28 research outputs found
Understanding effects of multiple farm management practices on barley performance
Because of the complexity of farming systems, the combined effects of farm management practices on nitrogen availability, nitrogen uptake by the crop and crop performance are not well understood. To evaluate the effects of the temporal and spatial variability of management practices, we used data from seventeen farms and projections to latent structures analysis (PLS) to examine the contribution of 11 farm characteristics and 18 field management practices on barley performance during the period 2009-2012. Farm types were mixed (crop livestock) and arable and were categorized as old organic, young organic or conventional farms. The barley performance indicators included nitrogen concentrations in biomass (in grain and whole biomass) and dry matter at two growing stages. Fourteen out of 29 farm characteristics and field management practices analysed best explained the variation of the barley performance indicators, at the level of 56%, while model cross-validation revealed a goodness of prediction of 31%. Greater crop diversification on farm, e.g., a high proportion of rotational leys and pasture, which was mostly observed among old organic farms, positively affected grain nitrogen concentration. The highest average grain nitrogen concentration was found in old organic farms (2.3% vs. 1.7 and 1.4% for conventional and young organic farms, respectively). The total nitrogen translocated in grain was highest among conventional farms (80 kg ha(-1) vs. 33 and 39 kg ha(-1) for young and old organic farms, respectively). The use of mineral fertilizers and pesticides increased biomass leading to significant differences in average grain yield which became more than double for conventional farms (477 +/- 24 g m(-2)) compared to organic farms (223 +/- 37 and 196 +/- 32 g m(-2) for young and old organic farms, respectively). In addition to the importance of weed control, management of crop residues and the organic fertilizer application methods in the current and three previous years, were identified as important factors affecting the barley performance indicators that need closer investigation. With the PLS approach, we were able to highlight the management practices most relevant to barley performance in different farm types. The use of mineral fertilizers and pesticides on conventional farms was related to high cereal crop biomass. Organic management practices in old organic farms increased barley N concentration but there is a need for improved management practices to increase biomass production and grain yield. Weed control, inclusion of more leys in rotation and organic fertilizer application techniques are some of the examples of management practices to be improved for higher N concentrations and biomass yields on organic farms
Effect of grassland cutting frequency on soil carbon storage – a case study on public lawns in three Swedish cities
Soils contain the largest terrestrial carbon pool and thus play a crucial
role in the global carbon cycle. Grassland soils have particularly high soil
organic carbon (SOC) stocks. In Europe (EU 25), grasslands cover 22 % of
the land area. It is therefore important to understand the effects of
grassland management and management intensity on SOC storage. City lawns
constitute a unique study system in this context, since they provide a high
functional diversity and thus a wide range of different management
intensities per unit area. In this study we investigated frequently mown (on
average eight times per season) utility lawns and rarely mown (once per season)
meadow-like lawns at three multi-family housing areas in each of three
Swedish cities: Uppsala, Malmö, and Gothenburg. The two different lawn
types were compared regarding their aboveground net primary production (NPP)
and SOC storage. In addition, root biomass was determined in Uppsala. We
found significantly higher aboveground NPP and SOC concentrations and
significantly lower soil C : N ratio for the utility lawns compared with the
meadow-like lawns. On average, aboveground NPP was 24 % or 0.7 Mg C ha<sup>−1</sup> yr<sup>−1</sup>
higher and SOC was 12 % or 7.8 Mg ha<sup>−1</sup> higher.
Differences in SOC were well explained by differences in aboveground NPP
(<i>R</i><sup>2</sup> = 0.39), which indicates that the increase in productivity due to
more optimum CO<sub>2</sub>-assimilating leaf area, leading to higher carbon input
to the soil, was the major driver for soil carbon sequestration. Differences
in soil C : N ratio indicated a more closed N cycle in utility lawns, which
might have additionally affected SOC dynamics. We did not find any
difference in root biomass between the two management regimes, and concluded
that cutting frequency most likely only exerts an effect on SOC when
cuttings are left on the surface