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In order to reveal the synergistic effect of biological and engineering measures on improving saline-alkali soil, and to clarify the suitable buried spacing and organic-inorganic fertilizer application ratio for sunflower production in coastal agricultural areas, this paper designs three different hidden pipe spacing of 10 m (S1), 15 m (S2), and 20 m (S3), as well as six fertilization treatments of 100% organic fertilizer (100% OF), 75% organic fertilizer+25% inorganic fertilizer (75% OF), 50% organic fertilizer+50% inorganic fertilizer (50% OF), 25% organic fertilizer+75% inorganic fertilizer (25% OF), 100% inorganic fertilizer (0% OF) and no fertilization (CK). The response of sunflower yield, quality, nitrogen utilization, and soil available nutrients, organic matter, and total salt content is observed. The results show that under the same distance between tubes, the 25% OF fertilization treatment has the most significant yield increase effect, while under the same fertilization treatment, the S2 spacing is at a higher level in sunflower yield. Under different treatments, the 25% of fertilization treatment has the highest sunflower yield under S2 condition, reaching 3.82 t/hm2. Increasing the proportion of organic fertilizer application is beneficial for increasing the content of crude fat, oleic acid, and linoleic acid in sunflower seeds. Fertilization treatment significantly increases the nitrogen uptake amount of sunflower plants, with an increase of 18.1-47.2%, 8.6-40.5%, and 8.8-34.5% under S1, S2, and S3 spacing compared with CK treatment, respectively. The nitrogen utilization efficiency of sunflowers shows a trend of first increasing and then decreasing with the increase in organic fertilizer proportion, S2-25% OF and S1-25% OF treatments at a higher level, reaching 44.2% and 43.9%, respectively. The content of available nitrogen, available phosphorus, and available potassium in soil is positively correlated with the proportion of organic fertilizer application. Under S1-S3 spacing, the content of available nitrogen, available phosphorus, and available potassium in organic fertilizer treatment is on average 22.0%, 2.4%, and 26.4% higher than CK. The smaller the distance between hidden pipes and the higher the proportion of organic fertilizer application will lead to the higher the salt reduction rate of the topsoil. The salt reduction rate of the 100% of treatment under S1 spacing has reached 42.6%. Considering the factors such as yield, quality, and nitrogen fertilizer utilization efficiency, this paper recommends using a 25% organic fertilizer application ratio under 15 m dark tube spacing as the optimal plan for sunflower production in saline alkali soil. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to analyze the spatial-temporal agglomeration changes and driving factors of three major oil crops in China from 2000 to 2020, namely soybean, peanut and rape, so as to provide reference for optimizing the production layout of edible oil crops. [Method] The spatiotemporal agglomeration evolution characteristics and driving factors of soybean, peanut and rape production were analyzed by using the gravity shift model, exploratory spatial data analysis, spatiotemporal geographical weighted regression model and other methods. [Result] (i) The yield of soybean was the highest, followed by peanut, and the yield of rape was the lowest. The yield of soybeans showed a significant fluctuation increase, while the yield of rapeseed and peanut showed a slight fluctuation increase. Soybean production was mainly distributed in Heilongjiang, Inner Mongolia, Henan and Anhui. Peanut production was mainly distributed in Shandong, Henan and Guangdong. Rape production was mainly distributed in Sichuan, Hubei and Hunan. (ii) From 2000 to 2020, the yield agglomeration degree of three oil crops showed a weakening trend, and the high-high accumulation areas of soybean yield were in Heilongjiang and Jilin, and the low-low accumulation area was in Xinjiang; The high-high accumulation areas of peanut yield were in Shandong, Henan and Anhui, and the low-low accumulation area was in Xinjiang; The high-high accumulation areas of rape yield were in Hubei, Anhui and Jiangxi, and the low-low accumulation area was in Inner Mongolia. The production center of soybean moved to the northwest from Tanghai county in Hebei province to Ningcheng county in Inner Mongolia. The production center of peanut was located in Henan province and was moving to- wards the northwest of Henan province; The production center of rapeseed shifted to the southwest from Nanzhang county in Hubei province to Fengjie county in Chongqing. (iii) The driving factors of different oil production had different effects in different provinces. Soybean pro- duction was mainly affected by population density, fertilizer application and GDP growth rate; Peanut production was mainly affected by chemical fertilizer application, total mechanical power and irrigation area; Rapeseed production was mainly affected by population density, urbanization rate and road density. [Conclusion] The production of three main oil crops has obvious spatial agglomeration characteristics, and the influencing factors are different, which are mainly affected by social and economic factors such as chemical fertilizer application. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to study the effects of combined application of biochar and nitrogen fertilizer on SPAD value, photo- synthetic characteristics, dry matter accumulation, transport, grain filling rate and yield of spring wheat in irrigation area of northern Xinjiang, which provided a basis for rational application of different amounts of nitrogen fertilizer and combined application of biochar in irrigation area of northern Xinjiang and increasing yield and efficiency of farmland. (Method) In the study, the high-quality spring wheat variety Xinchun 37' in Xinjiang was used as the test material, and a randomized block design was used, four nitrogen fertilizer levels were set up as non-nitro- gen fertilizer (NO:0 kg/hm²), conventional nitrogen fertilizer (N1: 300 kg/hm²), nitrogen fertilizer reduction 15% (N²: ²55 kg/hm²), nitrogen fertilizer reduction 30% (N3: ²10 kg/hm²); Two biochar levels were set up as non-biochar (BO:0 kg/hm²) and biochar (B1: ²0 x 10³ kg/hm²), including 8 treatments as BONO, BINO, BONI, BINI, BON², BIN², BON3, BI N3; The SPAD value of flag leaf, photosynthetic indexes (net photosynthetic rate, stomatal conductance, transpiration rate, intercellular CO, concentration), dry matter accumulation and transport during growth period, grain filling rate, yield and its composition of spring wheat were measured, to clarifying the effects of different a-mounts of nitrogen fertilizer and biochar on the growth of spring wheat. (Result) Compared with non-biochar and non-nitrogen fertilizer (BONO),15% reduction of nitrogen fertilizer combined with biochar (B1N²) could significantly increased the SPAD value of flag leaf, net photosynthetic rate, stomatal conductance, transpiration rate, dry matter accumulation and transport rate, grain filling rate and yield of spring wheat. Under the BIN² treatment, the SPAD value increased by 13.17%-91.70%, the net photosynthetic rate increased by 17.4²% 87.30%, the stomatal conductance increased by 16.00%-²9.41%, and the transpiration rate increased by ²5.35% -79.81%. At the maturity stage of spring wheat, the dry matter of grains increased by ²8.87%, and the yield increased by 30.²3%. [Conclusion] Appropriate amount of biochar ²0 x 10³ kg/hm² and nitrogen fertilizer ²55 kg/hm² (B1 N²) can initially achieve the purpose of increasing spring wheat yield and reducing nitrogen fertilizer application, and provide a theoretical basis for the formulation of scientific application strategies of nitro- gen fertilizer and biochar in farmland in northern Xinjiang irrigation area. [ABSTRACT FROM AUTHOR]