Browsing by Subject "Water use efficiency"

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A study of pasture cropping as an alternative cropping system for sub-saharan Africa
(2020) Orford, Rohan; Asch, Folkard
With food security and soil degradation being a major concern and hurdle in the development goals of sub-Saharan Africa (SSA), there has been and continues to be an attempt to find an alternative cropping system to conventional monocropping that rehabilitates soils whilst increasing productivity and efficiency of the subsistence cropping system. Such a cropping system needs to be realistically adoptable within the SSA social and ecological constraints. An alternative Australian winter rainfall relay cropping system coined pasture cropping (PaCr) was identified as an option that may surmount some of these limitations.This research involved completing a field trial through to model scale introductory assessment of the water dynamics in PaCr and the implications thereof in yield, water use efficiency (WUE) and competition for water; ultimately assessing the potential of PaCr in SSA. PaCr was adapted to an intercropping system for SSA summer rainfall conditions. The three treatments included the representative subsistence crop cowpea (Vigna unguiculate) and a common indigenous pasture (Eragrostis curvula) and an additive PaCr setup of cowpea directly seeded into pasture in water limited (rainfed) field trials in Pretoria, South Africa between 2013-2015. The DM yields of PaCr were 17% and 293% higher in both seasons compared to the conventional cowpea monocrop yield. When comparing PaCr yield to conventional pasture, there was a 12% and 89% higher yield in both seasons compared to the conventional pasture monocrop yield. The greater yield advantage in 2015 with the limited rainfall indicates that PaCr was most advantageous in terms of DM yield in a drier year which is a time of greatest risk and food insecurity. PaCr was also more WUE in both seasons, being significantly higher than the cowpea monocrop in 2015. Competition also showed a higher degree of competitiveness by cowpea in the wetter 2013-14 season and lower competitive ability in the drier 2015, whereas pasture showed little competitive response in 2013-14 and attaining significantly higher yields than the monocrop in 2015. The results of the field trials were used to adapt the University of Pretoria’s Soil Water Balance (SWBsci) crop model to simulate an intercropping system. Observed field results were compared to simulated results and statistical goodness of fit indicators were assessed, concluding that with all the variations of season and systems, the results were acceptable as an inaugural adaptation of the Soil Water Balance model. Other relevant crop water use parameters were extrapolated from the simulated data allowing for a more complete insight into the field trials. With the adapted SWBsci model, 14-year simulations were run in three different climates and on three different soil types for all three cropping systems to map out the viability of PaCr across an aridity index continuum as a reference for further application in research or in industry and to stress test SWBsci. Results demonstrated that PaCr was only advantageous in dry sub-humid to humid conditions on clay-loam to sandy soils, whereas pasture was dominant in more semi-arid conditions on the three different soils. Cowpea only performed better on clay soils in dry-sub humid to sub humid conditions. These advantages are attributed to differing plant water availability at various root depths suiting growth and/or competition of either one or both crops. These plant water availability differences were determined by water holding capacity of various soil types and rainfall volumes. From a WUE perspective, the pasture and PaCr did have a higher WUE but with the extreme variation in rainfall there was no significant difference. But pasture and PaCr both had a very high WUE in arid to semi-arid conditions due to the deeper roots of pasture accessing stored soil water. Competition also showed insignificant results due to the variation in the rainfall. However, in more arid to semi-arid conditions on clay-loam and sand competition outweighed facilitation thus resulting in land equivalent ratios (LER) of below 1, whereas on clay for the same aridity levels the average LER was greater than one. This was attributed to cowpea have a better competitive ability when clay water holding capacity confined plant available water to the top soil layers. The converse is true in the dry sub-humid conditions and wetter conditions because LER was less than one on clay soils while being greater than one on clay-loam and sand. This was attributed to the lower water holding capacity of sand spreading the plant available water through the profile allowing for niche root partitioning to be effective. For subsistence farmers, PaCr out-yielded the cowpea monocrop in arid conditions on all three soil types and on clay in semi-arid conditions. In the wetter dry sub-humid conditions, PaCr out-yielded cowpea on sand. In the wet sub-humid conditions PaCr does well on clay-loam and sand, but cowpea yields under these conditions are more than adequate to make the choice of PaCr debatable form a yield point of view. However, if soil rehabilitation is a necessity in the sub-humid areas, this makes PaCr a very realistic option.
