18th Congress of the European Society for Agronomy

Soil-improving management practices in a dynamic long-term experiment in NE Germany

Not scheduled

15m

Les Dortoirs (1st floor) (The Couvent des Jacobins)

Poster Synergies between short- and long-term goals Poster session #1

Speaker

Genís Simon-Miquel (Leibniz Centre for Agricultural Landscap Research (ZALF))

Description

1. Introduction:
   Management practices can modify certain aspects of soil quality such as the soil organic C (SOC) content, thus affecting the cropping system performance. While the use of cover crops or perennial forages is associated with increases in SOC stocks (Börjesson et al., 2018; Poeplau & Don, 2015), the effects of tillage, crop rotations or irrigation are more location-dependent. Climate change will affect the interaction between management practices and crop performance. In this scenario, it is necessary to understand the responses of these factors in the present climate to be able to adapt them in the future (Olesen et al., 2011). Long-term experiments (LTE) provide precious datasets for robust analyses of the effects of different management practices on cropping systems' productivity and sustainability (Cusser et al., 2020). The objective of this work was to explore alternative management practices for increasing crop productivity while maintaining (or improving) soil quality. The hypothesis was that a diversified crop rotation could outperform a continuous maize cropping system and that no-till practices could achieve the same yields as ploughing.

2. Materials and methods:
   A long-term field experiment was set up in Müncheberg (NE Germany) in 2000. Within one experimental cycle (2008-2015), the following factors were tested: irrigation (yes/no), tillage (plough/no-till) and crop rotation (continuous maize (Zea mays L.)/crop rotation). Irrigation rates ranged from 44 mm (2011) to 400 mm (2015). The crop rotation treatment consisted of a four-year sequence including winter rye (Secale cereale (L.)M.Bieb) + sorghum (Sorghum bicolor (L.) Moench), winter triticale (× Triticosecale), alfalfa (Medicago sativa L.)-clover (Trifolium repens L.)-grass (Lolium perenne L.) mixture and maize (Figure 1B). All crops were harvested for biomass for biogas production. While the use of cropland for biogas production is under debate in Germany, forage production is still a valuable source of livestock feed. Besides productivity, biomass N concentration was analysed, soil mineral nitrogen and water contents were measured five times per year and soil organic carbon concentration was measured every other year.

3. Results:
   The results refer to two rotation cycles of the experiment (2008-2016). Continuous maize yields averaged 18.3 t ha-1 (± 3.6 t ha-1) across years. Instead, the crop rotation system (four phases with five different crops) achieved an average biomass yield of 15.5 t ha-1 (± 4.9 t ha-1). Overall, the continuous maize system showed more stable yields across years (Figure 1A). Irrigation increased maize yields by 83 % in two years (2008 and 2015), whereas the increase was below 10% in the rest of them. Regarding the tillage effect, the differences were accentuated towards the later years, with the ploughing treatment achieving higher yields. Under crop rotation, the biomass yields were less stable due to the different crop species involved in the sequence (Figure 1B). Irrigation led to a 151% yield increase in 2015, while the average yield increase in the 2008-2014 period was 8%. Similarly to continuous maize, tillage differences were more patent towards the later experimental years.
   Figure 1: Crops’ biomass yield under continuous maize (A) and crop rotation (B). In sub-figure B, abbreviations at the bottom refer to the crop grown each year (WR+S: winter rye + sorghum; WT: winter triticale; ACG: alfalfa-clover-grass mixture; M: maize). Error bars refer to standard error.

4. Discussion:
   Overall, the diversified cropping system did not outperform the continuous maize in terms of productivity. Nonetheless, the crop rotation system included a perennial mixture, a key element for nutrient loss reduction and SOC accumulation. Irrigation effects on yield were highly variable, thus raising the question of the profitability and amortization times for irrigation infrastructure under the current conditions and cropping systems. While no-tillage slightly reduced crop yields, the reduced costs associated with this management (gas and time, mainly) can potentially offset the yield reduction. Furthermore, no-till benefits can still appear after periods of over 10 years, stressing the importance of such field experiments (Cusser et al., 2020). From the environmental perspective, the evaluation of soil organic carbon concentrations and stock changes over the experimental period will be essential to estimate the carbon sequestration potential of such practices under these pedoclimatic conditions.

5. References:
   Börgesson et al. 2018. https://doi.org/10.1007/s00374-018-1281-x
   Cusser et al. 2020. https://doi.org/10.1111/gcb.15080
   Olesen et al. 2011. https://doi.org/10.1016/J.EJA.2010.11.003
   Poeplau & Don, 2015. https://doi.org/10.1016/j.agee.2014.10.024