Seasonal changes in wind regime have driven the formation and emergence of reversing dunes and crest reversal in the inland arid and coastal areas of Asia, but due to the strong prevailing winds, the reversing dunes or reversing crest can be flipped. Therefore, the transient reversing dunes or crest reversal will be ignored and unobserved. To investigate dune morphology and sedimentology concerning seasonal alternation of the wind regime, we reconstructed dune topographies using aerial drone photos and analyzed the grain‐size parameters and internal sedimentary structures of dunes. Morphological results show that wind‐blown sands from the lee side are transported and deposited on the upper stoss side because of the reversing winds. Then, the dune crestal area is flattened, surface sand compositions were reorganized from fining to coarsening at the dune crest. Combining these field surveys with numerical simulation results, we found that the internal sedimentary structures are composed of high‐angle cross‐strata and low‐angle bounding surfaces. The dip angles of the bounding surfaces gradually decrease from the bottom to the top because of the reversing wind erosion on the lee side. The increase in sand flux on the lee side plays a critical role in shaping the dip angle of the bounding surfaces due to the speed‐up effect.

Ammonia (NH3) volatilization is a major pathway of nitrogen (N) loss from soil-crop systems. As vegetable cultivation is one of the most important agricultural land uses worldwide, a deeper understanding of NH3 volatilization is necessary in vegetable production systems. We therefore conducted a 3-year (2010–2012) field experiment to characterize NH3 volatilization and evaluate the effect of different N fertilizer treatments on this process during the growth period of Chinese cabbage. Ammonia volatilization rate, rainfall, soil water content, pH, and soil NH4+ were measured during the growth period. The results showed that NH3 volatilization was significantly and positively correlated to topsoil pH and NH4+ concentration. Climate factors and fertilization method also significantly affected NH3 volatilization. Specifically, organic fertilizer (OF) increased NH3 volatilization by 11.77%–18.46%, compared to conventional fertilizer (CF, urea), while organic–inorganic compound fertilizer (OIF) reduced NH3 volatilization by 8.82%–12.67% compared to CF. Furthermore, slow-release fertilizers had significantly positive effects on controlling NH3 volatilization, with a 60.73%–68.80% reduction for sulfur-coated urea (SCU), a 71.85%–78.97% reduction for biological Carbon Power® urea (BCU), and a 77.66%–83.12% reduction for bulk-blend controlled-release fertilizer (BBCRF) relative to CF. This study provides much needed baseline information, which will help in fertilizer choice and management practices to reduce NH3 volatilization and encourage the development of new strategies for vegetable planting.

The excessive use of nitrogen (N) fertilizer for crop production can cause substantial N losses through surface runoff, generating serious nonpoint pollution. A thorough understanding of N runoff losses is necessary for optimal N management in vegetable production systems. A 3-year field experiment was conducted at a Chinese cabbage field in the Taihu Lake Basin of China to evaluate the characteristics of N runoff losses and the effect of different N fertilizer treatments on N runoff losses during the autumn and winter, 2010-2012. The results demonstrated that surface runoff was significantly and positively related to rainfall. The highest risk of N runoff loss occurred one week after fertilization, and top dressing increased this risk. NO3-- N was the main runoff component, accounting for 49.32-71.82% of the total N losses. The concentration of NO3--N was significantly and positively related to the concentration of total N in the runoff. Significant differences in N runoff losses were observed between N fertilizer treatments. N runoff losses from conventional fertilizer were 10.43-22.68 kg ha(-1), significantly higher than from other treatments, and the total N net runoff loss rates for conventional fertilizer treatment were 3.48-7.56%. The application of organic fertilizer reduced N runoff loss by 15.70-18.14% compared to conventional fertilizer application. Organic-inorganic compound fertilizer reduced N runoff loss by 27.37-36.27% compared with conventional fertilizer. Slow-release fertilizers had very significant positive effects in controlling N runoff loss, with a 58.29-61.01% reduction for sulfur-coated urea, a 49.33-56.05% reduction for biological carbon power urea, and a 59.79-63.59% reduction for bulk-blend controlled-release fertilizer relative to conventional fertilizer. This study provides vital baseline information for fertilizer choice and management practices, which can be used to reduce N runoff losses and encourage the development of new fertilizer strategies for vegetable planting. (C) 2015 Elsevier B.V. All rights reserved.

This paper discussed the biomass growth and consumption processes in grazed pasture ecosystems from a theoretical point of view, simulated the dynamics of these two processes with mathematical models, and analyzed the mechanism of ecological balance in pasture ecosystems from the perspective of these two processes. With the proposed biomass growth and consumption models, the dynamics of cumulative biomass consumption during one production cycle was simulated, and the optimal grazing strategies of pastures were proposed. The results could be valuable for pasture grazing management in practice.

Field and water tank plot experiments were conducted in Zhejiang Province in 1999 to determine the effects of nitrogen application amount and times on rice growth and yield, and rice growth simulation model ORYZA-0 and nitrogen management module were used to establish a modified nitrogen effect-rice growth model. The simulated results presented a higher positive relationship with the measured results. According to the simulated and measured results, 160 kg.hm-2 was the economic nitrogen application amount for two rice varieties production, and the nitrogen application strategies were: 1) < 100 kg.hm-2 nitrogen fertilizer should be applied within 35 days after transplanting; 2) when the nitrogen application level was between 100-200 kg.hm-2, it should be applied within 45 days after transplanting; 3) if the nitrogen application amount exceeded 200 kg.hm-2, it should be put into paddy field within 60 days after transplanting; 4) as the nitrogen application amount increased, the nitrogen supply at the later rice growth stage should be increased. As for the second cropping rice, the more times the nitrogen applied in the field, the more closeness the rice yield reached the APCUM curve(optimized nitrogen curve) suggested. But in real rice production, it is impossible for farmers to adopt more times of N applying, since labor and cost will increase. Based on the experimental parameters and real rice production situation, the reasonable nitrogen application under 160 kg.hm-2 levels for high yielding second cropping rice was split into 4 times with fraction 0.2:0.3:0.3:0.2 at 5, 20, 30, 40 days after transplanting. The rice yield could reach 5,916 kg.hm-2, resulted in a 3.12% increase as compared with the yield under actual fertilizer application amount and timing.

Integrated index method was used to evaluate the practices of eco-agriculture in Deqing County in 1990-1998. The results showed that the integrated benefit, resources use, and ecological, economic and social benefits appeared a rising trend. The value of integrated benefit index in 1998 was 2.36 times of that in 1990. The benefit index, however, also fluctuated in these years, which meant that the eco-agricultural system of Deqing County still had some problems to be resolved. Adjusting industry structure in rural areas, lessening pollution produced by rural industry, and improving stability of eco-agricultural system should be highlighted in the next stage.