The influence of long-term inputs of catch crops and cereal straw on yield, protein composition and technological quality of a spring and a winter wheat

Under conditions of restricted nitrogen (N) input such as in organic farming systems, crop N uptake must rely on N mineralised from applied animal manure, crop residues and native soil organic matter. Scarcity of N may impede the production of quality grain for bread production, and input and retention of N in soil are therefore important parameters for soil fertility. Toretain N in the crop-soilsystem, catch crops may be grown in breaks between main crops where they provide a significant sink for N mineralised in late summer and autumn (Thomsen, 2005). In corporation of straw may likewise retain mineralised N by microbial immobilisation (Christensen, 1986) and will also directly add to the N mineralisation potential when the N supplied in the straw accumulates (Thomsen & Christensen, 2004). Under northern European conditions, winter wheat may generally be of lower quality than spring wheat, but winter wheat has a higher yield potential. When the N uptake is mainly based on N mineralised from either applied or indigenous soil organic matter, however, this may even out the quality difference between winter and spring wheat as the longer growing season of winter wheat may boost its N utilisation. Growing conditions are highly important for protein quantity whereas main lygenetic factors influence protein composition (Amesetal., 1999; Luoetal., 2000). Wheat grain proteins have been classified as albumins, globulins, gliadins and glutenins on the basis of their solubility (Osborne, 1907). Reverse-phase (RP) high performance liquid chromatography (HPLC) allows the quantitative determination of these different flour protein groups together with single proteins (α5-, α1,2-, α-, γc-type gliadins, x- and γ-type high (HMW) and low (LMW) molecular weights subunits of glutenin) (Wieser & Seilmeier, 1998). The proteins can also be divided into polymers (glutenins) or monomers (gliadins, albumins, globulins) based on their aggregating properties. The polymeric proteins are critical for governing wheat flour processing properties, and their quantity and size distribution reliably measured by size-exclusion (SE) HPLC techniques have been shown to be important indicators of baking quality (Dachkevitch & Autran, 1989; Bateyetal., 1991). The aim of this study was to examine whether wheat yield and baking quality determined by chromatographic techniques together with rheological and chemical quality measurements could be improved by combining agronomic strategies consisting of wheat cultivars and long-term organic matter inputs. The variables tested were (A) a winter wheat and a spring wheat cultivar, (B) three catch crop strategies and (C) four straw incorporation rates

Do nutrient uptakes and grain yields differ between spring barley varieties grown for organic farming as mono-crop and in mixture: Characteristics of spring barley varieties for organic farming

Manure application increased yield. Hence the study was conducted under the conditions of moderate nutrient stress and in all probability nitrogen stress. Under this condition nutrient uptakes, biomass production and grain yields did vary between Otira, Orthega, Landora, Brazil, Svani, NK96-300, Mixture 1 (Otira, Orthega, Landora) and Mixture 2 (Brazil, Svani and NK96-300). Interaction between variety and soil fertility treatments were also significant. These findings open new possibilities for selection or plant breeding for genotypes with improved capability of nutrient acquisition from soils at different soil fertility levels e.g. in organic farming. Cropping of barley varieties in mixtures seems to increase (stimulate) nutrient uptakes (N, P, S, K, Mg, Ca, Mn, Zn, Cu and Mo) and biomass production

Sortsforskelle i næringsstofoptagelse, vækst og kerneudbytter af vårbyg til økologisk dyrkning

Vårbyggens optagelse og udnyttelse af næringsstoffer, konkurrenceevne over for ukrudt samt sygdomsresistens har stor betydning for den økologiske planteavl. Opnåelse af en optimal ernæring forudsætter den rette kombination af et stort antal biologiske, fysiske og kemiske jord- og plantefaktorer. Kulturplanter, som sås om foråret, starter i reglen med en moderat mangel på fosfor og kalium (Nielsen et al., 2003). I pløjelaget findes hovedparten af det plantetilgængelige fosfor og i en vis udstrækning tillige kalium og mikronæringsstoffer, mens det plantetilgængelige kvælstof og svovl ofte er fordelt i hele roddybden

