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Worldwide, soil degradation due to erosion is still a major issue. Minimum tillage, intercropping, and alley cropping are important features of conservation agriculture and food security, but the farming communities are reluctant to accept these practices due to area reduction and plant competition. We investigated maize sole cropping (T1) as current farmers’ practice; T2: maize intercropped with chilies, tillage and fertilization; T3: maize-chili intercrop, mini. tillage, fertilization, Jack-bean relay cropping; T4: Like T3 but with hedges; T5 and T6 like T3 and T4, respectively, but without fertilization on Thai uplands during 2010 and 2011. Maize above ground biomass (AGB) was higher in T2 than T1 during both years. Light use efficiency (LUE) for AGB was 1.44–1.56 and 1.44–1.96 g DM MJ−1 in T4 during 2010 and 2011, 17–47% higher than T1, respectively. Land equivalent ratio was 1.23 and 1.17 in T2 while 1.28 and 1.21 in T4 during 2010 and 2011, respectively. Maize grain nitrogen (Ng) was significantly lower in unfertilized treatments. Intercropping with soil conservation enhanced land use efficiency with soil protection against erosion. Understanding spatial variations of LUE, Ng, as well as their impact on crop productivity are useful for fine-tuning crop management in conservation agriculture and sustainable land use on uplands.

Acrocomia spp., a genus of wild-growing palms in the neotropics, is rapidly gaining interest as a promising multipurpose crop. Diverse products can be derived from various components of the palm, the oils being of highest interest. Acrocomia shows similar oil yield and fatty acid composition to the African oil palm (Elaeis guineensis). It is, however, able to cope with a wider range of environmental conditions, including temporary water scarcity and lower temperatures, thus potentially a more sustainable alternative to its tropical counterpart. Acrocomia’s research history is recent compared to other traditional crops and thus knowledge gaps, uncertainty, and challenges need to be addressed. This review attempts to assess the acrocomia’s preparedness for cultivation by highlighting the state-of-the-art in research and identifying research gaps. Based on a systematic literature search following a value web approach, it (a) provides a comprehensive overview of research topics, (b) shows the development of publication activities over time and the drivers of this development, and (c) compiles main findings to assess the acrocomia’s preparedness for commercial cultivation. Our results confirm its multipurpose characteristic as a potential feedstock for manifold sectors. Research has continued to increase over the last decade, especially on A. aculeata and is driven by the interest in bioenergy. Increasing knowledge on botany has contributed to understanding the genetic diversity and genus-specific biology. This has enabled applied research on seed germination and propagation toward domestication and initial plantation activities, mostly in Brazil. Main research gaps are associated with genotype–environment interaction, planting material, crop management, and sustainable cropping systems. Overall, we conclude that acrocomia is at an early phase of development as an alternative and multipurpose crop and its up-scaling requires the integration of sustainability strategies tailored to location-based social-ecological conditions.

Agroforestry systems have a large potential to increase systems’ productivity and provide soil conservation in hilly terrain but comprise complex interactions at the crop-soil-tree interface. Modelling can be an operational approach to unravel the later. We used the spatially explicit, dynamic Water Nutrient and Light Capture in Agroforestry Systems model to (i) predict maize above ground biomass (AGB) and interactions at the crop-soil-hedge interface, (ii) improve our understanding of trees’ impact on crops in alley cropping, and (iii) identify mitigation strategies. A 2-year-data set from a soil conservation experiment in Western Thailand with maize farmers’ practice (monocropping, tillage), maize-chili-hedgerow intercropping (±fertilization; minimum tillage) was used as model input. Model validation showed satisfactory results for maize AGB (R2 = 0.76, root mean square error = 4.2, model efficiency = 0.69). Simulations revealed nitrogen (N) and phosphorus (P), rather than light and water, as main limiting factors at the crop-soil-hedge interface reducing maize AGB in rows close to hedgerows. Growth limitation by P was stronger than that of N while light competition was alleviated by four to six hedgerow prunings already. WaNuLCAS simulations clearly indicated that small-targeted additional N and P dressings to maize in rows close to hedges helped overcoming nutrient competition. Such strategic management options can be done for local farmers’ and hence, foster adaptation of soil conservation techniques for sustainable crop production in future.

Hedgerow cropping decreases erosion in hillside agriculture but also competes for water and nutrients with crops. This study combined two methods for an improved understanding of water and nutrient competition at the crop-soil-hedge interface. δ13C isotopic discrimination in plants and soil electrical resistivity tomography (ERT) imaging were used in a field trial with maize monocropping (MM) vs. leucaena hedgerow intercropping with and without fertilizer (MHF+ and MHF−) in Thailand. Hedges significantly reduced maize grain yield and aboveground biomass in rows close to hedgerows. ERT revealed water depletion was stronger in MM than in MHF+ and MHF- confirming time domain reflectometry and leaf area data. In MHF+, water depletion was higher in maize rows close to the hedge compared to rows distant to hedges and maize grain δ13C was significantly less negative in rows close to hedges (-10.33‰) compared to distant ones (-10.64‰). Lack of N increased grain δ13C in MHF- (-9.32‰, p ≤ 0.001). Both methods were correlated with each other (r = 0.66, p ≤ 0.001). Combining ERT with grain δ13C and %N allowed identifying that maize growth close to hedges was limited by N and not by water supply. Combining ERT imaging and 13C isotopic discrimination approaches improved the understanding of spatial-temporal patterns of competition at the hedge-soil-crop interface and allowed distinguishing between water and N competition in maize based hedgerow systems.

