Productivity of organic and conventional arable cropping systems in long-term experiments in Denmark

A field experiment comparing different arable crop rotations was conducted in Denmark during 1997–2008 on three sites varying in climatic conditions and soil types, i.e. coarse sand (Jyndevand), loamy sand (Foulum), and sandy loam (Flakkebjerg). The crop rotations followed organic farm management, and from 2005 also conventional management was included for comparison. Three experimental factors were included in the experiment in a factorial design: 1) crop rotation (organic crop rotations varying in use of whole-year green manure (O1 and O2 with a whole-year green manure, and O4 without), and a conventional system without green manure (C4)), 2) catch crop (with and without), and 3) manure (with and without). The experiment consisted of three consecutive cycles using four-course rotations with all crops present every year, i.e. 1997–2000 (1st cycle), 2001–2004 (2nd cycle), and 2005–2008 (3rd cycle). In the 3rd cycle at all locations C4 was compared with two organic rotations, i.e. O2 and O4. The O2 rotation in the third cycle included spring barley, grass-clover, potato, and winter wheat, whereas C4 and O4 included spring barley, faba bean, potato, and winter wheat. For the O2 rotation with green manure there was a tendency for increased DM yield over time at all sites, whereas little response was seen in N yield. In the O4 rotation DM and N yields tended to increase at Foulum over time, but there was little change at Flakkebjerg. The DM yield gap between organic and conventional systems in the 3rd cycle varied between sites with 34–66% at Jyndevad, 21–44% at Foulum, and 32–52% at Flakkebjerg. The inclusion of grass-clover resulted in lower cumulated yield over the rotation than the treatment without grass-clover. The use of manure reduced the DM yield gap between conventional and organic systems on an average by 15 and 21%-points in systems with and without grass-clover, respectively, and the use of catch crops reduced the yield gap by 3 and 5%-points in the respective systems. Across all crops the agronomic efficiency of N in manure (yield benefit for each kg of mineral N applied) was greater in O4 compared with O2 for all crops.     

Integrated sustainability assessment of cropping systems with agro-ecological and economic indicators in northern Italy

The sustainability of agricultural systems is frequently evaluated with indicators, which are synthetic variables describing complex systems. Each indicator deals with one aspect of sustainability (e.g. nutrients, pesticides, energy), and therefore the result of a complete assessment usually includes several indicator values. These values are frequently presented separately, while an integrated evaluation could benefit from the calculation of a single sustainability index. The aim of this work was to integrate 15 economic and environmental indicator values into a global sustainability index (S_g) ranging from 0 to 1.To calculate the indicators, we used a large data set of cropping systems management for 131 fields cultivated with arable crops in northern Italy, obtained through periodic interviews with farmers over a 2-year period. The fields were chosen to represent the main cropping systems in the area (cereals and forages, on animal and cereal farms). The 15 indicators describe a large variety of sustainability aspects, i.e. the economic performance and the management of energy, nutrients, soil, and pesticides.The indicator values were first converted into a sustainability score (S_i; 0–1) applying continuous non-linear sustainability functions that use thresholds defining what is sustainable, unsustainable, or intermediate. We obtained 15 values of S_i per each field, which we aggregated into S_g using indicator-specific weights provided by different stakeholders. This procedure permits not only the single indicators evaluation, but also to combine indicators for an assessment of cropping systems at field level.Permanent meadows, due to good management of soil, pesticides and nutrients, obtained the highest S_g, even when different weights were used. Continuous rice obtained the lowest S_g (due to unsatisfactory soil management, low energy production, and high pest and weed pressure, which involved a large use of pesticides), while maize was intermediate, with good economic and energetic performance.The methodology allows a transparent, repeatable, sound, and quantitative evaluation of sustainability of agricultural systems. It can be easily expanded by adding other indicators, and can be tailored by changing the thresholds used to calculate S_i and the weights assigned by stakeholder groups.     

