Field-level model approach to assess water and nutrient use efficiencies : WaterFARMING project. Report for deliverable 2.1

- Two models have been chosen for field-level assessment of crop yields and water- and nutrient use efficiencies: WOFOST and DAISY.- For WOFOST a post-doc (João Vasco Silva), who is an expert in this modelling approach has been added to the team. He is also the lead author of this report.- For DAISY, a brief description of the model and data requirements are provided as a guide for the consortium on data needs.- For WOFOST calibration and evaluation protocols and associated data needs have been worked out. Detailed templates have been developed and distributed in the team.- For sites in Germany and the Netherlands detailed experiments have been chosen that are ideally suited for model calibration and evaluation. The quality and detail of the data available is very high. In Denmark, data are available from a combined food and energy system for the modelling task.- Finding suitable experimental data for the other countries is ongoing, there being some challenges in this regard. In view of this we aim to find experimental data for at least one site in South Europe and one in North Africa

Irrigation system performance in potato production in Northern Algeria : a case study of the portable sprinkler system

This report presents a case study of the performance of the irrigation system commonly used in potato production in Northern Algeria, the portable sprinkler system. The aim is to determine water use, water losses and water distribution uniformity. Furthermore, it is evaluated whether the applied irrigation water can be stored in the root zone, and if irrigation applications match with crop water demand. Based on the findings, some recommendations will be given to improve the system. Algeria is among the countries with the lowest renewable water resources per capita in the world, but currently, data and information on irrigation system performance is lacking. In this study, the portable sprinkler system is evaluated by means of field measurements (catch can test, sprinkler discharge measurement, soil moisture measurements) and modelling (CROPWAT 8.0 model). It was found that water losses due to wind drift and evaporation are rather high (36%) compared to values found in literature, whereas the water distribution uniformity was low (DU 34.6% and CU 51.2%), from which it can be concluded that the system performs poorly. Furthermore, it was found that water applications are too high, especially in the beginning of the growing season. The most important recommendation to improve the performance of the irrigation system is an alternative irrigation schedule, adapting the timing and duration of irrigation events to crop water demand and the water storage capacity of the root zone

Current potato production in Algeria : an explorative research of the current potato production systems in two regions

While Algeria is among the countries with the lowest renewable water resources per capita in the world, agriculture accounts for 70-80% of the total water use and municipal water use is expected to almost double in the next twenty years. As potato is in Algeria the main irrigated crop and the first vegetable crop in terms of area and production, improving the potato production system and rationalizing the use of water is key to sustain the production in the future and to maintain and enhance food safety. Coherent information of the current potato production system is crucial to improve a system and since this is lacking, we research what is the current situation for potato production in two main production areas of Algeria, in a Mediterranean and desert climate. Through interviews with farmers, other stakeholders and field visits in both areas the current systems are described, analysed on main weaknesses, followed by and advice regarding improvement and implementation of the subsequent project which will be a setup of a demonstration farm to introduce a more productive and sustainable system. It was found that the systems have many points for improvement regarding productivity and sustainability. That both regions have a lack of technology and accurate data of 1) the exact inputs applied, and 2) the exact requirements, especially regarding water supply, lies on the basis of most weaknesses, resulting in rough irrigation, fertilizer and pest management. The main recommendation is to elaborate research of the current system with productivity as focal point to make clear what are the economic advantages for a farmer to adapt the new system. Farmer Field Schools are proposed as a practical and hands-on management approach to implement suggested improvement practices and to introduce a new production system

Phosphorus recovered from human excreta: A socio-ecological-technical approach to phosphorus recycling

This article provides a comprehensive and cross-disciplinary overview of the phosphorus cycle through the wastewater and agri-food system. While mineral phosphorus stocks are finite, the use of mined phosphorus is accompanied with many losses, leading to pollution of water bodies. Recovering phosphorus from human excreta can contribute to more efficient use of phosphorus to ensure its availability for food production in the future. Phosphorous can be recovered through different recovery technologies and consequently used in agriculture via different recycling routes. Each recycling route has its own particularities in terms of interactions with technologies, actors and the environment to bring the recovered phosphorus back into agriculture. In this literature review, we adopt a socio-ecological-technical approach to map three phosphorus-recycling routes, via municipal sewage sludge, struvite recovered from municipal wastewater and source-separated urine. We firstly show that improvements are still needed in all three routes for achieving high P recovery efficiency, and a combination of these recycling routes are needed to achieve maximum recovery of phosphorus. Second, we identify key issues for each recycling route that currently limit the use of recovered phosphorus in agriculture. We indicate where interaction between disciplines is needed to improve recycling routes and identify gaps in research on how recovered phosphorus accesses agriculture

