Effects of different manuring systems with and without biogas digestion on nitrogen cycle and crop yield in mixed organic dairy farming systems

Abstract

Field trials were carried out between 2002 and 2005 to investigate the effects of biogas digestion in a mixed organic dairy farming system with arable land and grassland on nutrient cycling, nitrogen (N) uptake and crop yields within a cropping system comprising a whole crop rotation. Five treatments were carried out: (i) solid farmyard manure, (ii) undigested liquid slurry, (iii) digested liquid slurry, (iv) digestion of liquid slurry and field residues such as crop residues and cover crops, and (v) similar to iv, but with additional N inputs at the equivalent of 40 kg N ha -1 farmland through digestion of purchased substrates. The term ''manure'' is used in the present study to mean all kind of aboveground organic residues left on the field (''immobile manures'', such as crop residues and green manures incorporated directly into the soil) or added as stable wastes or effluents of biogas digestion (''mobile manures''). The total aboveground biomass growth and the overall aboveground N uptake of non-legume maincrops were higher in the liquid slurry manure treatment than in the solid farmyard manure system (?5% and ?9%, respectively). The digestion of the liquid slurry increased N uptake and crop yields only after soil incorporation of the slurry shortly after field spreading. The additional collection and digestion of field residues such as cover crops and crop residues, combined with a reallocation of the effluents, strongly increased the amounts of ''mobile'' manure, allowing a more focussed allocation of the available N. This led to an increase in the aboveground N uptake (?12%) and biomass yield (?4%) of the five non-legume crops, due to a better adapted allocation of nutrients in space and time. Results obtained with spring wheat showed that removal of cover crops in autumn, and their digestion, combined with subsequent use as manure in spring resulted in a better synchronisation of the crop N demand and the soil N availability, in comparison with a strategy where the biomass was left on the field as green (immobile) manure. The inclusion of external substrates led to a further increase of 8% in N uptake, but not to a significant increase in aboveground dry matter yields.

Closing the Global Energy and Nutrient Cycles through Application of Biogas Residue to Agricultural Land – Potential Benefits and Drawback

“…The anaerobic digestion procedure leads to a decreased C/N ratio from 17.0 in raw swine manure to 10.5 in biogas residue, which may be explained by loss of carbon as CH 4 and CO 2 during this process [71]. This finding is consistent with other studies reporting a lower C/N ratio in biogas residue after anaerobic digestion [48,49]. When considering the organic fractions only, the C/N org ratio is increased following anaerobic digestion due to a decrease in the organic N concentration [50].…”

“…Essential nutrients (N, P, K, Mg), including trace elements required by plants, are conserved in the residue [44][45][46][47][48][49][50][51]. However, nutrients are present in inorganic plant-available forms at a markedly higher extent in digested residue, compared to untreated waste [47,48,50,[52][53][54], due to the large input of organic nutrients that are mineralized during the digestion process [7]. For instance, digested residue contains 25% more accessible ammonium (NH 4 + -N) than untreated liquid manure [55].…”

Short-term effects of biogas digestate and cattle slurry application on greenhouse gas emissions affected by N availability from grasslands on drained fen peatlands and associated organic soils

“…There over a limited range (slurry DM of 2-5 %), NH 3 losses increase by approximately 6 % for every 1 % DM content (Smith et al, 2000). Although the observed dry matter content of the biogas digestates was very low and at the lower end of values reported in the literature (e.g., Gutser et al, 2005;Möller et al, 2008;Quarkernack et al, 2011), no corresponding effect was found in the present study, as was also reported by Möller and Stinner (2009). According to Döhler and Horlacher (2010) and Smith et al (2000), water-saturated grassland soils as well as very dry grassland soils high in organic matter lead to higher NH 3 -losses due to the reduced infiltration of slurries.…”

“…Furthermore it can be assumed that the plant N-uptake and the N 2 O emissions are closely interconnected since N-uptake can be considered as a proxy for N availability, affecting N gaseous losses as well. Currently, the effect of anaerobic digestates on crop growth after surface application under field conditions is contradictory, since some authors reported higher crop yields compared to undigested slurries (e.g., Odlare, 2005 cited in Möller and Müller, 2012) whereas others found no effects (e.g., Möller et al, 2008). Only a few studies exist for grassland but it seems that fertilization with biogas digestates positively affects grass yields, but only in single years (Elsässer et al, 1995;Rubaek et al, 1996;Möller et al, 2008;Möller and Müller, 2012).…”

Agro economic performance of Bio-slurry on boro rice cultivation in some sites of Moulvibazar district

“…Bonten et al (2014) asserted that nutrients in bio-slurry, especially nitrogen, are more readily available than in manure, leading to a larger short term fertilization effect. Although Moller et al (2008) found that the yields did not significantly differ between the different treatments (Bio-slurry, undigested liquid slurry and solid FYM) except for spring wheat, where the bio-slurry treatment led to higher yields due to immediate use of the readily available NH4 + -N. However, other study suggested that rice yields increased by 23% compared to synthetic fertilizer application (Warnars and Oppenoorth, 2014). Application of slurry can increase both late and early rice yields to 44.3 and 31% while combined application with ammonium bicarbonate, the rice yields can increase to 12.1% (SNV, 2011).…”