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A glasshouse study was conducted to compare the rhizosphere characteristics of two wheat genotypes, Xiaoyan54 (XY54) and Jing411 (J411) on two soils. The results showed that supplying phosphorus (P) increased the biomass and P content of two wheat lines significantly on alkaline soil, but P fertilization altered their biomass and P content on acidic soil only slightly. XY54 decreased rhizosphere pH more significantly than J411 on Fluvo-aquic soil without P addition, but similar acidity ability was shown when P applied. On red soil, two wheat genotypes showed similar rhizosphere pH. Two wheat lines showed similar rhizoshphere phosphatase activity on alkaline soil, whereas XY54 demonstrated greater rhizoshphere phosphatase activity than J411 on acidic soil. Rhizoshphere phosphatase activities of two wheat lines on acidic soil were greater than alkaline soil. Therefore, stronger acidity on alkaline soil and greater phosphatase activity on acidic soil are principal rhizosphere mechanisms for XY54 to adapt to low-P soils. [ABSTRACT FROM PUBLISHER]

Agricultural soils are the largest anthropogenic emission source of nitrous oxide (N 2 O). National agricultural policies have been implemented to increase crop yield and reduce nitrogen (N) losses to the environment. However, it is difficult to effectively quantify crop-specific and regional N 2 O mitigation priorities driven by policies, due to lack of long-term, high-resolution crop-specific activity data, and oversimplified models. Here, we quantify the spatiotemporal changes and key drivers of crop-specific cropland-N 2 O emissions from China between 1980 and 2017, and future N 2 O mitigation potentials, using a linear mixed-effect model and survey-based data set of agricultural management measures. Cropland-N 2 O emissions from China tripled from 102.5 to 315.0 Gg N yr -1 between 1980 and 2017, and decelerated since 1998 mainly driven by country-wide deceleration and decrease in N rate and the changes in sowing structure. About 63% of N 2 O emissions could be reduced in 2050, primarily in the North China Plain and Northeast China Plain; 83% of which is from the production of maize (33%), vegetables (27%), and fruits (23%). The deceleration of N 2 O emissions highlights that policy interventions and agronomy practices (i.e., optimizing N rate and sowing structure) are potential pathways for further ambitious N 2 O mitigation in China and other developing countries.

The huge excrement quantity from the increasing large-scale livestock stressed the ecological, environmental deterioration. As a major benefit for handling livestock manure, the slurry of biogas (BS) is developed during the production of biogas that might increase plant productivity. However, nitrous oxide (N 2 O) emissions from BS are considered a significant danger to the environment due to global warming potential. Furthermore, applying different proportions of BS combined with chemical fertilizer (CF) on N 2 O productions in the North China Plain (NCP) remains unclear. Herein, two sequential field trials were performed by maize-wheat rotations to substitute the CF by BS and reduce N 2 O emissions while keeping the crop yield stable. Four treatments were conducted, including T1, T3, T6, and CK. A total of 226.5 kg N ha -1 used in the maize-wheat rotation system. Additionally, different ratios of BS (100%, 80%, and 50%) combined with CF were used in wheat season in the tillering stage. Results showed integrated applications of BS with CF have potential for reducing N 2 O emission. Our findings showed that the maximum grain yield of CF was 6250 kg ha -1 , which might be achieved by applying 38% BS and 62% of CF. This ratio yielded 1.03 kg ha -1 N 2 O emissions, which was 15% lesser than the N 2 O emission of CK, 1.21 kg ha -1 . Considering whole growing period of wheat biogas treatments significantly reduced the cumulative N 2 O emissions from 17% to 26% compared to CF. To achieve maximum yield and minimum N 2 O emissions, an optimum 38% BS ratio has been suggested. The integrated use of BS and CF provided the greatest grain yield because of necessary nutrients provided by both slurry and CF. Consequently, N 2 O emissions reduced based on frequency and type of fertilizer. In conclusion, 38% ratio of BS combined with 62% CF would be a suitable approach to mitigate N 2 O emission and simultaneously increase crop yield in NCP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)