Conventional Cropping Systems Research Articles

Global changes in soil stocks of carbon, nitrogen, phosphorus, and sulphur as influenced by long-term agricultural production.

Quantifying changes in stocks of C, N, P, and S in agricultural soils is important not only for managing these soils sustainably as required to feed a growing human population, but for C and N, they are also important for understanding fluxes of greenhouse gases from the soil environment. In a global meta-analysis, 102 studies were examined to investigate changes in soil stocks of organic C, total N, total P, and total S associated with long-term land-use changes. Conversion of native vegetation to cropping resulted in substantial losses of C (-1.6kgm-2 , -43%), N (-0.15kgm-2 , -42%), P (-0.029kgm-2 , -27%), and S (-0.015kgm-2 , -33%). The subsequent conversion of conventional cropping systems to no-till, organic agriculture, or organic amendment systems subsequently increased stocks, but the magnitude of this increase (average of +0.47kgm-2 for C and +0.051kgm-2 for N) was small relative to the initial decrease. We also examined the conversion of native vegetation to pasture, with changes in C (-11%), N (+4.1%), and P (+25%) generally being modest relative to changes caused by conversion to cropping. The C:N ratio remained relatively constant irrespective of changes in land use, whilst in contrast, the C:S ratio decreased by 21% in soils converted to cropping - this suggesting that biochemical mineralization is of importance for S. The data presented here will assist in the assessment of different agricultural production systems on soil stocks of C, N, P, and S - this information assisting not only in quantifying the effects of existing agricultural production on these stocks, but also allowing for informed decision-making regarding the potential effects of future land-use changes.

Planting date and yield benefits from conservation agriculture practices across Southern Africa

Managing production risks under high rainfall variability remains a research priority in Southern Africa. In this region, conservation agriculture (CA) has been promoted as useful set of principles that could improve farmers' resilience to climate variability and change. However, matching practices to agro-ecological and farmers' socio-economic conditions remain contentious. Here we combine empirical data and results from a cropping system model to quantify benefits and trade-offs, in terms of sowing opportunity, yield, and yield variability, from adopting CA practices. We hypothesized that CA practices would require less labour, allow farmers to plant earlier, at times closer to optimum planting times and consequently result in higher maize yields.We tested the hypothesis using available household labour and the outputs from a cropping systems model (DSSAT) run for six locations in Malawi, Mozambique and Zimbabwe. Thirty years of climate records and soil characterisations were available for each site. Modelled CA practices included, a basin planting system prepared early during winter (CA-Basins early); a basin planting system prepared late and at the onset of the rains (CA-basins late); an animal draught direct seeder e.g. using a Fitarelli animal traction planter (CA-Direct seed); an animal traction ripper (CA-Ripper); and a dibble stick manual planting system (CA-Dibble). Check conventional cropping systems included conventional mouldboard ploughing prepared early (CMP-early), and late (CMP-late), which mimicked farmers having early or late access to draft power, respectively.Simulated results showed that CA-Ripper, CA-Direct seeding and CA-Basins improved timeliness of operations and enabled earlier planting across all locations compared to conventional systems. Mechanized CA systems potentially offered farmers flexibility on when to plant. However, timely planting of CA systems did not translate into higher yields when carried out during periods of high rainfall variability. Yield benefits of early plantings in CA were only apparent in Zimbabwe. Rainfall patterns showed a shift of 0.28 and 0.39daysyr−1 in planting dates at Chitala and Chitedze, over the simulated 30years. However, this was not evident at the other four locations. Optimum planting dates established for the six locations were 5th to 27th December for Malawi; 26th December to 7th January for Mozambique; and 4th to 7th December for Zimbabwe. For each location, planting maize close to the optimum period resulted in higher yields, irrespective of cropping system. Significantly (P<0.05) lower yield variability values i.e. 25% compared to 32 and 36%, were observed for optimum date plantings. Model generated optimum planting dates could be used to provide farmers with site-specific planting date recommendations.

Impact of Cropping Systems, Soil Inoculum, and Plant Species Identity on Soil Bacterial Community Structure.

