Impact of newly introduced perennial bioenergy crops on soil quality parameters at three different locations in W‐Germany

The land areas used for bioenergy crop cultivation are increasing across Europe. For several years now, various perennial crops have been cultivated, including Miscanthus , switchgrass and reed canary grass, and the newly introduced cup plant, giant knotweed, tall wheatgrass, virginia mallow, and wild plant mixtures. We investigated the impact that many of these perennial bioenergy crops (PECs) have on the soil organic C and N pools, microbial properties, and earthworm activity at three different study sites in W‐Germany with varying soil conditions after an experimental period of five years. Silage maize (Zea maize ) in rotation with green rye (Cecale cereale ) or Triticale was used for comparison (= annual energy crops; AEC). The overall intention of this study was to gain insights into the future trends of soil quality with changes in land‐use towards bioenergy production. Our results emphasized that in general, soil quality was improved through the cultivation of perennials. For example, after five years of investigation, the mean soil organic carbon contents increased, on average, by 1–2% at two of the three study sites, the soil microbial biomass increased from 13% (virginia mallow) to 27% (tall wheatgrass) (p < 0.05) compared to AEC treatment and the mean earthworm activity (cast production) was significantly improved in PECs compared to AEC. These trends were mainly found in silty to loamy soils, but the results were slightly different in sandy soils and dry climate conditions. We suggest that this might be traced back to unfavourable growing conditions for perennial crops during the first years of establishment. To our knowledge, this is the first comprehensive field investigation of the impact of these newly introduced perennial crops on soil quality indicators that considers various site‐ and soil‐specific growth conditions.     

Anaerobic co‐digestion of perennials: Methane potential and digestate nitrogen fertilizer value

Co‐digestion of crop biomass improves the traditional manure‐based biogas yield due to an increased content of easily degradable carbon compounds. In this study, the methane potential of three perennials (grass, legumes, and grass+legume) was determined using various amounts together with animal manure. The nitrogen (N) mineralization dynamics in soil and the N‐fertilizer value of the derived digestates were subsequently tested in both a soil incubation study and a pot experiment with spring barley. Digestion of all tested perennials together with a manure‐based inoculum increased the cumulative methane yield four to five times compared to digestion of the inoculum alone, with the highest increases observed with pure grass. However, the methane potential decreased along with increasing grass biomass concentration. In the plant pot experiment, all tested digestates increased barley shoot biomass by 40–170%, to an extent statistically comparable to mineral N fertilizer. However, the application of the digestate originating from fermentation with pure grass resulted in lower plant growth and a more fluctuating soil mineral N content throughout the incubation study compared to the other digestates. Considering the high dry matter and methane yield ha^?1, the possibility to substitute mineral N fertilizer inputs by leguminous biological N₂ fixation capacity, and the digestate fertilizer value, the integration of grass–legume mixtures or sole legumes into anaerobic digestion systems as co‐substrate for manure seems to be promising. This could furthermore contribute to the diversification of cropping systems for bioenergy production.     

浅谈宿根花卉在北方园林花境中的应用

介绍了宿根花卉在花境中应用的主要品种、形式及应注意的问题,旨在促进优良的宿根花卉在园林绿化中广泛合理地应用。     

Differential Growth Response to Salt Stress Among Selected Ornamentals

Evaluation of salt tolerance in herbaceous perennials was performed with mature potted plants under greenhouse conditions. Six herbaceous perennial species were evaluated for their tolerance to aqueous solutions of various sodium chloride (NaCl) concentrations over a 21 day period by measuring growth, water transpiration, and leaf nutrient content. Potential exists for utilization of these species in somewhat challenging saline environments along roadsides and in urban landscapes. Species evaluated in a mature growth stage included Achemilla mollis, Nepeta x faassenii, Sedum acre, Thymus praecox, Phlox subulata and Solidago cutleri. On the basis of relative growth rate and water transpiration responses to NaCl (0–400 mM) treatments, groundcovers were grouped into three tolerance categories: highly sensitive to salt treatment (S. acre), those with intermediate sensitivity (A. mollis, N. x faassenii, T. praecox, and P. subulata), and those exhibiting tolerance (S. cutleri). Sodium content in leaf foliage of S. cutleri was about ten-fold lower than other groundcover species in the 200 mM NaCl treatment, consistent with greater tolerance to NaCl treatments in terms of transpiration, biomass accumulation, and retention of green foliage. Comparison of foliar nutrient levels among groundcover species and treatments suggested strong differential response to NaCl treatment, indicating that changes in nutrient levels over time may be a reasonable way to predict NaCl tolerance in groundcovers.     

