Influence of soil animals on C and N turnover in rice-based cropping systems
Final Report Abstract
SP3 studied the structure and function of soil fauna communities in rice cropping systems across the Philippines. A particular focus was on the potential of edaphic invertebrates to mitigate water loss and greenhouse gas emissions after introducing upland crops into rice production systems that had previously been permanently flooded. SP3 elucidated time-course and pattern of a terrestrial food web recovery and succession associated with this management change. Additionally, it defined conditions and management schemes under which soil ecosystem engineers (in particular earthworms) most efficiently mitigate greenhouse gas emissions and stabilize the nutrients that are released from rice straw residues. SP3 also assessed the effect of soil-induced variations in community dynamics and functional structure affect greenhouse gas mitigation and rice straw degradation after the introduction of upland crops. It was shown that the introduction of upland crops significantly accelerates soil invertebrate succession. However, this effect depends on soil type and is particularly low in lighter sandy soils (Tarlac province). The consolidation of these findings requires further multiregional assessments. SP3 nevertheless confirmed that the soil fauna becomes an increasingly important agent after the introduction of upland crops into permanent wet rice-growing systems that critically affects the mitigation of greenhouse gas emissions, rice straw recycling and plant growth. Experimental manipulation of earthworm density revealed that the impact of these important macro-engineers on the stabilization of carbon from rice straw is more efficient in sandy than in clay soils. However, management of earthworm biomass proved to be a very promising option for both mitigating greenhouse gas emissions and stabilizing C and N originating from rice straw. Moreover, earthworms seem to stimulate the growth of upland rice in sandy soils. The results of SP3 highlight the fact that earthworm effects in rice ecosystems can be enhanced by other groups of the soil fauna. Especially enchytraeids, which are particularly active during wet stages of the crop rotation cycle, can significantly mitigate greenhouse gas emissions. This promotes the development of a multi-species straw recycling system, which makes best use of the capabilities of earthworms and enchytraeids at different periods of the crop rotation cycle. SP3 thus laid the foundation for the establishment of a management approach that significantly increases the sustainability of the conversion of rice production by manipulating the abundance of certain soil fauna taxa or even inoculating paddy soils with carefully prepared multiple species ensembles. The achievements of SP3 are in very good agreement with those of the other subprojects and thus improve the prospects for the establishment of climate-friendly and water-saving rice production landscapes and the development of environmentally friendly rice-residue-recycling biotechnologies.
Publications
- (2015) Earthworm bioturbation stabilizes carbon in nonflooded paddy soil at the risk of increasing methane emissions under wet soil conditions. Soil Biology & Biochemistry 91: 127-132
John K, Marxsen J, Zaitsev AS, Wolters V
(See online at https://doi.org/10.1016/j.soilbio.2015.08.033) - (2015) Effects of residue management on decomposition in irrigated rice fields are not related to changes in the decomposer community. PLOS ONE 10: e0134402
Schmidt A, John K, Arida G, Auge H, Brandl R, Horgan FG, Hotes S, Marquez L, Radermacher N, Settele J, Wolters V, Schädler M
(See online at https://doi.org/10.1371/journal.pone.0134402) - (2016) Compensatory mechanisms of litter decomposition under alternating moisture regimes in tropical rice fields. Applied Soil Ecology 107: 79-90
Schmidt A, John K, Auge H, Brandl R, Horgan FG, Settele J, Zaitsev AS, Wolters V, Schadler M
(See online at https://doi.org/10.1016/j.apsoil.2016.05.014) - (2019) Enchytraeids simultaneously stimulate rice straw degradation and mitigate CO2 release in a paddy soil. Soil Biology and Biochemistry 131: 191–194
John K, Degtyarev M, Gorbunova A, Korobushkin D, Knöss H, Wolters V, Zaitsev AS
(See online at https://doi.org/10.1016/j.soilbio.2019.01.014)
