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The growing global population and the ongoing loss of arable soils increase the pressure on agricultural production. In conjunction with climate change, this causes new challenges for agricultural production systems worldwide and requires a more sustainable approach for the future. The concept of ‘sustainable land management’ (SLM) is known as a concretisation of the sustainable development goals in the field of agriculture. The Western Siberian grain belt covers 1 million km² in Asiatic Russia and is of global importance for agricultural production as well as an important carbon sink and of international interest for biodiversity preservation. The work was conducted as part of the interdisciplinary German-Russian SASCHA project, which focused on SLM strategies at the intersection of climate change and land-use change in Tyumen region of Western Siberia. The objective of this work was to identify strategies for sustainable agricultural land management in Western Siberia with a focus on arable farming issues. Therefore, specifically the following research questions were addressed: (i) What does the history of agricultural land use across the Western Siberian grain belt tell us for developing future strategies? (ii) How can the eco-efficiency of Western Siberian cereal cropping systems be increased under the strain of changing climatic conditions? (iii) Is soybean cultivation capable of diversifying crop rotations in the southern part of Western Siberia? Triggered by the dissolution of the Soviet Union and the collapse of the state farm system, massive land-use changes took place in the region. A normalised input-oriented intensity index was developed to quantify these changes and patterns in land-use intensity (LUI). Based on subnational, annual statistical data, two separate indices for cropland and grassland were calculated and applied on two spatial scales (provinces and districts). The spatio-temporal analysis showed significant opposite trends: decreasing intensity on grassland by -0.015 LUI units per year and intensification on cropland by +0.014 LUI units per year. The land-use changes that accompanied the post-Soviet transition from a planned to a market-driven economy also implied substantial socio-economic consequences for agricultural production. Based on the LUI analysis, locally adapted SLM scenarios were developed for Tyumen province and priority areas for implementation were identified. The findings clearly showed the need for having a different SLM strategy for grassland (predominantly used by livestock of households) and cropland (predominantly managed by large agricultural enterprises), which have to be addressed specifically by the different land users. Two major strategies were derived for the Western Siberian grain belt: low-intensity grazing for grassland conservation and sustainable intensification (SI) on cropland instead of cropland expansion. The system of conservation agriculture is a known possibility for SI in dryland cropping systems. Particularly under climate change predictions of drier and warmer growing conditions, no-till farming could be a promising way to increase eco-efficiency in Western Siberian cereal production systems. Therefore, a full-factorial split-split-plot field trial was conducted on a farmer’s field to test adaptations of tillage (usual conventional tillage ‘CT’ vs. no-till ‘NT’), seeding depth (usual deep 6.5 vs. shallow 4.5 cm) and seeding rate (usual high 600 vs. reduced 450 grains m-2) for the potential to increase water use efficiency and grain yield. Results from two above-average wet and cold growing seasons showed significantly better soil water storage of NT (+40 %) and no adverse effect on spring wheat grain yield and grain quality. Impacts of variations in seeding rate and seed placement were less pronounced. The highest yields of 3.19 and 3.82 t ha-1 were observed with NT treatment in 2014 and 2015, respectively. Other alternatives implemented to increase eco-efficiency of dryland cropping systems are enhanced fertilizer strategies. In Western Siberia, nitrogen (N) fertilizers (urea or ammonium-nitrate ‘Selitra’) in cereal production are commonly banded during sowing directly into the seed furrow. The performance of a new kind of slow-release fertilizer was tested in a field trial under on-farm conditions. A modified urea with silicate coating and urease inhibitor was compared in four N-levels (25/50/75/100 %) to 100 % of conventional urea, 100 % of Selitra and an unfertilized control in RCBD. Results showed significant differences in soil nitrate availability but no differences in ammonium release and no significant impact on grain yield or quality. From the results of this field trial there seemed to be no beneficial advantage of the tested novel slow-release fertilizer so far. More field site years and further improvements of the laboratory-scale fertilizer production are needed for scientifically founded results. Climate change is likely to considerably affect future growing conditions in regions around the current high-latitude boundaries of agricultural production. Specifically for soybeans, this leads to a northwards shift of the northernmost limit for cultivation. Therefore, the effect of soybean seed inoculation with Bradyrhizobium japonicum was investigated in comparison to an untreated control in a small-scale split-plot field trial under high latitude conditions. Leaf chlorophyll content by SPAD-meter readings was used as proxy for biological nitrogen fixation. Inoculation was always successful, since nodulation took only place in plots with seed treatment. Effect sizes of SPAD-values were significantly positive at beginning of seed filling but did not differ earlier. Except for the warmest site year, inoculation had no impact on seed yield and protein yield. Under cold growing conditions of high latitude regions, temperature sums seemed to limit soybean yield and the effectiveness of inoculation with B. japonicum. To implement soybeans as legumes in crop rotations, nevertheless, inoculation is mandatory, since soils in high latitudes lack soy-specific rhizobia bacteria. The trials and studies compiled in this thesis are examples of contributions to SLM strategies on varying spatial and temporal scales. Besides all the promising benefits of the described SI applications, some drawbacks must be considered: NT and CA often result in increased herbicide applications, genetically modified varieties (GMO) and herbicide resistances. Diverse crop rotations including legumes, however, would be a base for resilient cropping systems with a reduced reliance on a single herbicide. Moreover, Western Siberia has a great potential to become a key contributor to non-GMO dryland cropping. Even though the focus of this thesis was on agronomic strategies, the integration of livestock and arable farming is crucial for sustainable agriculture. The agricultural system of the Western Siberian grain belt could considerably benefit from crop-livestock integration by better soil fertility and enhanced nutrient management. The current observed trend of cropland intensification, however, will require increased attention paid to the sustainability of Siberian arable farming. Considering the forest steppes’ peculiarities and the unique land-use history, SI implemented on cropland and a moderate grazing regime on grassland seems to be the best combination for SLM across the Western Siberian grain belt.