Agrivoltaics mitigate drought effects in winter wheat
(2023) Pataczek, Lisa; Weselek, Axel; Bauerle, Andrea; Högy, Petra; Lewandowski, Iris; Zikeli, Sabine; Schweiger, Andreas
Climate change is expected to decrease water availability in many agricultural production areas around the globe. At the same time renewable energy concepts such as agrivoltaics (AV) are necessary to manage the energy transition. Several studies showed that evapotranspiration can be reduced in AV systems, resulting in increased water availability for crops. However, effects on crop performance and productivity remain unclear to date. Carbon‐13 isotopic composition (δ13C and discrimination against carbon‐13) can be used as a proxy for the effects of water availability on plant performance, integrating crop responses over the entire growing season. The aim of this study was to assess these effects via carbon isotopic composition in grains, as well as grain yield of winter wheat in an AV system in southwest Germany. Crops were cultivated over four seasons from 2016–2020 in the AV system and on an unshaded adjacent reference (REF) site. Across all seasons, average grain yield did not significantly differ between AV and REF (4.7 vs 5.2 t ha−1), with higher interannual yield stability in the AV system. However, δ13C as well as carbon‐13 isotope discrimination differed significantly across the seasons by 1‰ (AV: −29.0‰ vs REF: −28.0‰ and AV: 21.6‰ vs REF: 20.6‰) between the AV system and the REF site. These drought mitigation effects as indicated by the results of this study will become crucial for the resilience of agricultural production in the near future when drought events will become significantly more frequent and severe.
Domestic and agricultural water use by rural households in the Oueme River Basin (Benin): an economic analysis using recent econometric approaches
(2009) Arouna, Aminou; Dabbert, Stephan
Improving the management of water resources as well as an efficient use of available water are particularly important to address the increasing scarcity of water and the low level of water accessibility in many developing countries. However, better water management requires an understanding of the existing pattern of water use for domestic and agricultural activities. With a view towards contributing to such knowledge, this dissertation analyzes domestic and agricultural water use by rural households in the Oueme river basin of Benin. This is done within the scope of three research articles. The specific objectives of the dissertation were: 1) to analyze determinants of domestic water use in the rainy and dry seasons; 2) to estimate households? willingness to pay for water supply improvements and analyze its determinants; and 3) to quantify the efficiency of water use for agricultural production and identify factors explaining the differences in water use efficiency among households. The analyses are built on primary data collected from a household survey administrated to a sample of 325 households in the Oueme river basin, in 2007. To analyze domestic water demand, we identified three types of households: those that use only free water sources, those that use only purchased sources and those that combine both free and purchased sources. A system of two demand equations (one equation for free water and another for purchased water) was estimated using a Seemingly Unrelated Tobit (SURT) approach. The advantage of using the SURT approach is that it is appropriate to account simultaneously for the censored nature of water demand and the correlation between the error terms of two equations. In the analysis of households? willingness to pay (WTP) for water supply improvements, particular attention was given to the distribution of WTP, which has been addressed using (arbitrary) parametric assumptions in many previous studies. To avoid distributional assumptions, the dissertation introduced a semi-nonparametric bivariate probit approach to estimate WTP. To analyze water use efficiency, the dissertation combined an input-specific Data Envelopment Analysis (DEA) with a bootstrapped Tobit model. Bootstrapped Tobit takes care of the dependency problem between efficiency estimates. The analysis of water use efficiency focused on vegetable production in the dry season when water is scarce. Results showed that the average daily domestic water consumption per household during the rainy season (252 liters) is significantly higher than in the dry season (216 liters). SURT estimation results showed that water demand from purchased sources is perfectly price inelastic in the rainy season; indicating that rural households in Benin are very insensitive to changes in water price. This suggests that households are willing to pay more for water supply improvements, due not only to the necessity nature of water but also to its scarcity. Factors affecting domestic water use in the rainy season are household size and composition, education, time for fetching and accessibility to water sources. In the dry season, econometric analysis revealed that there is a positive relationship between wealth and the use of water from free and purchased sources. This result suggests that poverty reduces water use. Purchased water demand in the dry season is also perfectly price inelastic. However, a comparison of determinants of water use between seasons revealed that variables such as time for fetching water, access to water sources and wealth have differential influence on water use during the rainy and dry seasons. These results imply that policy makers must consider among other factors seasonal variation of the determinants of water use. The results of this dissertation provided the first evidence that, in rural Benin, households wanting to improve water supplies are willing to pay more than existing water prices. Households are willing to pay over one and a half times the present average water price. Furthermore, results revealed that estimated WTP would generate substantial revenue from the community, which can lead to significant reductions in subsidies. The supply of safe and adequate water based on estimated WTP will reinforce both the participation of the rural population in water supply management and the sustainability of water facilities. A related policy is that a demand-side management approach can be successfully implemented in rural areas for water supply improvements and sustainability. The important determinants of WTP for water supply improvements were education, age of household head, wealth, queue time at existing water sources and preferred improvements. The policy implication of these findings is that a combination of socio-economic factors affecting WTP, and a demand-side management approach, are likely to improve the sustainability of water projects in rural areas of Benin. Average water use efficiencies were 0.38 and 0.50 under constant and variable returns to scale specification, respectively. This implies that if vegetable farmers in the study area become more efficient in water use, significant amounts of water could be saved and made available for dry season farming land expansion. In addition, many farmers operated at an increasing return to scale (average scale efficiency is 0.70), revealing that most farms should be larger than they currently are to produce efficiently. Water use efficiency in vegetable production was determined by market access, land fragmentation, extension service, ratio of children to adults, water expenditure, water sources, off-farm income and wealth. Results suggest that policy makers should focus on improving farmers? access to input and output markets as well as their access to technical information and training through extension service or NGOs. The findings also showed that households paying for irrigation water or systems are more efficient in water use. However, any price policy should be combined with other policy options such as training and development of improved irrigation techniques adapted to socio-economic conditions of farmers. Overall, various socio-economic characteristic of households and institutional factors are found to explain water use for both domestic and agricultural activities. These factors must be carefully considered for the design and implementation of water management programs that can lead to sustainable accessibility to water. Although the research focuses on Benin, most of the conclusions and policy implications are relevant and could be applicable to many developing countries with similar socio-economics conditions. The dissertation also applies and extends recent econometric approaches that may be used for empirical studies on water management policy in developing countries.