Effects of Trampling on Morphological and Mechanical Traits of Dryland Shrub Species Do Not Depend on Water Availability

In semiarid drylands water shortage and trampling by large herbivores are two factors limiting plant growth and distribution. Trampling can strongly affect plant performance, but little is known about responses of morphological and mechanical traits of woody plants to trampling and their possible interaction with water availability. Seedlings of four shrubs (Caragana intermedia, Cynanchum komarovi, Hedysarum laeve and Hippophae rhamnoides) common in the semiarid Mu Us Sandland were grown at 4% and 10% soil water content and exposed to either simulated trampling or not. Growth, morphological and mechanical traits were measured. Trampling decreased vertical height and increased basal diameter and stem resistance to bending and rupture (as indicated by the increased minimum bend and break force) in all species. Increasing water availability increased biomass, stem length, basal diameter, leaf thickness and rigidity of stems in all species except C. komarovii. However, there were no interactive effects of trampling and water content on any of these traits among species except for minimum bend force and the ratio between stem resistance to rupture and bending. Overall shrub species have a high degree of trampling resistance by morphological and mechanical modifications, and the effects of trampling do not depend on water availability. However, the increasing water availability can also affect trade-off between stem strength and flexibility caused by trampling, which differs among species. Water plays an important role not only in growth but also in trampling adaptation in drylands

15N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods

Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated N-15 abundance (delta N-15) in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of N-15-depleted nitrate from the soil, following anthropogenic nitrogen deposition over the last decades. To find further evidence for altered nitrogen cycling in tropical forests, we measured long-term delta N-15 values in trees from Bolivia, Cameroon, and Thailand. We used two different sampling methods. In the first, wood samples were taken in a conventional way: from the pith to the bark across the stem of 28 large trees (the "radial" method). In the second, delta N-15 values were compared across a fixed diameter (the "fixed-diameter" method). We sampled 400 trees that differed widely in size, but measured delta N-15 in the stem around the same diameter (20 cm dbh) in all trees. As a result, the growth rings formed around this diameter differed in age and allowed a comparison of delta N-15 values over time with an explicit control for potential size-effects on delta N-15 values. We found a significant increase of tree-ring delta N-15 across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring delta N-15 values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of delta N-15 values within trees reflect tree ontogeny (size development). However, for the trees from Cameroon and Thailand, a low statistical power in the fixed-diameter method prevents to conclude this with high certainty. For the trees from Bolivia, statistical power in the fixed-diameter method was high, showing that the temporal trend in tree-ring delta N-15 values in the radial method is primarily caused by tree ontogeny and unlikely by a change in nitrogen cycling. We therefore stress to account for tree size before tree-ring delta N-15 values can be properly interpreted

The cocoa yield gap in Ghana: a quantification and an analysis of factors that could narrow the gap

Open Access Article; Published online: 28 Jul 2022CONTEXT Global cocoa production is largely concentrated in West Africa where over 70% of cocoa is produced. Here, cocoa farming is largely a rain-fed, low-input system with low average yields, which are expected to decline with climate change. With increasing demand, there is a need to evaluate opportunities to increase production whilst avoiding deforestation and expansion to croplands. Thus, it is important to know how much additional cocoa can be produced on existing farmland, and what factors determine this potential for increased yield. OBJECTIVE The objective was to quantify the cocoa yield gap in Ghana and identify the factors that can contribute to narrowing the gap. METHODS We calculated the cocoa yield gap as the difference between potential yield (i. water-limited potential(Yw) quantified using a crop model, ii. attainable yield in high-input systems(YE), iii. attainable yield in low-input systems(YF)) and actual farmer yield. Both absolute and relative yield gaps were calculated. We then related each yield gap (absolute & relative) as a function of environment and management variables using mixed-effects models. RESULTS AND CONCLUSIONS There were considerable yield gaps on all cocoa farms. Maximum water-limited yield gaps (YGW) were very large with a mean absolute gap of 4577 kg/ha representing 86% of Yw. Attainable yield gap in high-input (YGE) was lower with mean absolute gap of 1930 kg/ha representing 73% of YE. The yield gap in low-input (YGF) was even lower with mean absolute gap of 469 kg/ha representing 42% of YF. Mixed-effects models showed that, absolute YGW were larger at sites with higher precipitation in the minor wet and minimum temperature in the minor dry season explaining 22% of the variability in YGW. These same factors and cocoa planting density explained 28% of variability in absolute YGE. Regardless of climate, absolute YGF and relative YGW, YGE and YGF were reduced by increasing cocoa planting density and application of fungicide against black pod. The models explained 25% of the variability in absolute YGF, and 33%, 33% and 25% in relative YGW, YGE and YGF respectively. In conclusion, climate determined absolute YGW in Ghana whilst absolute YGE were determined by both climate and management. In contrast, absolute YGF and relative YGW, YGE and YGF can be reduced by agronomic management practices. SIGNIFICANCE Our study is one of the first to quantify cocoa yield gaps in West Africa and shows that these can be closed by improved agronomic practices