We investigate the light quarkonium spectrum using a covariant Dyson-Schwinger-Bethe-Salpeter-equation approach to QCD. We discuss splittings among as well as orbital angular momentum properties of various states in detail and analyze common features of mass splittings with regard to properties of the effective interaction. In particular, we predict the mass of sbars exotic 1-+ states, and identify orbital angular momentum content in the excitations of the rho meson. Comparing our covariant model results, the rho and its second excitation being predominantly S-wave, the first excitation being predominantly D-wave, to corresponding conflicting lattice-QCD studies, we investigate the pion-mass dependence of the orbital-angular-momentum assignment and find a crossing at a scale of $m_\pi$ ~ 1.4 GeV. If this crossing turns out to be a feature of the spectrum generated by lattice-QCD studies as well, it may reconcile the different results, since they have been obtained at different values of $m_\pi$., Comment: 26 pages, 21 figures, 3 tables, revised version according to reviewer comments

We conducted a field experiment on a 53 %-slope in Northwest Vietnam using 15N-labelled urea to trace its fate in maize (Zea mays) under intensive tillage and fertilization (T1, control) versus maize with Panicum maximum grass barriers (T2), under minimum tillage (MT) with Arachis pintoi as cover crop (T3) or relay cropped with Phaseolus calcaratus (T4). 15N-labelled urea was applied to one maize row at the top of each plot one year after trial establishment. At harvest, 21.6 % of the labelled 15N were recovered by maize in T1, 8.9 % in T2, 29 % in T3, and 30.9 % in T4. In T2, maize and P. maximum competed heavily for N with a total 38.1 % of 15N recovered in barriers. Less than 6 % of 15N applied was found in maize rows along the slope regardless of the treatment. MT reduced 15N translocation to deeper soil layers (40–80 cm), indicating a safety net function. Less than 0.1 kg N ha−1 of applied 15N reached the collection devices at the bottom of plots; the majority of added 15N was intercepted by plants along the slope. Current farming practice (T1) induced a negative N balance of −142 kg N ha−1 in which residue burning and erosion were major pathways for N losses. Reduced N losses by erosion in T2 contributed to a less negative N balance as compared to T1. Positive N balances of MT treatments were associated with strongly reduced N losses by erosion and abandonment of burning residues, indicating a viable option for hillside cropping.

Soil conservation approaches and agroforestry systems can play an important role in controlling erosion from tropical hillside cropping systems. Experimental testing of their potential application domain and design, however, is costly and time consuming. We, therefore, tested the ability of the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model. The specific objectives of the study were: (i) to evaluate the WaNuLCAS model for predicting water induced erosion under different soil conservation strategies, (ii) to use the model for a better understanding of various soil conservation measures in controlling erosion, and (iii) to assess the magnitude and dynamics of key processes influencing the efficiency of soil conservation measures. A 3-year-data set (2003–2005) from a field experiment from the Loei province in Northeast Thailand on the impact of soil conservation (Leucaena hedgerow, Jack bean relay cropping) under minimum tillage on runoff and soil loss was tested. Results indicated that WaNuLCAS was able to predict soil loss and runoff well at the test site; i.e. R 2 = 0.80 and 0.82, respectively. In the calibration procedure a sub data set was used, where adjusting crop development parameters was an important step for improving simulated soil loss (R 2 = 0.75) and runoff (R 2 = 0.89). Soil conservation measures such as Leucaena hedges were effective techniques to control runoff and soil loss. Implementing a dynamic soil structure module in combination with minimum tillage reduced runoff and soil loss via an increase in available macropores and hence drainage over time which improved simulation results. Relay cropping with Jack bean played an important role in the control treatment in reducing soil loss during the third year due to its additional soil cover and positive impact on soil fertility as suggested by the model. Hence, the WaNuLCAS model is a valuable tool to study and understand processes and to explore management options for improving tropical hillside cropping threatened by soil degradation.

Competition for nutrients and water between crops and associated hedgerows reduces overall performance of contour hedgerow systems and hampers its acceptance by rural communities in tropical mountainous regions. Therefore, it is imperative to better understand competition leading to a decline in crop response close to hedges. In the highlands of North East Thailand spatial variability in grain yield of maize (Zea mays L., cv. Suwan 1) was assessed for two contour hedgerow systems based on Brachiaria ruziziensis Germain et Evrard (Ruzi grass) barriers or Leucaena leucocephala (Lam) de Wit hedges without or with fertilizer (60 kg N ha−1 and 14 kg P ha−1). Available % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX!% MathType!MTEF!2!1!+-% feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX% garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz% aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq% Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq% Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca% WGobGaam4tamaaDaaaleaacaaIZaaabaGaeyOeI0caaOGaeyOeI0Ia% amOtaaaa!3CD8! $$NO^{ - }_{3} - N$$ was analyzed across the slope. In addition, shoot N concentration and δ13C values in leaves were measured for maize plants in the center of the alley and in the row next to and at the upper side of barriers or hedges. Despite variable field conditions, δ13C values were significantly (p