Nitrogen fertilizer value of digestates from anaerobic digestion of animal manures and crops

After anaerobic digestion (AD) of manures for biogas production the concentration of ammonium-N is increased and the concentration of decomposable carbon in manure is decreased. That implies that the first year fertilizer value of the manure can be increased by the treatment. However, pH is also increased by AD thereby increasing the risk of ammonia losses while the lowered dry matter content on the other hand improves the manure infiltration in soil and reduces the risk of ammonia loss. Therefore the effects of AD on plant N availability can be expected to interact with the manure application method used. In stockless organic farming it has been suggested that nitrogen utilization can be improved by using anaerobic digestion of plant-based green manures, but the information about such manures is scarce. We have compared nitrogen fertilizer values of 1) pig and cattle slurries before and after AD and 2) digested plant-based manures. Mineral fertilizer replacement values (MFRV) were determined after direct injection to barley and oats crops and after surface-banding in a winter wheat crop. The manures were digested in continuously fed pilot digesters at thermophilic conditions (ca. 50°C). The manures were applied to small framed plots and grain yields and N uptake were compared to plots receiving increasing amounts of mineral N fertilizer. The three tested plant-based manures derived from crops of either grass clover, yellow lupine or a triticale-winter vetch mixture. The MFRV of total N in two different injected cattle slurries increased from 58-75% to 69-82% after AD. The MFRV of cattle slurry after surface-banding in winter wheat was much lower: 30-37% for untreated slurry and 38-49% after AD. The low availability after surface-banding can be ascribed to high ammonia volatilization. The MFRV of injected pig slurry was high and similar with and without AD: 89-91%. After surface banding of pig slurry MFRV was 75% for untreated and 87% for digested pig slurry. The plant-based manures contained a high proportion of ammonium-N (59-68% of total N) after AD and the MFRVs of total manure N were comparable to the digested cattle slurries: 73-77% after injection, but only 43-57% after surface-banding of the manure. The influence of AD of manure on N turnover in soil has also been evaluated in a soil incubation study with some of the same manures, and the differences between untreated and digested manures were more distinct in this incubation study than the observed differences in fertilizer value. We conclude that the potential plant availability of pig and cattle slurry can be increased by 10-15% points after AD. However, after surface-banding of digested manures rich in fibers, such as cattle and plant-based manures, significant ammonia loss can be expected resulting in relative poor N utilization

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Foreløbige forsøgsresultater viser, at vinterfaste kvælstoffikserende efterafgrøder på sandjord giver det højeste udbytte i vårbyg året efter. I det aktuelle forsøg var hvid- og rødkløver de to bedste efterafgrøder og efterlod kvælstof i jorden til den efterfølgende vårbyg, svarende til 80 kg kvælstof pr. ha tildelt i kunstgødning

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Økologisk dyrkning

Indeholder resultater fra økologiske forsøg med vintersædsarter, vårsædsarter, vinterhvedesorter, vinterspeltsorter og -dyrkning, vinterrybsdyrkning, vårbyg sortsvalg og -dyrkning, havre dyrkning, vårhvede dyrkning, vårspelt og våremmer sortsvalg, vårtriticale sortsvalg, smalbladet lupin dyrkning, kløvergræs dyrkning, majs dyrkning, foderafgrøder dyrkning, quinoa sortsvalg, demonstrationer og projekte

The effect of nutrient supply on the baking quality of organic wheat cultivars

Five different wheat cultivars (Thifun, Triso, Thasos, Spelt and Emmer) were cultivated in an organic study using six different organic compost types (two different household waste composts, sewage sludge compost, fruit and vegetable compost and two different renescience compost types) and one control with no manure applied. Bread was baked with flour from each of the samples. The protein content, the gluten content and the falling number were measured for the flour samples and specific volume, the sensory quality and instrumental measured hardness were measured on the bread samples. Different compost types resulted in distinct different sensory profiles of the bread. However, the tested cultivars responded very different towards the different compost types leading to very different sensory profiles. Furthermore, compost type has an effect on the protein content and gluten content. However, the cultivars reacted different when different compost types were applied. Likewise, the specific volume depended on both the compost types and the cultivar. In contrast, the falling number was primarily affected by the compost types and not the cultivar. The protein content, gluten content, Falling number as well as specific volume of the bred differed between the two cultivation years. The sensory attributes were highly correlated to …

Baking performance and sensory quality of organic wheat cultivars

Eleven different wheat cultivars (Thaifun, Triso, Thasos, Trappe, Amaretto, Diskett, Økilde, Dache, Koga, Spelt and Emmer) were cultivated in an organic study using three different organic treatments (no manure, household waste compost and sewage sludge compost). Bread was baked with flour from each of the samples. The protein content, the gluten content and the Falling Number (FN) were measured for the flour samples and specific volum and sensory quality were measured on the bread samples. A big variation was found in protein and gluten content and Falling Number between flour samples of eleven different wheat cultivars that were grown using three different field treatments. A correlation was found between the protein content and the gluten content (R2 = 0.86). Based on the protein and gluten content the eleven cultivars could be divided into two groups: One group having low protein and gluten content and one group having appropriate protein and gluten content for organic bread production. The specific volume of the bread also showed significant differences for the eleven cultivars. The bread samples of Diskett resulted in the biggest volume, and rather high bread volume for Trappe and Spelt. Koga and Dache resulted in low bread volume even though they both had an appropriate protein and gluten content. Thus, this study did not show a direct relationship between the protein- and gluten content and bread volume. The sensory profiles of the bread for the eleven cultivars were very different, leading to big differences in both textural-, aroma- and taste attributes. The sensory profile of Emmer was very different from the sensory profile of Spelt and Diskett

The effect of nutrient supply on the baking quality of organic wheat cultivars

Six different of cultivars of spring wheat (Triticum aestivum cv.: Thaifun, Triso, Thasos and Amaretto), Spelt (Triticum spelta cv.) and Emmer (Triticum dicoccum cv.) were cultivated in an organic study using six different organic compost types (two different household waste composts, sewage sludge compost, fruit and vegetable compost and two different renescience compost types) and one control with no manure applied. Bread was baked with flour from each of the samples. The protein content, the gluten content and the Falling Number (FN) were measured for the flour samples and specific volume, the sensory quality and instrumental measured hardness were measured on the bread samples. Different compost types resulted in significant differences in the content of protein, gluten and specific volume as well as distinct different sensory profiles of the bread. However, the tested cultivars responded significantly different towards the different compost types leading to very different sensory profiles as well as content of protein, gluten and specific volume due to a high interaction effect between compost type and cultivar. Hence, this study shows the importance of testing more than one cultivar in nutrient supply field experiments and the results make it hard to conclude which of the N-compost sources that are the best in order to obtain the highest content of protein and gluten as well as the optimal sensory profile