Farming practices affect the soil microbial community, which in turn impacts crop growth and crop-weed interactions. This study assessed the modification of soil bacterial community structure by organic or conventional cropping systems, weed species identity [Amaranthus retroflexus L. (redroot pigweed) or Avena fatua L. (wild oat)], and living or sterilized inoculum. Soil from eight paired USDA-certified organic and conventional farms in north-central Montana was used as living or autoclave-sterilized inoculant into steam-pasteurized potting soil, planted with Am. retroflexus or Av. fatua and grown for two consecutive 8-week periods to condition soil nutrients and biota. Subsequently, the V3-V4 regions of the microbial 16S rRNA gene were sequenced by Illumina MiSeq. Treatments clustered significantly, with living or sterilized inoculum being the strongest delineating factor, followed by organic or conventional cropping system, then individual farm. Living inoculum-treated soil had greater species richness and was more diverse than sterile inoculum-treated soil (observed OTUs, Chao, inverse Simpson, Shannon, P < 0.001) and had more discriminant taxa delineating groups (linear discriminant analysis). Living inoculum soil contained more Chloroflexi and Acidobacteria, while the sterile inoculum soil had more Bacteroidetes, Firmicutes, Gemmatimonadetes, and Verrucomicrobia. Organically farmed inoculum-treated soil had greater species richness, more diversity (observed OTUs, Chao, Shannon, P < 0.05), and more discriminant taxa than conventionally farmed inoculum-treated soil. Cyanobacteria were higher in pots growing Am. retroflexus, regardless of inoculum type, for three of the four organic farms. Results highlight the potential of cropping systems and species identity to modify soil bacterial communities, subsequently modifying plant growth and crop-weed competition.

Soil microbial diversity and activity linked to crop yield and quality in a dryland organic wheat production system

One of the primary goals of organic agriculture is increasing soil quality through the enhancement of soil biological diversity and activity. Greater soil microbial activity and diversity increase soil organic matter turnover and contribute to soil fertility, one of the main challenges associated with organic management. The objectives of this study were to 1) compare soil microbial abundance and activity between organic and conventional cropping systems, and 2) explore connections between soil microbial community indicators and crop productivity in organic and conventional winter wheat (Triticum aestivum)/spring wheat/winter pea (Pisum sativum) rotations. Soil and plant tissue was sampled following six years of organic and conventional management, and soil was analyzed for microbial abundance and activity. Fungal and bacterial abundance, soil enzyme activity, and soil organic carbon (C) were greater in the organic system than in the conventional system, and all four measures were positively correlated. Community-level physiological profiling (CLPP) indicated that C substrate utilization was greater in the organic than in the conventional system, though bacterial T-RFLP data did not demonstrate different community structure between systems, suggesting that management type affected bacterial community function, but not structure. Fungal T-RFLP results indicated that fungal community structure was different between the organic and conventional systems. Hay yield and tissue nitrogen (N) were greater in the organic system, and were positively correlated with fungal and bacterial abundance, but grain yield and protein were greater in the conventional system. The results of this study indicate that management type (organic vs. conventional) has implications for microbial abundance and microbial community function, and that differences in soil microbial abundance and activity likely impact crop yields and N uptake.

Long-term weed dynamics and crop yields under diverse crop rotations in organic and conventional cropping systems in the Canadian prairies

Alternative cropping systems are gaining attention throughout the world in order to increase the sustainability of agro-ecosystems. On the Canadian prairies, the tillage-based crop-fallow system has been replaced by no-till reduced input systems or tillage-based organic systems with more diversity in crop rotations but with no external inputs. However, the long-term effects of these alternative systems on weed and yield parameters have not been assessed. A study to examine weed and crop yield dynamics under diverse cropping systems was conducted within a 18-year cropping systems study near Scott, Saskatchewan. The trial was laid out in a split-split-plot design with four replicates. The main plots were three levels of inputs; a high input system (HIGH) that used tillage and inputs to maximize yield, a reduced system (RED) that used no-till practices and minimal inputs, and a tillage-based organic system (ORG) with no external inputs. The subplots were cropping diversity (rotations); fallow-annual grains (LOW), diversified annual grains (DAG), and diversified annuals and perennial forage (DAP). The sub-sub plots were the six phases of each rotation. There was an input by rotation interaction for weed biomass but not for weed density and crop yields. ORG systems had 7× and 4× greater weed density (107 plants m−2), 4× higher weed biomass (154kgha−1), and 32% and 35% lower yields (1052kgha−1) than RED and HIGH systems respectively. RED and HIGH input systems had similar crop yields and lower weed density than ORG. The LOW rotation had the lowest weed density. LOW and DAG rotations had similar yields, which were higher than in DAP. All systems showed an increase in weed density and biomass over time but did not impact on crop yields which was increasing over time likely influenced by a concurrent increase in rainfall. This study concludes that eliminating tillage and reducing agrochemicals is possible but eliminating agrochemicals requires better crop rotations for weed management as well as for nutrient management.

