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The 19F(p, αγ)16O reaction is of crucial importance for Galactic 19F abundances and CNO cycle loss in first generation Population III stars. Due to its extremely small cross sections, the 19F(p, αγ)16O reaction has not been measured in the low energy part of the Gamow window(70-200 keV). As a day-one campaign, the experiment was performed under the extremely low cosmicray-induced background environment of the China JinPing Underground Laboratory(CJPL), one of the deepest underground laboratories in the world. The γ-ray yields were measured over Ec.m. =72.4–344 keV, covering the full Gamow window for the first time. The direct experimental data will help people to expound the fluorine over-abundances, energy generation, as well as heavy-element nuclosynthesis scenario in asymptotic giant branch (AGB) stars, with the astrophysical model on the firm ground.

A high temperature silicon on insulator pressure sensor utilising a Ti/TiN/Pt/Au electrode is presented for improving the thermal stability of ohmic contacts, which can work stably at high temperatures of up to 500°C. To analyse the characteristics of the electrode at high temperatures, a special test structure is measured using the linear transmission line method and Auger electron spectroscopy. To solve the measurement problem, a novel calibration setup is designed to calibrate the absolute pressure sensor at extremely high temperatures. The measurement results have shown that the pressure sensor has a nonlinearity error of 0.17%FS and a sensitivity of 0.24 mV/kPa with a measurement range of 30–150 kPa at 500°C, indicating the good thermal stability of the ohmic contacts.

Excited states in 63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from 68Fe. Similar level schemes, consisting of the 11/2−, 9/2−, 7/2− and 5/2g.s.− level sequence, connected by I→I−1 transitions, were established, the first time for 65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K=5/2. State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass 53−67Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the N=40 “island of inversion”. Keywords: In-beam γ-ray spectroscopy, “Island of inversion” around N=40, Strong coupling, Structure evolution

Although the concept of producing higher yields with reduced greenhouse gas (GHG) emissions is a goal that attracts increasing public and scientific attention, the trade-off between high yields and GHG emissions in intensive agricultural production is not well understood. Here, we hypothesize that there exists a mechanistic relationship between wheat grain yield and GHG emission, and that could be transformed into better agronomic management. A total 33 sites of on-farm experiments were investigated to evaluate the relationship between grain yield and GHG emissions using two systems (conventional practice, CP; high-yielding systems, HY) of intensive winter wheat (Triticum aestivum L.) in China. Furthermore, we discussed the potential to produce higher yields with lower GHG emissions based on a survey of 2938 farmers. Compared to the CP system, grain yield was 39% (2352 kg ha−1) higher in the HY system, while GHG emissions increased by only 10%, and GHG emission intensity was reduced by 21%. The current intensive winter wheat system with farmers' practice had a median yield and maximum GHG emission rate of 6050 kg ha−1 and 4783 kg CO2 eq ha−1, respectively; however, this system can be transformed to maintain yields while reducing GHG emissions by 26% (6077 kg ha−1, and 3555 kg CO2 eq ha−1). Further, the HY system was found to increase grain yield by 39% with a simultaneous reduction in GHG emissions by 18% (8429 kg ha−1, and 3905 kg CO2 eq ha−1, respectively). In the future, we suggest moving the trade-off relationships and calculations from grain yield and GHG emissions to new measures of productivity and environmental protection using innovative management technologies.