Nutrient contribution and maize performance in alley cropping systems

Dry matter yield and potential contribution of N, P and K of some woody perennials as well as performance of maize were assessed in an alley cropping system at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Dry matter yield was highest forCassia, followed byGliricidia and theFlemingia. Whereas dry matter yields ofCassia varied significantly at the various pruning times, those ofGliricidia andFlemingia were relatively uniform.Gliricidia contributed the highest amount of N from the cutback (first pruning) and three subsequent prunings. Dry wood yield at cutback was 14.5, 6.8 and 29.7 tonnes/ha forGliricidia, Flemingia andCassia respectively. Coppicing rate was faster inGliricidia thanFlemingia andCassia. Maize height, stover and cob weights were reduced though insignificantly, for the maize rows close to the shrub hedgerows compared to those in the middle of the alleys. For the plots without N application and prunings removed, the maize near the hedgerows showed better performance than those in the middle of the alleys. The results indicate that N supplementation is needed in the alley cropping systems to optimize yield. The amount of N required is higher inFlemingia alleys than forGliricidia andCassia. Root growth of maize was found to be restricted in control plots without hedges; uptake of the major nutrients (N, P and K) was also found to be similarly affected in those plots.     

Hydrological behaviour of rain gardens and plant suitability: A study in the Veneto plain (north-eastern Italy) conditions

Since spring 2011 the roof of a building on the Agripolis Campus of the University of Padova (Italy) has been used as a drainage area for two rain gardens with a circular area of about 10% and 20% of the drainage area respectively. To improve soil infiltration, the topsoil was removed up to the depth of 1 m and filled with a mix of 50% sand, 25% compost and 25% of the existing topsoil. Herbaceous perennials were selected and planted to test their adaptability to different soil water conditions in the rain garden. To evaluate the capacity of each rain garden to manage stormwater runoff a simplified water balance was done, estimating actual evapotranspiration using the WUCOLS method. From autumn 2012 runoff volumes were collected just from one pitch of the roof, and directed only into the smaller rain garden that became equal to 15% of the new roof drainage area. We thus had the possibility to test the functionality of rain gardens with three different percentages of roof drainage area: 10, 15 and 20%, even if in different periods. Results are presented relating to a four-year experimental period. Regarding hydrological behaviour, the input water volumes caused a slight overflow only during a few rainfall events. Consequently, the results showed a high capacity to manage stormwater runoff and also in the smaller rain garden almost the total roof runoff volumes infiltrated into the soil. As regards plants, the results indicated that the growth is affected by their position in the rain garden, from the wettest condition in the centre to the driest at the perimeter, except for Hemerocallis hybrida that showed great adaptability in all positions. Aster novi-belgii, Echinacea purpurea, Iris pseudacorus, Molinia caerulea and Rudbeckia fulgida also showed good adaptation, even if not in all rain garden zones, with highly aesthetic results. Lythrum salicaria and Saponaria officinalis plants appeared to be unsuitable for rain gardens. The results of the experiment have shown that, in the Veneto plain environment, rain gardens with a size of 10–15% of the roof drainage area can ensure both the sustainable management of stormwater runoff and a high aesthetic functionality.     

Impact of Brassica juncea biofumigation on viability of propagules of pernicious weed species

Biofumigation may be a promising tool for depletion of persistent weed seedbanks/bud banks. This technique is based on the incorporation of chopped glucosinolate‐rich plant biomass into the soil, upon which isothiocyanates with herbicidal properties are released. To gain acceptance by farmers and foster its implementation, the biofumigation process should be further optimised. This study elucidated the impact of biological (species), technical (burial depth, ground cover) and pedohydrological (temperature and moisture content) factors on efficacy of Brassica juncea biofumigation under (semi‐)natural conditions. In a first experiment (field experiment), seeds and vegetative propagules of various weed species were buried at different depths and exposed to different doses of fresh fine‐chopped B. juncea biomass in the presence or absence of a plastic ground cover. In a second experiment (container experiment), buried seeds of ten species were subjected to biofumigation at diverging soil organic matter content, soil moisture content and soil temperature. In a third experiment (dose–response Petri dish bioassay), unburied seeds of eight species were subjected to various doses of rehydrated B. juncea powder. Biofumigation efficacy was determined by analysing viability of treated and untreated propagules. In general, efficacy of biofumigation increased with decreasing burial depth and increasing B. juncea dose. Biofumigation was highly effective (mortality >85%) against small‐seeded species but less effective (mortality 0%–20%) against hard‐seeded and large‐seeded species at 200 t ha^?1. Vegetative propagules of Sonchus arvensis, Equisetum arvense and Convolvulus sepium were highly sensitive (mortality >90%) to biofumigation. Efficacy was most pronounced under moist warm incubation conditions, in the presence of a plastic ground cover.     