Vinterhvede og vårhvede - efterafgrøder påvirkede udbyttet men ikke kvaliteten

Kvælstofoptaget i afgrøder stammer dels fra minerali-sering fra jordens organiske materiale dels fra evt. tilført gødning. Jordens evne til at frigive kvælstof ved mineralisering, og dermed dens evne til at forsyne en afgrøde med kvælstof, påvirkes bl.a. af dyrknings-systemet, herunder hvor meget organisk materiale der tilføres jorden f.eks. i form af afgrøderester. Planters evne til at udnytte mineraliseret kvælstof afhænger bl.a. af vækstsæsonens længde. Det forven-tedes derfor, at afgrøder med lang vækstsæson bedre er i stand til at udnytte en høj mineralisering end afgrøder med kort vækstsæson

Soil porosity as a habitat for microorganisms

The soil pore system has to be characterized quantitatively in order to describe the soil as a habitat for microorganisms. Soil pore morphology as determined by soil structure may be as important as the size distribution for the transport of gases and nutrients. This study adresses the physical properties of differently textured soils in undisturbed and remoulded state and their effect on microbial activity. Bulk soil was retrieved from 0-20 cm depth at six locations along a textural gradient in an arable field in Denmark. The samples ranged in clay content from 11 to 45%. The soils were crushed in air dry state, mixed, re-moistened, and exposed to a 9 month period of structure regeneration. Following application of 14C-labelled organic residues, the soils (labelled NA1 - NA6) were exposed to a further 8 month period of structure regeneration. Intact soil cores were then sampled and drained to four different matric potentials, analyzed for physical characteristics and subjected to a 15 weeks period of incubation with collection of evolved carbon dioxide. Cores of undisturbed but recently tilled topsoil from each sampling location in the field (labelled RE1 - RE6) were included as reference samples for the physical characteristics. The previously disturbed (NA) soils regained some of their secondary structure during storage under field-like conditions, but they were still structurally different from undisturbed (RE) soils of similar texture. The habitable and the protective pore space defined as the volume of pores ranging in size from 0.8-30 µm and 0.8-3 µm, respectively, appeared to be nearly constant across soils with different clay content. NA soils had slightly smaller volume of protective pore space compared with RE soils. Although partly aggregated, disturbed clayey soils showed less continuous / more tortuous pore systems than the texturally corresponding and structurally intact soils. Generally, the disturbed NA soils had a pore system with relatively small pores 'enmeshed' in the soil matrix, whereas the undisturbed RE soils exhibited larger pores. Measurements of oxygen diffusion confirmed that the relative water content - often quantified as the percentage of water filled pore space (WFPS) - may be a reasonable parameter in models simulating the activity of aerobic micro-organisms in remoulded soils. However, differences in the structure of undisturbed soils were shown to invalidate the use of WFPS as a universal parameter in simulation models applied to field conditions. The results indicated that turnover of soil OM was mainly controlled by the soil volume occupied by water. Soil texture affected turnover indirectly through its effect on the soil water regime. The turnover of the native OM was regulated by the total volume of water, whereas water in micropores and cavities <0.2 µm in diameter was not involved in the decomposition process of recently added OM. The studies encourage further investigations of the activity of soil microorganisms as related to the soil physical framework and the physical processes of importance for the function of the microbial community

Integrated nitrogen input systems in Denmark

Cycling of N in agriculture through the use of mineral fertilizers, manures and N-fixing crops gives rise to many forms of N emissions to the environment, including nitrate (NO3) leaching, ammonia (NH3) volatilization and nitrous oxide (N2O) emissions, resulting in ground water pollution, eutrophication of surface waters, soil acidification and contributions to global warming. The high rates of N input in intensive North European agricultural systems have given rise to high loss rates, and the focus in Danish agriculture during the past two decades has been on increasing the N use efficiency with the aim of reducing losses. The N use efficiency at the system level can be increased by improved handling of manure, targeted application of fertilizers and manures, and through adjustments of the crop rotation