Nitrous oxide (N2O) is a long-lived greenhouse gas with a large radiation intensity and it is emitted mainly from agricultural land. Accurate estimates of total direct N2O emissions from croplands on a country scale are important for global budgets of anthropogenic sources of N2O emissions and for the development of effective mitigation strategies. The objectives of this study were to re-estimate direct N2O emissions using localized emission factors and a database of measurements from Chinese croplands. We obtained N2O emission factors for paddy fields (0.41 ± 0.04%) and uplands (1.05 ± 0.02%) from a normalization process through cube root transformation of the original data. After comparing the results of normalization from the original values, Logarithmic and cube root transformations were used because the frequency of the original data was not normally distributed. Direct N2O emissions from Chinese croplands from 1980 to 2007 were estimated using IPCC (2006) guidelines combined with separate localized emission factors for paddy fields and upland areas. Direct N2O emissions from paddy fields showed little change, increasing by 10.5% with an annual rate of increase of 0.4% from 32.3 Gg N2O-N in 1980 to 35.7 Gg N2O-N in 2007. In contrast, emissions from uplands changed dramatically, increasing by 308% with an annual rate of 11% from 68.0 Gg N2O-N in 1980 to 278 Gg N2O-N in 2007. Total direct N2O emissions from Chinese croplands increased by 213% with an annual rate of 7.6% from 100 Gg N2O-N in 1980 to 313 Gg N2O-N in 2007, and were determined mainly by upland emissions (accounting for 67.8–88.6% of total emissions from 1980 to 2007). Synthetic N fertilizers played a major role in N2O emissions from agricultural land, and the magnitude of the contributions to total direct N2O emissions made by different amendments was synthetic N fertilizer > manure > straw, representing about 78, 15, and 6% of total direct N2O emissions, respectively, between 2000 and 2007. The spatial pattern of total N2O emissions in 2007 in China shows that high direct N2O emissions occurred mainly in the north and in the Sichuan Basin in the southwest. The provinces with the highest emissions were Henan (35.4 Gg) and Shandong (31.6 Gg) and Tibet had the lowest (0.65 Gg). High direct N2O emissions per unit of arable land occurred mainly on the North China Plain and the southeast coast. The mean value nationally was 2.52 kg N ha−1, with 18 provinces above this value and with emissions of >4.0 kg N ha−1 in Beijing, Tianjin and in Jiangsu, Shandong, Fujian and Henan provinces.

In recent years large areas of conventional cereal production in China have been transferred to greenhouse production with huge excessive nitrogen (N) fertilizer application and massive irrigation. However, the effects of this change in land use on soil carbon and nitrogen pools remain to be explored. Here we report a comparative study in which paired soil samples were taken from four greenhouses and from adjacent conventional cereal fields. Soil organic carbon (SOC), carbonate carbon (IC), total nitrogen (TN) and mineral nitrogen (N min ) to 100 cm depth and the soil active organic pools, including particulate organic matter (POM), soil microbial biomass (SMB) and dissolved organic matter (DOM), to 0–40 cm depth were determined. The natural isotopic signatures of SOC, TN and POM were also analyzed. In both production systems all of the carbon and nitrogen pools in the surface soil (0–10 cm) were greater than deeper in the soil profile except for dissolved organic nitrogen (DON) and NH 4 -N. SOC and TN and dissolved organic carbon (DOC) concentrations were higher in the greenhouse system than in conventional cereal soils ( P > 0.05). A similar trend was found for POM ( P 3 -N ( P P > 0.05) and IC in the greenhouse system showed a dramatic decline. The SOC/TN ratios of different pools in the greenhouse soils were lower than in the conventional cereal system ( P > 0.05). The SOC/TN ratio ranged from 8.4 to 10.0 in greenhouse soils and 8.5 to 11.7 in the cereal soils. At each depth POM content in the greenhouses (1.5–7.1 g kg −1 ) was significantly greater than that in the field soils (0.8–2.9 g kg −1 ) ( P

The pressures of development and major shifts in land use have increased the need to assess the impact of land use change on soil nutrients. This study was conducted in an area with intensive agricultural land use in north China to assess effects of land use change on soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP) and available potassium (AK). Soil samples were collected from rainfed land, irrigated land, virgin grassland and vegetable land in 1980 and 1999. SOC, TN and AP were higher in 1999 than in 1980, and the increases followed the following order: vegetable land > irrigated land > rainfed land, except for AK. Soil nutrient contents were increased when land uses underwent the following changes (except for AK): virgin grassland → rainfed land → irrigated farmland → vegetable land. The SOC, TN and AP fluxes (rate of change in C, N, P and K as kg(ha y) −1 ) in the transition systems from rainfed land to vegetable land were 518.46, 69 and 3.9 kg(ha y) −1 , respectively, which were considerably higher than the transition systems from rainfed land to irrigated land. The SOC, TN and AP fluxes in the transition systems from virgin grassland to irrigated land were 297.83, 56.3, 2.1 kg(ha y) −1 , respectively, which were higher than the transition systems from virgin grassland to rainfed land. The study shows that land use intensification can increase soil nutrient contents if accompanied by increased fertilizer application.