Introduction of micro-sprinkler systems to mango production into theuplands Northern Thailand
(2011) Müller, Joachim; Spreer, Wolfram; Schulze, Karin; Srikasetsarakul, Umavadee; Ongprasert, Somchai
In order to asses water saving potentials of advanced irrigation methods in irrigated mango production in Northern Thailand, micro sprinklers have been introduced and compared into the area. Three micro sprinkler treatments were established on two commercial orchards: a. Full irrigation based on climate data, b. Partial Rootzone Drying, c. Farmer?s decision. These treatments were compared to the traditional irrigation methods. It was found that by the introduction of micro sprinklers, farmers were able to increase their water use efficiency, while the fruit size distribution was more favourable for export marketing.
Role of irrigation water pricing in sustainable water resources management along the Tarim river, Northwest China
(2016) Mamitimin, Yusuyunjiang; Doluschitz, Reiner
The main objectives of the study are to explore whether irrigation water pricing can lead to efficient water use in agriculture along the Tarim River. To understand land and water use development and driving forces along the Aksu-Tarim Basin, a workshop was conducted in Urumqi which is capital city of Xinjiang Uyghur Autonomous Region. Local experts from different research disciplines as well as relevant stakeholder participated in the workshop. Besides, data were collected and analyzed from preselected sources such as statistical yearbook and government’s official document. Research results embedded in the first article revealed that there was a huge land expansion and increase in water use for agriculture during the period from 1989 to 2011. The results also indicate that interaction of vast population growth, positive price development, agricultural profitability increase, government’s afforestation program (Grain for Green) and insufficient control of land expansion were the main driving forces for those developments. Farmers’ behavior towards the changes of irrigation water pricing is one of the important factor determining efficiency of water pricing to elicit water conservation and demand reduction. Therefore, a total of 257 farm household interviews were conducted, of which 128 served to find out farmers’ responses towards the changes of water pricing in different parts of Tarim River in July and August 2012. The results of statistical analyses are presented in the second article. Results show that only less than half of the interviewed farm households would react to increased water prices with proper changes of their farming practices leading to a more efficient water use. Results also show that increasing water prices encourage the farmers to shift their irrigation from surface water to groundwater which may result in further environmental problems. In the second article it is not possible to access the impact of different water price levels and changes in the water pricing practices because of its technicality and complexity. Besides, an irrigation water pricing reform needs to consider institutional aspects which are usually ignored in research on water pricing. Therefore, an innovative approach, Bayesian network modeling, was employed to find out the effects of different water price levels, changes in water pricing practices, and other agricultural policy options on the water use efficiency along the Tarim River. Results presented in the third article show no significant impact of water prices increased by 0-50% on water use efficiency. Solely an increase of 100% may have a relevant positive effect on water use efficiency. The model results also reveal that water pricing may provide a promising option to increase water use efficiency provided that volumetrically measuring systems, subsidies for water saving technologies, and technical support are available. The fourth article discusses the economics of cotton production and land use changes along the Tarim River from 1989 to 2009 using data from official statistical yearbooks. The results of a trend analysis indicate that the land area of cotton increased. In contrast, the area of other crops slightly decreased. Results of comparative advantage index of cotton production show that most farmers in the upper stream are more efficient in cotton production compared to farmers of the lower stream, whereas farmers in Xinjiang Production and Construction Corps are more efficient than farmers outside the Xinjiang Production and Construction Corps. The overall results of the study indicate that irrigation water pricing is not the best option to achieve an efficient water use in agriculture along the Tarim River. It requires additional adjustments and supportive agricultural policies such as the availability of volumetric measuring systems, subsidies for water-saving technologies, technological support for farmers, as well as a further institutional reform. Besides, special attention should be given to the protection of groundwater resources, especially when water prices increase. Furthermore, additional research is needed to examine the impacts of water pricing on farmers’ welfare, and the role of transferable water rights and water user associations in terms of an efficient water use along the Tarim River.