during the baseline period (965 and 1000 mm, respectively) should be revised to accommodate the additional 100–200 mm of irrigation water per season; otherwise, the study area will face an acute water shortage in the future.

Energy and Protein Requirements for the Maintenance of Growing Male Sika Deer (Cervus nippon).

The objective of this study is to study the effects of dietary intake levels on energy metabolism, carbon (C), and nitrogen (N) balance and to determine the maintenance requirements of energy and protein for male sika deer during their growing period. A total of 16 1-year-old male sika deer with similar body weight (BW) (63.25 ± 2.42 kg) were selected, with four animals per feed intake level. The feeding levels of the four groups for deer were 40, 60, 80, and 100% of the recommended amount, respectively. The nutrient digestibility and methane production were measured through digestion trials and respiratory trials. A 4 × 4 Latin Square design was performed in a respirometry trial. The results show that the apparent digestibility of C and N gradually increased as the level of feed intake decreased. Furthermore, with a decrease in feed intake level, the metabolic energy intake (MEI), heat production (HP), and retained energy (RE) of male sika deer significantly decreased (P < 0.01). The requirements of metabolic energy for maintenance (MEm) and net energy for maintenance (NEm) of growing deer are 251.17 and 223.62 kJ kg−1BW0.75d−1, respectively, as estimated according to the logarithmic regression equations between HP and MEI. The net N requirement for maintenance (NNm) and net protein requirement for maintenance (NPm) of growing male sika deer based on the linear relationship between retained nitrogen (RN) and daily nitrogen intake (NI) were 251.8 mg kg−1BW0.75d−1 and 1.57 g kg−1BW0.75d−1, respectively. The NEm and NPm values obtained from this experiment fill the gap in net energy and protein requirements and serve as basic data for establishing the nutritional standards forsika deer breeding in China.

Systems Analysis of Coupled Natural and Human Processes in the Mekong River Basin

The Mekong River Basin is one of the world’s major transboundary basins. The hydrology, agriculture, ecology, and other watershed functions are constantly changing as a result of a variety of human activities carried out inside and by neighboring countries including China, Myanmar, Thailand, Laos, Cambodia, and Vietnam in order to meet increased food and water demands for an increasing population. The Mekong River, which provides irrigation and fishing for a population of over 60 million people, also has an estimated 88,000 MW of untapped hydropower potential. The construction of dams for energy supply has a wide-ranging impact on downstream reservoir regions, resulting in unprecedented changes in hydrologic functions, the environment, and people’s livelihoods. We present a holistic view of how external stressors such as climate change and variability, land cover, and land-use change affect supply and demand. We present an integrated modeling framework for analyzing the supply–demand scenarios and tradeoffs between different sectors. Specifically, we evaluated the impacts of future climate on irrigation, hydropower, and other needs in the basin through a feedback loop. We focused on hydrologic extremes to evaluate their impacts on the reservoir operations during flood and low flow events. The inflow is projected to change by +13% to −50% in the future, while a 0.25% (15.24 billion m3) reduction is projected for the net irrigation water requirement (NIWR). A unit percentage increase in irrigation demand will reduce energy generation by 0.15%, but climate change has a beneficial impact on dam performance with a predicted increase in energy generation and supply to all sectors. Flood events will cause excessive stress on reservoir operation to handle up to six times more flow volumes; however, the low-flow events will marginally affect the system. While the flow and storage rule curves consider both supply and demand, changing human water use comes second to changing climate or other biophysical considerations. This paper emphasizes the importance of considering feedback between climate–water–human society in the systems modeling framework in order to meet societal and ecological challenges. The findings will provide information on the risks and tradeoffs that exist in the water, energy, and food sectors of the basin.

Climate Change Effect on Irrigation Water Requirement of Wheat and Maize in Northern Part of Bangladesh

Bangladesh is one of the most vulnerable countries for climate change in agricultural water management. A research had been done to assess climate change effects on irrigation water use of wheat and maize in the northern part of Bangladesh. The twenty nine years of data (1990-2018) were analyzed with Mann-Kendall test as well as Sen’s slope for climate change impact and the responsible weather parameters due to climate change were identified with correlation coefficients. The crop water requirement of wheat in Bogura and Rangpur was declining at the rate of 3.3mm and 2.3mm per decade respectively. Net irrigation water requirement of wheat at both Bogura and Rangpur was inclining at the rate of 1mm and 10mm per decade respectively because the effective rainfall of these regions was decreasing at 5mm and 11mm per decade respectively. The crop water requirement of maize for similar districts was increasing at the rate of 3.2mm and 2.5mm per decade respectively although net irrigation water requirement had statistically non-significance for climate change effect. The weather parameter, which was mainly responsible for climatic change in irrigation water requirement, was increasing temperature. Therefore, wheat cultivation might be coped with climate change in the northern part of Bangladesh rather than maize on the basis of irrigation and water management.

