No abstract

The management of biodiversity represents a research topic that needs to involve not only several (sub-) disciplines from the natural sciences but, in particular, also the social sciences and humanities. Furthermore, over the last couple of years, the need for the integration of other kinds of knowledge (experience based or indigenous knowledge) is increasingly acknowledged. For instance, the incorporation of such knowledge is indispensable for place-based approaches to sustainable land management, which require that the specific ecological and social context is addressed. However, desirable as it may be, such an engagement of the holders of tacit knowledge is not easy to achieve. It demands reconciling well-established scientific procedural standards with the implicit or explicit criteria of relevance that apply in civil society — a process that typically causes severe tensions and comes up against both habitual as well as institutional constraints. The difficulty of managing such tensions is amplified particularly in large integrated projects and represents a major challenge to project management. At the Helmholtz Centre for Environmental Research — UFZ, several integrated research projects have been conducted over the past years in which experience has been gained with these specific challenges. This paper presents some of the lessons learned from large integrated projects, with an emphasis on project design and management structure. At the centre of the present contribution are experiences gained in the coordination and management of LEGATO (LEGATO stands for Land-use intensity and Ecological EnGineering — Assessment Tools for risks and Opportunities in irrigated rice based production systems, see www.legato-project.net), an ongoing, large-scale, inter- and transdisciplinary research project dealing with the management of irrigated rice landscapes in Southeast Asia. In this project, local expertise on traditional production systems is absolutely crucial but needs to be integrated with natural and social science research to identify future-proof land management systems.

Soil salinity may damage crop production. Besides proper management of irrigation water, salinity reduction can be achieved through soil amendment. The objectives of this study were to evaluate the effects of rice husk biochar and compost amendments on alleviation of salinity and rice growth. Field experiments were conducted at two salt-affected paddy rice fields located in distinct sites for five continuous crops. Treatments, with four replicates, consisted of continuous three rice crops per year (RRR), two rice crops rotated with fallow in spring–summer crop (FRR), FRR plus compost at 3 Mg ha−1 crop−1 (FRR + Comp), and biochar at 10 Mg ha−1 crop−1 (FRR + BC). Salt contents and hydraulic properties of soils, plant biomass, and plant uptake of cations were investigated. Soil bulk density (BD), exchangeable sodium (Na+), and exchangeable sodium percentage (ESP) were reduced remarkably by biochar application. Biochar application significantly increased other soil properties including total porosity, saturated hydraulic conductivity (Ksat), soluble and exchangeable potassium (K+), K+/Na+ ratio, available P, and total C. Compost application also improved BD, total porosity, and available P, but not exchangeable Na+ and ESP. Total aboveground biomass of rice showed a trend of FRR + BC > FRR + Comp > FRR > RRR. Relatively higher K+ uptake and lower Na+ uptake in rice straw in FRR + BC resulted in a significant two times higher K+/Na+ ratio over other treatments. Our results highlight that biochar amendment is a beneficial option for reducing ESP and providing available K+ and P under salinity-affected P-deficient conditions, hence improving straw biomass.

Acid sulfate soil (ASS) has major problems related to phosphorus deficiency and high potential for N2O emissions, as well as strong acidity. The objective of this study was to evaluate the effects of rice husk biochar and compost on P availability and greenhouse gas (GHG) emissions in ASS in in vitro incubation studies. An ASS was amended with two types of rice husk biochar (at rates of 0 g kg−1, 20 g kg−1, and 50 g kg−1, equivalent to 0 Mg ha−1, 20 Mg ha−1, and 50 Mg ha−1, assuming that bulk density was 1 g cm−3 and evenly applied for 10 cm in depth) and compost (at rates of 0 g kg−1, 10 g kg−1, and 20 g kg−1, equivalent to 0 Mg ha−1, 10 Mg ha−1, and 20 Mg ha−1) and incubated. Application of compost increased labile P by 100% and 200% at rates of 10 g kg−1 and 20 g kg−1, respectively. Both biochars showed an increase in NaHCO3-soluble inorganic P by 16% to 30%, decreases in NaOH-soluble inorganic P and NaHCO3-soluble organic P. N2O emissions were significantly decreased by 80% by a biochar with a higher surface area and higher NH4+ adsorption capacity at a rate of 50 g kg−1 as compared with those in un-amended soil. In contrast, compost amendment at a rate of 10 g kg−1 significantly increased N2O emission by 150%. These results suggest that in ASS, whilst compost is more effective in improving P availability, biochar is more effective in mitigating GHG emissions, emphasizing that fundamental characteristics of organic amendments influenced the outcomes in terms of desirable effects.