Agronomical techniques to improve technological and sanitary quality

In spite of variable grain protein contents, baking quality of organic wheat was found to be acceptable to good. Mycotoxin (DON) infestation was generally low on tested grain samples. Choice of wheat cultivar was the most efficient way to obtain higher grain quality. Fertilization with readily available nitrogen and, to a lower extent, association with legumes and green manures with mixtures containing fodder legumes also improved grain quality. Reduced tillage affected soil quality and wheat yield but had little effects on grain quality

New challenges to improve organic bread wheat production in Europe

The total organic area in the EU-27 had an annual average growth rate of nearly 15% from 1998 to 2006 with winter wheat being the most important cereal crop. Wheat yield in organic farming is around 30% to 70% of yield of conventional farming but higher premia for organic wheat may to some extent compensate for this. Bread wheat is grown in a variety of crop rotations and farming systems and four basic organic crop production systems have been defined. Nitrogen deficiency and weed infestation are considered to be the most serious threat in organic wheat production. Organic wheat producers will have to fulfil the technological needs of bakers although the requirements differ widely from small artisan bakers to large enterprises handling the organic bread processing. To maintain and expand organic wheat production, there is a need to control weed population, manage nitrogen nutrition and maintain crop diversity in the cropping system. In order to obtain a share in the premium price of organic wheat products, farmers may involve in further processing and marketing

Catch crop strategy and nitrate leaching following grazed grass-clover

Cultivation of grassland presents a high risk of nitrate leaching. This study aimed to determine if leaching could be reduced by growing spring barley (Hordeum vulgare L.) as a green crop for silage with undersown Italian ryegrass (Lolium multiflorum Lam.) compared with barley grown to maturity with or without an undersown conventional catch crop of perennial ryegrass (Lolium perenne L.). All treatments received 0,60 or 120 kg of ammonium-N ha-1 in cattle slurry. In spring 2003, two grass-clover fields (3 and 5 years old, respectively, with different management histories) were ploughed. The effects of the treatments on yield and nitrate leaching were determined in the first year, while the residual effects of the treatments were determined in the second year in a crop of spring barley⁄perennial ryegrass. Nitrate leaching was estimated in selected treatments using soil water samples from ceramic cups. The experiment showed that compared with treatments without catch crop, green barley⁄Italian ryegrass reduced leaching by 163–320 kg Nha-1, corresponding to 95–99%, and the perennial ryegrass reduced leaching to between 34 and 86 kg Nha-1, corresponding to a reduction of 80 and 66%. Also, in the second growing season, leaching following catchcrops was reduced compared with the bare soil treatment. It was concluded that the green barley⁄Italian ryegrass offers advantages not only for the environment but also for farmers, for whom it provides a fodder high in roughage and avoids the difficulties with clover fatigue increasingly experienced by Danish farmers

Wheat yield and quality as influenced by reduced tillage in organic farming

Organic farmers are interested in soil conservation by reduced tillage, techniques well known in conventional agriculture to protect soil quality and limit labor time and energy costs. However, organic farming and reduced tillage can modify weeds, soil structure, and thus soil nitrogen (N) mineralization which strongly influences wheat yield and quality. The main objectives of this study were to analyze how reduced tillage applied to organic wheat influenced (1) grain yield, protein concentration, and weed infestation; (2) deoxynivalenol (DON) contamination on grain; (3) technological quality parameters such as dry gluten, zeleny index, falling number, and gluten index; (4) protein composition (F1, F2, F3, F4, and F5 fractions, and UPP, gliadin/glutenin ratio); and (5) baking test. For this purpose, we analyzed five site-years of data from winter wheat crops where mouldboard ploughing and reduced tillage were compared in three experimental trials (two in France and one in Switzerland). Main results concern wheat yields: the effect of reduced tillage on wheat yield was influenced by several factors such as weed competition. No significant increase in mycotoxin content (DON) due to reduced tillage was detected. Contamination with DON was always below the European threshold for human consumption. The technological quality parameters were less affected by the tillage treatments than grain yield: protein content, gluten index, zeleny index, and falling number showed on average no significant difference between treatments although the protein composition was slightly different. The main results of this study are that the effect of reduced tillage on grain yield depends very much on soil type, weather conditions, and time after conversion, whereas there is only minor impact on wheat quality. This is in contrast to the hypothesis that reduced tillage under organic farming will cause problems in baking quality