High N2O variations induced by agricultural practices in integrated weed management systems

Integrated weed management aims to decrease the dependence of cropping systems on herbicides by using a combination of several agricultural practices. Environmental impacts of individual practices under various conditions are already known. However, there is scarce knowledge on the impact of combining several practices. Therefore, we studied N2O emissions of weed management cropping systems that use differing practices such as crop diversity, tillage, and herbicide pressure, during about 1 year. Data were compared with a conventionally managed cropping system. Results were also simulated using the NOE model. Results show a large variation of N2O emissions, ranging from 177 g N2O-N/ha for intensive tillage integrated weed management to 362 g N2O-N/ha for the conventional cropping system, 777 g N2O-N/ha for the no herbicide cropping system and 5226 g N2O-N/ha for no-till integrated weed management. Most N2O emissions occurred in spring, despite the absence of fertilizing related N2O peaks. The lowest emissions occurred in autumn and winter. Emissions are explained by interactions between specific soil potential denitrification rate, soil bulk density, temperature, soil water, and inorganic N contents. N2O emissions are accurately predicted by the model NOE, with a global Nash-Sutcliffe coefficient of efficiency equal to 0.80.

Does yield loss due to weed competition differ between organic and conventional cropping systems?

SummaryHigh weed abundance in organic crops is thought to be a key factor contributing to the greater yield loss in organic as compared with conventional cropping systems. However, even with greater weed densities than conventional systems, some organic systems have yields comparable to conventional systems, suggesting that cropping systems might differ in yield loss due to weed competition. The diversity in soil nutrient resources due to diversity in crop rotations and variable inputs might enhance crop tolerance to weed competition. We assessed the long‐term effects of contrasting levels of crop rotations (low, medium and high diversity) on weed density, weed biomass and wheat yield loss in organic and no‐till conventional cropping systems using a microplot study within a long‐term cropping systems trial at Scott, Saskatchewan, Canada. Weed density and biomass were found to be four times higher in the organic systems than in the conventional systems. Under standard weed management practices, organic had 44% lower yield than the conventional system. Lower yields in organic, even without weed competition, suggest that the lower yields are due to low soil productivity rather than weed competition. No differences in yield loss were observed among the organic and conventional systems or among the diverse crop rotations. We conclude that the organic management practices and/or increased crop rotation diversity did not enhance yield or reduce yield loss due to weed competition, due to the factors associated with lower soil fertility.

Adaptability and stability of pepper hybrids under conventional and organic production systems

ABSTRACT Pepper is one of the main vegetable crops commercialized in Brazil and it is grown throughout the country. The objective of this study was to estimate genetic parameters and predict the genotypic values involved in agronomic traits of hybrid pepper in two different cropping systems in order to verify adaptability and genotypic stability. The experiment was carried out at the Experimental Station Luiz Jorge da Gama Wanderley from IPA, located in Vitoria de Santo Antão, Pernambuco State, Brazil, from October 2010 to March 2011. Seven hybrids were evaluated in two trials, the first in conventional farming system and the second in organic cultivation system. Randomized blocks were used with seven treatments, four replications and plots consisting of six plants. We evaluated the following fruit variables: total mass (MTF), total number (NTF), average length (CMF), average diameter (DMF), number of locules (NL) and average thickness of the pericarp (EP). Statistical analyzes and estimation of genetic parameters were based on mixed models of type REML/BLUP, using the statistical model and software SELEGEN 151. All traits showed good accuracy. The genotype average heritability (h2mg) was lower than 80% only for the trait NTF. Some characters had h2mg close to 100% such as CMF and DMF with 99.1% and 98.3%, respectively. The hybrids presenting a predicted genotypic effect higher than the average were: Atlantis, Máximos, Solario and Rubia R for NTF, Solario and Atlantis for MFT, Impacto, Máximos, Atlantis, Hebron and Rubia R to CMF, Solario and Enterprise for DMF, Solario, Impacto, Rubia R and Atlantis for NL and Solario and Enterprise for EP. Hybrids presenting the highest performance in the traits evaluated for each system were the same selected based on the joint analysis of the studied systems, showing stability and enabling their indication for organic and conventional cropping systems.