The expansion of livestock husbandry and biogas production in large parts of northwestern Germany during the last two decades increased the amount of accruing manure, as well as the demand for maize as fodder crop and substrate for biogas plants. To overcome phosphorus deficiency symptoms during early growth of maize, farmers commonly apply mineral starter fertilizers containing ammonium-nitrogen and phosphorus on top of the usual manure applications required to meet crop nutrient demand. This practice typically leads to overfertilization of N and P and the excess nutrients are then prone to be lost into the environment. Recent developments of agricultural machinery allow for the injection of slurry bands into the soil prior to maize planting. Due to high concentrations of ammonium and phosphorus in the manure band, chemical transformation and translocation of these nutrients is reduced. When the bands are placed near the seeds, even the radicles can access the applied nutrients. Hence, application of mineral starter fertilizers might be obviated. Earlier investigations showed insufficient knowledge of nutrient transformations in manure bands and their consequences on crop growth. To resolve these problems a research project at the University of Applied Sciences Osnabrück was conducted in close cooperation with the local agricultural extension services, machinery producers and farmers. In a series of field trials, broadcasting of liquid manure was compared to injection with and without a nitrification inhibitor in three consecutive growing seasons (2013 to 2015). The trials were conducted in a split-plot design, where all liquid manure treatments were divided in subplots with and without a mineral starter fertilizer. Biomass samplings at eight leaves stage and harvest gave insight into the performance of the treatments. Compared to broadcast application with starter fertilizer, manure injection showed slightly retarded early growth in some trials. However, yields and nitrogen uptake at harvest were similar. When a nitrification inhibitor was added to the injected manure, early growth was not retarded, yields were alike broadcast and injection treatments, but nitrogen uptake was higher in all seasons (on average ~7%). To further investigate nitrogen dynamics and crop growth, another field trial was conducted on a sandy soil close to Osnabrück in 2014 and 2015. Manure injection with and without a nitrification inhibitor was compared to broadcast application with mineral starter fertilizer and an unfertilized control treatment. Plant samplings were taken at regular intervals. Major precipitation events in May and June 2014 led to significant nitrate leaching, especially in the broadcast treatment. Manure injection delayed the nitrification of slurry ammonium and consequently the translocation out of the root zone. Thus, plants in injection treatments could accumulate more nitrogen in their biomass and showed less nitrogen deficiency symptoms. This led to increased yield (+16.5%) and nitrogen uptake (+9.6%) for injection treatment with nitrification inhibitor compared to broadcast treatment. In 2015, low temperatures impaired seminal root growth and phosphorus availability. The mineral starter fertilizer in the broadcast treatment led to better early growth than injected slurry. When a nitrification inhibitor was added to the injected manure, less P deficiency symptoms were observed, and the crop growth was only slightly retarded. Due to the high compensation potential of silage maize, these differences were equalized until harvest. Nevertheless, the mean apparent nitrogen recovery efficiency of both seasons was higher in injection treatments with and without nitrification inhibitor, compared to broadcast with mineral starter fertilizer (48%, 56% and 43%, respectively). To ease the handling of field trial series by decreasing the number of tissue samplings, the use of a handheld sensor was tested during vegetative growth of maize. In the series of field trials with the local extension service, the derived vegetation index showed significant correlations to biomass and nitrogen uptake at eight leaves stage. Measurements of the vegetative growth observed during the nitrogen dynamics trial showed that the sensor needs sufficient leaf area to deliver precise data, but also tends to saturate when maize tassels evolve. The best estimates were found between six and ten leaves. Thus, the sensor can be a valuable tool to reduce numbers of tissue samples and, thus, time and effort needed in fertilization trials. Altogether, these results should encourage farmers to obviate mineral starter fertilizers by using manure injection when cropping maize on sandy soils. The advantages that come along with manure injection based on the present research indicate higher shares of manure nutrients find their way into the plants due to delayed biochemical transformations. These nutrients are consequently not lost into the environment. Nitrification inhibitors have shown a positive effect on crop performance and led to a further reduction of nitrogen losses. However, further knowledge of their decomposition with special regard to the ecological impact of their compounds and metabolites need to be thoroughly evaluated.

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