Soil organic matter (SOM) is strongly related to soil type and management practices. Changes in government policy have brought drastic changes in farm management practices in the last two decades in rural China. This study investigates changes in SOM in two different soils: Ustepts and Udolls. Ustepts, in the North China Plain where the climate is warm and sub-humid, developed from an alluvial flood plain with organic matter −1 . Udolls, in Northeastern China where the climate is cool and sub-humid, developed from loess-like materials with organic matter >20 g kg −1 . Two locations for Ustepts and three locations for Udolls were used to collect 567 soil samples in 1980–1982 and again in 2000 for SOM analysis. Soil organic matter increased for Ustepts and decreased for Udolls soils over the sampling period, resulting from differences in fertilizer rates and crop residue input to soil. Higher fertilizer input and crop intensity and initially very low SOM content in Ustepts all contributed to greater OM input than oxidation release. In contrast, lower fertilizer input and crop intensity, and initially high SOM content in the Udolls, led to lower OM input than oxidation release. Increasing SOM content through higher mineral fertilizer input is a valuable option for sustainable agriculture production in areas where SOM is low and there is a shortage or potential shortage of food supply.

Following land reform in China in the early 1980s, farm management practices, such as the type of crops grown and their rotations, intensity of cropping and fertilizer and pesticide use, underwent drastic changes. To investigate how these changes affected soil properties and ultimately the sustainability of agricultural production, a case study was conducted in Daxing County (southern Beijing Municipality). Soil in the Daxing area was sampled in 1982 at the onset of land reform and again in 2000. Surface soil (0–20 cm) samples were collected and analyzed for organic matter (OM), total nitrogen (TN), and available N (AN), P (AP) and K (AK) contents. The soil OM, TN, AN, and AP all increased significantly while AK decreased slightly, but significantly, for the sampling area over the 18-year study period. Increased crop yield (higher biomass production) with increasing fertilizer application combined with soil conservation measures that have retained more crop residue on land, are responsible for the increases in soil OM, N and P concentrations. However, the slight decreases in AK reflect the increased cropping intensity and low AK supplying power of these coarse textured soils as well as the low K fertilizer input.

Simulation of atmospheric nitrogen (N) deposition in the North China Plain (NCP) at high resolution, 5 × 5 km2, was conducted for the first time by the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. The total N deposition budget was 1481 Gg in this region, with 77 % from reduced N and 23 % from oxidized N, and the annual deposition rate (47 kg N ha−1) was much higher than previously reported values for other parts of the world such as the UK (13 kg N ha−1), Poland (7.3 kg N ha−1) and EU27 (8.6 kg N ha−1). The exported N component (1981 Gg) was much higher than the imported N component (584 Gg), suggesting that the NCP is an important net emission source of N pollutants. Contributions of N deposition budgets from the seven provinces in this region were proportional to their area ratios. The calculated spatial distributions of N deposition displayed high rates of reduced N deposition in the south and of oxidized N deposition in the eastern part. The N deposition exceeded an upper limit of 30 kg N ha−1 for natural ecosystems over more than 90 % of the region, resulting in terrestrial ecosystem deterioration, impaired air quality and coastal eutrophication not only in the NCP itself but also in surrounding areas including the Bohai Sea and the Yellow Sea.