Eleven-year results on soft and durum wheat crops grown in an organic and in a conventional low input cropping system

Eleven-year results on yields and apparent balances of organic matter and nitrogen (N) are reported for soft and durum wheat crops grown in the BIOSYST long-term experiment for the comparison between an organic and a conventional low-input system in Central Italy. The N supply to organic wheat consisted of 40 kg N ha–1 as poultry manure plus the supposed residual N left by green manures carried out before the preceding summer vegetable, while the N supply to conventional wheat consisted of 80 kg N ha–1 as mineral fertilisers, split in two applications of 40 kg ha–1 each, at tillering and pre-shooting. In every year, above ground biomass and N accumulation of each wheat species, including weeds, and the partitioning between grain yield and crop residues were determined. Apparent dry matter and N balances were calculated at the end of each crop cycle by taking into account the amounts of dry matter and N supplied to the system as fertilisers, and those removed with grain yield. Soft wheat yielded more than durum wheat. For both species, grain yield and protein content were more variable across years and generally lower in the organic than in the conventional system. In both systems, grain yield of both species resulted negatively correlated with fall-winter rainfall, likely for its effect on soil N availability. Both species caused a lower return of biomass and a higher soil N depletion in the organic than in the conventional system. Our experiment confirmed that winter wheat can help exploit the soil N availability and reduce N leaching in fall winter, especially after summer vegetables, but in stockless or stock-limited organic systems it needs to be included in rotations where soil fertility is restored by fall winter green manures to be carried out before summer crops.

Comparative Study of Population Dynamics and Breeding Patterns of Mastomys natalensis in System Rice Intensification (SRI) and Conventional Rice Production in Irrigated Rice Ecosystems in Tanzania

Mastomys natalensis is among the most important rodent pests in Sub-Saharan Africa. This study investigated the population dynamics and breeding patterns of this mouse in system rice intensification (SRI) and in conventional cropping systems in irrigated rice ecosystem in eastern Tanzania. The Mastomys natalensis population varied with years and season, but not with either SRI or conventional cropping system which would be expected as the all fields are in the same area. The highest population peak was observed during the dry season i.e., August to September. Breeding patterns of this rodent pest was not influenced by the cropping system or season, indicating that M. natalensis is sexually active throughout the year and does not be affected by the rice production systems. Regular control and sustainable operations, such as the use trap barrier system (TBS), are therefore essential if the populations are to be kept within tolerable limits.

Nutrient balance of ecological and conventional cropping system

The field trial was conducted during 1999–2005 at the RIPP in Piesťany in water protected zone. The nutrient balance of N, P, K, Mg and Ca was calculated for individual crops and for six crop rotation pattern as a whole. Incorporation of straw, catch crops and FYM was used. Crop rotation pattern of common pea – winter wheat – early potato – spring barley – red clover – winter wheat was growing under ecological system and conventional system with two level of nitrogen input. Balance of nutrients for the whole crop rotation in both systems was positive. Incorporation of fertility building crops (green manures and catch crops) in sufficient way positively influence the nutrient balance across the whole crop rotation. In ecological system balance of main nutrients in kg ha-1 was as follows: N+52.5, P+1.2, K+35.8, Mg+7.3, Ca+95.9. Keywords: ecological system, conventional system, crop rotation, nutrient balance

Inoculated Soybean Response to Starter Nitrogen in Conventional Cropping System in Moghan