Long-term evaluation of productivity,stability and sustainability for cropping systems in Mediterranean rainfed conditions

Mediterranean cropping systems in rainfed conditions are generally based on rotations with a very high frequency of winter wheat and, therefore, they are at risk of declining trends for yield and soil health in the long-term. In order to quantify this risk, a long-term experiment was set-up in 1971 in central Italy, which is still running at present (2016). This experiment is based on 13 rotations, i.e. three continuous winter wheat systems with different N fertilization rates (W150, W200 and W250), five maize/winter wheat rotations with increasing wheat frequency (maize preceded by 1–5 years of wheat: i.e., WM, 2WM, 3WM, 4WM and 5WM) and five two-year rotations of winter wheat with either pea (WP), faba bean (WFB), grain sorghum (WGS), sugar beet (WSB) or sunflower (WSU). All these rotations are managed either with the removal of crop residues after harvest (REM), or with their burial into the soil at ploughing (BUR). For each rotation, all phases are simultaneously grown in each year, according to a split-plot design (with REM and BUR randomised to main plots), with three replicates in complete blocks and plots of 24.5 m² each. The following data are considered: (1) total and marketable biomass yields from 1983 to 2012; (2) content of Organic carbon (OC) and total nitrogen (N) in soil, as determined in 2014. Considering the 30-year period, BUR resulted in an average positive effect on yield (+3.7%), increased OC (+13.8%) and total N content (+9.4%) in soil, while the C/N ratio was not significantly affected. Wheat in two-year rotations showed a significantly higher (+19.4%) average yield level than in continuous cropping or in 2WM, 3WM, 4WM and 5WM, mainly due to a drop in yield occurring in the first (−13%) and second (−19%) year of recropping. Increasing N fertilisation level from 150 to 250 kg N ha⁻¹ with continuous cropping resulted in an increase (+3.7%) in long-term average yield and in a decrease in yield stability. All rotations heavily based on wheat (continuous cropping and 5WM) produced the highest amount of buried biomass (>175 t ha⁻¹ in 30 years), with the highest increase in soil OC content (>16 t ha⁻¹). All the other rotations produced a lower amount of residues and were less efficient in terms of carbon sequestration in soil, apart from WFB, which gave a high increase in soil organic carbon content (+18.9 t ha⁻¹ in 30 years), in spite of a low amount of buried residues (158 t ha⁻¹).     

Assessing the sustainability of cropping systems in single- and multi-site studies. A review of methods

The multiple new challenges facing agriculture require the development of innovative cropping systems with high environmental, economic and social performances. Many research programmes are currently focusing on the design of such cropping systems. Some include the multicriteria assessment of cropping systems by diverse methods and approaches. Some of these research programmes are supported by experimental or farmers’ networks, generating new opportunities for data analysis and raising new research and methodological questions. In this article, we provide an overview based on a review of 56 articles, comparing the various methods for sustainability assessment in single- and multi-site studies. Articles were classified according to three characteristics: (i) their objectives, (ii) the study design (single- vs. multi-site), (iii) the type of system assessed (fictitious vs. real). Our analysis was structured around four items: (i) the variables used to describe cropping systems and production situations and the use of these variables in the assessment process, (ii) the criteria and associated indicators assessed, (iii) the methods used to explore multiple aspects of the performance of cropping systems, (iv) the use of reference values. We identified key points to be taken into account in multi-site studies. The application of the proposed guidelines to experimental networks should facilitate the identification of high-performance cropping systems and the identification of the drivers of cropping system performance.     

Inner farm nutrient flows between arable land and permanent grassland via the stable in organic cropping systems

Organic farming systems are characterized by the strong regulation of the import of nutrients into the farming system. Recently, nutrient budgets in organic farming especially with regard to potassium (K) and phosphorus (P) have gained interest. In the present study inner farm mineral nutrient flows of P, K and magnesium (Mg) among the farmland sub-compartments arable land and permanent grassland via the dairy stable were analysed. The objectives of the current study were (1) to quantify the inner farm nutrient flows among different farmland sub-compartments, and (2) to assess the effect of purchased biomass on inner farm nutrient cycles. Results indicated that the ratio of the nutrients N, P and K in the stable inputs (feed, bedding) greatly differed depending on the kind of biomass introduced into the stable (roughage in comparison to concentrates or straw for bedding), i.e. via grassland biomass much more K (7.9 kg) per kg P were introduced than with feeds harvested on arable land like silage maize (4.9 kg K per kg P), concentrates like cereals (1.3–1.6 kg K per kg P) or grain pulses like peas (2.4 kg K per kg P). The different inputs are mixed in the manures leading to intermediate concentration in the stable manures, with the consequence that nutrient composition of the manures does not match the composition of the single stable inputs. Therefore, balances of nutrient flows in such mixed systems indicate a relative transfer of K from grassland to arable land via the stable manure (approximately 10–30% of the manure derived from grassland K, depending among others on the amounts of straw high in K needed for animal bedding), if P was used as reference nutrient for stable manure allocation to permanent grassland and arable land. Yields of non-legumes in arable cropping in organic farming systems is very often limited by nitrogen (N) supply, whereas it is well known that manure additions are rather ineffective on permanent grassland high in legumes. The higher N demand of arable crops as well as P and K offtakes from arable land via sold animal and plant products give some scope for a preferable use of stable manures for manuring arable land to replace mineral nutrient outputs and to improve the soil N and the soil humus status, increasing the demand for supplement of mineral nutrients on the permanent grassland area to avoid long-term impoverishment of soil fertility.     