Determination of energy and protein requirements of preweaned dairy calves: A multistudy approach

The first studies concerning nutrient requirements for preweaned dairy calves were from the 1920s and 1930s; however, few studies were published in the following decades. We aimed to determine energy and protein requirements of preweaning Holstein and Holstein × Gyr dairy calves in a multistudy meta-regression. We used a database composed of individual measurements of 166 preweaned male calves (138 submitted to treatments and 28 used as the reference group) from 4 studies that used the methodology of comparative slaughter. Animals with less than 15/16 of Holstein genetic composition were considered crossbred Holstein × Gyr, whereas other animals were considered Holstein. Net energy requirements for maintenance (NEM) were determined by the regression between heat production and metabolizable energy intake (MEI). The metabolizable energy requirements for maintenance were calculated by the iterative method, and the efficiency of use of metabolizable energy for maintenance was obtained by NEM divided by the metabolizable energy requirements for maintenance. Net energy requirements for gain (NEG) were estimated using a regression of the retained energy (RE) as a function of empty body weight (EBW) and empty body gain (EBG). The efficiency of use of metabolizable energy for gain was estimated by the regression of RE as a function of MEI, but with partitioning the MEI into MEI from liquid feed and MEI from starter feed. Additionally, the effect of a liquid feed (milk or milk replacer) was tested on the slope of the regression. The metabolizable protein requirements for maintenance (MPM) were estimated using the intercept of the regression between the metabolizable protein intake (MPI) and average daily gain. The MPM was determined as the ratio between the intercept and the metabolic body weight. Net protein requirements for gain (NPG) were estimated by the regression between retained protein, EBG, and RE. The efficiency of use of metabolizable protein for gain was estimated by the regression of the retained protein as a function of MPI, but with partitioning the MPI into MPI from liquid feed and MPI from starter feed. Additionally, the effect of a liquid feed (milk or milk replacer) was tested on the regression slope. Breed did not influence any of the nutrient requirements' estimates. The NEM was estimated as 70.2 kcal/metabolic body weight per day. The efficiency of use of metabolizable energy for maintenance observed was 66%. The NEG was estimated by the equation NEG = 0.0901 × EBW0.75 × EBG0.9539. The efficiency of use of metabolizable energy for gain was estimated as 57.6, 49.3, and 41.2% for milk, milk replacer, and starter feed, respectively. The MPM was estimated as 4.22 g/EBW0.75 per day, and the NPG was determined by the equation: NPG = 30.06 × EBG + 70.98 × RE. The efficiency of use of metabolizable protein for gain was estimated as 71.9, 59.2, and 44.4% for milk, milk replacer, and starter feed, respectively. We concluded that no differences were observed in energy and protein requirements between Holstein and Holstein × Gyr crossbred cows. The efficiencies of use of metabolizable energy and protein are greater for milk when compared with milk replacer and starter feed. Therefore, we propose that the equations generated herein should be used to estimate energy and protein requirements of preweaned Holstein and Holstein × Gyr crossbred dairy calves raised under tropical conditions.

Using AquaCrop as a Decision-Support Tool for Small-Scale Irrigation Systems Was Dictated by the Institutional and Market Incentives in Ethiopia

The threat of water scarcity in sub-Saharan Africa is exacerbated by the expanding agricultural water needs, increasing climate variability and inappropriate land use. It calls for technological and institutional innovations to improve water productivity, while sustaining the resources base. This study was undertaken to examine the effect of deficit and supplementary irrigation for staggered production of potato driven by market opportunities at different periods in northeastern Ethiopia. We used potato (Solanum tuberosum) to demonstrate AQUACrop as a tool for improving water productivity during Belg (short) and Meher (long) rainfall seasons. A field experiment was undertaken using supplementary irrigation at different levels of potato crop water satisfaction (50% ETc, 75% ETc, 100% ETc and rainfed conditions) during the Belg (February–May 2020) and Meher (July–October 2020) seasons. Upon proper calibration of AquaCrop for the local potato variety (Belete), long-term simulations revealed that the mean net irrigation requirements were 249 mm during Belg season while the probability of applying supplementary irrigation during Meher was &amp;lt;10% when the effective precipitation was greater than the crop water requirement (ETc) in more than 75% of the years. Although there was significantly higher potato tuber yield from the 100% ETc than that from the 75% ETc, the latter had higher water supply efficiency than the former. Long-term simulations further revealed that the number of rainfall days was more important than the amount of rainfall during the growing period. We engaged water users' associations to employ the recommendation and enforce supplementary irrigation as predicted by the model and we present farmers' response and reasons for resistance toward water saving approaches. Hence, we concluded that 50% ETc and 75% ETc irrigation levels can still be recommended upon proper scheduling to address long dry spells, especially during the middle growth stages in the face of irrigation conflict. However, the institutional settings and market incentives associated with it are the major drivers of adopting improved irrigation water management practices.