A B S T R A C T To investigate the effects of inoculated seeds at different amounts of nitrogen on soybean growth and yield, we conducted a randomized complete block design with three replications on the Research Farm of the Moghan College of Agriculture and Natural Resources. Treatments were 0, 50, 100 and 150 kg haG 1 urea; inoculation with Biosoy, 50 kg haG 1 urea+inoculation with Biosoy, 100 kg haG 1 urea+inoculation with Biosoy, 150 kg haG 1 urea+inoculation with Biosoy. Increasing nitrogen fertilizer in non-inoculated plants reduced nodule dry weight but enhanced plant height, stems dry weight, the pods dry weight, biological yield and grains per plant. When seeds inoculated, non-application and application of 100 kg haG 1 urea produced more stems dry weight, pods dry weight, biological yield, grain numbers per plant and grain yield which were as much as application of 150 kg haG 1 urea for non-inoculated plants. Therefore, based on this investigation results we suggest applying of diammonium phosphate as a P fertilizer at the rate of 200 kg haG 1 +non application or 50 kg haG 1 urea application plus inoculation of soybean seeds by Biosoy in Moghan region. As a result, we can save all or part of the urea fertilizer.

Studies on long-term performance of organic and conventional cropping systems in Pennsylvania

Since 1981, organic and conventional cropping systems have been compared in a field trial at the Rodale Institute in Kutztown, Pennsylvania. Cropping system differences were evaluated for yields, soil quality, economic, and energy performance. Results showed that overall organic systems produced yields equal to conventional plots while at the same time improving soil quality. Organic systems also led to greater profitability while requiring less energy and emitting fewer greenhouse gases to produce the same amount of crops as the conventional systems.

Upscaling of agroforestry homestead gardens for economic and livelihood security in mid–tropical plain zone of India

Agroforestry homestead garden plays a significant role in improving food and nutritional security for the smallholders in developing countries like India, Bangladesh, Sri Lanka and other Asian countries. A study was conducted in two agro-ecological situations of Tripura, with the aid of farm inputs, improved technological support and direct observation during the year 2011–2014. Upscaling of homestead gardens with a number of components such as vegetables, spices, tubers, fruits, mushroom, poultry and goatery products ensured a year-round supply of a wide spectrum of food materials. Besides ensuring household food and nutritional security, this large variety of homestead garden products also contributed to income security when sold in nearby market. It also helps in improving water and organic fertilizer use through the recycling of rainwater and farm wastes from the enterprises involved. Besides facilitating cash income, homestead farming system generated employment for family labour and minimizes the risk associated with conventional cropping system.

Intercropping maize and wheat with conservation agriculture principles improves water harvesting and reduces carbon emissions in dry areas

Abstract In arid and populated areas or countries, water shortage and heavy carbon emissions are threatening agricultural sustainability with food security severely, and becoming a major issue. It is unclear whether improved farming systems can be developed to tackle those issues through a sustainable agriculture. Here three farming practices that have proven to be essential and successful, which were: (a) crop intensification through strip intercropping, (b) water harvesting through conservation tillage; and (c) carbon sequestration through improved crop residue management options, were integrated in one cropping system. We hypothesize that the integrated system allows the increase of crop yields with improved water use efficiency, while reducing carbon emissions from farming. The hypothesis was tested in field experiments at Hexi Corridor (37°96′N, 102°64′E) in northwest China. We found that the integrated system increased soil moisture (mm) by 7.4% before sowing, 10.3% during the wheat–maize co-growth period, 8.3% after wheat harvest, and 9.2% after maize harvest, compared to the conventional sole cropping systems. The wheat/maize intercrops increased net primary production by 68% and net ecosystem production by 72%; and when combined with straw mulching on the soil surface, it decreased carbon emissions by 16%, compared to the monoculture maize without mulch. The wheat/maize intercrops used more water but increased grain yields by 142% over the monoculture wheat and by 23% over the monoculture maize, thus, enhancing water use efficiency by an average of 26%. We conclude that integrating strip intercropping, conservation tillage as well as straw mulching in one cropping system can significantly boost crop yields, improve the use efficiency of the limited water resources in arid areas, while, lowering the carbon emissions from farming. The integrated system may be considered in the development of strategies for alleviating food security issues currently experienced in the environment-damaged and water-shortage areas.