宿根花卉在园林中的应用与展望

近年来,出于对生态环境的关注,景观设计理念与方法发生了极大变化。融合生态学观点的设计成为一种趋势。宿根花卉种类与品种丰富、景观效果好、养护管理便利,在园林中得到广泛应用。在概述宿根花卉的国内外研究现状基础上,结合石家庄花卉园改造案例,分析宿根花卉的园林应用形式,进一步讨论分析了宿根花卉应用趋势、限制宿根花卉应用的因素、宿根花卉产业的健康、可持续发展策略。     

Comparative analysis of laboratory freezing methods to establish cold tolerance of detached rhizomes and intact crowns in garden chrysanthemums (Dendranthema × grandiflora Tzvelv.)

Since 1926, the University of Minnesota herbaceous perennial breeding program has released N = 84 garden chrysanthemum cultivars (Dendranthema × grandiflora) with important traits for northern temperate climates, such as winter hardiness. Recent breeding objectives have identified the need for development of non-destructive phenotypic markers and destructive laboratory freezing tests for co-selection of cold tolerance in Dendranthema, Gaura, and other herbaceous perennial flower crops. Such methods have become critical to flower breeding programs in northern temperate regions during periods of above-average winter temperatures and minimal snow cover due to the ‘el Niño’ effect. Two different, destructive laboratory freezing tests were evaluated for their effectiveness in determining cold tolerance. Acclimated crowns of n = 6 garden chrysanthemum genotypes, ranging from hardy to non-hardy in USDA Z3-4, were used in Omega Block (using detached, emergent rhizomes) and chamber (using entire, intact crowns with emergent, non-emergent rhizomes) freezing test methods. Comparative winter survival in the field was monitored over locations and years. Cold tolerance was assessed at 0 to −12 °C with varying ramp and soak time periods. LT₅₀ temperatures and number of living emergent rhizomes were also determined. Rhizome quality at 1, 3, and 5 cm depths was rated for regrowth on a 0 (dead) to 5 (undamaged) scale. The chamber freezing method was the most powerful to discern accurate LT₅₀ values. Cold tolerant genotypes included ‘Duluth’ and Mn. Selection 98-89-7 (LT₅₀ = −12 °C). Four genotypes were rated as non-hardy (LT₅₀ = ≤−10 °C). Cold-tolerant genotypes also had significantly higher regrowth ratings for rhizomes at 1 and 3 cm depths. Future research will implement the chamber freezing method to assay the inheritance of winter hardiness in intact crowns of segregating populations.     

Survival and growth of rattan intercropped with coffee and cacao in the agroforests of Indonesia

This study investigated the intercropping of rattan, an important non-timber forest product, in coffee and cacao agroforests in Sulawesi, Indonesia. The viability of producing seedlings from seeds and vegetative cuttings with the large-diameter rattan, Calamus zollingeri Beccari, and initial seedling survival, growth and response to light and soil drainage were investigated in village nurseries and perennial farms. Over 96% of seeds and 61% of vegetative cuttings were raised to transplanting size (25 cm with two to three leaves) over 20 months. One hundred C. zollingeri seedlings produced from cuttings were transplanted into each of three coffee or cacao farms and one primary forest site and exhibited an overall survival rate of 96%, 12.7 cm of height growth and the production of 0.8 new leaves per plant after eight months. No significant differences were observed between the four sites with respect to seedling survival, growth, or leaf production and no significant differences were found between seedling survival, growth or leaf production and light intensity (based on multiple PAR measurements). However, poorly drained sites exhibited significantly reduced C. zollingeri seedling survival and growth. The cultivation of C. zollingeri rattan in coffee and cacao agroforests represents a potential means of intensifying and diversifying perennial cash crop farming systems.This revised version was published online in November 2005 with corrections to the Cover Date.