黄淮海平原南部不同种植体系周年气候资源分配与利用特征研究

探明不同种植体系周年产量、气候资源分配及其利用效率特征,建立周年气候资源优化配置的定量指标,为进一步提升黄淮海区域周年产量潜力和资源利用效率提供理论依据。本研究利用2011—2015年河南新乡定位试验数据,定量分析了冬小麦–夏玉米、冬小麦–夏大豆、双季玉米和一季春玉米4个种植体系产量、生物量、干物质产能、光温资源分配及其利用效率。结果表明,冬小麦–夏玉米和双季玉米体系4年产量、生物量和干物质产能差异均不显著,但显著高于冬小麦–夏大豆和一季春玉米体系,平均增幅分别为45.4%～61.5%、37.3%～71.3%和35.7%～70.7%;双季玉米和一季春玉米体系周年辐射生产效率、籽粒及总生物量光能利用效率均显著高于冬小麦–夏玉米和冬小麦–夏大豆体系,其中周年辐射生产效率平均增幅为11.8%～66.7%,籽粒及总生物量光能利用效率分别提高0.13～0.42和0.18～0.69百分点。进一步分析周年气候资源分配特征,冬小麦–夏玉米体系两季积温分配率分别为45.6%和54.4%,积温比值为0.8,双季玉米两季积温分配率为51.4%和48.6%,积温比值为1.1。综合分析产量和资源利用效率,冬小麦...     

Diversity of methodologies to experiment Integrated Pest Management in arable cropping systems: Analysis and reflections based on a European network

Integrated Pest Management (IPM) aims to promote physical and biological regulation strategies that help farmers contain populations of pests (pathogens, animal pests and weeds) and to finally reduce the reliance on pesticides. It is based on the holistic combination of multiple management measures rather than on the sum of single methods, each of them having only small effects on pests reduction. Thus, to analyse the interactions between IPM measures and to evaluate the sustainability of their implementation, we require an approach considering the whole cropping system (CS), i.e. a functional entity whose complexity is more than the sum of its parts. A network of European experiments at the CS level was set up recently, and aimed at sharing data and expertise to enhance knowledge of IPM. Comparison of existing methodologies highlighted a diversity of CS designs and experimental layouts. We deduced that the concept of CS itself was viewed differently among scientists, and this affected experimental protocols. Other differences were related to the research context and objectives. Some experiments aimed to explore very innovative strategies and generated knowledge on both their effects on the agroecosystem and their ability to satisfy a set of performance targets, while others aimed to provide quickly adoptable solutions for local farmers in line with the current socio-economic constraints. In some research programmes, the experiment was part of the CS design process — and tested CS were regularly revised based on an continuous improvement loop — while in other cases CS were kept stable across years so as to enable the evaluation of their long-term cumulative effects. A critical aspect contributing to the diversity among CS experiments was the distinction between a factorial design of experimental CS and systemic approaches: factorial experiments allowed quantification of the effects of each IPM component regardless of the consistency between components defining the CS. In contrast, systemic approaches focused on the overall evaluation of CS designed with consideration of their consistency, hence maximising their ability to meet the objectives. Because CS experiments represent a huge investment in terms of economics and time, preliminary reflections of the relevance of the experimental strategy is of critical importance.     