Meta-analysis-based estimates of efficiency of calcium utilisation by ruminants

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R2 = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

Crop water requirements and crop coefficients for jute mallow (Corchorus olitorius L.) using the SIMDualKc model and assessing irrigation strategies for the Syrian Akkar region

Jute mallow (Corchorus olitorius L.) is an annual crop grown for human consumption of its nutritious leaves in many regions of the world. Despite its importance for household food security and farmers’ income, reliable information on the crop’s water requirements is still quite scarce. To overcome this knowledge gap, the irrigation needs of jute mallow grown in the Akkar region in Syria were investigated. The analysis focused on a three-year period (2017–2019) where the SIMDualKc model was calibrated and validated for simulating soil water contents and computing the soil water balance in jute mallow plots irrigated with basin and drip methods. The model was further used to determine the probabilities of the demand for irrigation water in scenarios considering different crop season lengths, irrigation methods, and application depths over a longer period of 23 years (1998–2020). The SIMDualKc model was able to simulate soil water contents measured in the field plots, returning root mean square error values lower than 0.001 m3 m-3 and modeling efficiencies ranging from 0.358 to 0.812. The calibrated basal (non-stressed) crop coefficients (Kcb) were 0.15, 0.95, and 0.95 for the initial (Kcb ini), mid-season (Kcb mid), and end-season (Kcb end) stages, respectively. The crop was harvested twice per season, with the drip treatments presenting the highest water productivity and economic indicators. In contrast, the basin treatment resulted in substantial percolation losses, which affected yields and indicators. Although net irrigation requirements showed a large variation for the extremes of the long-term weather time series, differences between the years representing average water demand and those representing very high water demand were only found for the drip irrigation scenarios. This study contributes to improving irrigation water management of jute mallow in the Syrian Akkar region, and for the sustainability of local production systems.

Estimation of crop water requirement for rice- wheat and rice- maize cropping system using CROPWAT model for Pusa, Samastipur district, Bihar

This study is about estimation of crop water requirement for rice-wheat and rice-rabi maize cropping system for Pusa Region of Samastipur district of Bihar using CROPWAT model for year 2017-18.The effective rainfall was calculated using USDA S.C. Method. Reference crop evaporation was calculated using meteorological data viz temperature, relative humidity, wind speed and Sunshine using Penman Monteith equation. The meteorological data were collected from university observatory of R.P.C.A.U Pusa. Crop coefficient (Kc) value was taken according to crop growth stages. Effective rainfall and crop water requirement was used for determining net irrigation requirement. The annual crop water requirement of Rice- Wheat cropping system was found to be 904.1 mm whereas the crop-water requirement of Rice- Rabi Maize cropping system was 991.7 mm.

Macromineral and trace element requirements for Santa Ines sheep

Minerals play an important role in animal metabolism. Knowledge of mineral requirements allows well-formulated diets to be provided, which is the main factor that affects performance. To determine the macromineral and trace element requirements for growth and maintenance, thirty-eight 2-month-old Santa Ines lambs with initial body weight (BW) of 13.0 ± 1.49 kg were distributed in a factorial design with feeding levels (ad libitum, 30% and 60% feed restriction) and sex classes [castrated (CM) and intact males (IM)]. The net mineral requirements for gain were higher (P < 0.05) with increasing BW and average daily gain, except for Ca and Na, which remained constant as the empty BW (EBW) increased. The macromineral net requirement for maintenance (g/kg EBW0.75) and the true retention coefficient (k; %) were 0.0784 and 65.2 for Ca, 0.0926 and 80.0 for P, and 0.0379 and 59.0 for K, respectively. The k of Mg was higher (P < 0.05) for IM (11.3 for IM and 7.9 for CM). Sex did not affect (P > 0.05) the maintenance requirement of the trace elements Co, Cu, Zn and Cr which were 0.0015, 0.037, 0.698, and 0.0055 (mg/kg EBW0.75), respectively. Our study indicated that the Santa Ines net mineral requirements are different from the main nutritional requirements established by committees for sheep, which may result in unbalanced diets.