FOR 1701: Introducing Non-Flooded Crops in Rice-Dominated Landscapes: Impact on Carbon, Nitrogen and Water Cycles (ICON)
Medicine
Final Report Abstract
The interdisciplinary and transdisciplinary research unit ICON concentrated on the consequences of altered fertilization (conventional, site-specific and zero), intercropping mitigation measures (straw mulching and cover crop introduction), flooding regimes (flooded vs. non-flooded) and crop diversification (wet rice vs. dry rice vs. maize) on the biogeochemical cycling of C and N, associated greenhouse gas emissions, the water balance, biological activity and diversity in soil and other important ecosystem services of rice cropping systems in SE Asia with the focus on Philippines. The overarching goal was to provide the basic process understanding necessary for balancing the revenues and environmental impacts of high-yield rice cropping systems while maintaining their vital ecosystem services. A huge field experiment was established at the International Rice Research Institute (IRRI, Philippines), which was complemented by laboratory experiments as well as extended field studies and experiments at other regions of the Philippines, representing different soil types. It was shown that pollution swapping based on GHG emissions associated with crop diversification seems not to be a major risk as was initially hypothesized. Losses of soil organic carbon could reverse positive changes of the GWP if they exceed 0.5 t C ha^-1 per cropping season. Overall, introduction of upland crops in the dry season dramatically reduces irrigation water use and CH4 emissions. Concerning management practices including upland crops, CH4 emissions in the subsequent wet season with paddy rice were significantly reduced (-54–60%). The release of trace gases can partly be buffered by macro- and micro-bioturbation of the soil fauna. Crop diversification reduced water retention with the long-term balance depending on climatic fluctuations. Crack dynamics seem to be the critical driver of hydrological cycling. However, maize cropping in the dry season could save water and reduce nutrient leaching in the long term compared to continuous paddy-rice cropping. Concerning the long-term reduction of nutrient and water losses from rice paddies, straw mulching and mung bean as cover crop failed to eliminate transient losses of water, nitrogen and organic carbon in the first year after the introduction of maize. In contrast, rice straw amendment substantially affected the microbial uptake of root-released carbon in the rhizosphere. Earthworms, enchytraeids and other soil invertebrates increase the sustainability of paddy soils by forming a hierarchical multi-taxon system that efficiently stabilizes organic matter and mitigates greenhouse gas emissions. This ecological system is effective in rice fields with upland crops. The model LandscapeDNDC was further developed to allow simulating the effect of seasonal changes of lowland (wet and dry season rice) systems to mixed lowland-upland systems (wet season rice – dry season maize or “upland” rice) on the net greenhouse gas balance of agricultural systems. Simplified algorithms capable of representing the significant diurnal variability of CH4 emissions in the early growing season if measurements are only done once per day were also developed. To conclude, ICON successfully prepared the scientific ground for future changes in rice production in SE Asia towards greater sustainability. This was only possible through the combination of process-oriented and organism-oriented research. New options in rice productions inter alia include the biological management of rice straw residues along with the mitigation of greenhouse gas emissions and upland crop growth stimulation.
Publications
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(2013) Set up of an automatic water quality sampling system in irrigation agriculture. Sensors. 14: 212–228
Heinz E., Kraft P., Buchen C., Frede H.-G., Aquino E., Breuer L.
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(2014) Methane and nitrous oxide emissions from rice and maize production in diversified rice cropping systems. Nutrient Cycling in Agroecosystems 101, 37-53
Weller S, Kraus D, Ayag K, Wassmann R, Alberto M, Butterbach-Bahl K, Kiese R
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(2015) A new LandscapeDNDC biogeochemical module to predict CH4 and N2O emissions from lowland rice and upland cropping systems. Plant and Soil 386, 125-149
Kraus D, Weller S, Klatt S, Haas E, Wassmann R, Kiese R, Butterbach-Bahl K
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(2015) Carbon release from rice roots under paddy rice and maize–paddy rice cropping. Agriculture Ecosystem and Environment 210: 15-24
He Y, Siemens J, Amelung W, Goldbach H, Wassmann R, Alberto MCR, Lücke A, Lehndorff E
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(2015) Diurnal patterns of methane emissions from paddy rice fields at the Philippines. Journal of Plant Nutrition and Soil Science 178, 755-767
Weller S, Kraus D, Butterbach-Bahl K, Wassmann R, Tirol-Padre A, Kiese R
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(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 A.S., Wolters V.
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(2015) Roots shaping their microbiome: Global hot spots for microbial activity. Annu Rev Phytopathol 53: 403-424
Reinhold-Hurek B, Bünger W, Burbano CS, Sabale M, Hurek T
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(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 F.G., Settele J., Zaitsev A.S., Wolters V., Schädler M.
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(2016) Greenhouse gas emissions and global warming potential of traditional and diversified tropical rice rotation systems. Global Change Biology 22
Weller, S., Janz, B., Jörg, L., Kraus, D., Racela, H.S.U., Wassmann, R., Butterbach-Bahl, K., Kiese, R.
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(2016) How well can we assess impacts of agricultural land management changes on the total greenhouse gas balance (CO2, CH4 and N2O) of tropical rice-cropping systems with a biogeochemical model? Agriculture Ecosystem and Environment 224, 104-115
Kraus D, Weller S, Klatt S, Santabárbara I, Haas E, Wassmann R, Werner C, Kiese R, Butterbach- Bahl K
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(2017) Leaching losses of water, nitrogen, and dissolved organic carbon after introducing maize into a continuous paddy rice crop rotation. Agriculture Ecosystem and Environment 249: 91-100
He Y., Lehndorff E., Amelung W., Wassmann R., Alberto M.C.R., von Unold G., Siemens J.
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(2018) High-frequency water isotopic analysis using an automatic water sampling system in rice-based cropping systems. Water 2018,10, 1327
Mahindawansha A, Breuer L, Chamorro C, Kraft P
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(2018) Nitrogen fertilizer fate after introducing maize and upland-rice into continuous paddy rice cropping systems. Agric. Ecosyst. Environ. 258: 162-171
Fuhrmann I, He Y., Lehndorff E, Brüggemann N, Amelung W, Wassmann R, Siemens J
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(2018) Quantification of plant water uptake by water stable isotopes in rice paddy systems. Plant and Soil 429, 281-302
Mahindawansha A., Orlowski N., Kraft P., Rothfuss Y., Racela H., Breuer L.
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(2018) Temporal dynamics and compartment specific rice straw degradation in bulk soil and the rhizosphere of maize. Soil Biol Biochem 127: 220-212
Maarastawi SA, Frindte K, Geer R, Kröber E, Knief C
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(2019) Greenhouse gas footprint of diversifying rice cropping systems: Impacts of water regime and organic amendments. Agriculture Ecosystem and Environment 270-271, 41-54
Janz B., Weller S., Kraus D., Racela H.S., Wassmann R., Butterbach-Bahl K., Kiese R.
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(2019) Preferential flow pathways in paddy rice soils as hot spots for nutrient cycling. Geoderma 337: 594-606
Fuhrmann I, Maarastawi S, Neumann J, Amelung W, Frindte K, Knief C, Lehndorff E, Wassmann R, Siemens J
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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 A.S.