An empirical analysis of risk in conventional and organic arable farming in The Netherlands

This paper assesses and compares risk in conventional and organic arable farming in The Netherlands with respect to family farm income and underlying price and production variables. To investigate the risk factors the farm accountancy data network was used containing unbalanced panel data from 196 conventional and 29 organic representative Dutch arable farms (for the period 2002 up to and including 2011). Variables with regard to price and production risk were identified using a family farm income analysis scheme. Price risk variables are input and output prices, while yield volatility of different crops is the main production risk variable. To assess risk, an error components implicit detrending method was applied and the resulting detrended standard deviations were compared between conventional and organic farms. Results indicate that the risk at the level of family farm income is higher in organic farming. The underlying variables show higher risk for organic farms in crop yields, crop prices and variable input costs per crop.     

松嫩平原耕作黑土土壤动物群落的区系组成和生态分布

摘要：为了解松嫩平原不同纬度耕作黑土的环境差异及对土壤动物群落组成的影响。2009年5月、8月、10月在松嫩平原（黑龙江省境内）选取5个代表性耕作黑土土壤动物群落进行研究,共捕获大型土壤动物41类,2242只,中小型土壤动物获49类,15050只,隶属于3门7纲22目57科。研究结果表明,5个样地的土壤动物个体数和类群数水平分布具有明显的差异,在海伦,无论是大型土壤动物还是中小型土壤动物个体数和类群数都占有绝对优势,最北部的嫩江最少。耕作黑土中的大型土壤动物垂直分布表聚性不明显,中小型土壤动物的表聚性则较明显,但与森林土壤相比其表聚性不显著。分析表明不同地区土壤动物多样性指数H＇,大型土壤动物：嫩江>依安>海伦>呼兰>绥化;中小型土壤动物：海伦>呼兰>绥化>嫩江>依安。     

Genotypic yield responses of lowland rice in high-altitude cropping systems

Rising global mean temperatures open opportunities in high-altitude production systems for temperature-sensitive crops such as lowland rice. Currently, the cropping window for rice in higher altitudes is still narrow, and thus, genotypes that tolerate a certain degree of chilling are needed to achieve their potential yield. Final yield depends on the interaction between genotype and environmental conditions. Exposing the genotype to a wide range of environments is a way to evaluate its adaptability into an expanding cropping calendar. Over a 2-year period, an experiment was conducted in lowland rice systems in Madagascar at two locations differing in altitude. Twenty genotypes with contrasting levels of tolerance to low temperature were sown monthly in a non-replicated rice garden trial. Plant development was monitored and yield and yield components were determined. Yield stability across the different growing environments was investigated. While crop duration was affected by sowing dates and altitude, yield was mainly determined by sowing date. Panicle number per m² and number of spikelets per panicle were the most limiting factors for yield potential in mid-altitude, while in high altitude, yield was mainly limited by spikelet fertility. Resulting cropping calendar and genotype recommendations are discussed.     

Design,rationale and methodological considerations for a long term alternative cropping experiment in the Canadian plain region

An interdisciplinary field experiment was initiated to evaluate sustainability of crop production in the Canadian Prairie region. The objective was to develop a resource that would be used to measure change over time associated with input and cropping diversity strategies. The knowledge generated would serve to provide early indications of potential problems and to guide development of improved systems. The study was located near the geographic center of the region on the transition between the semi-arid prairie and the sub-humid parkland regions. The design of the study is reported here, while later papers will report and discuss treatment responses. The study is based on three levels of inputs; organic, reduced and high combined with three levels of cropping diversity: low, diversified annual grains and diversified annual perennial to give a matrix of nine treatments. The site was uniformly cropped and characterized for one year prior to imposition of the treatments, and results used to validate the experimental design. Systems were defined by general principles that incorporate flexibility and allow systems to be changed so they could function in a near optimal state. Several grassland sites and one native prairie site located nearby were characterized as reference points for examining biodiversity and soil quality attributes of the treatments. To accommodate multidisciplinary use of the data, a central database was developed that allows all collaborating scientists to access the data, yet protects data integrity. Overall results to date provide a clear indication that the study provides a resource that is well suited to meet the objectives.     