Soil carbon stocks in different bioenergy cropping systems including subsoil

Despite the growing importance of energy cropping systems, little is known about their soil organic carbon (SOC) stocks in topsoils and subsoils. Furthermore, information regarding the impact of N-fertilization on C-sequestration for perennial compared with annual energy cropping systems is scarce. In order to study SOC changes in the soils of different energy cropping systems, a long-term study was established in southwestern Germany with the following cropping systems: energy maize (Zea mays) with reduced tillage, Miscanthus (M. x giganteus), switchgrass (Panicum virgatum) and willow (Salix schwerinii x viminalis), as well as a crop rotation with conventional tillage (CT) and no-till (NT) consisting of oilseed rape (Brassica napus ssp. oleifera), winter triticale (Triticale triticosecale) and winter wheat (Triticum aestivum). The soil is a Haplic Luvisol (Siltic). For each cropping system three N-fertilization regimes adapted to the needs of each crop were applied. With the main hypothesis that perennial energy cropping systems increase SOC stocks compared with conventional annual cropping systems, the SOC stocks were analyzed to a depth of 90cm after 11 years of continuous cropping (2002–2012). Compared with the control (CT) with 76 Mg SOC ha−1, the perennial crops had significantly higher SOC stocks in all N-fertilization regimes, which amounted to 92–95 Mg SOC ha−1 in the N1-fertilization regime. The crop rotation with NT also had higher SOC stocks with 93 Mg SOC ha−1 in the N1-fertilization regime. N-fertilization generally led to higher SOC stocks in all cropping systems, although SOC stocks did not increase any further from reduced to highest crop-specific N-fertilization, with the exception of energy maize. The current findings also stress the importance of subsoil carbon analyses: SOC stocks at a depth from 30 to 90cm made up 44–55% of the total stocks and differed significantly between cropping systems.

Yield and apparent dry matter and nitrogen balances for muskmelon in a long-term comparison between an organic and a conventional low input cropping system

Nine-year yields and apparent balances of dry matter and nitrogen (N) are reported for muskmelon cultivated in a long-term comparison trial between an organic and a conventional low input system in Central Italy. In every year, yield, above ground biomass and N accumulation of each cash crop, green manure and weeds, and the partitioning between marketable yield and crop residues were determined. Apparent dry matter and nitrogen balances were calculated at the end of each crop cycle by taking into account the amounts of dry matter and ex novo N supplied to the system as green manure legume Ndfa (i.e., an estimate of N derived from the atmosphere via symbiotic fixation) and fertilisers, and those removed with marketable yield. Differences between systems varied across years. On average, organic muskmelon yielded 16% less than the conventional one, while the fruit quality was similar in the two cropping systems. Fruit ripening began one week later and it was more scaled than in the crop grown conventionally. This was the consequence of a slow initial growth of the organic crop, due to inadequate green manure N total supply or timing of N release. Moreover such a wide spaced crop (0.5 plants m–2, in rows 2 m apart) was not efficient in intercepting N released from green manure biomass incorporated broadcast. Compared to the conventional crop management, the organic crop management resulted in much higher organic matter supply to the soil and in higher residual N after harvest. Thus, the choice of cultivating wheat just after melon to prevent postharvest residual N loss appears a key strategy especially in organic systems. Fall-winter green manure crops contributed to the self-sufficiency of the organic system by supplying muskmelon with either N absorbed from the soil or ex novo legume Ndfa.

Comparative analysis of performance and stability among composite cross populations, variety mixtures and pure lines of winter wheat in organic and conventional cropping systems