Intercropping, growing two or more crop species in the same field, is a practice that can contribute to ecological intensification of agriculture. Intercropping has been shown to increase productivity in low phosphorus (P) soils compared to sole crops. The ecological mechanisms underlying these benefits mainly include complementarity and facilitation with respect to resource acquisition. The contribution of these mechanisms to the yield benefit of intercropping probably depends on crop species traits, soil nutrient availability and agronomic practices. This thesis aims to contribute to the design of intercropping systems for improved P acquisition and yield gain by testing the resource partitioning hypothesis (dissimilarity in P acquisition traits among plant species leads to enhanced P uptake by mixtures of crop species compared to sole crops), and by quantifying the absolute yield gain of intercrops and the effect of agronomic practices. It presents results from empirical studies and meta-analyses.It appeared that the conditions under which the P resource partitioning hypothesis can be tested are limited. The tested crop species had inconsistent abilities to access the sparingly soluble Ca-bound P, phytate P, P-coated Fe(hydr)oxide, and competitive inequality between them largely determined the interaction. In a pot experiment with low P soils containing a mixture of organic and inorganic P sources, complementarity and facilitation did not result in increased P uptake by species mixtures, because P uptake was also affected by the competitive equality of species in the mixture. In a field experiment on a low P soil, complementarity and facilitation with respect to P uptake occurred in millet/chickpea relay strip intercropping, but they were not the main drivers for overyielding. In the subsequent meta-analysis on intercropping at the field level, the absolute yield gain of intercropping was mainly attributed to a positive complementarity effect, an outcome of any mechanism reducing competition. This positive complementarity effect was related to complementarity in using resources at different times caused by a relay sequence in the sowing and harvesting of intercropped species. The temporal complementarity in using resources plays an important role in competitive relaxation and hence overyielding. On a global level, there was a set of coordinated management factors rather than a single factor that drove the yield gain of intercropping, resulting in two contrasting syndromes of production in intercropping. The first syndrome was a high input - high output strategy that is maize-based with species arranged in relay strips and with high fertilizer input. The second syndrome was a low input - low output strategy that is legume-based and arranged in simultaneous full mixtures or alternate row intercrops with low fertilizer input. Both intercropping strategies saved 16-29% land and 19-36% fertilizer compared to monocultures grown under the same management as the intercrop.To conclude, there was no evidence for the resource partitioning hypothesis for P sources in species mixtures. Designing intercropping systems for improved P acquisition cannot be through the mechanisms of complementarity in P acquisition from different P sources. Further research on designing intercropping systems could consider a set of management strategies such as using strip intercropping, a relatively short co-growth period of the two crop species, and including species with high productivity (e.g., maize).

Door menselijk handelen (verandering in van natuurlijke vegetatie naar landbouw) is de organische C voorraad in de bodem met 10-59% afgenomen, afhankelijk van de landgebruiksverandering. Dit heeft geleid tot een toename van de CO2 concentratie in de atmosfeer. Deze toename heeft bijgedragen aan opwarming van de aarde en de daaraan gerelateerde milieuproblemen. Een ander risico van de vermindering van de organische C voorraad in de bodem is vermindering van de bodemvruchtbaarheid. Mede hierdoor wordt de opgave om de voedselproductie de komende 50 jaar te verdubbelen, een grote uitdaging. Vastlegging van C in de bodem kan een goedkope en milieuvriendelijke maatregel zijn die bijdraagt aan vermindering van effecten van klimaatverandering op een termijn van 20 – 50 jaar. Deze maatregel kan bovendien bijdragen aan voedselzekerheid doordat ze de bodemkwaliteit in landbouwsystemen verhoogt.

Keywords:Arbuscular mycorrhiza, Exudation, Oryza sativa , Rhizosphere, Rice, Soil, ZincZinc deficiency is a wide-spread constraint for crop production and human health. This thesis should contribute to alleviation of Zn deficiency problems and aimed at identifying soil and plant factors affecting Zn bioavailability in rice ( Oryza sativa L.). Two main research questions were: 1) what is the consequence of a cultivation shift from flooded to aerobic rice on Zn bioavailability and 2) which mechanisms control Zn mobilization by aerobic rice? Field experiments demonstrated that the cultivation shift from flooded to aerobic may increase Zn deficiency problems. Lower Zn uptake and mass fraction in shoot and brown rice were observed in aerobic fields. Results of a soil incubation experiment and modeling showed that the difference found in plant Zn uptake between the two cultivation systems was orders of magnitude lower compared to what can be expected based on chemical equilibria in the bulk soil. This discrepancy suggests that soil chemical properties such as pH, DOC level and redox conditions in rhizosphere need consideration. We observed considerable variation among aerobic rice genotypes in tolerance to Zn deficiency under both field and pot conditions. In a pot experiment we found that variation in tolerance was mainly associated with Zn uptake. Plant Zn uptake from low Zn soils can be increased by both Zn-mobilizing rhizosphere processes and inoculation with arbuscular mycorrhizal fungi. We demonstrated that mycorrhizal inoculation significantly increased Zn uptake, but only in genotypes with a low inherent Zn uptake. High Zn mobilization by a combination of chemical rhizosphere and mycorrhizal effects seems impossible and may not be feasible as a target for breeders. In a rhizotron experiment and a nutrient solution experiment, aerobic rice genotypes responded to Zn deficiency with increased root exudation of malate.Genotypes with a higher Zn uptake showed a stronger increase in malate exudation in response to Zn deficiency.These results confirm our hypothesis that genotypic variation in Zn uptake of aerobic rice can partly be explained by root exudation of malate.