Mutations affecting nodulation in grain legumes and their potential in sustainable cropping systems

Many spontaneous and a large number of induced mutants that show altered nodulation pattern have been isolated in pea, soybean, common bean, faba bean, chickpea, groundnut and pigeonpea. Available information on nodulation mutants in these crops is summarised. The importance of nodulation mutants in basic studies on plant-microbe symbiotic interactions, nitrogen fixation and breeding of cultivars with higher yield and nitrogen fixation rate are examined. The nodulation mutants, after inoculation with specific bacterial strains or a number of different strains, show either: no nodulation (nod-), few nodules (nod+/-), ineffective nodulation (fix-), hyper nodulation (nod++) or hypernodulation even in the presence of otherwise inhibitory nitrate levels (nts). No spontaneous hypernodulation or nts mutants have been found, all have been induced in independent experiments using different cultivars of pea, soybean and common bean after mutagenising seeds. Most nodulation mutants show monogenic recessive inheritance, though semi-dominant and dominant inheritance is also reported. Nodule number is controlled by a process known as autoregulation; hypernodulating mutants show relaxed autoregulation. By grafting shoots of hypernodulating soybean mutant on normal nodulating soybean, mungbean and hyacinth bean, presence of a common, translocatable signal has been shown. Nodulation mutants have contributed to the understanding of the genetic regulation of host-symbiont interactions, nodule development and N fixation. Initially, the hypernodulating mutants were found to be poor in yield. Using the induced hypernodulating mutant, a new soybean cultivar ‘Nitrobean 60’, has been released in Australia. This cultivar is reported to have given 15% higher yield over cv. ‘Bragg,’ and contributed a higher amount of fixed N to the following cereal crop in rotation. Prospects of using the nodulation mutants in developing grain legume cultivars that combine high yield with high residual N, within the bioenergetic constraints, for developing sustainable cropping systems are examined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Designing cropping systems for efficient use of limited water in southern Australia

There has been continuous change in the systems of cereal production in southern Australia where the climate is semi-arid with moderately wet winters and hot dry summers. At the outset wheat (c. 1840) was grown in continuous culture as the land was gradually cleared for cropping, but yields declined to uneconomic levels by 1900. That system was then replaced with fallow-wheat rotations, and using phosphorus fertilizer, yields recovered, but not to the original level. From 1945, the high profitability of sheep production encouraged improvement of legume-based pastures and the introduction of pasture-crop sequences – ley-farming. Productivity was greatly increased and the yield of wheat crops regained the original level. But such were the rates of acidification and salinization of soil that reduced productivity and, in the case of salinity, reduced stream quality and threatened adjacent natural ecosystems. This ley-farming system was used until the late 1980s when prices for wool fell dramatically, and farmers reduced sheep numbers and intensified cropping. The thrust since then has been to design cropping systems that are economically as well as environmentally acceptable with salinity control as the major objective. There is now a search for systems that use more water to reduce drainage through the soil and lower saline water tables. A major contribution is the much restricted use of fallow but summer active plants are also required to provide a soil water storage buffer to retain autumn–winter rainfall. New systems under evaluation include herbaceous perennials such as lucerne that are readily integrated into a crop-livestock system and agroforestry combinations with various trees. The design and appropriate distribution of the new systems is aided by remote sensing techniques to locate areas of saline discharge and linkages to zones of groundwater recharge, geographical information systems to arrange the data for land system analysis, and computer models of crops and cropping systems. There is a substantial challenge for farmers, agronomists and others to identify and assess suitable new systems and to bring the public into the debate and into the solution.     

Using a multicriteria assessment model to evaluate the sustainability of conservation agriculture at the cropping system level in France

Several international research and development organizations are promoting conservation agriculture in a wide range of contexts. Conservation agriculture is based on a combination of three main principles: (i) minimal or no mechanical soil disturbance; (ii) diversified crop rotations and (iii) permanent soil cover (consisting of a growing crop or a dead mulch of crop residues). However, in the face of the diversity of practices that can be associated with conservation agriculture, of goals assigned to agricultural systems, and pedoclimatic contexts, there is still no empirical evidence about the overall performance of conservation agriculture in France. Global assessments of conservation agriculture, with the full or partial application of its principles and in different contexts, are required to provide a more comprehensive picture of the performance of such systems. We tackled these objectives simultaneously, by evaluating 31 cropping systems with the MASC^® model (for Multicriteria Assessment of the Sustainability of Cropping Systems). These systems were selected to represent a wide diversity of practices, from ploughed conventional systems to crop sequences based on the full application of conservation agriculture principles. Positive interactions were observed between the key elements of conservation agriculture, resulting in better sustainability performances (particularly in terms of environmental criteria). Nevertheless, the systems most closely respecting the principles of conservation agriculture displayed several weaknesses, principally of a social or technical nature, in this study. Careful attention should be paid to attenuating these weaknesses. A more detailed analysis of the results also suggested that decreasing soil tillage tends to decrease the overall performance of the system unless associated with a diversification of the crop rotation.     