This study investigated the effects of increased genetic diversity in winter wheat (Triticum aestivum L.), either from hybridization across genotypes or from physical mixing of lines, on grain yield, grain quality, and yield stability in different cropping environments. Sets of pure lines (no diversity), chosen for high yielding ability or high quality, were compared with line mixtures (intermediate level of diversity), and lines crossed with each other in composite cross populations (CCPn, high diversity). Additional populations containing male sterility genes (CCPms) to increase outcrossing rates were also tested. Grain yield, grain protein content, and protein yield were measured at four sites (two organically-managed and two conventionally-managed) over three years, using seed harvested locally in each preceding year. CCPn and mixtures out-yielded the mean of the parents by 2.4% and 3.6%, respectively. These yield differences were consistent across genetic backgrounds but partly inconsistent across cropping environments and years. Yield stability measured by environmental variance was higher in CCPn and CCPms than the mean of the parents. An index of yield reliability tended to be higher in CCPn, CCPms and mixtures than the mean of the parents. Lin and Binns’ superiority values of yield and protein yield were consistently and significantly lower (i.e. better) in the CCPs than in the mean of the parents, but not different between CCPs and mixtures. However, CCPs showed greater early ground cover and plant height than mixtures. When compared with the (locally non-predictable) best-yielding pure line, CCPs and mixtures exhibited lower mean yield and somewhat lower yield reliability but comparable superiority values. Thus, establishing CCPs from smaller sets of high-performing parent lines might optimize their yielding ability. On the whole, the results demonstrate that using increased within-crop genetic diversity can produce wheat crops with improved yield stability and good yield reliability across variable and unpredictable cropping environments.

Root development of fodder radish and winter wheat before winter in relation to uptake of nitrogen

The nitrate (N) present in soil at the end of autumn is prone to leach during winter and spring in temperate climates if not taken up by plants. In Denmark catch crops are used as a regulatory tool to reduce N leaching and therefore a shift from winter cereals to spring cereals with catch crops has occurred. Quantitative data is missing on N leaching of a catch crop compared to a winter cereal in a conventional cereal-based cropping system. The aim of the study was to investigate whether fodder radish (Raphanus sativus L.) (FR) would be more efficient than winter wheat (Triticum aestivum L.) (WW) at depleting the soil of mineral nitrogen (Nmin) before winter. A secondary aim was to study the agreement between three different root measuring methods: root wash (RW), core break (CB) and minirhizotron (MR). The third aim of the was to correlate the N uptake of FR and WW with RLD. An experiment was made to see if and how root growth was affected by the minirhizotron tube. The experiments were conducted on a Danish sandy loam soil. From September to November the amount of soil Nmin decreased from 49kgNha−1 to 14kgNha−1 under FR and increased from 28kgNha−1 to 44kgNha−1 under WW. A test of correlations between root measuring methods showed that there was only a significant positive correlation for FR between CB and RW (R2=0.77) and for WW between CB and MR (R2=0.26). We conclude that FR is more efficient than WW at tightening the N cycle in the autumn by a greater depletion of soil Nmin. From the comparison of root methods, we conclude that root growth in the subsoil was overestimated for FR by the MR method. This was due to preferential root growth along the MR tubes. The root densities/intensities measured with the three root measuring methods were not directly comparable.

Nitrous oxide emissions and nitrate leaching in an organic and a conventional cropping system (Seine basin, France)

Agricultural activities can lead to nitrogen losses in the environment, particularly nitrate (NO3−) leaching and nitrous oxide (N2O) emissions. This study aims to measure N losses from organic farming (OF) and conventional farming (CF) arable cropping systems, both adopted in a single farm, located on the same drained loamy soil in the Seine basin, in the North of France. Leaching was measured with ceramic cups and N2O emissions with automatic and manual chambers over the 2011–2014 period.Manual chambers showed the same trend as automatic chambers but underestimated small variations and overestimated peak emissions. On average, N2O emissions were lower in OF (0.65±0.64kgNha−1yr−1) than in CF fields (0.95±0.77kgNha−1yr−1). The mean amount of N leached was 13.3kgNha−1yr−1 in the OF system during the 8-crops rotation (alfalfa 1, alfalfa 2, wheat, green bean, wheat, faba bean, wheat, flax) and 18.4kgNha−1yr−1 in the CF system for a 3-crops CF rotation (legume, wheat, wheat), corresponding to 9 and 10% of total N inputs, respectively. Leached N and N2O emissions expressed per unit of protein-N harvested were slightly higher in CF (0.11kg NO3–Nkg−1Nyr−1 and 5.4 N2O–Nkg−1Nyr−1, respectively) than in OF systems (0.10kg NO3–Nkg−1Nyr−1 and 4.7g N2O–Nkg−1Nyr−1, respectively). These results show a relative lower environmental impact of OF practices compared to CF practices (−30% area-scaled and −12% yield-scaled for leaching and N2O emissions), with further margins of progress in both systems, including a better management of fertilisers, legumes and catch-crops.