Effects of sub-lethal single, simultaneous, and sequential abiotic stresses on phenotypic traits of Arabidopsis thaliana

Plant responses to abiotic stresses are complex and dynamic, and involve changes in different traits, either as the direct consequence of the stress, or as an active acclimatory response. Abiotic stresses frequently occur simultaneously or in succession, rather than in isolation. Despite this, most studies have focused on a single stress and single or few plant traits. To address this gap, our study comprehensively and categorically quantified the individual and combined effects of three major abiotic stresses associated with climate change (flooding, progressive drought and high temperature) on 12 phenotypic traits related to morphology, development, growth and fitness, at different developmental stages in four Arabidopsis thaliana accessions. Combined sub-lethal stresses were applied either simultaneously (high temperature and drought) or sequentially (flooding followed by drought). In total, we analyzed the phenotypic responses of 1782 individuals across these stresses and different developmental stages. Overall, abiotic stresses and their combinations resulted in distinct patterns of effects across the traits analyzed, with both quantitative and qualitative differences across accessions. Stress combinations had additive effects on some traits, whereas clear positive and negative interactions were observed for other traits: 9 out of 12 traits for high temperature and drought, 6 out of 12 traits for post-submergence and drought showed significant interactions. In many cases where the stresses interacted, the strength of interactions varied across accessions. Hence, our results indicated a general pattern of response in most phenotypic traits to the different stresses and stress combinations, but it also indicated a natural genetic variation in the strength of these responses. Overall, our study provides a rich characterization of trait responses of Arabidopsis plants to sub-lethal abiotic stresses at the phenotypic level and can serve as starting point for further in-depth physiological research and plant modelling efforts

Evolutionarily Stable Leaf Area Production in Plant Populations

Using an analytical model, it was shown that for a given amount of nitrogen in the canopy of a stand (N-T), there exists an evolutionarily stable leaf area index (ES-LAI), and therefore an evolutionarily stable average leaf nitrogen content (n(anu)(ES); n(anu)(ES) = N-T/ES - LAI), at which no individual plant in the stand can increase its photosynthesis by changing its leaf area. It was also shown that this ES-LAI is always greater than the optimal LAI that maximizes photosynthesis per unit N-T of the stand. This illustrates that the canopy structure that maximizes photosynthesis of a population is not the same as the canopy structure that maximizes photosynthesis of individuals within a population. It was further derived that the ES-LAI at given N-T increases with the ratio between the light-saturated photosynthesis and the N content per unit leaf area (leaf-PPNUE) and that it decreases with the canopy extinction coefficient for light (K-L), the light availability and the apparent quantum yield (Phi). These. hypotheses were tested by comparing calculated ES-LAI and n(anu)(ES) values to actual LAIs and leaf N contents measured for stands of a large variety of herbaceous plants. There was a close correspondence between the calculated and measured values. As predicted by the model, plants with high leaf-PPNUEs produced more leaf area per unit nitrogen than those with low leaf-PPNUEs while plants with horizontal leaves, forming stands with higher K-L values, produced less leaf area than those with more vertically inclined leaves. These results suggest that maximization of individual plant photosynthesis per unit of nitrogen plays an important role in determining,leaf area production of plants and the resulting canopy structure of stands of vegetation. They further suggest this optimization to be a mechanism by which leaf traits such as leaf-PPNUE and leaf inclination angle are causally related to structural characteristics of the population, i.e. the leaf area index of the stand. (C) 2002 Elsevier Science Ltd. All rights reserved