Improvement of large-seeded common bean cultivars under sustainable cropping systems in Spain

Approaches are needed to broaden the genetic base and improve earliness and yield potential of large-seeded beans under sustainable cropping systems. The objective of this research was to develop adapted dwarf bean populations having a commercial seed quality and yield suitable for the production in the South of Europe. The original base populations were produced from crosses between genotypes within each Mesoamerica, Nueva Granada and Peru races, and between Peru and Nueva Granada, and Mesoamerica and Nueva Granada races. Visual mass selection for plant performance was practised in the F₂ and F₃ generations. In the F₄ and F₅, single plants were harvested under two cropping systems (sole cropping and intercropping with maize). From F₄, selection was based on precocity, combined with seed yield and seed commercial type. The F_4:7 selected lines from each original population were compared with their parents and five checks at four environments and two cropping systems. Differences among environments, populations, parents and checks were observed for all traits. Under intercropping with maize, there was a 50% reduction in seed yield. Yield of parents and checks belonging to Andean South American races, intraracial (Nueva Granada × Nueva Granada) and interracial (Nueva Granada × Peru) populations, was higher than that of those of Middle American origin. Intraracial crosses within large-seeded Andean South American (Peru race) and Middle American gene pools (Mesoamerica race) did not produce lines yielding more than the highest yielding parent. Only two large-seeded lines selected from crosses between small- and large-seeded gene pools out-yielded the best parent and check cultivar.     

Yield-rainfall relationships in cereal cropping systems in the Ebro river valley of Spain

Wheat and barley yields from three farms in the Ebro river valley are shown to be strongly dependent on seasonal rainfall, particularly that during November-January and March-May of the cropping season. In the driest farm, in Monegrillo, Zaragoza province (seasonal rainfall, 251 mm), yields increased by c. 5.9 (wheat) and 9.4 (barley) kg ha⁻¹ per mm of extra rain during the entire cropping season, taken as October-May inclusive. The other farms, at El Canós and Selvanera in Lleida province, had seasonal rainfalls of 364 and 334 mm, and yields of barley increased by 4.3 and 9.0 kg ha⁻¹, respectively, per mm of extra rain in the cropping season, taken as September to May inclusive.

In Monegrillo, cereals are grown in a cereal-fallow rotation. Normal fallowing (duration 17 months) compared to minimum fallowing (5 months) increased the calculated water content of the top 100 cm of the dominant soils by 19 mm. This extra water was estimated to benefit yield by 7.0% (wheat) and 6.2% (barley), raising the average yields of crops greater than 300 kg ha⁻¹ to 1222 and 1522 kg ha⁻¹, respectively. Agronomic practices in Monegrillo during the fallow should focus on means of increasing the proportion of the rain stored in the profile during the fallow. At all three locations, decreasing water evaporation from the soil during the cropping season would likely benefit yield.     

Season-specific varietal management as an option to increase rainfed lowland rice production in East African high altitude cropping systems

Due to land expansion and an increase in productivity, rice production in sub-Saharan Africa has been growing at a rate of 6% in the past decade. Rainfed rice production systems have accounted for a large share of this expansion. In these systems, the potential growing period not only depends on the length of the rainy season and thus water availability, but is often, especially in the highlands of East Africa, bordered by the onset of the cool period of the year, when low minimum temperatures compromise rice yields. The objective of this study was to investigate the yield potential of 30 rice varieties contrasting in crop duration and cold tolerance in the highlands of East Africa, with its limited length of growing period. A field trial was conducted in the cropping seasons in 2016 and 2017 at the Fogera rice research station, Ethiopia. As a function of the onset of rains, rice was sown mid-July in 2016 and early July in 2017. Early sowing in 2017 led to an extended crop duration and significantly lower yields of the short-duration varieties, and to a shortened duration and significantly higher yields of the medium- and long-duration varieties, when compared to late sowing in 2016. Late sowing compromised yield of the medium- and long-duration varieties because of low temperatures during booting stage, which led to high spikelet sterility. Early sowing resulted in low yields of the short-duration varieties, probably due to low solar radiation during the cloudy rainy season, which coincided with the vegetative stage. Therefore, choice of variety should be a function of the variable onset of the rainy season and related sowing date. However, crop models precisely calibrated for potential varieties and the respective environmental conditions could fully support the selection of a suitable variety, depending on the date of sowing, for example with the help of online tools or smartphone applications.     

Multivariate analysis of traits determining adaptation in cultivated barley

Thirty‐nine barley varieties of different origin, representing different growth types, were included in a series of experiments aimed at analysing the variability in vernalization response, photoperiod sensitivity and earliness per se and establishing the types of ecoclimatic adaptability using multivariate analysis. In the case of spring barley varieties there was no correlation between any of the three traits. For winter barleys, a negative correlation was found between photoperiod sensitivity and vernalization response and between photoperiod sensitivity and earliness per se. Vernalization response and earliness per se showed a positive correlation. Among the winter barley varieties large variations were apparent in photoperiod sensitivity, vernalization response and earliness per se, which resulted in a tremendous variation in flowering patterns and frost tolerance. Between the spring barley varieties only wider variations in photoperiod sensitivity were detected. Based on the cluster analysis, the 39 varieties could be separated into seven groups. The spring barley varieties were placed in two groups, and the winter barleys in five groups representing different adaptational types. Among these five groups two represented the two opposing extreme combinations of photoperiod sensitivity and vernalization response. The combination of large photoperiod sensitivity and no vernalization response resulted in better frost tolerance than did the combination of photoperiod insensitivity and large vernalization response.     

Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

The effect of variation in seasonal temperature and precipitation on soil water nitrate (NO₃N) concentration and leaching from winter and spring cereals cropping systems was investigated over three consecutive four-year crop rotation cycles from 1997 to 2008 in an organic farming crop rotation experiment in Denmark. Three experimental sites, varying in climate and soil type from coarse sand to sandy loam, were investigated. The experiment included experimental treatments with different rotations, manure rate and cover crop, and soil nitrate concentrations was monitored using suction cups. The effects of climate, soil and management were examined in a linear mixed model, and only parameters with significant effect (P < 0.05) were included in the final model. The model explained 61% and 47% of the variation in the square root transform of flow-weighted annual NO₃N concentration for winter and spring cereals, respectively, and 68% and 77% of the variation in the square root transform of annual NO₃N leaching for winter and spring cereals, respectively. Nitrate concentration and leaching were shown to be site specific and driven by climatic factors and crop management. There were significant effects on annual N concentration and NO₃N leaching of location, rotation, previous crop and crop cover during autumn and winter. The relative effects of temperature and precipitation differed between seasons and cropping systems. A sensitivity analysis revealed that the predicted N concentration and leaching increased with increases in temperature and precipitation.     

Comparing the performance of cereal varieties in organic and non-organic cropping systems in different European countries

Top ranking varieties are tested in multiple environments before and after registration in order to assess their value for cultivation and use (VCU testing). Recently, interest has increased in obtaining varieties specifically adapted to organic farming conditions. This raised the question if an independent system of trials may be required for this purpose. To help answering this question, through the exchange network of European cereal researchers SUSVAR (), a number of data sets of agronomic traits from barley, wheat and winter triticale, from trials performed in Denmark, Sweden, The Netherlands, France, Switzerland, UK and Germany, were made available and analysed using an approach based on mixed models involving parameters describing genetic correlation between the two types of experiments, i.e., organic and non-organic (high or low input). Estimated variance components and correlations were used to evaluate response to selection and index selection. The response to index selection was analysed as a function of the fraction of available trials assigned to the organic system. The genetic correlations were interpreted in terms of ranking agreement. We found high genetic correlations between both systems for most traits in all countries. Despite high genetic correlations, the chances of very good agreement in observed rankings were moderate. Combining information from both organic and non-organic systems is shown to be beneficial. Further, ignoring information from non-organic trials when making decisions regarding performance under organic conditions is a sub-optimal strategy.